WorldWideScience

Sample records for rock mechanics studies

  1. Rock mechanics studies for SMES

    International Nuclear Information System (INIS)

    Haimson, B.C.

    1981-01-01

    Superconducting magnetic energy storage (SMES) systems capable of storing thousands of MWh develop tremendous magnetically induced forces when charged. To prevent rutpure of the magnets these forces must be confined. Bedrock offers a practical and relatively inexpensive magnet containment structure. This paper examines the need for rock mechanics research in connection with the construction and use of SMES rock caverns; the unique problems related to housing superconducting magnets in bedrock; site investigations of granite, quartzite and dolomite deposits in Wisconsin; and cavern design requirements to assure cavern stability and limited deformation under the expected mechanical leads. Recommendations are made for siting SMES caverns

  2. Study on Excitation-triggered Damage Mechanism in Perilous Rock

    Science.gov (United States)

    Chen, Hongkai; Wang, Shengjuan

    2017-12-01

    Chain collapse is easy to happen for perilous rock aggregate locating on steep high slope, and one of the key scientific problems is the damage mechanism of perilous rock under excitation action at perilous rock rupture. This paper studies excitation-triggered damage mechanism in perilous rock by wave mechanics, which gives three conclusions. Firstly, when only the normal incidence attenuation spread of excitation wave is considered, while the energy loss is ignored for excitation wave to spread in perilous rock aggregate, the paper establishes one method to calculate peak velocity when excitation wave passes through boundary between any two perilous rock blocks in perilous rock aggregate. Secondly, following by Sweden and Canmet criteria, the paper provides one wave velocity criterion for excitation-triggered damage in the aggregate. Thirdly, assuming double parameters of volume strain of cracks or fissures in rock meet the Weibull distribution, one method to estimate micro-fissure in excitation-triggered damage zone in perilous rock aggregate is established. The studies solve the mechanical description problem for excitation-triggered damage in perilous rock, which is valuable in studies on profoundly rupture mechanism.

  3. A comparative study on dynamic mechanical performance of concrete and rock

    Directory of Open Access Journals (Sweden)

    Xia Zhengbing

    2015-10-01

    Full Text Available of underground cavities and field-leveling excavation. Dynamic mechanical performance of rocks has been gradually attached importance both in China and abroad. Concrete and rock are two kinds of the most frequently used engineering materials and also frequently used as experimental objects currently. To compare dynamic mechanical performance of these two materials, this study performed dynamic compression test with five different strain rates on concrete and rock using Split Hopkinson Pressure Bar (SHPB to obtain basic dynamic mechanical parameters of them and then summarized the relationship of dynamic compressive strength, peak strain and strain rate of two materials. Moreover, specific energy absorption is introduced to confirm dynamic damage mechanisms of concrete and rock materials. This work can not only help to improve working efficiency to the largest extent but also ensure the smooth development of engineering, providing rich theoretical guidance for development of related engineering in the future

  4. Review of important rock mechanics studies required for underground high level nuclear waste repository program

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Cho, W. J

    2007-01-15

    Disposal concept adapting room and pillar method, which is a confirmed technique in mining and tunnel construction for long time, has advantages at cost, safety, technical feasibility, flexibility, and international cooperation point of views. Then the important rock mechanics principals and in situ and laboratory tests for understanding the behavior of rock, buffer, and backfill as well as their interactions will be reviewed. The accurate understanding of them is important for developing a safe disposal concept and successful operation of underground repository for permanent disposal of radioactive wastes. First of all, In this study, current status of rock mechanics studies for HLW disposal in foreign countries such as Sweden, USA, Canada, Finland, Japan, and France were reviewed. After then the in situ and laboratory tests for site characterization were summarized. Furthermore, rock mechanics studies required during the whole procedure for the disposal project from repository design to the final closure will be reviewed systematically. This study will help for developing a disposal system including site selection, repository design, operation, maintenance, and closure of a repository in deep underground rock. By introducing the required rock mechanics tests at different stages, it would be helpful from the planning stage to the operation stage of a radioactive waste disposal project.

  5. Review of important rock mechanics studies required for underground high level nuclear waste repository program

    International Nuclear Information System (INIS)

    Kwon, S.; Cho, W. J.

    2007-01-01

    Disposal concept adapting room and pillar method, which is a confirmed technique in mining and tunnel construction for long time, has advantages at cost, safety, technical feasibility, flexibility, and international cooperation point of views. Then the important rock mechanics principals and in situ and laboratory tests for understanding the behavior of rock, buffer, and backfill as well as their interactions will be reviewed. The accurate understanding of them is important for developing a safe disposal concept and successful operation of underground repository for permanent disposal of radioactive wastes. First of all, In this study, current status of rock mechanics studies for HLW disposal in foreign countries such as Sweden, USA, Canada, Finland, Japan, and France were reviewed. After then the in situ and laboratory tests for site characterization were summarized. Furthermore, rock mechanics studies required during the whole procedure for the disposal project from repository design to the final closure will be reviewed systematically. This study will help for developing a disposal system including site selection, repository design, operation, maintenance, and closure of a repository in deep underground rock. By introducing the required rock mechanics tests at different stages, it would be helpful from the planning stage to the operation stage of a radioactive waste disposal project

  6. Experimental Studies on the Mechanical Behaviour of Rock Joints with Various Openings

    Science.gov (United States)

    Li, Y.; Oh, J.; Mitra, R.; Hebblewhite, B.

    2016-03-01

    The mechanical behaviour of rough joints is markedly affected by the degree of joint opening. A systematic experimental study was conducted to investigate the effect of the initial opening on both normal and shear deformations of rock joints. Two types of joints with triangular asperities were produced in the laboratory and subjected to compression tests and direct shear tests with different initial opening values. The results showed that opened rock joints allow much greater normal closure and result in much lower normal stiffness. A semi-logarithmic law incorporating the degree of interlocking is proposed to describe the normal deformation of opened rock joints. The proposed equation agrees well with the experimental results. Additionally, the results of direct shear tests demonstrated that shear strength and dilation are reduced because of reduced involvement of and increased damage to asperities in the process of shearing. The results indicate that constitutive models of rock joints that consider the true asperity contact area can be used to predict shear resistance along opened rock joints. Because rock masses are loosened and rock joints become open after excavation, the model suggested in this study can be incorporated into numerical procedures such as finite-element or discrete-element methods. Use of the model could then increase the accuracy and reliability of stability predictions for rock masses under excavation.

  7. Site study plan for routine laboratory rock mechanics, Deaf Smith County Site, Texas: Revision 1

    International Nuclear Information System (INIS)

    1987-12-01

    This Site Study Plan for Routine Laboratory Rock Mechanics describes routine laboratory testing to be conducted on rock samples collected as part of the characterization of the Deaf Smith County site, Texas. This study plan describes the early laboratory testing. Additional testing may be required and the type and scope of testing will be dependent upon the results of the early testing. This study provides for measurements of index, hydrological, mechanical, and chemical properties with tests which are standardized and used widely in geotechnical investigations. Another Site Study Plan for Nonroutine Laboratory Rock Mechanics describes laboratory testing of samples from the site to determine mechanical, thermomechanical, and thermal properties by less widely used methods, many of which have been developed specifically for characterization of the site. Data from laboratory tests will be used for characterization of rock strata, design of shafts and underground facilities, and modeling of repository behavior in support of resolution of both preclosure and postclosure issues. A tentative testing schedule and milestone log are given. A quality assurance program will be utilized to assure that activities affecting quality are performed correctly and that appropriate documentation is maintained. 18 refs., 8 figs., 3 tabs

  8. Effect of Particle Shape on Mechanical Behaviors of Rocks: A Numerical Study Using Clumped Particle Model

    Science.gov (United States)

    Rong, Guan; Liu, Guang; Zhou, Chuang-bing

    2013-01-01

    Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied. PMID:23997677

  9. Effect of particle shape on mechanical behaviors of rocks: a numerical study using clumped particle model.

    Science.gov (United States)

    Rong, Guan; Liu, Guang; Hou, Di; Zhou, Chuang-Bing

    2013-01-01

    Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied.

  10. Mechanical degradation of Emplacement Drifts at Yucca Mountain - A Modeling Case Study. Part I: Nonlithophysal Rock

    International Nuclear Information System (INIS)

    M. Lin; D. Kicker; B. Damjanac; M. Board; M. Karakouzian

    2006-01-01

    This paper outlines rock mechanics investigations associated with mechanical degradation of planned emplacement drifts at Yucca Mountain, which is the designated site for the proposed U.S. high-level nuclear waste repository. The factors leading to drift degradation include stresses from the overburden, stresses induced by the heat released from the emplaced waste, stresses due to seismically related ground motions, and time-dependent strength degradation. The welded tuff emplacement horizon consists of two groups of rock with distinct engineering properties: nonlithophysal units and lithophysal units, based on the relative proportion of lithophysal cavities. The term 'lithophysal' refers to hollow, bubble like cavities in volcanic rock that are surrounded by a porous rim formed by fine-grained alkali feldspar, quartz, and other minerals. Lithophysae are typically a few centimeters to a few decimeters in diameter. Part I of the paper concentrates on the generally hard, strong, and fractured nonlithophysal rock. The degradation behavior of the tunnels in the nonlithophysal rock is controlled by the occurrence of keyblocks. A statistically equivalent fracture model was generated based on extensive underground fracture mapping data from the Exploratory Studies Facility at Yucca Mountain. Three-dimensional distinct block analyses, generated with the fracture patterns randomly selected from the fracture model, were developed with the consideration of in situ, thermal, and seismic loads. In this study, field data, laboratory data, and numerical analyses are well integrated to provide a solution for the unique problem of modeling drift degradation

  11. Rock Mechanics Studies During Continuous Miner Bases Coal Pillar Extraction in Indian Coalfields

    Czech Academy of Sciences Publication Activity Database

    Ram, S.; Kumar, D.; Koníček, Petr; Singh, A. K.; Kumar, R.; Singh, A. Kr.; Singh, R.

    2015-01-01

    Roč. 111, April 2014-March 2015 (2015), s. 89-104 ISSN 0254-8003 Institutional support: RVO:68145535 Keywords : mining * mechanized depillaring scenario * rock mechanics Subject RIV: DH - Mining, incl. Coal Mining

  12. Studying physical properties of deformed intact and fractured rocks by micro-scale hydro-mechanical-seismicity model

    Science.gov (United States)

    Raziperchikolaee, Samin

    The pore pressure variation in an underground formation during hydraulic stimulation of low permeability formations or CO2 sequestration into saline aquifers can induce microseismicity due to fracture generation or pre-existing fracture activation. While the analysis of microseismic data mainly focuses on mapping the location of fractures, the seismic waves generated by the microseismic events also contain information for understanding of fracture mechanisms based on microseismic source analysis. We developed a micro-scale geomechanics, fluid-flow and seismic model that can predict transport and seismic source behavior during rock failure. This model features the incorporation of microseismic source analysis in fractured and intact rock transport properties during possible rock damage and failure. The modeling method considers comprehensive grains and cements interaction through a bonded-particle-model. As a result of grain deformation and microcrack development in the rock sample, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. In addition, geometric description of the complex pore structure is regenerated to predict fluid flow behavior of fractured samples. Numerical experiments are conducted for different intact and fractured digital rock samples, representing various mechanical behaviors of rocks and fracture surface properties, to consider their roles on seismic and transport properties of rocks during deformation. Studying rock deformation in detail provides an opportunity to understand the relationship between source mechanism of microseismic events and transport properties of damaged rocks to have a better characterizing of fluid flow behavior in subsurface formations.

  13. Experimental study on influence of carbon dioxide on porous structure and mechanical properties of shale rock

    Directory of Open Access Journals (Sweden)

    Danuta Miedzińska

    2017-12-01

    Full Text Available Shale rocks are geological formations which can be unconventional gas reservoirs. During their interaction with carbon dioxide, which can be used as a fracturing fluid in shale gas recovery process, many phenomena take place that can influence rock structure and mechanical properties. The research on changes in rock structure under super critical carbon dioxide interaction and their influence of shale properties were presented in the paper. The structural tests were carried out with the use of microscopic techniques with different resolutions of visualization. The uniaxial compression test was applied as a mechanical properties’ assessment experiment. As a result of research, some dependence was observed. The bigger decrease was in porosity after infiltration in lower zooms, the bigger increase in porosity in high zooms and mechanical properties was noticed. Keywords: geomechanics, shale rock, carbon dioxide

  14. Study on Mechanical Characteristics of Fully Grouted Rock Bolts for Underground Caverns under Seismic Loads

    Directory of Open Access Journals (Sweden)

    Guoqing Liu

    2017-01-01

    Full Text Available This study establishes an analytical model for the interaction between the bolt and surrounding rock based on the bearing mechanism of fully grouted rock bolts. The corresponding controlled differential equation for load transfer is deduced. The stress distributions of the anchorage body are obtained by solving the equations. A dynamic algorithm for the bolt considering shear damage on the anchoring interface is proposed based on the dynamic finite element method. The rationality of the algorithm is verified by a pull-out test and excavation simulation of a rounded tunnel. Then, a case study on the mechanical characteristics of the bolts in underground caverns under seismic loads is conducted. The results indicate that the seismic load may lead to stress originating from the bolts and damage on the anchoring interface. The key positions of the antiseismic support can be determined using the numerical simulation. The calculated results can serve as a reference for the antiseismic optimal design of bolts in underground caverns.

  15. Hydromechanical coupling in fractured rock masses: mechanisms and processes of selected case studies

    Science.gov (United States)

    Zangerl, Christian

    2015-04-01

    Hydromechanical (HM) coupling in fractured rock play an important role when events including dam failures, landslides, surface subsidences due to water withdrawal or drainage, injection-induced earthquakes and others are analysed. Generally, hydromechanical coupling occurs when a rock mass contain interconnected pores and fractures which are filled with water and pore/fracture pressures evolves. In the on hand changes in the fluid pressure can lead to stress changes, deformations and failures of the rock mass. In the other hand rock mass stress changes and deformations can alter the hydraulic properties and fluid pressures of the rock mass. Herein well documented case studies focussing on surface subsidence due to water withdrawal, reversible deformations of large-scale valley flanks and failure as well as deformation processes of deep-seated rock slides in fractured rock masses are presented. Due to pore pressure variations HM coupling can lead to predominantly reversible rock mass deformations. Such processes can be considered by the theory of poroelasticity. Surface subsidence reaching magnitudes of few centimetres and are caused by water drainage into deep tunnels are phenomenas which can be assigned to processes of poroelasticity. Recently, particular focus was given on large tunnelling projects to monitor and predict surface subsidence in fractured rock mass in oder to avoid damage of surface structures such as dams of large reservoirs. It was found that surface subsidence due to tunnel drainage can adversely effect infrastructure when pore pressure drawdown is sufficiently large and spatially extended and differential displacements which can be amplified due to topographical effects e.g. valley closure are occurring. Reversible surface deformations were also ascertained on large mountain slopes and summits with the help of precise deformation measurements i.e. permanent GPS or episodic levelling/tacheometric methods. These reversible deformations are often

  16. Study on Mechanical Features of Brazilian Splitting Fatigue Tests of Salt Rock

    Directory of Open Access Journals (Sweden)

    Weichao Wang

    2016-01-01

    Full Text Available The microtest, SEM, was carried out to study the fracture surface of salt rock after the Brazilian splitting test and splitting fatigue test were carried out with a servo-controlled test machine RMT-150B. The results indicate that the deviation of using the tablet splitting method is larger than that of using steel wire splitting method, in Brazilian splitting test of salt rock, when the conventional data processing method is adopted. There are similar deformation features in both the conventional splitting tests and uniaxial compression tests. The stress-strain curves include compaction, elasticity, yielding, and failure stage. Both the vertical deformation and horizontal deformation of splitting fatigue tests under constant average loading can be divided into three stages of “loosening-tightness-loosening.” The failure modes of splitting fatigue tests under the variational average loading are not controlled by the fracturing process curve of the conventional splitting tests. The deformation extent of fatigue tests under variational average loading is even greater than that of conventional splitting test. The tensile strength of salt rock has a relationship with crystallization conditions. Tensile strength of thick crystal salt rock is lower than the bonded strength of fine-grain crystals.

  17. Mechanism of Rock Burst Occurrence in Specially Thick Coal Seam with Rock Parting

    Science.gov (United States)

    Wang, Jian-chao; Jiang, Fu-xing; Meng, Xiang-jun; Wang, Xu-you; Zhu, Si-tao; Feng, Yu

    2016-05-01

    Specially thick coal seam with complex construction, such as rock parting and alternative soft and hard coal, is called specially thick coal seam with rock parting (STCSRP), which easily leads to rock burst during mining. Based on the stress distribution of rock parting zone, this study investigated the mechanism, engineering discriminant conditions, prevention methods, and risk evaluation method of rock burst occurrence in STCSRP through setting up a mechanical model. The main conclusions of this study are as follows. (1) When the mining face moves closer to the rock parting zone, the original non-uniform stress of the rock parting zone and the advancing stress of the mining face are combined to intensify gradually the shearing action of coal near the mining face. When the shearing action reaches a certain degree, rock burst easily occurs near the mining face. (2) Rock burst occurrence in STCSRP is positively associated with mining depth, advancing stress concentration factor of the mining face, thickness of rock parting, bursting liability of coal, thickness ratio of rock parting to coal seam, and difference of elastic modulus between rock parting and coal, whereas negatively associated with shear strength. (3) Technologies of large-diameter drilling, coal seam water injection, and deep hole blasting can reduce advancing stress concentration factor, thickness of rock parting, and difference of elastic modulus between rock parting and coal to lower the risk of rock burst in STCSRP. (4) The research result was applied to evaluate and control the risk of rock burst occurrence in STCSRP.

  18. Mechanical behaviour and rupture in clayey rocks studied by x-ray micro tomography

    International Nuclear Information System (INIS)

    Lenoir, N.

    2006-03-01

    Within the framework of feasibility studies of underground repositories for radioactive waste, the study of permeability evolution with damage of the host layer is crucial. The goals of this work were: (i) to characterize experimentally the damage of two clayey rocks (BEAUCAIRE MARL and EAST SHALE) with x-ray micro tomography, (ii) to develop a high pressure triaxial set-up adapted to permeability measurement on very low permeability rocks.A number of original triaxial devices have been realised to characterize damage of clayey rocks, under deviatoric loading, with x-ray micro tomography on a synchrotron beamline at the ESRF (Grenoble). Localized damage and its evolution have been characterized at a fine scale (of order of ten microns). Digital image correlation techniques, extended to 3d images, have been used to measure incremental strain fields from tomographic images. we demonstrated that these techniques are very useful in the study of the localized damage of geo-materials and especially for the initiation. A high pressure triaxial device has been realised to measure permeability evolution of the east shale as a function of applied stress (isotropic and deviatoric). The particularity of this set-up is the small size of the test specimen (cylinder of 10 mm in diameter and 20 mm in height) which allows significant reduction of test duration. (author)

  19. Rock mechanics for hard rock nuclear waste repositories

    International Nuclear Information System (INIS)

    Heuze, F.E.

    1981-09-01

    The mined geologic burial of high level nuclear waste is now the favored option for disposal. The US National Waste Terminal Storage Program designed to achieve this disposal includes an extensive rock mechanics component related to the design of the wastes repositories. The plan currently considers five candidate rock types. This paper deals with the three hard rocks among them: basalt, granite, and tuff. Their behavior is governed by geological discontinuities. Salt and shale, which exhibit behavior closer to that of a continuum, are not considered here. This paper discusses both the generic rock mechanics R and D, which are required for repository design, as well as examples of projects related to hard rock waste storage. The examples include programs in basalt (Hanford/Washington), in granitic rocks (Climax/Nevada Test Site, Idaho Springs/Colorado, Pinawa/Canada, Oracle/Arizona, and Stripa/Sweden), and in tuff

  20. Radionuclide fixation mechanisms in rocks

    International Nuclear Information System (INIS)

    Nakashima, S.

    1991-01-01

    In the safety evaluation of the radioactive waste disposal in geological environment, the mass balance equation for radionuclide migration is given. The sorption of radionuclides by geological formations is conventionally represented by the retardation of the radionuclides as compared with water movement. In order to quantify the sorption of radionuclides by rocks and sediments, the distribution ratio is used. In order to study quantitatively the long term behavior of waste radionuclides in geological environment, besides the distribution ratio concept in short term, slower radionuclide retention reaction involving mineral transformation should be considered. The development of microspectroscopic method for long term reaction path modeling, the behavior of iron during granite and water interaction, the reduction precipitation of radionuclides, radionuclide migration pathways, and the representative scheme of radionuclide migration and fixation in rocks are discussed. (K.I.)

  1. An experimental study of the mechanism of failure of rocks under borehole jack loading

    Science.gov (United States)

    Van, T. K.; Goodman, R. E.

    1971-01-01

    Laboratory and field tests with an experimental jack and an NX-borehole jack are reported. The following conclusions were made: Under borehole jack loading, a circular opening in a brittle solid fails by tensile fracturing when the bearing plate width is not too small. Two proposed contact stress distributions can explain the mechanism of tensile fracturing. The contact stress distribution factor is a material property which can be determined experimentally. The borehole tensile strength is larger than the rupture flexural strength. Knowing the magnitude and orientation of the in situ stress field, borehole jack test results can be used to determine the borehole tensile strength. Knowing the orientation of the in situ stress field and the flexural strength of the rock substance, the magnitude of the in situ stress components can be calculated. The detection of very small cracks is essential for the accurate determination of the failure loads which are used in the calculation of strengths and stress components.

  2. Summary of rock mechanics work completed for Posiva before 2005

    International Nuclear Information System (INIS)

    Hudson, J.A.; Johansson, E.

    2006-06-01

    To plan Posiva's rock mechanics work for 2005-2006 and beyond, it was necessary to have a clear understanding of the individual components of work that had been completed for Posiva before 2005 and to assess the cumulative rock mechanics knowledge base. This review summarizes the 80 individual completed documents, which include rock mechanics reports and other reports containing rock mechanics material. They are summarised within a structured framework of rock properties, analyses and the effects of excavation. Following the introductory section, the method of structuring the rock mechanics information is presented. Then the tabulation highlighting the features of all the previous rock mechanics work is explained. This tabulation forms the Appendix; the content of each rock mechanics report that has been produced is summarized via the table headings of document number, subject area, document reference, subject matter, objectives, methodology, highlighted figures, conclusions and comments. In addition to the direct usefulness of the tabulation in summarizing each report, it has been possible to draw overall conclusions: Information has also been obtained worldwide, especially Sweden and Canada; The rock stress state has been measured but further work is required related both to in situ measurements and numerical modelling to study, e.g., the influence of deformation zones on the local stress state; The intact rock has been extensively studied: there is a good knowledge of the parameters and their values, including the anisotropic nature of the site rocks; The geometry of the fractures is included in the geological characterisation but more rock mechanics work is required on the mechanical properties; The mechanical properties of the deformation zones have not been studied in detail; The thermal properties of the site rock are relatively well understood; A new classification has been developed for constructability and long-term safety assessment. This classification

  3. Temperature effect on the poro-mechanical or hydraulic behaviour of a carbonated rock and a mortar: experimental studies

    International Nuclear Information System (INIS)

    Lion, M.

    2004-07-01

    The main objective of this study is to evaluate the temperature effect on the hydraulic and poro-mechanical behaviour of a limestone. Many experimental tests (porosity and permeability measurements, uniaxial and hydrostatic compressions tests) were carried out in order to study the thermal treatments effect and so the thermal microcracking effect on rock behaviour. Moreover, an experimental device for permeability measurements under high temperatures (until 200 C) was realized. This experimental device permitted to study the permeability variation of the limestone under thermal stresses. Finally, the behaviour of cementitious materials was studied; the temperature effect on the permeability of a mortar was examined. (author)

  4. Study of the strain's mechanism of deep argillaceous rocks: interest of microstructure and petro-physical analysis

    International Nuclear Information System (INIS)

    Gasc-Barbier, M.

    2002-09-01

    This study was carried out in order to better understand the behaviour of deep argillaceous rocks and in particular those chosen by ANDRA to build an underground laboratory to study the feasibility to set up an underground storage for highly radioactive wastes. We have studied experimentally different mechanisms (chemo-mechanical and hygro-mechanical coupling and creep behaviour) that could lead to macroscopic strain so as to attempt to characterize them from a microstructural point of view, Hence we have implemented innovative experimental tests such as the conception of a triaxial cell where fluids can circulate or the use of mercury porosimetry on dry or wet samples. We have thus been able to show the importance of the clay-calcite relation in the argillite studied both from the chemical point of view (chemical balance dominated by calcite) and from a structural point of view (micro-fissuration seems to take place preferentially at the grain / clayey material interface). (author)

  5. A Study of the Large Deformation Mechanism and Control Techniques for Deep Soft Rock Roadways

    Directory of Open Access Journals (Sweden)

    Xiaojie Yang

    2018-04-01

    Full Text Available Large deformation control of deep soft rock roadways has been a major problem in mining activities worldwide. This paper considers the supporting problem related to large deformation of a deep soft rock roadway in Chao’hua coal mine. The discrete element simulation method (UDEC software is adopted to simulate a tailgate of panel 31041 in Chao’hua coal mine. The failure patterns of unsupported and primary supported roadway are simulated, and these reveal the characteristics of deformation, stress and crack propagation. The excavation of roadway leads to high deviator stress, which exceeds the peak strength of shallow surrounding rock and causes it to enter the post-failure stage. Tensile failures then initiate and develop around the roadway, which causes the fragmentation, dilation and separation of shallow surrounding rock. The compressive capacity of the primary support system is low, which results in serious contraction in the full section of the roadway. An improved control scheme is put forward for the support of a tailgate. The underground test results confirm that the improved support system effectively controlled large deformation of the surrounding rocks, which can provide references for support in the design of roadways excavated in deep soft stratum.

  6. Technology of Rock Destruction by Combined Explosion-Mechanical Load

    Directory of Open Access Journals (Sweden)

    Oleg M. Terentiev

    2017-10-01

    Full Text Available Background. Rock drilling is characterized by an energy capacity of more than 120 kWh/m3. This is due to the fact that about 90 % of the energy is expended on the “preparation” of rocks for destruction. This study proposes to combine explosive and mechanical loads to reduce specific energy consumption of rock destruction. Objective. The aim of the paper is energy effective technology development for rock destruction by combined explosive-mechanical loads. Methods. Analytical studies; regression analysis; math modeling; experimental research; technical and economic analysis. Results. Specific energy decreasing for explosive-mechanical rock drilling by 4–16 % was experimentally proved. Conclusions. As a result of the implementation of explosive-mechanical rock drilling on the created full-sized experimental device, the efficiency coefficient increased from 77 to 80 %.

  7. The rock mechanical stability of the VLJ repository

    International Nuclear Information System (INIS)

    Kuula, H.; Johansson, E.

    1991-03-01

    The aim of the study was to determine the rock mechanical stability around the VLJ repository based on the rock mechanical monitoring and rock mechanical modeling. Rock mechanical calculations were made in order to calculate the rock mass displacements and to analyze the stability around the VLJ repository The calculations were performed with three diiferent methods: continuum finite difference code FLAC, distinct element code UDEC and three dimensional distinct element code 3DEC. The first analyses were based on preliminary site investigations. The final modeling was based on investigations and rock mechanical monitoring done during the excavation. Some sensitive analyses were also performed. The modelled rock mass behaviour and the measured behaviour are generally close to each other. Both results show that the VLJ repository is rock mechanically stable. The modelled displacements and stresses were small enough to cause no instability around the rock caverns. The measured values do not indicate any discontinuous deformations like block movements or joint slip. The measured displacements in the extensometers during excavation indicates that the rock mass is even stiffer than anticipated

  8. A Rock Mechanics and Coupled Hydro mechanical Analysis of Geological Repository of High Level Nuclear Waste in Fractured Rocks

    International Nuclear Information System (INIS)

    Min, Kibok

    2011-01-01

    This paper introduces a few case studies on fractured hard rock based on geological data from Sweden, Korea is one of a few countries where crystalline rock is the most promising rock formation as a candidate site of geological repository of high level nuclear waste. Despite the progress made in the area of rock mechanics and coupled hydro mechanics, extensive site specific study on multiple candidate sites is essential in order to choose the optimal site. For many countries concerned about the safe isolation of nuclear wastes from the biosphere, disposal in a deep geological formation is considered an attractive option. In geological repository, thermal loading continuously disturbs the repository system in addition to disturbances a recent development in rock mechanics and coupled hydro mechanical study using DFN(Discrete Fracture Network) - DEM(Discrete Element Method) approach mainly applied in hard, crystalline rock containing numerous fracture which are main sources of deformation and groundwater flow

  9. A rock mechanics study of fracture zone 2 at the Finnsjoen site

    International Nuclear Information System (INIS)

    Leijon, B.; Ljunggren, C.

    1992-01-01

    Comprehensive field investigations at the Finnsjoen study site have revealed a subhorizontal zone, termed Zone 2, that exhibits anomalous characteristics in terms of high hydraulic conductivity, governing the groundwater transport pattern on a regional scale. The present study provides an assessment of the characteristics of Zone 2. Thus, estimates of the deformational characteristics of the zone, based on available borehole information, show that the zone forms a diffuse and rather moderate mechanical contrast to the surrounding bedrock. As also verified by stress measurement results, major stress anomalies attributable to the zone are therefore not to be expected. Bound estimates of stress conditions during periods of glaciation and deglaciation are also derived, and possible impacts of these loadings on the fracture zone are discussed. It is concluded that glaciation represents stable conditions, whilst the complex loading mechanisms encountered during deglaciation may trigger reactivation of structures at shallow depth. Taking the above results as an example, implications of a feature like Zone 2 on the integrity of a hypothetical repository are discussed in more general terms. Considering the likely spatial extension of the mechanical disturbances related to the repository excavations and the fracture zone respectively, it is suggested that a mutual distance of the order of one hundred metres is sufficient to avoid mechanical interaction. (au)

  10. The results of experimental studies of VLF-ULF electromagnetic emission by rock samples due to mechanical action

    Science.gov (United States)

    Panfilov, A. A.

    2014-06-01

    The paper presents the results of laboratory experiments on electromagnetic emissions excitation (the electric component of electromagnetic fields) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, change with an increasing number of hits. It was found that strong electromagnetic signals, generated while rock samples were fracturing, were accompanied by repetitive weak but perceptible variations in the electric field intensity in short frequency ranges.

  11. The results of experimental studies of VLF–ULF electromagnetic emission by rock samples due to mechanical action

    OpenAIRE

    A. A. Panfilov

    2013-01-01

    The paper presents the results of laboratory experiments on electromagnetic emission excitation (electric component of electromagnetic field) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, cha...

  12. Mechanical properties of rock at high temperatures

    International Nuclear Information System (INIS)

    Kinoshita, Naoto; Abe, Tohru; Wakabayashi, Naruki; Ishida, Tsuyoshi.

    1997-01-01

    The laboratory tests have been performed in order to investigate the effects of temperature up to 300degC and pressure up to 30 MPa on the mechanical properties of three types of rocks, Inada granite, Sanjoume andesite and Oya tuff. The experimental results indicated that the significant differences in temperature dependence of mechanical properties exist between the three rocks, because of the difference of the factors which determine the mechanical properties of the rocks. The effect of temperature on the mechanical properties for the rocks is lower than that of pressure and water content. Temperature dependence of the mechanical properties is reduced by increase in pressure in the range of pressure and temperature investigated in this paper. (author)

  13. Phosphine from rocks: mechanically driven phosphate reduction?

    Science.gov (United States)

    Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

    2005-11-01

    Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks.

  14. Experimental Study of Bacterial Penetration into Chalk Rock: Mechanisms and Effect on Permeability

    DEFF Research Database (Denmark)

    Halim, Amalia Yunita; Shapiro, Alexander; Eliasson Lantz, Anna

    2014-01-01

    Bacterial selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery, as bacteria can plug the water-swept zones of a reservoir, thus altering the flow paths and improving sweep efficiency. However, complete understanding of the penetration...... behavior of bacteria is lacking, especially in chalk formations where characteristic pore throat sizes are comparable with the sizes of bacterial cells. In this study, two bacterial strains, Bacillus licheniformis 421 (spore-forming) and Pseudomonas putida K12 (non-spore forming) were used to investigate...... the penetration of bacteria into chalk and its effect on permeability reduction. The core plugs were produced from Stevns Klint outcrop with low permeability (2–4 mD) and with pore sizes comparable to bacterial sizes. Both types of bacteria were able to penetrate and to be transported through the cores to some...

  15. Theoretical Modeling of Rock Breakage by Hydraulic and Mechanical Tool

    Directory of Open Access Journals (Sweden)

    Hongxiang Jiang

    2014-01-01

    Full Text Available Rock breakage by coupled mechanical and hydraulic action has been developed over the past several decades, but theoretical study on rock fragmentation by mechanical tool with water pressure assistance was still lacking. The theoretical model of rock breakage by mechanical tool was developed based on the rock fracture mechanics and the solution of Boussinesq’s problem, and it could explain the process of rock fragmentation as well as predicating the peak reacting force. The theoretical model of rock breakage by coupled mechanical and hydraulic action was developed according to the superposition principle of intensity factors at the crack tip, and the reacting force of mechanical tool assisted by hydraulic action could be reduced obviously if the crack with a critical length could be produced by mechanical or hydraulic impact. The experimental results indicated that the peak reacting force could be reduced about 15% assisted by medium water pressure, and quick reduction of reacting force after peak value decreased the specific energy consumption of rock fragmentation by mechanical tool. The crack formation by mechanical or hydraulic impact was the prerequisite to improvement of the ability of combined breakage.

  16. Thermo-hydro-mechanical simulation of a 3D fractured porous rock: preliminary study of coupled matrix-fracture hydraulics

    International Nuclear Information System (INIS)

    Canamon, I.; Javier Elorza, F.; Ababou, R.

    2007-01-01

    We present a problem involving the modeling of coupled flow and elastic strain in a 3D fractured porous rock, which requires prior homogenization (up-scaling) of the fractured medium into an equivalent Darcian anisotropic continuum. The governing equations form a system of PDE's (Partial Differential Equations) and, depending on the case being considered, this system may involve two different types of 'couplings' (in a real system, both couplings (1) and (2) generally take place): 1) Hydraulic coupling in a single (no exchange) or in a dual matrix-fracture continuum (exchange); 2) Thermo-Hydro-Mechanical interactions between fluid flow, pressure, elastic stress, strain, and temperature. We present here a preliminary model and simulation results with FEMLAB R , for the hydraulic problem with anisotropic heterogeneous coefficients. The model is based on data collected at an instrumented granitic site (FEBEX project) for studying a hypothetical nuclear waste repository at the Grimsel Test Site in the Swiss Alps. (authors)

  17. On the question of determining the amount of experiments, reliability and accuracy of the results in the study of physical-mechanical properties of rocks

    Directory of Open Access Journals (Sweden)

    Kuznetcov n.n.

    2015-06-01

    Full Text Available A comparative analysis of the methods for determining the required amount of experiments, the accuracy and reliability of the results of physical-mechanical rock properties study has been conducted. The advantages and disadvantages of the existing specialized method for determining the compressive strength of the samples have been discussed. On the basis of the investigation the optimal approach has been proposed to solve a wide range of the problems associated with the rock properties' parameters using

  18. Preliminary rock mechanics laboratory: Investigation plan

    International Nuclear Information System (INIS)

    Oschman, K.P.; Hummeldorf, R.G.; Hume, H.R.; Karakouzian, M.; Vakili, J.E.

    1987-01-01

    This document presents the rationale for rock mechanics laboratory testing (including the supporting analysis and numerical modeling) planned for the site characterization of a nuclear waste repository in salt. This plan first identifies what information is required for regulatory and design purposes, and then presents the rationale for the testing that satisfies the required information needs. A preliminary estimate of the minimum sampling requirements for rock laboratory testing during site characterization is also presented. Periodic revision of this document is planned

  19. Experimental Study on Mechanical and Acoustic Emission Characteristics of Rock-Like Material Under Non-uniformly Distributed Loads

    Science.gov (United States)

    Wang, Xiao; Wen, Zhijie; Jiang, Yujing; Huang, Hao

    2018-03-01

    The mechanical and acoustic emission characteristics of rock-like materials under non-uniform loads were investigated by means of a self-developed mining-induced stress testing system and acoustic emission monitoring system. In the experiments, the specimens were divided into three regions and different initial vertical stresses and stress loading rates were used to simulate different mining conditions. The mechanical and acoustic emission characteristics between regions were compared, and the effects of different initial vertical stresses and different stress loading rates were analysed. The results showed that the mechanical properties and acoustic emission characteristics of rock-like materials can be notably localized. When the initial vertical stress and stress loading rate are fixed, the peak strength of region B is approximately two times that of region A, and the maximum acoustic emission hit value of region A is approximately 1-2 times that of region B. The effects of the initial vertical stress and stress loading rate on the peck strain, maximum hit value, and occurrence time of the maximum hit are similar in that when either of the former increase, the latter all decrease. However, peck strength will increase with the increase in loading rate and decrease with the increase in initial vertical stress. The acoustic emission hits can be used to analyse the damage in rock material, but the number of acoustic emission hits cannot be used alone to determine the degree of rock damage directly.

  20. Soil and Rock Mechanics Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The 10,000-sq ft soil mechanics research facility is the largest in the Department of Defense and has a loading capability of 250,000 lb on triaxial specimens up to...

  1. Study of the Rock Mass Failure Process and Mechanisms During the Transformation from Open-Pit to Underground Mining Based on Microseismic Monitoring

    Science.gov (United States)

    Zhao, Yong; Yang, Tianhong; Bohnhoff, Marco; Zhang, Penghai; Yu, Qinglei; Zhou, Jingren; Liu, Feiyue

    2018-05-01

    To quantitatively understand the failure process and failure mechanism of a rock mass during the transformation from open-pit mining to underground mining, the Shirengou Iron Mine was selected as an engineering project case study. The study area was determined using the rock mass basic quality classification method and the kinematic analysis method. Based on the analysis of the variations in apparent stress and apparent volume over time, the rock mass failure process was analyzed. According to the recent research on the temporal and spatial change of microseismic events in location, energy, apparent stress, and displacement, the migration characteristics of rock mass damage were studied. A hybrid moment tensor inversion method was used to determine the rock mass fracture source mechanisms, the fracture orientations, and fracture scales. The fracture area can be divided into three zones: Zone A, Zone B, and Zone C. A statistical analysis of the orientation information of the fracture planes orientations was carried out, and four dominant fracture planes were obtained. Finally, the slip tendency analysis method was employed, and the unstable fracture planes were obtained. The results show: (1) The microseismic monitoring and hybrid moment tensor analysis can effectively analyze the failure process and failure mechanism of rock mass, (2) during the transformation from open-pit to underground mining, the failure type of rock mass is mainly shear failure and the tensile failure is mostly concentrated in the roof of goafs, and (3) the rock mass of the pit bottom and the upper of goaf No. 18 have the possibility of further damage.

  2. Experimental study of chemical-mechanical coupling during percolation of reactive fluid through rocks under stress, in the context of the CO2 geological sequestration

    International Nuclear Information System (INIS)

    Le Guen, Y.

    2006-10-01

    CO 2 injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO 2 . Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10 -12 s -1 on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO 2 -rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO 2 which increases rock solubility and reaction kinetics. On the opposite, small effect of CO 2 on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)

  3. Site study plan for non-routine laboratory rock mechanics, Deaf Smith County Site, Texas: Revision 1

    International Nuclear Information System (INIS)

    1987-12-01

    This Site Study Plan describes the non-routine rock mechanics and thermal properties laboratory testing program planned for the characterization of site-specific geologic materials for the Deaf Smith County site, Texas. The study design provides for measurements of index, mechanical, thermomechanical, thermal and special properties for the host salt, and where appropriate, for nonhost lithologies. The types of tests which will be conducted are constant stress (creep) tests, constant strain (stress relaxation) tests, constant strain-rate tests, constant stress-rate tests, cyclic loading tests, hollow cylinder tests, uniaxial and triaxial compression tests, direct tension tests, indirect (triaxial) shear tests, thermal property determinations (conductivity, specific heat, expansivity, and diffusivity), fracture healing tests, thermal decrepitation tests, moisture content determinations, and petrographic and micromechanics analyses. Tests will be conducted at confining pressures up to 30 MPa and temperatures up to 300/degree/C. These data are used to construct mathematical models for the phenomenology of salt deformation. The models are then used in finite-element codes to predict repository response. A tentative testing schedule and milestone log are given. The duration of the testing program is expected to be approximately 5 years. 44 refs., 13 figs., 13 tabs

  4. Failure Mechanisms of Brittle Rocks under Uniaxial Compression

    Science.gov (United States)

    Liu, Taoying; Cao, Ping

    2017-09-01

    The behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

  5. Mechanical dispersion in fractured crystalline rock systems

    International Nuclear Information System (INIS)

    Lafleur, D.W.; Raven, K.G.

    1986-12-01

    This report compiles and evaluates the hydrogeologic parameters describing the flow of groundwater and transport of solutes in fractured crystalline rocks. This report describes the processes of mechanical dispersion in fractured crystalline rocks, and compiles and evaluates the dispersion parameters determined from both laboratory and field tracer experiments. The compiled data show that extrapolation of the reliable test results performed over intermediate scales (10's of m and 10's to 100's of hours) to larger spatial and temporal scales required for performance assessment of a nuclear waste repository in crystalline rock is not justified. The reliable measures of longitudinal dispersivity of fractured crystalline rock are found to range between 0.4 and 7.8 m

  6. ONKALO rock mechanics model (RMM). Version 2.3

    Energy Technology Data Exchange (ETDEWEB)

    Haekkinen, T.; Merjama, S.; Moenkkoenen, H. [WSP Finland, Helsinki (Finland)

    2014-07-15

    The Rock Mechanics Model of the ONKALO rock volume includes the most important rock mechanics features and parameters at the Olkiluoto site. The main objective of the model is to be a tool to predict rock properties, rock quality and hence provide an estimate for the rock stability of the potential repository at Olkiluoto. The model includes a database of rock mechanics raw data and a block model in which the rock mechanics parameters are estimated through block volumes based on spatial rock mechanics raw data. In this version 2.3, special emphasis was placed on refining the estimation of the block model. The model was divided into rock mechanics domains which were used as constraints during the block model estimation. During the modelling process, a display profile and toolbar were developed for the GEOVIA Surpac software to improve visualisation and access to the rock mechanics data for the Olkiluoto area. (orig.)

  7. THM-coupled modeling of selected processes in argillaceous rock relevant to rock mechanics

    International Nuclear Information System (INIS)

    Czaikowski, Oliver

    2012-01-01

    Scientific investigations in European countries other than Germany concentrate not only on granite formations (Switzerland, Sweden) but also on argillaceous rock formations (France, Switzerland, Belgium) to assess their suitability as host and barrier rock for the final storage of radioactive waste. In Germany, rock salt has been under thorough study as a host rock over the past few decades. According to a study by the German Federal Institute for Geosciences and Natural Resources, however, not only salt deposits but also argillaceous rock deposits are available at relevant depths and of extensions in space which make final storage of high-level radioactive waste basically possible in Germany. Equally qualified findings about the suitability/unsuitability of non-saline rock formations require fundamental studies to be conducted nationally because of the comparatively low level of knowledge. The article presents basic analyses of coupled mechanical and hydraulic properties of argillaceous rock formations as host rock for a repository. The interaction of various processes is explained on the basis of knowledge derived from laboratory studies, and open problems are deduced. For modeling coupled processes, a simplified analytical computation method is proposed and compared with the results of numerical simulations, and the limits to its application are outlined. (orig.)

  8. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Krogsbøll, Anette; Jakobsen, Finn; Madsen, Lena

    1997-01-01

    The main objective of the project is to combine geological descriptions of fractures, chalk types and rock mechanical properties in order to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. This report deals with 1) geological descriptions of outcrop locality...

  9. Fractures and Rock Mechanics, Phase 1

    DEFF Research Database (Denmark)

    Havmøller, Ole; Krogsbøll, Anette

    1997-01-01

    The main objectives of the project are to combine geological description of fractures, chalk types and rock mechanical properties, and to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. Five chalk types, representing two outcrop localities: Stevns...

  10. Rock Burst Mechanics: Insight from Physical and Mathematical Modelling

    Directory of Open Access Journals (Sweden)

    J. Vacek

    2008-01-01

    Full Text Available Rock burst processes in mines are studied by many groups active in the field of geomechanics. Physical and mathematical modelling can be used to better understand the phenomena and mechanisms involved in the bursts. In the present paper we describe both physical and mathematical models of a rock burst occurring in a gallery of a coal mine.For rock bursts (also called bumps to occur, the rock has to possess certain particular rock burst properties leading to accumulation of energy and the potential to release this energy. Such materials may be brittle, or the rock burst may arise at the interfacial zones of two parts of the rock, which have principally different material properties (e.g. in the Poíbram uranium mines.The solution is based on experimental and mathematical modelling. These two methods have to allow the problem to be studied on the basis of three presumptions:· the solution must be time dependent,· the solution must allow the creation of cracks in the rock mass,· the solution must allow an extrusion of rock into an open space (bump effect. 

  11. Thermo-hydro-mechanical simulation of a 3D fractured porous rock: preliminary study of coupled matrix-fracture hydraulics

    Energy Technology Data Exchange (ETDEWEB)

    Canamon, I.; Javier Elorza, F. [Universidad Politecnica de Madrid, Dept. de Matematica Aplicada y Metodos Informaticas, ETSI Minas (UPM) (Spain); Ababou, R. [Institut de Mecanique des Fluides de Toulouse (IMFT), 31 (France)

    2007-07-01

    We present a problem involving the modeling of coupled flow and elastic strain in a 3D fractured porous rock, which requires prior homogenization (up-scaling) of the fractured medium into an equivalent Darcian anisotropic continuum. The governing equations form a system of PDE's (Partial Differential Equations) and, depending on the case being considered, this system may involve two different types of 'couplings' (in a real system, both couplings (1) and (2) generally take place): 1) Hydraulic coupling in a single (no exchange) or in a dual matrix-fracture continuum (exchange); 2) Thermo-Hydro-Mechanical interactions between fluid flow, pressure, elastic stress, strain, and temperature. We present here a preliminary model and simulation results with FEMLAB{sup R}, for the hydraulic problem with anisotropic heterogeneous coefficients. The model is based on data collected at an instrumented granitic site (FEBEX project) for studying a hypothetical nuclear waste repository at the Grimsel Test Site in the Swiss Alps. (authors)

  12. Rock mechanics models evaluation report

    International Nuclear Information System (INIS)

    1987-08-01

    This report documents the evaluation of the thermal and thermomechanical models and codes for repository subsurface design and for design constraint analysis. The evaluation was based on a survey of the thermal and thermomechanical codes and models that are applicable to subsurface design, followed by a Kepner-Tregoe (KT) structured decision analysis of the codes and models. The primary recommendations of the analysis are that the DOT code be used for two-dimensional thermal analysis and that the STEALTH and HEATING 5/6 codes be used for three-dimensional and complicated two-dimensional thermal analysis. STEALTH and SPECTROM 32 are recommended for thermomechanical analyses. The other evaluated codes should be considered for use in certain applications. A separate review of salt creep models indicate that the commonly used exponential time law model is appropriate for use in repository design studies. 38 refs., 1 fig., 7 tabs

  13. Thermo-hydro-mechanical behavior of fractured rock mass

    International Nuclear Information System (INIS)

    Coste, F.

    1997-12-01

    The purpose of this research is to model Thermo-Hydro-Mechanical behavior of fractured rock mass regarding a nuclear waste re-depository. For this, a methodology of modeling was proposed and was applied to a real underground site (EDF site at Nouvelle Romanche). This methodology consists, in a first step, to determine hydraulic and mechanical REV. Beyond the greatest of these REV, development of a finite element code allows to model all the fractures in an explicit manner. The homogenized mechanical properties are determined in drained and undrained boundary conditions by simulating triaxial tests that represent rock mass subject to loading. These simulations allow to study the evolution of hydraulic and mechanical properties as a function of stress state. Drained and undrained boundary conditions enable to discuss the validity of assimilation of a fractured rock mass to a porous medium. The simulations lead to a better understanding of the behavior of the fractured rock masses and allow to show the dominant role of the shear behavior of the fractures on the hydraulic and mechanical homogenized properties. From a thermal point of view, as long as conduction is dominant, thermal properties of the rock mass are almost the same as those the intact rock. (author)

  14. Rock mechanics related to Jurassic underburden at Valdemar oil field

    DEFF Research Database (Denmark)

    Foged, Niels

    1999-01-01

    .It has been initiated as a feasibility study of the North Jens-1 core 12 taken in the top Jurassic clay shale as a test specimens for integrated petrological, mineralogical and rock mechanical studies. Following topics are studied:(1) Pore pressure generation due to conversion of organic matter...... and deformation properties of the clay shale using the actual core material or outcrop equivalents.(3) Flushing mechanisms for oil and gas from source rocks due to possibly very high pore water pressure creating unstable conditions in deeply burried sedimentsThere seems to be a need for integrating the knowledge...... in a number of geosciences to the benefit of common understanding of important reservoir mechanisms. Rock mechanics and geotechnical modelling might be key points for this understanding of reservoir geology and these may constitute a platform for future research in the maturing and migration from the Jurassic...

  15. Strategy for future laboratory rock mechanics programs

    International Nuclear Information System (INIS)

    Butcher, B.M.; Jones, A.K.

    1985-01-01

    A strategy for future experimental rock mechanics laboratory programs at Sandia National Laboratories is described. This strategy is motivated by the need for long range planning of rock mechanics programs addressing the stability of complex underground structures, changes in in situ stress states during resource recovery and underground explosion technology. It is based on: (1) recent advances in underground structure stability analysis which make three-dimensional calculations feasible, and (2) new developments in load path control of laboratory stress-strain tests which permit duplication of stress and strain histories in critical parts of a structure, as determined by numerical analysis. The major constraint in the strategy is the assumption that there are no in situ joint features or sample size effects which might prevent simulation of in situ response in the laboratory. 3 refs., 5 figs

  16. Rock mechanics stability at Olkiluoto, Haestholmen, Kivetty and Romuvaara

    International Nuclear Information System (INIS)

    Johansson, E.; Rautakorpi, J.

    2000-02-01

    Posiva Oy is studying the suitability of the Finnish bedrock for the geological disposal of spent nuclear fuel at four sites, Olkiluoto in Eurajoki, Haestholmen in Loviisa, Kivetty in Aeaenekoski and Romuvaara in Kuhmo. To enable the rock properties to be specified in great detail, the site-selection research programme has included rock mechanics investigations such as the measurement of in-situ rock stress and laboratory tests on rock samples. This report presents the results of the rock mechanics analyses performed on the main rock types at the Olkiluoto, Romuvaara, Kivetty and Haestholmen sites. The objective of this study was to assess the near-field stability of the final disposal tunnels and deposition holes at each of the investigation sites. Two empirical methods and a numerical method based on three-dimensional element code (3DEC) were used the analysis tools. A statistical approach was used to select the necessary input data and to specify the cases being analysed. The stability of the KBS-3 and MLH (Medium Long Hole) repository concepts during the pre-closure and post-closure phases was analysed. The repository depths investigated lay between 300 m and 700 m. The empirical methods are based on the study of the ratios between rock strength and the in-situ stress which could result in possible fracturing of the rock mass. Interpretation of the numerical analyses is based on the assumption of an elastic distribution of stress around the disposal tunnel and the deposition hole and the brittle rock strength criterion. The results obtained in this study indicate that in general, the rock mechanics conditions during the pre-closure and post-closure phases at each of the investigated sites remain good and stable between the studied depth levels, especially when the deposition rooms are oriented in a direction parallel to the major in-situ stress. If the disposal tunnels are orientated in a direction perpendicular to the major in-situ stress, the resultant

  17. Application of rock mechanics in opencast mining

    Energy Technology Data Exchange (ETDEWEB)

    Desurmont, M; Feuga, B

    1979-07-01

    The significance of opencast mining in the world today is mentioned. With the exception of coal, opencast workings provide approximately 80% of output. The importance of opencast has continued to increase over the last ten years. Access to the mineral usually necessitates the removal of large quantities of rock. The aim is to reduce the quantity of the latter as much as possible in order to minimize the dirt/mineral ratio. For this purpose use has been made of the operating techniques of rock mechanics in order to determine the optimum dimensions of the access trench compatible with safety requirements. The author illustrates this technique by means of three examples: the Luzenac talc workings, the Mont-Roc fluorine workings and the Big Hole at Kimberley.

  18. Results of monitoring at Olkiluoto in 2004. Rock mechanics

    International Nuclear Information System (INIS)

    Riikonen, S.

    2005-09-01

    This report presents Posiva Oy's results of the rock mechanical monitoring programme from the year 2004. Monitoring programme was established for long time monitoring of modifications in the bedrock during the excavation of the ONKALO underground research facility stated in Olkiluoto island. This is the first annual report where rock mechanical research work has being reported also from the monitoring point of view. Rock mechanical research work consists of both GPS measurements and microseismic measurements carried out in Olkiluoto island. Both measurements have been performed during several years even before monitoring programme was established. GPS measurements have been carried out since 1995 and microseismic network has operated since 2002. There have been no significant changes in observations when studying rock mechanical results from the year 2004 and comparing them to results from the previous years. Therefore it can be said, that so far ONKALO has barely had any effect on rock mechanics in Olkiluoto. Report has been composed from the annual reports of GPS measurements.(orig.)

  19. Rock mechanics activities at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Francke, C.; Saeb, S.

    1996-01-01

    The application of rock mechanics at nuclear waste repositories is a true multidisciplinary effort. A description and historical summary of the Waste Isolation Pilot Plant (WIPP) is presented. Rock mechanics programs at the WIPP are outlined, and the current rock mechanics modeling philosophy of the Westinghouse Waste Isolation Division is discussed

  20. Experimental and numerical study of the failure process and energy mechanisms of rock-like materials containing cross un-persistent joints under uniaxial compression.

    Directory of Open Access Journals (Sweden)

    Rihong Cao

    Full Text Available Joints and fissures in natural rocks have a significant influence on the stability of the rock mass, and it is often necessary to evaluate strength failure and crack evolution behavior. In this paper, based on experimental tests and numerical simulation (PFC2D, the macro-mechanical behavior and energy mechanism of jointed rock-like specimens with cross non-persistent joints under uniaxial loading were investigated. The focus was to study the effect of joint dip angle α and intersection angle γ on the characteristic stress, the coalescence modes and the energy release of jointed rock-like specimens. For specimens with γ = 30° and 45°, the UCS (uniaxial compression strength, CIS (crack initiation stress and CDiS (critical dilatancy stress increase as α increases from 0° to 75°. When γ = 60° and 75°, the UCS, CIS and CDiS increase as α increases from 0° to 60° and decrease when α is over 60°. Both the inclination angle α and intersection angle γ have great influence on the failure pattern of pre-cracked specimens. With different α and γ, specimens exhibit 4 kinds of failure patterns. Both the experimental and numerical results show that the energy of a specimen has similar trends with characteristic stress as α increases.

  1. Mechanical properties of granitic rocks from Gideaa, Sweden

    International Nuclear Information System (INIS)

    Ljunggren, C.; Stephansson, O.; Alm, O.; Hakami, H.; Mattila, U.

    1985-10-01

    The elastic and mechanical properties were determined for two rock types from the Gideaa study area. Gideaa is located approximately 30 km north-east of Oernskoeldsvik, Northern Sweden. The rock types that were tested were migmatitic gneiss and migmatitic granite. The following tests were conducted: - sound velocity measurements; - uniaxial compression tests with acoustic emission recording; - brazilian disc tests; - triaxial tests; - three point bending tests. All together, 12 rock samples were tested with each test method. Six samples of these were migmatic gneiss and six samples were migmatitic granite. The result shows that the migmatitic gneiss has varying strength properties with low compressive strength in comparison with its high tensile strength. The migmatitic granite, on the other hand, is found to have parameter values similar to other granitic rocks. With 15 refs. (Author)

  2. Proceedings of the 3. Canada-US rock mechanics symposium and 20. Canadian rock mechanics symposium : rock engineering 2009 : rock engineering in difficult conditions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This conference provided a forum for geologists, mining operators and engineers to discuss the application of rock mechanics in engineering designs. Members of the scientific and engineering communities discussed challenges and interdisciplinary elements involved in rock engineering. New geological models and methods of characterizing rock masses and ground conditions in underground engineering projects were discussed along with excavation and mining methods. Papers presented at the conference discussed the role of rock mechanics in forensic engineering. Geophysics, geomechanics, and risk-based approaches to rock engineering designs were reviewed. Issues related to high pressure and high flow water conditions were discussed, and new rock physics models designed to enhance hydrocarbon recovery were presented. The conference featured 84 presentations, of which 9 have been catalogued separately for inclusion in this database. tabs., figs.

  3. Laboratory rock mechanics testing manual. Public draft

    Energy Technology Data Exchange (ETDEWEB)

    Shuri, F S; Cooper, J D; Hamill, M L

    1981-10-01

    Standardized laboratory rock mechanics testing procedures have been prepared for use in the National Terminal Waste Storage Program. The procedures emphasize equipment performance specifications, documentation and reporting, and Quality Assurance acceptance criteria. Sufficient theoretical background is included to allow the user to perform the necessary data reduction. These procedures incorporate existing standards when possible, otherwise they represent the current state-of-the-art. Maximum flexibility in equipment design has been incorporated to allow use of this manual by existing groups and to encourage future improvements.

  4. Integrated Experimental and Modeling Studies of Mineral Carbonation as a Mechanism for Permanent Carbon Sequestration in Mafic/Ultramafic Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhengrong [Yale Univ., New Haven, CT (United States); Qiu, Lin [Yale Univ., New Haven, CT (United States); Zhang, Shuang [Yale Univ., New Haven, CT (United States); Bolton, Edward [Yale Univ., New Haven, CT (United States); Bercovici, David [Yale Univ., New Haven, CT (United States); Ague, Jay [Yale Univ., New Haven, CT (United States); Karato, Shun-Ichiro [Yale Univ., New Haven, CT (United States); Oristaglio, Michael [Yale Univ., New Haven, CT (United States); Zhu, Wen-Iu [Univ. of Maryland, College Park, MD (United States); Lisabeth, Harry [Univ. of Maryland, College Park, MD (United States); Johnson, Kevin [Univ. of Hawaii, Honolulu, HI (United States)

    2014-09-30

    A program of laboratory experiments, modeling and fieldwork was carried out at Yale University, University of Maryland, and University of Hawai‘i, under a DOE Award (DE-FE0004375) to study mineral carbonation as a practical method of geologic carbon sequestration. Mineral carbonation, also called carbon mineralization, is the conversion of (fluid) carbon dioxide into (solid) carbonate minerals in rocks, by way of naturally occurring chemical reactions. Mafic and ultramafic rocks, such as volcanic basalt, are natural candidates for carbonation, because the magnesium and iron silicate minerals in these rocks react with brines of dissolved carbon dioxide to form carbonate minerals. By trapping carbon dioxide (CO2) underground as a constituent of solid rock, carbonation of natural basalt formations would be a secure method of sequestering CO2 captured at power plants in efforts to mitigate climate change. Geochemical laboratory experiments at Yale, carried out in a batch reactor at 200°C and 150 bar (15 MPa), studied carbonation of the olivine mineral forsterite (Mg2SiO4) reacting with CO2 brines in the form of sodium bicarbonate (NaHCO3) solutions. The main carbonation product in these reactions is the carbonate mineral magnesite (MgCO3). A series of 32 runs varied the reaction time, the reactive surface area of olivine grains and powders, the concentration of the reacting fluid, and the starting ratio of fluid to olivine mass. These experiments were the first to study the rate of olivine carbonation under passive conditions approaching equilibrium. The results show that, in a simple batch reaction, olivine carbonation is fastest during the first 24 hours and then slows significantly and even reverses. A natural measure of the extent of carbonation is a quantity called the carbonation fraction, which compares the amount of carbon removed from solution, during a run, to the maximum amount

  5. Rock mechanics contributions from defense programs

    International Nuclear Information System (INIS)

    Heuze, F.E.

    1992-02-01

    An attempt is made at illustrating the many contributions to rock mechanics from US defense programs, over the past 30-plus years. Large advances have been achieved in the technology-base area covering instrumentation, material properties, physical modeling, constitutive relations and numerical simulations. In the applications field, much progress has been made in understanding and being able to predict rock mass behavior related to underground explosions, cratering, projectile penetration, and defense nuclear waste storage. All these activities stand on their own merit as benefits to national security. But their impact is even broader, because they have found widespread applications in the non-defense sector; to name a few: the prediction of the response of underground structures to major earthquakes, the physics of the earth's interior at great depths, instrumentation for monitoring mine blasting, thermo-mechanical instrumentation useful for civilian nuclear waste repositories, dynamic properties of earthquake faults, and transient large-strain numerical modeling of geological processes, such as diapirism. There is not pretense that this summary is exhaustive. It is meant to highlight success stories representative of DOE and DOD geotechnical activities, and to point to remaining challenges

  6. The Usability of Rock-Like Materials for Numerical Studies on Rocks

    Science.gov (United States)

    Zengin, Enes; Abiddin Erguler, Zeynal

    2017-04-01

    The approaches of synthetic rock material and mass are widely used by many researchers for understanding the failure behavior of different rocks. In order to model the failure behavior of rock material, researchers take advantageous of different techniques and software. But, the majority of all these instruments are based on distinct element method (DEM). For modeling the failure behavior of rocks, and so to create a fundamental synthetic rock material model, it is required to perform related laboratory experiments for providing strength parameters. In modelling studies, model calibration processes are performed by using parameters of intact rocks such as porosity, grain size, modulus of elasticity and Poisson ratio. In some cases, it can be difficult or even impossible to acquire representative rock samples for laboratory experiments from heavily jointed rock masses and vuggy rocks. Considering this limitation, in this study, it was aimed to investigate the applicability of rock-like material (e.g. concrete) to understand and model the failure behavior of rock materials having complex inherent structures. For this purpose, concrete samples having a mixture of %65 cement dust and %35 water were utilized. Accordingly, intact concrete samples representing rocks were prepared in laboratory conditions and their physical properties such as porosity, pore size and density etc. were determined. In addition, to acquire the mechanical parameters of concrete samples, uniaxial compressive strength (UCS) tests were also performed by simultaneously measuring strain during testing. The measured physical and mechanical properties of these extracted concrete samples were used to create synthetic material and then uniaxial compressive tests were modeled and performed by using two dimensional discontinuum program known as Particle Flow Code (PFC2D). After modeling studies in PFC2D, approximately similar failure mechanism and testing results were achieved from both experimental and

  7. Effects of bioleaching on the mechanical and chemical properties of waste rocks

    Science.gov (United States)

    Yin, Sheng-Hua; Wu, Ai-Xiang; Wang, Shao-Yong; Ai, Chun-Ming

    2012-01-01

    Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks, and play an important role in metal recovery and dump stability. This study focused on the characteristics of waste rocks subjected to bioleaching. A series of experiments were conducted to investigate the evolution of rock properties during the bioleaching process. Mechanical behaviors of the leached waste rocks, such as failure patterns, normal stress, shear strength, and cohesion were determined through mechanical tests. The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump. The mineralogical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching. The dump porosity and rock size change under the effect of dissolution, precipitation, and clay transportation. The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.

  8. Thermo-hydro-mechanics of fractured rock mass in nuclear waste studies. The measurement of electrical conductivity during the thermo-hydro-mechanical experiment

    International Nuclear Information System (INIS)

    Mursu, J.; Peltoniemi, M.

    1996-12-01

    The report reviews and summarizes the present state-of-the-art knowledge about electrical conductivity measurements of rock samples in high-temperature, high-pressure conditions. The special requirements for these measurements have been studied in terms of sample preparation, instrumentation, and experimental procedures. Possibilities to utilize a MTS System 815 testing unit, currently available at the Helsinki University of Technology, for these measurements have been studied. (17 refs.)

  9. Study of Post-Peak Strain Softening Mechanical Behaviour of Rock Material Based on Hoek–Brown Criterion

    OpenAIRE

    Qibin Lin; Ping Cao; Peixin Wang

    2018-01-01

    In order to build the post-peak strain softening model of rock, the evolution laws of rock parameters m,s were obtained by using the evolutionary mode of piecewise linear function regarding the maximum principle stress. Based on the nonlinear Hoek–Brown criterion, the analytical relationship of the rock strength parameters m,s, cohesion c, and friction angle φ has been developed by theoretical derivation. According to the analysis on the four different types of rock, it is found that, within ...

  10. ONKALO rock mechanics model (RMM) - Version 2.0

    International Nuclear Information System (INIS)

    Moenkkoenen, H.; Hakala, M.; Paananen, M.; Laine, E.

    2012-02-01

    The Rock Mechanics Model of the ONKALO rock volume is a description of the significant features and parameters related to rock mechanics. The main objective is to develop a tool to predict the rock properties, quality and hence the potential for stress failure which can then be used for continuing design of the ONKALO and the repository. This is the second implementation of the Rock Mechanics Model and it includes sub-models of the intact rock strength, in situ stress, thermal properties, rock mass quality and properties of the brittle deformation zones. Because of the varying quantities of available data for the different parameters, the types of presentations also vary: some data sets can be presented in the style of a 3D block model but, in other cases, a single distribution represents the whole rock volume hosting the ONKALO. (orig.)

  11. Finite element simulations of two rock mechanics tests

    International Nuclear Information System (INIS)

    Dahlke, H.J.; Lott, S.A.

    1986-04-01

    Rock mechanics tests are performed to determine in situ stress conditions and material properties of an underground rock mass. To design stable underground facilities for the permanent storage of high-level nuclear waste, determination of these properties and conditions is a necessary first step. However, before a test and its associated equipment can be designed, the engineer needs to know the range of expected values to be measured by the instruments. Sensitivity studies by means of finite element simulations are employed in this preliminary design phase to evaluate the pertinent parameters and their effects on the proposed measurements. The simulations, of two typical rock mechanics tests, the plate bearing test and the flat-jack test, by means of the finite element analysis, are described. The plate bearing test is used to determine the rock mass deformation modulus. The flat-jack test is used to determine the in situ stress conditions of the host rock. For the plate bearing test, two finite element models are used to simulate the classic problem of a load on an elastic half space and the actual problem of a plate bearing test in an underground tunnel of circular cross section. For the flat-jack simulation, a single finite element model is used to simulate both horizontal and vertical slots. Results will be compared to closed-form solutions available in the literature

  12. High-pressure mechanical instability in rocks.

    Science.gov (United States)

    Byerlee, J D; Brace, W F

    1969-05-09

    At a confining pressure of a few kilobars, deformation of many sedimentary rocks, altered mafic rocks, porous volcanic rocks, and sand is ductile, in that instabilities leading to audible elastic shocks are absent. At pressures of 7 to 10 kilobars, however, unstable faulting and stick-slip in certain of these rocks was observed. This high pressure-low temperature instability might be responsible for earthquakes in deeply buried sedimentary or volcanic sequences.

  13. Digital Rock Studies of Tight Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  14. The Usability of Noise Level from Rock Cutting for the Prediction of Physico-Mechanical Properties of Rocks

    Science.gov (United States)

    Delibalta, M. S.; Kahraman, S.; Comakli, R.

    2015-11-01

    Because the indirect tests are easier and cheaper than the direct tests, the prediction of rock properties from the indirect testing methods is important especially for the preliminary investigations. In this study, the predictability of the physico-mechanical rock properties from the noise level measured during cutting rock with diamond saw was investigated. Noise measurement test, uniaxial compressive strength (UCS) test, Brazilian tensile strength (BTS) test, point load strength (Is) test, density test, and porosity test were carried out on 54 different rock types in the laboratory. The results were statistically analyzed to derive estimation equations. Strong correlations between the noise level and the mechanical rock properties were found. The relations follow power functions. Increasing rock strength increases the noise level. Density and porosity also correlated strongly with the noise level. The relations follow linear functions. Increasing density increases the noise level while increasing porosity decreases the noise level. The developed equations are valid for the rocks with a compressive strength below 150 MPa. Concluding remark is that the physico-mechanical rock properties can reliably be estimated from the noise level measured during cutting the rock with diamond saw.

  15. Underground laboratories for rock mechanics before radioactive waste

    International Nuclear Information System (INIS)

    Duffaut, P.

    1985-01-01

    Many rock mechanics tests are performed in situ, most of them underground since 1936 at the Beni Bahdel dam. The chief tests for understanding the rock mass behaviour are deformability tests (plate test and pressure cavern test, including creep experiments) and strength tests (compression of a mine pillar, shear test on rock mass or joint). Influence of moisture, heat, cold and freeze are other fields of investigation which deserve underground laboratories. Behaviour of test galleries, either unsupported or with various kinds of support, often is studied along time, and along the work progression, tunnel face advance, enlargement or deepening of the cross section. The examples given here help to clarify the concept of underground laboratory in spite of its many different objectives. 38 refs.; 1 figure; 1 table

  16. Impact of supercritical CO2 injection on petrophysical and rock mechanics properties of chalk: an experimental study on chalk from South Arne field, North Sea

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, Morten Leth; Christensen, Helle Foged

    2011-01-01

    Changes in chalk due to EOR by injecting supercritical CO2 (CO2-EOR) can ideally be predicted by applying geophysical methods designed from laboratory-determined petrophysical and rock mechanics properties. A series of petrophysical and rock mechanics tests were performed on Ekofisk Formation...... and Tor Formation chalk of the South Arne field to reveal the changes in petrophysical and rock mechanics properties of chalk due to the injection of CO2 at supercritical state. An increase in porosity and decrease in specific surface was observed due to injection of supercritical CO2. This indicates...... as indicated by NMR T2 relaxation time was observed. Rock mechanics testing indicates that in 30% porosity chalk from the South Arne field, injection of supercritical CO2 has no significant effect on shear strength and compaction properties, while there is probably a slight decrease in stiffness properties...

  17. Rock mechanics in the National Waste Terminal Storage Program

    International Nuclear Information System (INIS)

    Monsees, J.E.; Wigley, M.R.

    1982-01-01

    The overall objective of the rock mechanics program of the Office of Nuclear Waste Isolation is to predict the response of a rock mass hosting a waste repository during its construction, operation, and postoperational phases. The operational phase is expected to be 50 to 100 yr; the postoperational phase will last until the repository no longer poses any potential hazard to the biosphere, a period that may last several thousand years. The rock mechanics program is concerned with near-field effects on mine stability, as well as far-field effects relative to the overall integrity of the geologic waste isolation system. To accomplish these objectives, the rock mechanics program has established interactive studies in numerical simulation, laboratory testing, and field testing. The laboratory and field investigations provide input to the numerical simulations and give an opportunity for verification and validation of the predictive capabilities of the computer codes. Ultimately the computer codes will be used to predict the response of the geologic system to the development of a repository. 3 references, 5 figures

  18. Geometry, mechanics and transmissivity of rock fractures

    International Nuclear Information System (INIS)

    Lanaro, F.

    2001-04-01

    This thesis work investigates methods and tools for characterising, testing and modelling the behaviour of rock fractures. Using a 3D-laser-scanning technique, the topography of the surfaces and their position with respect to one another are measured. From the fracture topography, fracture roughness, angularity and aperture are quantified; the major features used for characterisation. The standard deviations for the asperity heights, surface slopes and aperture are determined. These statistical parameters usually increase/decrease according to power laws of the sampling size, and sometimes reach a sill beyond which they become constant. Also the number of contact spots with a certain area decreases according to a power-law function of the area. These power-law relations reveal the self affine fractal nature of roughness and aperture. Roughness is 'persistent' while aperture varies between 'persistent' and 'anti-persistent' probably depending on the degree of match of the fracture walls. The fractal models for roughness, aperture and contact area are used to develop a constitutive model, based on contact mechanics, for describing the fracture normal and shear deformability. The experimental testing results of normal deformability are simulated well by the model whereas fracture shear deformability is not as well modelled. The model predicts well fracture dilation but is too stiff compared to rock samples. A mathematical description of the aperture pattern during shearing is also formulated. The mean value and covariance of the aperture in shearing is calculated and verifies reported observations. The aperture map of samples is inserted in a numerical program for flow calculation. The 'integral transform method' is used for solving the Reynolds' equation; it transforms the fracture transmissivity pattern into a frequency-based function. This closely resembles the power laws that describe fractals. This function can be described directly from the fractal properties of

  19. Long term thermo-hydro-mechanical interaction behavior study of the saturated, discontinuous granitic rock mass around the radwaste repository using a steady state flow algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jhin Wung; Bae, Dae Suk; Kang, Chul Hyung; Choi, Jong Won [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-02-01

    The objective of the present study is to understand the long term (500 years) thermo-hydro-mechanical interaction behavior of the 500 m depth underground radwaste repository in the saturated, discontinuous granitic rock mass using a steady state flow algorithm. The numerical model includes a saturated granitic rock mass with joints around the repository and a 45 .deg. C fault passing through the tunnel roof-wall intersection, and a canister with PWR spent fuels surrounded by the compacted bentonite and mixed-bentonite. Barton-Bandis joint constitutive model from the UDEC code is used for the joints. For the hydraulic analysis, a steady state flow algorithm is used for the groundwater flow through the rock joints. For the thermal analysis, heat transfer is modeled as isotropic conduction and heat decays exponentially with time. The results show that the variations of the hydraulic aperture, hydraulic conductivity, normal stress, normal displacements, and shear displacements of the joints are high in the vicinity of the repository and stay fairly constant on the region away from the repository. 14 refs., 15 figs., 11 tabs. (Author)

  20. Rock mechanical conditions at the Aespoe HRL. A study of the correlation between geology, tunnel maintenance and tunnel shape

    International Nuclear Information System (INIS)

    Andersson, Christer; Soederhaell, Joergen

    2001-12-01

    Maintenance records including scaling, shotcreting and bolting have been kept since the excavation start of Aespoe HRL 1990 together with records of groundwater flow and all other activities taking place in the tunnels. When the facility was constructed one objective was to limit the rock support as much as possible. The reason for this was that it should be possible to go back and easily study the exposed rock surface. Support during the operational phase has only been carried out where and when necessary. This type of maintenance and its location is documented in the digital database each time. The maintenance records have been compiled and areas requiring more maintenance than average noted. An interview has also been held with one of the miners conducting scaling and bolting in the tunnel. His experiences together with the study of the database maintenance records led to the selection of certain areas in the tunnel to be studied by numerical modelling. The probable reason for the need of additional maintenance in all areas, not only these numerically modelled, has been investigated. Almost all maintenance in the main tunnel both during construction and the operational phase has been located in the widened curves of the access tunnel. The maintenance is also located in areas containing veins or intrusions of Smaaland granite or fine-grained granite. These areas are often located in fracture zones of different sizes or show an increasing fracture frequency. The areas numerically modelled indicate stress concentrations or unloaded stress conditions. The stress concentrations are created by the geometry of the niches and side-tunnels in relation to the in situ stress field. The angle between the tunnel and the major principal stress has an impact on the need for maintenance. The areas with the largest angles towards the principal stress direction need more maintenance than the areas almost parallel to the major principal stress direction. The maintenance work in

  1. A study of the depth of weathering and its relationship to the mechanical properties of near-surface rocks in the Mojave Desert

    Science.gov (United States)

    Stierman, D.J.; Healy, J.H.

    1985-01-01

    Weathered granite extends 70 m deep at Hi Vista in the arid central Mojave Desert of southern California. The low strength of this granite is due to the alteration of biotite and chlorite montmorillonite. Deep weathering probably occurs in most granites, although we cannot rule out some anomalous mechanisms at Hi Vista. Geophysical instruments set in these slightly altered rocks are limited by the unstable behavior of the rocks. Thus, tectonic signals from instruments placed in shallow boreholes give vague results. Geophysical measurements of these weathered rocks resemble measurements of granitic rocks near major faults. The rheology of the rocks in which instruments are placed limits the useful sensitivity of the instruments. ?? 1985 Birkha??user Verlag.

  2. Mechanical Properties and Acoustic Emission Properties of Rocks with Different Transverse Scales

    OpenAIRE

    Yan, Xi; Jun, Li; Gonghui, Liu; Xueli, Guo

    2017-01-01

    Since the stability of engineering rock masses has important practical significance to projects like mining, tunneling, and petroleum engineering, it is necessary to study mechanical properties and stability prediction methods for rocks, cementing materials that are composed of minerals in all shapes and sizes. Rocks will generate acoustic emission during damage failure processes, which is deemed as an effective means of monitoring the stability of coal rocks. In the meantime, actual mining a...

  3. Summary review of rock mechanics workshop on radioactive waste disposal

    International Nuclear Information System (INIS)

    Carter, N.L.; Goodman, R.E.; Merrill, R.H.

    1977-01-01

    Presentations, critiques and recommendations for the disposal of commercial radioactive waste based upon an analysis of the information presented at the Rock Mechanics Review/Workshop, Denver, Colorado, December 16-17, 1976 are summarized. The workshop, comprised of both formal and informal sessions, with about 50 participants, was hosted by RE/SPEC Inc. and Dr. Paul F. Gnirk, President and was sponsored by the Office of Waste Isolation (OWI), led by Dr. William C. McClain. The panel of reviewers, responsible for this report, consisted of Neville L. Carter, Richard E. Goodman, and Robert H. Merrill. These panel members were selected not only on the basis of their experience in various aspects of Rock Mechanics and Mining Engineering but also because they have had no previous active participation in problems concerning disposal of radioactive waste. By way of a general comment, the review panel was very favorably impressed with the Rock Mechanics research efforts, supported by OWI, on this problem and with the level of technical competence of those carrying out the research. Despite the rather preliminary nature of the results presented and the youth of the program itself, it is clear that the essential ingredients for a successful program are at hand, especially as regards disposal in natural salt formations. These include laboratory studies of appropriate rock deformation, numerical analyses of thermal and mechanical stresses around openings, and in situ field tests. We shall comment on each of these three major areas in turn. We shall then offer recommendations for their improvement, and, finally, we shall make more general recommendations for future considerations of the OWI radioactive waste disposal program

  4. Acoustic emission measurements in petroleum-related rock mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Unander, Tor Erling

    2002-07-01

    Acoustic emission activity in rock has usually been studied in crystalline rock, which reflects that rock mechanics has also mostly been occupied with such rocks in relations to seismology, mining and tunneling. On the other hand, petroleum-related rock mechanics focuses on the behaviour of sedimentary rock. Thus, this thesis presents a general study of acoustic emission activity in sedimentary rock, primarily in sandstone. Chalk, limestone and shale have also been tested, but to much less degree because the AE activity in these materials is low. To simplify the study, pore fluids have not been used. The advent of the personal computer and computerized measuring equipment have made possible new methods both for measuring and analysing acoustic emissions. Consequently, a majority of this work is devoted to the development and implementation of new analysis techniques. A broad range of topics are treated: (1) Quantification of the AE activity level, assuming that the event rate best represents the activity. An algorithm for estimating the event rate and a methodology for objectively describing special changes in the activity e.g., onset determination, are presented. (2) Analysis of AE waveform data. A new method for determining the source energy of an AE event is presented, and it is shown how seismic source theory can be used to analyze even intermediate quality data. Based on these techniques, it is shown that a major part of the measured AE activity originates from a region close to the sensor, not necessarily representing the entire sample. (3) An improved procedure for estimating source locations is presented. The main benefit is a procedure that better handles arrival time data with large errors. Statistical simulations are used to quantify the uncertainties in the locations. The analysis techniques are developed with the application to sedimentary rock in mind, and in two articles, the techniques are used in the study of such materials. The work in the first

  5. Thermo-mechanical ratcheting in jointed rock masses

    KAUST Repository

    Pasten, C.; Garcí a, M.; Santamarina, Carlos

    2015-01-01

    Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

  6. Thermo-mechanical ratcheting in jointed rock masses

    KAUST Repository

    Pasten, C.

    2015-09-01

    Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

  7. Latest progress of soft rock mechanics and engineering in China

    Directory of Open Access Journals (Sweden)

    Manchao He

    2014-06-01

    Full Text Available The progress of soft rock mechanics and associated technology in China is basically accompanied by the development of mining engineering and the increasing disasters of large rock deformation during construction of underground engineering. In this regard, Chinese scholars proposed various concepts and classification methods for soft rocks in terms of engineering practices. The large deformation mechanism of engineering soft rocks is to be understood through numerous experiments; and thus a coupled support theory for soft rock roadways is established, followed by the development of a new support material, i.e. the constant resistance and large deformation bolt/anchor with negative Poisson's ratio effect, and associated control technology. Field results show that large deformation problems related to numbers of engineering cases can be well addressed with this new technology, an effective way for similar soft rock deformation control.

  8. Application of a new thermo-mechanical model for the study of the nuclear waste disposal in clay rocks

    International Nuclear Information System (INIS)

    Dizier, A.; Li, X.L.; Francois, B.; Collin, F.; Charlier, R.

    2012-01-01

    (LY curve (Loading Yield)). This one may be considered analogous with the LC curve (Loading Collapse) met in the Barcelona Basic Model dedicated to unsaturated soil mechanics. This thermo-mechanical law has been used to model the PRACLAY experiment and particularly to analyse the evolution of the damaged zone with temperature. In this study, the damaged zone is considered as the sum of two plastic strain components, a deviatoric and a volumetric one. The deviatoric strains are induced when the internal friction criterion is reached while the volumetric strains are a consequence of the Cam - Clay model or the TY curve. The results of the evolution of the deviatoric strain show that the magnitude of this strain is modified near the wall but the extension of the size of the plastic deviatoric zone is not affected by temperature. The modification of the deviatoric strain near the wall can be explained by hydro-mechanical coupling caused by thermally induced excess pore water pressure which permits the stress path to reach the internal friction criterion. Concerning the volumetric plastic strains, these follow the effect of the thermal load and the size of the zone affected by these strains correspond to the zone affected by the temperature. On the contrary the magnitude of the strain depends on the state of stress of the clay as observed near the wall. Indeed, the stresses near the wall are reduced due to the process of excavation and the state of stress exhibits a kind of over-consolidation effect where only thermal dilation is possible. In that modelling, the set of parameters chosen doesn't allow the activation of the LY curve. Finally the results obtained with this new thermo-mechanical law have been compared with results obtained with other thermo-mechanical law, that is to say with ACMEG-T which is a thermo-plastic law developed at EPFL and a classical thermo-elastic law. The comparison shows that the results obtained with the two thermo-plastic constitutive laws

  9. Effects of confinement on rock mass modulus: A synthetic rock mass modelling (SRM study

    Directory of Open Access Journals (Sweden)

    I. Vazaios

    2018-06-01

    Full Text Available The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks (well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints. A synthetic rock mass modelling (SRM approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method (DEM-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the pre-existing joints is generated by employing discrete fracture network (DFN modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation (RQD, joint spacing, areal fracture intensity (P21, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index (GSI. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness. Keywords: Synthetic rock mass modelling (SRM, Discrete fracture network (DFN, Rock mass modulus, Geological strength index (GSI, Confinement

  10. Analysis of soft rock mineral components and roadway failure mechanism

    Institute of Scientific and Technical Information of China (English)

    陈杰

    2001-01-01

    The mineral components and microstructure of soft rock sampled from roadway floor inXiagou pit are determined by X-ray diffraction and scanning electron microscope. Ccmbined withthe test of expansion and water softening property of the soft rock, the roadway failure mechanism is analyzed, and the reasonable repair supporting principle of roadway is put forward.

  11. Mechanical Properties and Acoustic Emission Properties of Rocks with Different Transverse Scales

    Directory of Open Access Journals (Sweden)

    Xi Yan

    2017-01-01

    Full Text Available Since the stability of engineering rock masses has important practical significance to projects like mining, tunneling, and petroleum engineering, it is necessary to study mechanical properties and stability prediction methods for rocks, cementing materials that are composed of minerals in all shapes and sizes. Rocks will generate acoustic emission during damage failure processes, which is deemed as an effective means of monitoring the stability of coal rocks. In the meantime, actual mining and roadway surrounding rocks tend to have transverse effects; namely, the transverse scale is larger than the length scale. Therefore, it is important to explore mechanical properties and acoustic emission properties of rocks under transverse size effects. Considering the transverse scale effects of rocks, this paper employs the microparticle flow software PFC2D to explore the influence of different aspect ratios on damage mechanics and acoustic emission properties of rocks. The results show that (1 the transverse scale affects uniaxial compression strength of rocks. As the aspect ratio increases, uniaxial compression strength of rocks decreases initially and later increases, showing a V-shape structure and (2 although it affects the maximum hit rate and the strain range of acoustic emission, it has little influence on the period of occurrence. As the transverse scale increases, both damage degree and damage rate of rocks decrease initially and later increase.

  12. Rheological Characteristics of Cement Grout and its Effect on Mechanical Properties of a Rock Fracture

    Science.gov (United States)

    Liu, Quansheng; Lei, Guangfeng; Peng, Xingxin; Lu, Chaobo; Wei, Lai

    2018-02-01

    Grouting reinforcement, which has an obvious strengthening effect on fractured rock mass, has been widely used in various fields in geotechnical engineering. The rheological properties of grout will greatly affect its diffusion radius in rock fractures, and the water-cement ratio is an important factor in determining the grouting flow patterns. The relationship between shear stress and shear rate which could reflect the grout rheological properties, the effects of water-cement ratio, and temperature on the rheological properties of grouting was studied in the laboratory. Besides, a new method for producing fractured rock specimens was proposed and solved the problem of producing natural fractured rock specimens. To investigate the influences of grouting on mechanical properties of a rock fracture, the fractured rock specimens made using the new method were reinforced by grouting on the independent designed grouting platform, and then normal and tangential mechanical tests were carried out on fractured rock specimens. The results showed that the mechanical properties of fractured rock mass are significantly improved by grouting, the peak shear strength and residual strength of rock fractures are greatly improved, and the resistance to deformation is enhanced after grouting. Normal forces affect the tangential behavior of the rock fracture, and the tangential stress strength increases with normal forces. The strength and stability of fractured rock mass are increased by grouting reinforcement.

  13. Compositional, mechanical and transport properties of carbonate fault rocks and the seismic cycle in limestone terrains : A case study of surface exposures on the Longmenshan Fault, Sichuan, China

    NARCIS (Netherlands)

    Chen, Jianye

    2015-01-01

    Destructive earthquakes are common in tectonically active regions dominated by carbonate cover rocks. The catastrophic Wenchuan earthquake that struck Sichuan, China, also affected a section of carbonate cover terrain. Numerous studies have focused on characterizing the compositional, transport and

  14. Fluids and the evolution of rock mechanical properties

    International Nuclear Information System (INIS)

    Reuschle, Thierry

    1989-01-01

    This research thesis reports the study of the various phenomena of fluid-solid interaction (mechanical or chemical interaction with fracturing by fluid overpressure, slow crack propagation, and pore deformation by transfer in solution) which may occur in the interaction of fluids with rocks. The author first presents the formalism of slow crack propagation based on the generalisation of the Griffith criterion. The model results are compared with experimental results obtained on four materials (glass, quartz, sandstone, and micrite) by using the double-torsion test. In the second part, the author addresses the issue of pore deformation by transfer in solution: dissolution and crystallisation under stress. The Gibbs chemical potential equation is firstly generalised to the case of a circular pore, and a formalism combining mechanics and thermodynamics is then proposed. A set of simulations highlights important parameters. In the third part, the author addresses the problem of fluid-rock mechanical interaction by studying the mechanical role of fluid pressure in crack initiation and propagation [fr

  15. Current status of crushed rock and whole rock column studies

    International Nuclear Information System (INIS)

    Vine, E.N.; Daniels, W.R.; Rundberg, R.S.; Thompson, J.L.

    1980-01-01

    Measurements on a large number of crushed rock columns of tuff, granite, and argillite are discussed. The isotopes 85 Sr, 137 Cs, 133 Ba, 141 Ce, 152 Eu, /sup 95m/Tc, and 233 U were used. Flow rates were varied from approx. 30 to approx. 30000 m/y. Other parameters studied include isotope concentration and atmosphere. The sorption ratios calculated were compared with batch sorption ratios on the same samples. Methods of studying the movement of radionuclides through whole rock cores are described. The problems associated with sealing the cores to prevent leaking along the exterior surface and one possible solution are discussed. The strontium sorption ratio obtained by elution of one solid tuff core is compared with the batch and crushed rock column sorption ratios

  16. The three-dimension model for the rock-breaking mechanism of disc cutter and analysis of rock-breaking forces

    Science.gov (United States)

    Zhang, Zhao-Huang; Sun, Fei

    2012-06-01

    To study the rock deformation with three-dimensional model under rolling forces of disc cutter, by carrying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior under rolling disc cutter is studied, the mechanical model of disc cutter rolling around the groove is established, and the theory of single-point and double-angle variables is proposed. Based on this theory, the physics equations and geometric equations of rock mechanical behavior under disc cutters of tunnel boring machine (TBM) are studied, and then the balance equations of interactive forces between disc cutter and rock are established. Accordingly, formulas about normal force, rolling force and side force of a disc cutter are derived, and their validity is studied by tests. Therefore, a new method and theory is proposed to study rock-breaking mechanism of disc cutters.

  17. Geological and rock mechanics aspects of the long-term evolution of a crystalline rock site

    International Nuclear Information System (INIS)

    Cosgrove, J.W.; Hudson, J.A.

    2009-01-01

    We consider the stability of a crystalline rock mass and hence the integrity of a radioactive waste repository contained therein by, firstly, identifying the geological evolution of such a site and, secondly, by assessing the likely rock mechanics consequences of the natural perturbations to the repository. In this way, the potency of an integrated geological-rock mechanics approach is demonstrated. The factors considered are the pre-repository geological evolution, the period of repository excavation, emplacement and closure, and the subsequent degradation and natural geological perturbations introduced by glacial loading. It is found that the additional rock stresses associated with glacial advance and retreat have a first order effect on the stress magnitudes and are likely to cause a radical change in the stress regime. There are many factors involved in the related geosphere stability and so the paper concludes with a systems diagram of the total evolutionary considerations before, during and after repository construction. (authors)

  18. Rock mechanics models evaluation report: Draft report

    International Nuclear Information System (INIS)

    1985-10-01

    This report documents the evaluation of the thermal and thermomechanical models and codes for repository subsurface design and for design constraint analysis. The evaluation was based on a survey of the thermal and thermomechanical codes and models that are applicable to subsurface design, followed by a Kepner-Tregoe (KT) structured decision analysis of the codes and models. The end result of the KT analysis is a balanced, documented recommendation of the codes and models which are best suited to conceptual subsurface design for the salt repository. The various laws for modeling the creep of rock salt are also reviewed in this report. 37 refs., 1 fig., 7 tabs

  19. Mechanical study of the Chartreuse Fold-and-Thrust Belt: relationships between fluids overpressure and decollement within the Toarcian source-rock

    Science.gov (United States)

    Berthelon, Josselin; Sassi, William; Burov, Evgueni

    2016-04-01

    Many source-rocks are shale and constitute potential detachment levels in Fold-and-Thrust Belts (FTB): the toarcian Schistes-Cartons in the French Chartreuse FTB for example. Their mechanical properties can change during their burial and thermal maturation, as for example when large amount of hydrocarbon fluids are generated. A structural reconstruction of the Chartreuse FTB geo-history places the Toarcian Formation as the major decollement horizon. In this work, a mechanical analysis integrating the fluids overpressuring development is proposed to discuss on the validity of the structural interpretation. At first, an analogue of the Chartreuse Toarcian Fm, the albanian Posidonia Schist, is documented as it can provide insights on its initial properties and composition of its kerogen content. Laboratory characterisation documents the vertical evolution of the mineralogical, geochemical and mechanical parameters of this potential decollement layer. These physical parameters (i.e. Total Organic Carbon (TOC), porosity/permeability relationship, friction coefficient) are used to address overpressure buildup in the frontal part of the Chartreuse FTB with TEMISFlow Arctem Basin modelling approach (Faille et al, 2014) and the structural emplacement of the Chartreuse thrust units using the FLAMAR thermo-mechanical model (Burov et al, 2014). The hydro-mechanical modeling results highlight the calendar, distribution and magnitude of the overpressure that developed within the source-rock in the footwall of a simple fault-bend fold structure localized in the frontal part of the Chartreuse FTB. Several key geological conditions are required to create an overpressure able to fracture the shale-rocks and induce a significant change in the rheological behaviour: high TOC, low permeability, favourable structural evolution. These models highlight the importance of modeling the impact of a diffuse natural hydraulic fracturing to explain fluids propagation toward the foreland within

  20. Studies on the mechanical behavior of rock anchors. ; Results of in-situ pull-out tests. Rock anchor no rikigaku kyodo ni kansuru kenkyu. ; Gen prime ichi shiken ni okeru anchor no kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Arimoto, K.; Ebisu, S.; Nakagawa, M.; Usui, M.; Someya, T.; Machida, N. (Okumura Corp., Tokyo (Japan))

    1991-10-31

    The rock anchor method is planned to apply to some permanent structures but since this method was developed for temporary structures, the clarification of the transferring mechanism of force from an anchor to a rockmass, the fracture mechanism and the development of the dynamic model have not been established. This paper arranged the data obtained by a full-scale, in-situ pulling out test of a rock anchor as the first step to understand the dynamic behavior and analyzed by paying attetion to the modulus of deformation of the rockmass where the anchor was embedded to elucidate the affecting degree of rockmass modulus of deformation, the embedded length and the tendon diameter on the dynamic behavior of the anchor. The rock anchor behavior could be expressed accurately by applying a theoretical solution derived by the balancing condition of forces at the boundary face. Especially, when the rockmass is uniform and the fracture occurrs at the interface between the tendon and grout, this approach can express the fracture with the accuracy similar to that made by the finite element method. 6 refs., 11 figs.,1 tab.

  1. A microstructural study of fault rocks from the SAFOD: Implications for the deformation mechanisms and strength of the creeping segment of the San Andreas Fault

    Science.gov (United States)

    Hadizadeh, Jafar; Mittempergher, Silvia; Gratier, Jean-Pierre; Renard, Francois; Di Toro, Giulio; Richard, Julie; Babaie, Hassan A.

    2012-09-01

    The San Andreas Fault zone in central California accommodates tectonic strain by stable slip and microseismic activity. We study microstructural controls of strength and deformation in the fault using core samples provided by the San Andreas Fault Observatory at Depth (SAFOD) including gouge corresponding to presently active shearing intervals in the main borehole. The methods of study include high-resolution optical and electron microscopy, X-ray fluorescence mapping, X-ray powder diffraction, energy dispersive X-ray spectroscopy, white light interferometry, and image processing. The fault zone at the SAFOD site consists of a strongly deformed and foliated core zone that includes 2-3 m thick active shear zones, surrounded by less deformed rocks. Results suggest deformation and foliation of the core zone outside the active shear zones by alternating cataclasis and pressure solution mechanisms. The active shear zones, considered zones of large-scale shear localization, appear to be associated with an abundance of weak phases including smectite clays, serpentinite alteration products, and amorphous material. We suggest that deformation along the active shear zones is by a granular-type flow mechanism that involves frictional sliding of microlithons along phyllosilicate-rich Riedel shear surfaces as well as stress-driven diffusive mass transfer. The microstructural data may be interpreted to suggest that deformation in the active shear zones is strongly displacement-weakening. The fault creeps because the velocity strengthening weak gouge in the active shear zones is being sheared without strong restrengthening mechanisms such as cementation or fracture sealing. Possible mechanisms for the observed microseismicity in the creeping segment of the SAF include local high fluid pressure build-ups, hard asperity development by fracture-and-seal cycles, and stress build-up due to slip zone undulations.

  2. A dissolution-diffusion sliding model for soft rock grains with hydro-mechanical effect

    Directory of Open Access Journals (Sweden)

    Z. Liu

    2018-06-01

    Full Text Available The deformation and failure of soft rock affected by hydro-mechanical (HM effect are one of the most concerns in geotechnical engineering, which are basically attributed to the grain sliding of soft rock. This study tried to develop a dissolution-diffusion sliding model for the typical red bed soft rock in South China. Based on hydration film, mineral dissolution and diffusion theory, and geochemical thermodynamics, a dissolution-diffusion sliding model with the HM effect was established to account for the sliding rate. Combined with the digital image processing technology, the relationship between the grain size of soft rock and the amplitude of sliding surface was presented. An equation for the strain rate of soft rocks under steady state was also derived. The reliability of the dissolution-diffusion sliding model was verified by triaxial creep tests on the soft rock with the HM coupling effect and by the relationship between the inversion average disjoining pressure and the average thickness of the hydration film. The results showed that the sliding rate of the soft rock grains was affected significantly by the waviness of sliding surface, the shear stress, and the average thickness of hydration film. The average grain size is essential for controlling the steady-state creep rate of soft rock. This study provides a new idea for investigating the deformation and failure of soft rock with the HM effect. Keywords: Soft rock, Hydro-mechanical (HM effect, Mineral dissolution-diffusion, Grain sliding model

  3. Geological history and its impact on the rock mechanics properties of the Olkiluoto site

    International Nuclear Information System (INIS)

    Hudson, J.A.; Cosgrove, J.W.

    2006-03-01

    This report is one of three documents with background information for supporting the development of Posiva's future rock mechanics programme. The other two reports are a summary of all the rock mechanics work completed for Posiva before 2005 (Posiva Working Report) and a technical audit of the numerical modeling work that has been conducted previously for Posiva (REC Memo). The purpose of this report is to establish the extent to which the mechanical properties of the rocks at the Olkiluoto site can be estimated from a knowledge of the geological environment. The main information required for rock mechanics studies of the site is a knowledge of the prevailing stress state, the properties of the intact rock, and the properties of the fractures at all scales - from sizes that could form blocks in the tunnel roof up to the major brittle deformation zones that could be influence the location of the ONKALO and the subsequent repository. Thus, the summary of the geological history in Chapter 2 concentrates on these features and we summarise the ductile and brittle deformational tectonic history of the site, with emphasis on the inferred stress states causing the deformations. Then, in Chapter 3, the rock stress, the hierarchy of brittle fracturing, the fracture properties and the mechanical properties of the rock mass are considered in the light of the geological environment. These features provide the baseline knowledge of the host rock from which the logic of the future rock mechanics programme can be developed, based on: the bedrock model; the site investigation results; the requirements for generating the site descriptive model; the prediction-outcome ONKALO studies; and numerically modeling the effects of excavation for design and safety analysis. The implications of this study for the future rock mechanics work are outlined in Chapter 4 with emphasis on the key features for modeling. (orig.)

  4. Effects of water infusions on mechanical properties of carboniferous rocks

    Energy Technology Data Exchange (ETDEWEB)

    Vavro, M; Chlebik, J

    1977-01-01

    Method of water infusion is used in the Ostrava-Karvina coal region in Czechoslovakia, where the roof of the extracted coal seam consists of thick rock layers (sandstone, Namurian B series) characterized by high resistance to compression, high coefficient of linear elasticity and high capacity of accumulating energy. When the resistance boundary is crossed and the rocks are disturbed this energy is suddenly released and transferred to the surrounding rock masses, coal seam and support system. On the basis of laboratory experiments the physico-mechanical and energy properties of carboniferous rocks together with calculation of their energy coefficient and other parameters are described and calculated. The results of research and theoretical solutions are presented. Practical use of water infusions to influence mechanical properties of sandstone in the roof of coal seams is described with the example of the Dukla coal mine. (5 refs.) (In Polish)

  5. Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the empirical approach

    International Nuclear Information System (INIS)

    Roeshoff, Kennert; Lanaro, Flavio; Lanru Jing

    2002-05-01

    application of different classification systems, advantages and disadvantages of each method could be highlighted. Moreover, a comparison of the results of the methods could be made, so that the differences in the output parameters were studied and explained. This comparison also allowed establishing a range of possible values of the output parameters. Through this process, a suitable determination method was chosen for each rock mechanics property required as outcome of the Project. Based on the critical analysis and comparison of the different rock mass classification systems, a series of recommendations was provided concerning: i) the quality/quantity of the geological/rock mechanics input data; ii) the technique for partitioning of the rock mass in homogeneous domains; iii) the sensitivity and subjectivity of the empirical methods; iv) some limits of the methods; v) some warnings about difficulties, misleading techniques, and; vi) about the need of more studies for the validation of the empirical methods against results from case histories

  6. Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the empirical approach

    Energy Technology Data Exchange (ETDEWEB)

    Roeshoff, Kennert; Lanaro, Flavio [Berg Bygg Konsult AB, Stockholm (Sweden); Lanru Jing [Royal Inst. of Techn., Stockholm (Sweden). Div. of Engineering Geology

    2002-05-01

    by the application of different classification systems, advantages and disadvantages of each method could be highlighted. Moreover, a comparison of the results of the methods could be made, so that the differences in the output parameters were studied and explained. This comparison also allowed establishing a range of possible values of the output parameters. Through this process, a suitable determination method was chosen for each rock mechanics property required as outcome of the Project. Based on the critical analysis and comparison of the different rock mass classification systems, a series of recommendations was provided concerning: i) the quality/quantity of the geological/rock mechanics input data; ii) the technique for partitioning of the rock mass in homogeneous domains; iii) the sensitivity and subjectivity of the empirical methods; iv) some limits of the methods; v) some warnings about difficulties, misleading techniques, and; vi) about the need of more studies for the validation of the empirical methods against results from case histories.

  7. Mechanical Properties of Shock-Damaged Rocks

    Science.gov (United States)

    He, Hongliang; Ahrens, T. J.

    1994-01-01

    Stress-strain tests were performed both on shock-damaged gabbro and limestone. The effective Young's modulus decreases with increasing initial damage parameter value, and an apparent work-softening process occurs prior to failure. To further characterize shock-induced microcracks, the longitudinal elastic wave velocity behavior of shock-damaged gabbro in the direction of compression up to failure was measured using an acoustic transmission technique under uniaxial loading. A dramatic increase in velocity was observed for the static compressive stress range of 0-50 MPa. Above that stress range, the velocity behavior of lightly damaged (D(sub 0) less than 0.1) gabbro is almost equal to unshocked gabbro. The failure strength of heavily-damaged (D(sub 0) greater than 0.1) gabbro is approx. 100-150 MPa, much lower than that of lightly damaged and unshocked gabbros (approx. 230-260 MPa). Following Nur's theory, the crack shape distribution was analyzed. The shock-induced cracks in gabbro appear to be largely thin penny-shaped cracks with c/a values below 5 x 10(exp -4). Moreover, the applicability of Ashby and Sammis's theory relating failure strength and damage parameter of shock-damaged rocks was examined and was found to yield a good estimate of the relation of shock-induced deficit in elastic modulus with the deficit in compressive strength.

  8. Site investigations: Strategy for rock mechanics site descriptive model

    International Nuclear Information System (INIS)

    Andersson, Johan; Christiansson, Rolf; Hudson, John

    2002-05-01

    As a part of the planning work for the Site Investigations, SKB has developed a Rock Mechanics Site Descriptive Modelling Strategy. Similar strategies are being developed for other disciplines. The objective of the strategy is that it should guide the practical implementation of evaluating site specific data during the Site Investigations. It is also understood that further development may be needed. This methodology enables the crystalline rock mass to be characterised in terms of the quality at different sites, for considering rock engineering constructability, and for providing the input to numerical models and performance assessment calculations. The model describes the initial stresses and the distribution of deformation and strength properties of the intact rock, of fractures and fracture zones, and of the rock mass. The rock mass mechanical properties are estimated by empirical relations and by numerical simulations. The methodology is based on estimation of mechanical properties using both empirical and heroretical/numerical approaches; and estimation of in situ rock stress using judgement and numerical modelling, including the influence of fracture zones. These approaches are initially used separately, and then combined to produce the required characterisation estimates. The methodology was evaluated with a Test Case at the Aespoe Hard Rock Laboratory in Sweden. The quality control aspects are an important feature of the methodology: these include Protocols to ensure the structure and coherence of the procedures used, regular meetings to enhance communication, feedback from internal and external reviewing, plus the recording of an audit trail of the development steps and decisions made. The strategy will be reviewed and, if required, updated as appropriate

  9. Site investigations: Strategy for rock mechanics site descriptive model

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Johan [JA Streamflow AB, Aelvsjoe (Sweden); Christiansson, Rolf [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hudson, John [Rock Engineering Consultants, Welwyn Garden City (United Kingdom)

    2002-05-01

    As a part of the planning work for the Site Investigations, SKB has developed a Rock Mechanics Site Descriptive Modelling Strategy. Similar strategies are being developed for other disciplines. The objective of the strategy is that it should guide the practical implementation of evaluating site specific data during the Site Investigations. It is also understood that further development may be needed. This methodology enables the crystalline rock mass to be characterised in terms of the quality at different sites, for considering rock engineering constructability, and for providing the input to numerical models and performance assessment calculations. The model describes the initial stresses and the distribution of deformation and strength properties of the intact rock, of fractures and fracture zones, and of the rock mass. The rock mass mechanical properties are estimated by empirical relations and by numerical simulations. The methodology is based on estimation of mechanical properties using both empirical and heroretical/numerical approaches; and estimation of in situ rock stress using judgement and numerical modelling, including the influence of fracture zones. These approaches are initially used separately, and then combined to produce the required characterisation estimates. The methodology was evaluated with a Test Case at the Aespoe Hard Rock Laboratory in Sweden. The quality control aspects are an important feature of the methodology: these include Protocols to ensure the structure and coherence of the procedures used, regular meetings to enhance communication, feedback from internal and external reviewing, plus the recording of an audit trail of the development steps and decisions made. The strategy will be reviewed and, if required, updated as appropriate.

  10. Failure mechanism and supporting measures for large deformation of Tertiary deep soft rock

    Institute of Scientific and Technical Information of China (English)

    Guo Zhibiao; Wang Jiong; Zhang Yuelin

    2015-01-01

    The Shenbei mining area in China contains typical soft rock from the Tertiary Period. As mining depths increase, deep soft rock roadways are damaged by large deformations and constantly need to be repaired to meet safety requirements, which is a great security risk. In this study, the characteristics of deformation and failure of typical roadway were analyzed, and the fundamental reason for the roadway deformation was that traditional support methods and materials cannot control the large deformation of deep soft rock. Deep soft rock support technology was developed based on constant resistance energy absorption using constant resistance large deformation bolts. The correlative deformation mechanisms of surrounding rock and bolt were analyzed to understand the principle of constant resistance energy absorption. The new technology works well on-site and provides a new method for the excavation of roadways in Tertiary deep soft rock.

  11. In situ tests for investigating thermal and mechanical rock behaviors at an underground research tunnel

    International Nuclear Information System (INIS)

    Kwon, Sangki; Cho, Won-Jin

    2013-01-01

    The understanding of the thermal and mechanical behaviors expected to be happened around an underground high-level radioactive waste (HLW) repository is important for a successful site selection, construction, operation, and closure of the repository. In this study, the thermal and mechanical behaviors of rock and rock mass were investigated from in situ borehole heater test and the studies for characterizing an excavation damaged zone (EDZ), which had been carried out at an underground research tunnel, KURT, constructed in granite for the validation of a HLW disposal concept. Thermal, mechanical, and hydraulic properties in EDZ could be predicted from various in situ and laboratory tests as well as numerical simulations. The complex thermo-mechanical coupling behavior of rock could be modeled using the rock properties. (author)

  12. Dynamic Mechanical Behavior of Dry and Water Saturated Igneous Rock with Acoustic Emission Monitoring

    Directory of Open Access Journals (Sweden)

    Jun Guo

    2018-01-01

    Full Text Available The uniaxial cyclic loading tests have been conducted to study the mechanical behavior of dry and water saturated igneous rock with acoustic emission (AE monitoring. The igneous rock samples are dried, naturally immersed, and boiled to get specimens with different water contents for the testing. The mineral compositions and the microstructures of the dry and water saturated igneous rock are also presented. The dry specimens present higher strength, fewer strains, and rapid increase of AE count subjected to the cyclic loading, which reflects the hard and brittle behavior and strong burst proneness of igneous rock. The water saturated specimens have lower peak strength, more accumulated strains, and increase of AE count during the cyclic loading. The damage of the igneous rocks with different water contents has been identified by the Felicity Ratio Analysis. The cyclic loading and unloading increase the dislocation between the mineral aggregates and the water-rock interactions further break the adhesion of the clay minerals, which jointly promote the inner damage of the igneous rock. The results suggest that the groundwater can reduce the burst proneness of the igneous rock but increase the potential support failure of the surrounding rock in igneous invading area. In addition, the results inspire the fact that the water injection method is feasible for softening the igneous rock and for preventing the dynamic disasters within the roadways and working faces located in the igneous intrusion area.

  13. Ground water movements around a repository. Rock mechanics analyses

    International Nuclear Information System (INIS)

    Ratigan, J.L.

    1977-09-01

    The determination and rational assessment of groundwater flow around a repository depends upon the accurate analysis of several interdependent and coupled phenomenological events occuring within the rock mass. In particular, the groundwater flow pathways (joints) are affected by the excavation and thermomechanical stresses developed within the rock mass, and the properties, of the groundwater are altered by the temperature perturbations in the rock mass. The objective of this report is to present the results of the rock mechanics analysis for the repository excavation and the thermally-induced loadings. Qualitative analysis of the significance of the rock mechanics results upon the groundwater flow is provided in this report whenever such an analysis can be performed. Non-linear rock mechanics calculations have been completed for the repository storage tunnels and the global repository domain. The rock mass has been assumed to possess orthoganol joint sets or planes of weakness with finite strength characteristics. In the local analyses of the repository storage tunnels the effects of jointorientation and repository ventilation have been examined. The local analyses indicated that storage room support requirements and regions of strength failure are highly dependent upon joint orientation. The addition of storage tunnel ventilation was noted to reduce regions of strength failure, particularly during the 30 year operational phase of the repository. Examination of the local stresses around the storage tunnels indicated the potential for perturbed hydraulic permeabilities. The permeabilities can be expected to be altered to a greater degree by the stresses resulting from excavation than from stresses which are thermally induced. The thermal loading provided by the instantaneous waste emplacement resulted in stress states and displacements quite similar to those provided by the linear waste emplacement sequence

  14. Control of Rock Mechanics in Underground Ore Mining

    Science.gov (United States)

    Golik, V. I.; Efremenkov, A. B.

    2017-07-01

    Performance indicators in underground mining of thick iron fields can be insufficient since geo-mechanic specifics of ore-hosting fields might be considered inadequately, as a consequence, critical deformations and even earth’s surface destruction are possible, lowering the indicators of full subsurface use, this way. The reason for it is the available approach to estimating the performance of mining according to ore excavation costs, without assessing losses of valuable components and damage to the environment. The experimental approach to the problem is based on a combination of methods to justify technical capability and performance of mining technology improvement with regard to geomechanical factors. The main idea of decisions to be taken is turning geo-materials into the condition of triaxial compression via developing the support constructions of blocked up structural rock block. The study was carried out according to an integrated approach based on the analysis of concepts, field observations, and simulation with the photo-elastic materials in conditions of North Caucasus deposits. A database containing information on the deposit can be developed with the help of industrial experiments and performance indicators of the field can be also improved using the ability of ore-hosting fields to develop support constructions, keeping the geo-mechanical stability of the system at lower cost, avoiding ore contamination at the processing stage. The proposed model is a specific one because an adjustment coefficient of natural and anthropogenic stresses is used and can be adopted for local conditions. The relation of natural to anthropogenic factors can make more precise the standards of developed, prepared and ready to excavation ore reserves relying on computational methods. It is possible to minimize critical stresses and corresponding deformations due to dividing the ore field into sectors safe from the standpoint of geo-mechanics, and using less cost

  15. Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the theoretical approach

    Energy Technology Data Exchange (ETDEWEB)

    Staub, Isabelle; Fredriksson, Anders; Outters, Nils [Golder Associates AB, Uppsala (Sweden)

    2002-05-01

    In the purpose of studying the possibilities of a Deep Repository for spent fuel, the Swedish Nuclear and Fuel Management Company (SKB) is currently planning for Site Investigations. Data collected from these Site Investigations are interpreted and analysed to achieve the full Site Description, which is built up of models from all the disciplines that are considered of importance for the Site Description. One of these models is the Rock Mechanical Descriptive Model,which would be developed for any site in hard crystalline rock, and is a combination and evaluation of the characterisation of rock mass by means of empirical relationships and a theoretical approach based on numerical modelling. The present report describes the theoretical approach. The characterisation of the mechanical properties of the rock mass, viewed as a unit consisting of intact rock and fractures, is achieved by numerical simulations with following input parameters: initial stresses, fracture geometry, distribution of rock mechanical properties, such as deformation and strength parameters, for the intact rock and for the fractures. The numerical modelling was performed with the two-dimensional code UDEC, and the rock block models were generated from 2D trace sections extracted from the 3D Discrete Fracture Network (DFN) model. Assumptions and uncertainties related to the set-up of the model are considered. The numerical model was set-up to simulate a plain strain-loading test. Different boundary conditions were applied on the model for simulating stress conditions (I) in the undisturbed rock mass, and (II) at the proximity of a tunnel. In order to assess the reliability of the model sensitivity analyses have been conducted on some rock block models for defining the dependency of mechanical properties to in situ stresses, the influence of boundary conditions, rock material and joint constitutive models used to simulate the behaviour of intact rock and fractures, domain size and anisotropy. To

  16. Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the theoretical approach

    International Nuclear Information System (INIS)

    Staub, Isabelle; Fredriksson, Anders; Outters, Nils

    2002-05-01

    In the purpose of studying the possibilities of a Deep Repository for spent fuel, the Swedish Nuclear and Fuel Management Company (SKB) is currently planning for Site Investigations. Data collected from these Site Investigations are interpreted and analysed to achieve the full Site Description, which is built up of models from all the disciplines that are considered of importance for the Site Description. One of these models is the Rock Mechanical Descriptive Model,which would be developed for any site in hard crystalline rock, and is a combination and evaluation of the characterisation of rock mass by means of empirical relationships and a theoretical approach based on numerical modelling. The present report describes the theoretical approach. The characterisation of the mechanical properties of the rock mass, viewed as a unit consisting of intact rock and fractures, is achieved by numerical simulations with following input parameters: initial stresses, fracture geometry, distribution of rock mechanical properties, such as deformation and strength parameters, for the intact rock and for the fractures. The numerical modelling was performed with the two-dimensional code UDEC, and the rock block models were generated from 2D trace sections extracted from the 3D Discrete Fracture Network (DFN) model. Assumptions and uncertainties related to the set-up of the model are considered. The numerical model was set-up to simulate a plain strain-loading test. Different boundary conditions were applied on the model for simulating stress conditions (I) in the undisturbed rock mass, and (II) at the proximity of a tunnel. In order to assess the reliability of the model sensitivity analyses have been conducted on some rock block models for defining the dependency of mechanical properties to in situ stresses, the influence of boundary conditions, rock material and joint constitutive models used to simulate the behaviour of intact rock and fractures, domain size and anisotropy. To

  17. Rock mechanics issues and research needs in the disposal of wastes in hydraulic fractures

    International Nuclear Information System (INIS)

    Doe, T.W.; McClain, W.C.

    1984-07-01

    The proposed rock mechanics studies outlined in this document are designed to answer the basic questions concerning hydraulic fracturing for waste disposal. These questions are: (1) how can containment be assured for Oak Ridge or other sites; and (2) what is the capacity of a site. The suggested rock mechanics program consists of four major tasks: (1) numerical modeling, (2) laboratory testing, (3) field testing, and (4) monitoring. These tasks are described

  18. Mechanism of adsorption of cations onto rocks

    International Nuclear Information System (INIS)

    Kitamura, Akira; Yamamoto, Tadashi; Fujiwara, Kenso; Nishikawa, Sataro; Moriyama, Hirotake

    1999-01-01

    Adsorption behavior of cations onto granite was investigated. The distribution coefficient (K d ) of Sr 2+ and Ba 2+ onto granite was determined in the solution of which pH was ranged from 3.5 to 11.3 and ionic strength was set at 10 -2 and 10 -1 . The K d values were found to increase with increasing pH and with deceasing ionic strength. The obtained data were successfully analyzed by applying an electrical double layer model. The optimum parameter values of the double layer electrostatics and adsorption reactions were obtained, and the mechanism of adsorption of cations onto granite was discussed. Feldspar was found to play an important role in their adsorption. (author)

  19. Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique

    Directory of Open Access Journals (Sweden)

    Guoqing Chen

    2015-01-01

    Full Text Available Acoustic emission (AE technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1 small scale direct shear tests of rock bridge with different lengths and (2 large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope.

  20. Drill-back studies examine fractured, heated rock

    International Nuclear Information System (INIS)

    Wollenberg, H.A.; Flexser, S.; Myer, L.R.

    1990-01-01

    To investigate the effects of heating on the mineralogical, geochemical, and mechanical properties of rock by high-level radioactive waste, cores are being examined from holes penetrating locations where electric heaters simulated the presence of a waste canister, and from holes penetration natural hydrothermal systems. Results to date indicate the localized mobility and deposition of uranium in an open fracture in heated granitic rock, the mobility of U in a breccia zone in an active hydrothermal system in tuff, and the presence of U in relatively high concentration in fracture-lining material in tuff. Mechanical -- property studies indicate that differences in compressional- and shear-wave parameters between heated and less heated rock can be attributed to differences in the density of microcracks. Emphasis has shifted from initial studies of granitic rock at Stripa, Sweden to current investigations of welded tuff at the Nevada Test Site. 7 refs., 8 figs

  1. Correlating P-wave Velocity with the Physico-Mechanical Properties of Different Rocks

    Science.gov (United States)

    Khandelwal, Manoj

    2013-04-01

    In mining and civil engineering projects, physico-mechanical properties of the rock affect both the project design and the construction operation. Determination of various physico-mechanical properties of rocks is expensive and time consuming, and sometimes it is very difficult to get cores to perform direct tests to evaluate the rock mass. The purpose of this work is to investigate the relationships between the different physico-mechanical properties of the various rock types with the P-wave velocity. Measurement of P-wave velocity is relatively cheap, non-destructive and easy to carry out. In this study, representative rock mass samples of igneous, sedimentary, and metamorphic rocks were collected from the different locations of India to obtain an empirical relation between P-wave velocity and uniaxial compressive strength, tensile strength, punch shear, density, slake durability index, Young's modulus, Poisson's ratio, impact strength index and Schmidt hammer rebound number. A very strong correlation was found between the P-wave velocity and different physico-mechanical properties of various rock types with very high coefficients of determination. To check the sensitivity of the empirical equations, Students t test was also performed, which confirmed the validity of the proposed correlations.

  2. Probabilistic-Stochastic Model of Distribution of Physical and Mechanical Properties of Soft Mineral Rocks

    Directory of Open Access Journals (Sweden)

    O.O. Sdvizhkova

    2017-12-01

    Full Text Available The physical and mechanical characteristics of soils and soft rocks obtained as a result of laboratory tests are important initial parameters for assessing the stability of natural and artificial slopes. Such properties of rocks as adhesion and the angle of internal friction are due to the influence of a number of natural and technogenic factors. At the same time, from the set of factors influencing the stability of the slope, the most significant ones are singled out, which to a greater extent determine the properties of the rocks. The more factors are taken into account in the geotechnical model, the more closely the properties of the rocks are studied, which increases the accuracy of the scientific forecast of the landslide danger of the slope. On the other hand, an increase in the number of factors involved in the model complicates it and causes a decrease in the reliability of geotechnical calculations. The aim of the work is to construct a statistical distribution of the studied physical and mechanical properties of soft rocks and to substantiate a probabilistic statistical model. Based on the results of laboratory tests of rocks, the statistical distributions of the quantitative traits studied, the angle of internal friction φ and the cohesion, were constructed. It was established that the statistical distribution of physical mechanical properties of rocks is close to a uniform law.

  3. A new method to test rock abrasiveness based on physico-mechanical and structural properties of rocks

    Directory of Open Access Journals (Sweden)

    V.N. Oparin

    2015-06-01

    Full Text Available A new method to test rock abrasiveness is proposed based upon the dependence of rock abrasiveness on their structural and physico-mechanical properties. The article describes the procedure of presentation of properties that govern rock abrasiveness on a canonical scale by dimensionless components, and the integrated estimation of the properties by a generalized index. The obtained results are compared with the known classifications of rock abrasiveness.

  4. Mechanical Characteristics Analysis of Surrounding Rock on Anchor Bar Reinforcement

    Science.gov (United States)

    Gu, Shuan-cheng; Zhou, Pan; Huang, Rong-bin

    2018-03-01

    Through the homogenization method, the composite of rock and anchor bar is considered as the equivalent material of continuous, homogeneous, isotropic and strength parameter enhancement, which is defined as reinforcement body. On the basis of elasticity, the composite and the reinforcement are analyzed, Based on strengthening theory of surrounding rock and displacement equivalent conditions, the expression of reinforcement body strength parameters and mechanical parameters is deduced. The example calculation shows that the theoretical results are close to the results of the Jia-mei Gao[9], however, closer to the results of FLAC3D numerical simulation, it is proved that the model and surrounding rock reinforcement body theory are reasonable. the model is easy to analyze and calculate, provides a new way for determining reasonable bolt support parameters, can also provides reference for the stability analysis of underground cavern bolting support.

  5. Lithophysal Rock Mass Mechanical Properties of the Repository Host Horizon

    International Nuclear Information System (INIS)

    D. Rigby

    2004-01-01

    The purpose of this calculation is to develop estimates of key mechanical properties for the lithophysal rock masses of the Topopah Spring Tuff (Tpt) within the repository host horizon, including their uncertainties and spatial variability. The mechanical properties to be characterized include an elastic parameter, Young's modulus, and a strength parameter, uniaxial compressive strength. Since lithophysal porosity is used as a surrogate property to develop the distributions of the mechanical properties, an estimate of the distribution of lithophysal porosity is also developed. The resulting characterizations of rock parameters are important for supporting the subsurface design, developing the preclosure safety analysis, and assessing the postclosure performance of the repository (e.g., drift degradation and modeling of rockfall impacts on engineered barrier system components)

  6. Research on base rock mechanic characteristics of caverns for radioactive waste disposal

    International Nuclear Information System (INIS)

    Isei, Takehiro; Katsuyama, Kunihisa; Seto, Masahiro; Ogata, Yuji; Utagawa, Manabu

    1997-01-01

    It has been considered that underground space is mechanically stable as compared with on the ground, and superior for storing radioactive waste for long period. However, in order to utilize underground space for the place of radioactive waste disposal, its long term stability such as the aseismatic ability of base rocks must be ensured, and for this purpose, it is necessary to grasp the mechanical characteristics of the base rocks around caverns, and to advance the technology for measuring and evaluating minute deformation and earth pressure change. In this research, the study on the fracture mechanics characteristics of base rocks and the development of the technology for measuring long terms stress change of base rocks were carried out. In this research, what degree the memory of past stress is maintained by rocks was presumed by measuring AE and strain when stress was applied to rock test pieces. The rocks tested were tuff, sandstone and granite. The experimental method and the experimental results of the prestress by AE method and DRA are reported. (K.I.)

  7. Influence aqueous solutions on the mechanical behavior of argillaceous rocks

    International Nuclear Information System (INIS)

    Wakim, J.

    2005-12-01

    The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock

  8. Numerical study of influence of drilling depth and physico-mechanical characteristics of bedding of rock ores on stability of horizontal well

    International Nuclear Information System (INIS)

    Dzhukataev, Z.D.

    1997-01-01

    Stability of elastic and plastic equilibrium of deep horizontal well has been studied conformably to West Kazakhstan deposits conditions. Different forms of flat stability loss for rock ores massif are studied. This massif was weaken by deep horizontal well, on counter of this well uniformly distributed load is enclosed - pressure of drilling mortar. Linearized boundary conditions for stability are defined on the well counter and on boundary between field of elastic and inelastic deformations. The characteristic determinant is received. It is revealed, that greatest from critical pressures takes place under wave-formation by well counter equals to 1

  9. Statistical fracture mechanics approach to the strength of brittle rock

    International Nuclear Information System (INIS)

    Ratigan, J.L.

    1981-06-01

    Statistical fracture mechanics concepts used in the past for rock are critically reviewed and modifications are proposed which are warranted by (1) increased understanding of fracture provided by modern fracture mechanics and (2) laboratory test data both from the literature and from this research. Over 600 direct and indirect tension tests have been performed on three different rock types; Stripa Granite, Sierra White Granite and Carrara Marble. In several instances assumptions which are common in the literature were found to be invalid. A three parameter statistical fracture mechanics model with Mode I critical strain energy release rate as the variant is presented. Methodologies for evaluating the parameters in this model as well as the more commonly employed two parameter models are discussed. The experimental results and analysis of this research indicate that surfacially distributed flaws, rather than volumetrically distributed flaws are responsible for rupture in many testing situations. For several of the rock types tested, anisotropy (both in apparent tensile strength and size effect) precludes the use of contemporary statistical fracture mechanics models

  10. Failure mechanism and coupled static-dynamic loading theory in deep hard rock mining: A review

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2017-08-01

    Full Text Available Rock failure phenomena, such as rockburst, slabbing (or spalling and zonal disintegration, related to deep underground excavation of hard rocks are frequently reported and pose a great threat to deep mining. Currently, the explanation for these failure phenomena using existing dynamic or static rock mechanics theory is not straightforward. In this study, new theory and testing method for deep underground rock mass under coupled static-dynamic loading are introduced. Two types of coupled loading modes, i.e. “critical static stress + slight disturbance” and “elastic static stress + impact disturbance”, are proposed, and associated test devices are developed. Rockburst phenomena of hard rocks under coupled static-dynamic loading are successfully reproduced in the laboratory, and the rockburst mechanism and related criteria are demonstrated. The results of true triaxial unloading compression tests on granite and red sandstone indicate that the unloading can induce slabbing when the confining pressure exceeds a certain threshold, and the slabbing failure strength is lower than the shear failure strength according to the conventional Mohr-Column criterion. Numerical results indicate that the rock unloading failure response under different in situ stresses and unloading rates can be characterized by an equivalent strain energy density. In addition, we present a new microseismic source location method without premeasuring the sound wave velocity in rock mass, which can efficiently and accurately locate the rock failure in hard rock mines. Also, a new idea for deep hard rock mining using a non-explosive continuous mining method is briefly introduced.

  11. Panel discussion on rock mechanics issues in repository design

    International Nuclear Information System (INIS)

    Bieniawski, Z.T.; Kim, K.S.; Nataraja, M.

    1996-01-01

    The panel discussion was introduced by Mr. Z.T.(Richard) Bieniawski and then continued with five additional speakers. The topics covered in the discussion included rock mechanics pertaining to the design of underground facilities for the disposal of radioactive wastes and the safety of such facilities. The speakers included: Mr. Kun-Soo Kim who is a specialist in the area of rock mechanics testing during the Basalt Waste Isolation Project; Dr. Mysore Nataraja who is the senior project manager with the NRC; Dr. Michael Voegele who is the project manager for Science Applications International Corporation (SAIC) on the Yucca Mountain Project; Dr. Edward Cording who is a member of the Nuclear Waste Technical Review Board; and Dr. Hemendra Kalia who is employed by Los Alamos National Laboratory and coordinates various activities of testing programs at the Yucca Mountain Site

  12. Rock mechanics applied to cut and fill mining in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Willoughby, D. R.

    1980-05-15

    Cut and fill mining and recent changes made possible by the application of rock mechanics principles are briefly introduced. The principal interests of professional groups associated with the industry, and incentives that exist to encourage research of benefit to the industry in general, are identified. Details are given of recent advances in rock mechanics instrumentation and technique by drawing to a large extent on experience gained in projects that have been conducted jointly with the mining companies. Examples of the application of the results of this research are given on a mine site basis. Reference is made where possible to papers that describe the examples in more detail. The review is concluded with identification of topics that require further research.

  13. Assessment of rock wool as support material for on-site sanitation: hydrodynamic and mechanical characterization.

    Science.gov (United States)

    Wanko, Adrien; Laurent, Julien; Bois, Paul; Mosé, Robert; Wagner-Kocher, Christiane; Bahlouli, Nadia; Tiffay, Serge; Braun, Bouke; Provo kluit, Pieter-Willem

    2016-01-01

    This study proposes mechanical and hydrodynamic characterization of rock wool used as support material in compact filter. A double-pronged approach, based on experimental simulation of various physical states of this material was done. First of all a scanning electron microscopy observation allows to highlight the fibrous network structure, the fibres sizing distribution and the atomic absorption spectrum. The material was essentially lacunar with 97 ± 2% of void space. Static compression tests on variably saturated rock wool samples provide the fact that the strain/stress behaviours depend on both the sample conditioning and the saturation level. Results showed that water exerts plastifying effect on mechanical behaviour of rock wool. The load-displacement curves and drainage evolution under different water saturation levels allowed exhibiting hydraulic retention capacities under stress. Finally, several tracer experiments on rock wool column considering continuous and batch feeding flow regime allowed: (i) to determine the flow model for each test case and the implications for water dynamic in rock wool medium, (ii) to assess the rock wool double porosity and discuss its advantages for wastewater treatment, (iii) to analyse the benefits effect for water treatment when the high level of rock wool hydric retention was associated with the plug-flow effect, and (iv) to discuss the practical contributions for compact filter conception and management.

  14. Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Lin, M.; Hardy, M.P.; Bauer, S.J.

    1993-06-01

    Rock mass mechanical properties are important in the design of drifts and ramps. These properties are used in evaluations of the impacts of thermomechanical loading of potential host rock within the Yucca Mountain Site Characterization Project. Representative intact rock and joint mechanical properties were selected for welded and nonwelded tuffs from the currently available data sources. Rock mass qualities were then estimated using both the Norwegian Geotechnical Institute (Q) and Geomechanics Rating (RMR) systems. Rock mass mechanical properties were developed based on estimates of rock mass quality, the current knowledge of intact properties, and fracture/joint characteristics. Empirical relationships developed to correlate the rock mass quality indices and the rock mass mechanical properties were then used to estimate the range of rock mass mechanical properties

  15. Mizunami Underground Research Laboratory project. Rock mechanical investigations annual report for fiscal year 2013

    International Nuclear Information System (INIS)

    Sato, Toshinori; Sanada, Hiroyuki; Tanno, Takeo

    2015-02-01

    In order to establish the scientific and technical basis for geological disposal of technology, Japan Atomic Energy Agency (JAEA) is pursuing the geoscientific research project namely the Mizunami Underground Research Laboratory (MIU) in the crystalline rock environment at Tono Geoscience Center (TGC). In the MIU Project, geoscientific research is being carried out in three overlapping phases; Surface-based Investigation Phase (Phase I: FY1996 - 2004), Construction Phase (Phase II: FY2004- in progress) and Operation Phase (Phase III: FY2010- in progress). In the rock mechanical investigations at the Phase II, the research aims at “Characterization of geological environment in the Excavation Disturbed Zone (EDZ)” from the viewpoint of safety assessment. For the research, the specific information of the EDZ such as (1) size and structures, (2) petrophysical/geomechanical properties, and (3) stress state are required. The research also aims at “Characterization of geomechanical stability around tunnel” from the viewpoint of design and construction of underground facilities. For the research, the specific information such as (4) local stress regime, (5) spatial variability of petrophysical/geomechanical properties of rocks, and (6) distribution of discontinuities intersecting underground tunnels are required. The measurement system for rock mass behavior has been manufactured and set for groundwater recovery experiment in the Phase III. This report presents the results of following rock mechanical investigations conducted in FY 2013. In-situ stress measurements using Compact Conical-ended Borehole Overcoring Technique were performed at the - 500m stage. Measurement system for rock mass displacement using optical fiber was installed at the - 500m stage as part of the groundwater recovery experiment. Study on the modeling based on equivalent continuum model was continued. Phenomenological study and theoretical study on long-term behavior of crystalline rock were

  16. Geological and Rock Mechanics Perspectives for Underground Coal Gasification in India

    Science.gov (United States)

    Singh, Ajay K.; Singh, Rajendra

    2017-07-01

    The geological resources of coal in India are more than 308 billion tonnes upto a depth of 1200 m, out of which proved reserve has been reported at around 130 billion tonnes. There is an increasing requirement to increase the energy extraction efficiency from coal as the developmental prospects of India increase. Underground coal gasification (UCG) is a potential mechanism which may be utilized for extraction of deep-seated coal reserves. Some previous studies suggest that lignites from Gujarat and Rajasthan, along with tertiary coals from northeastern India can be useful from the point of view of UCG. We discuss some geological literature available for these areas. Coming to the rock mechanics perspectives, during UCG the rock temperature is considerable high. At this temperature, most empirical models of rock mechanics may not be applied. In this situation, the challenges for numerical modelling of UCG sites increases manifold. We discuss some of the important modelling geomechanical issues related to UCG in India.

  17. Rock deformation equations and application to the study on slantingly installed disc cutter

    Science.gov (United States)

    Zhang, Zhao-Huang; Meng, Liang; Sun, Fei

    2014-08-01

    At present the mechanical model of the interaction between a disc cutter and rock mainly concerns indentation experiment, linear cutting experiment and tunnel boring machine (TBM) on-site data. This is not in line with the actual rock-breaking movement of the disc cutter and impedes to some extent the research on the rock-breaking mechanism, wear mechanism and design theory. Therefore, our study focuses on the interaction between the slantingly installed disc cutter and rock, developing a model in accordance with the actual rock-breaking movement. Displacement equations are established through an analysis of the velocity vector at the rock-breaking point of the disc cutter blade; the functional relationship between the displacement parameters at the rock-breaking point and its rectangular coordinates is established through an analysis of micro-displacement vectors at the rock-breaking point, thus leading to the geometric equations of rock deformation caused by the slantingly installed disc cutter. Considering the basically linear relationship between the cutting force of disc cutters and the rock deformation before and after the leap break of rock, we express the constitutive relations of rock deformation as generalized Hooke's law and analyze the effect of the slanting installation angle of disc cutters on the rock-breaking force. This will, as we hope, make groundbreaking contributions to the development of the design theory and installation practice of TBM.

  18. Rock mechanics investigations of structural stability in the Bulli seam at West Cliff Colliery

    Energy Technology Data Exchange (ETDEWEB)

    Jaggar, F

    1978-03-01

    Rock mechanics investigations were conducted at West Cliff colliery to obtain rock properties and stress measurements and study the stability of mining structures. The roof and floor were drilled in order to obtain core for rock testing and lump samples of coal were collected in order to measure the coal properties. Absolute stress measurements were obtained using CSIR cells. The strata were sufficiently uniform and competent to overcore the emplaced cells. Testing revealed that the rocks were better than average for coal measure sedimentary strata and the stresses indicated the existence of a moderately high horizontal stress field. The coal is of average strength only with some marked variation relating to the very banded nature of the seam. Finite element analyses showed that the rectangular roadways driven using roof bolts and timber supports were stable and adequately stable by an indicative factor of safety of about l.5.

  19. Theoretical study of rock mass investigation efficiency

    International Nuclear Information System (INIS)

    Holmen, Johan G.; Outters, Nils

    2002-05-01

    The study concerns a mathematical modelling of a fractured rock mass and its investigations by use of theoretical boreholes and rock surfaces, with the purpose of analysing the efficiency (precision) of such investigations and determine the amount of investigations necessary to obtain reliable estimations of the structural-geological parameters of the studied rock mass. The study is not about estimating suitable sample sizes to be used in site investigations.The purpose of the study is to analyse the amount of information necessary for deriving estimates of the geological parameters studied, within defined confidence intervals and confidence level In other words, how the confidence in models of the rock mass (considering a selected number of parameters) will change with amount of information collected form boreholes and surfaces. The study is limited to a selected number of geometrical structural-geological parameters: Fracture orientation: mean direction and dispersion (Fisher Kappa and SRI). Different measures of fracture density (P10, P21 and P32). Fracture trace-length and strike distributions as seen on horizontal windows. A numerical Discrete Fracture Network (DFN) was used for representation of a fractured rock mass. The DFN-model was primarily based on the properties of an actual fracture network investigated at the Aespoe Hard Rock Laboratory. The rock mass studied (DFN-model) contained three different fracture sets with different orientations and fracture densities. The rock unit studied was statistically homogeneous. The study includes a limited sensitivity analysis of the properties of the DFN-model. The study is a theoretical and computer-based comparison between samples of fracture properties of a theoretical rock unit and the known true properties of the same unit. The samples are derived from numerically generated boreholes and surfaces that intersect the DFN-network. Two different boreholes are analysed; a vertical borehole and a borehole that is

  20. Results of monitoring at Olkiluoto in 2012. Rock mechanics

    International Nuclear Information System (INIS)

    Johansson, E.; Siren, T.

    2014-01-01

    The rock mechanics monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The rock mechanics monitoring programme 2012 consisted of seismic measurements, GPS measurements, surface levelling measurements and temperature measurements at Olkiluoto and vicinity and displacement measurements, temperature measurements and visual tunnel observations carried out in the ONKALO. The Posiva's microseismic network consists of 17 seismic stations and 22 triaxial sensors. Six stations are in the ONKALO. In spite of few breaks the network operated continuously and well during 2012. The number of located events was much smaller in 2012 than during the previous years due to the interruption of the excavation. Altogether 337 events were located in the Olkiluoto area of which about half (181) were explosions. Two excavation induced earthquakes were observed at -420 m level and were associated with a known tunnel crosscutting fracture. According to the seismic monitoring the rock mass has been stable in 2012. The local GPS network consists of 19 stations. The whole network was measured twice in 2012. Most of the inner network baselines showed very small motions as in the previous years: 80 % of change rates were smaller than 0.10 mm/a. Roughly one third of the change rates are statistically significant. One baseline was also measured using electronic distance measurements (EDM) and the results fitted well to the times series. The surface levelling network currently consists of 87 fixed measuring points. During 2012 only measuring loops VLJ, ONKALO and Olkiluoto Strait were measured. The results indicated that vertical deformations were small compared to 2011 results. The largest deformations around 0.6 mm upwards existed above the VLJ-repository. The displacement measurements in 2012 consisted of the extensometer measurements in the technical rooms of the ONKALO. Readings were taken continuously once a hour by a

  1. A Hydrous Seismogenic Fault Rock Indicating A Coupled Lubrication Mechanism

    Science.gov (United States)

    Okamoto, S.; Kimura, G.; Takizawa, S.; Yamaguchi, H.

    2005-12-01

    In the seismogenic subduction zone, the predominant mechanisms have been considered to be fluid induced weakening mechanisms without frictional melting because the subduction zone is fundamentally quite hydrous under low temperature conditions. However, recently geological evidence of frictional melting has been increasingly reported from several ancient accretionary prisms uplifted from seismogenic depths of subduction zones (Ikesawa et al., 2003; Austrheim and Andersen, 2004; Rowe et al., 2004; Kitamura et al., 2005) but relationship between conflicting mechanisms; e.g. thermal pressurization of fluid and frictional melting is still unclear. We found a new exposure of pseudotachylyte from a fossilized out-of-sequence thrust (OOST) , Nobeoka thrust in the accretionary complex, Kyushu, southwest Japan. Hanging-wall and foot-wall are experienced heating up to maximum temperature of about 320/deg and about 250/deg, respectively. Hanging-wall rocks of the thrust are composed of shales and sandstones deformed plastically. Foot-wall rocks are composed of shale matrix melange with sandstone and basaltic blocks deformed in a brittle fashion (Kondo et al, 2005). The psudotachylyte was found from one of the subsidiary faults in the hanging wall at about 10 m above the fault core of the Nobeoka thrust. The fault is about 1mm in width, and planer rupture surface. The fault maintains only one-time slip event because several slip surfaces and overlapped slip textures are not identified. The fault shows three deformation stages: The first is plastic deformation of phyllitic host rocks; the second is asymmetric cracking formed especially in the foot-wall of the fault. The cracks are filled by implosion breccia hosted by fine carbonate minerals; the third is frictional melting producing pseudotachylyte. Implosion breccia with cracking suggests that thermal pressurization of fluid and hydro-fracturing proceeded frictional melting.

  2. THM-coupled modeling of selected processes in argillaceous rock relevant to rock mechanics; THM-Gekoppelte Modellierung ausgewaehlter gesteinsmechanisch relevanter Prozesse im Tongestein

    Energy Technology Data Exchange (ETDEWEB)

    Czaikowski, Oliver [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Braunschweig (Germany). Repository Safety Research Div.

    2012-08-15

    Scientific investigations in European countries other than Germany concentrate not only on granite formations (Switzerland, Sweden) but also on argillaceous rock formations (France, Switzerland, Belgium) to assess their suitability as host and barrier rock for the final storage of radioactive waste. In Germany, rock salt has been under thorough study as a host rock over the past few decades. According to a study by the German Federal Institute for Geosciences and Natural Resources, however, not only salt deposits but also argillaceous rock deposits are available at relevant depths and of extensions in space which make final storage of high-level radioactive waste basically possible in Germany. Equally qualified findings about the suitability/unsuitability of non-saline rock formations require fundamental studies to be conducted nationally because of the comparatively low level of knowledge. The article presents basic analyses of coupled mechanical and hydraulic properties of argillaceous rock formations as host rock for a repository. The interaction of various processes is explained on the basis of knowledge derived from laboratory studies, and open problems are deduced. For modeling coupled processes, a simplified analytical computation method is proposed and compared with the results of numerical simulations, and the limits to its application are outlined. (orig.)

  3. Results of Monitoring at Olkiluoto in 2005. Rock Mechanics

    International Nuclear Information System (INIS)

    Riikonen, S.

    2006-08-01

    Programme of Monitoring (Posiva 2003 b) was introduced to study Olkiluoto investigation are both during and following the excavation of underground test facility, ONKALO. Programme consists of four main headings: rock mechanics, hydrology and hydrogeology, geochemistry and other types of disturbance. Monitoring programme in year 2005 consist of three fields of research: microseismic measurements, GPS measurements and precise levelling. This report presents Posiva's rock mechanical monitoring programme results from the year 2005. Report has been composed from annual reports of microseismic measurements, GPS measurements and precise levelling by Sanna Riikonen. In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. This report gives the results of microseismic monitoring during the year 2005. Also the changes in the structure and the operation procedure of the network are described. The network has operated nearly continuously. The total duration of network failures has been about 8 hours. Altogether 2159 events have been located in the Olkiluoto area, in reported time period. The magnitudes of the observed events range from ML = -2.1to ML = 1.6 (ML = magnitude in local Richter's scale). Most of them are explosions. Three of the observed events are be classified as microearthquakes. Evidence of activity that would has influence on the safety of the ONKALO, have not found. The GPS based deformation studies has been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Twenty GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. The local velocity components are small but

  4. Modelling of crustal rock mechanics for radioactive waste storage in Fennoscandia - problem definition

    International Nuclear Information System (INIS)

    Stephansson, O.

    1987-05-01

    Existing knowledge of crustal stresses for Fennoscandia is presented. Generic, two-dimensional models are proposed for vertical and planar sections of a traverse having a direction NW-SE in Northern Fennoscandia. The proposed traverse will include the major neotectonic structures at Lansjaerv and Paervie, respectively, and also the study site for storage of spent nuclear fuel at Kamlunge. The influence of glaciation, deglaciation, glacial rebound on crustal rock mechanics and stability is studied for the modelling work. Global models, with a length of roughly 100 km, will increase our over all understanding of the change in stresses and deformations. These can provide boundary conditions for regional and near-field models. Properties of strength and stiffness of intact granitic rock masses, faults and joints are considered in the modelling of the crustal rock mechanics for any of the three models described. (orig./HP)

  5. Results of monitoring at Olkiluoto in 2013, rock mechanics

    International Nuclear Information System (INIS)

    Johansson, E.

    2014-10-01

    The rock mechanics monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The rock mechanics monitoring programme 2013 consisted of seismic measurements, GPS measurements, surface levelling measurements and temperature measurements at Olkiluoto and vicinity and displacement measurements, temperature measurements and visual tunnel observations made in the ONKALO. The Posiva's microseismic network consists of 17 seismic stations and 21 triaxial sensors. Five stations are in the ONKALO. In spite of few breaks the network operated continuously and well during 2013. The number of located events (436) was slightly more than in 2012, but much less than in 2011. Nearly half of the observed explosions (237) in 2013 occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (137). One small induced earthquake (M L = -1.8) was detected at the depth of 429 m and was probably associated with smaller branches of the brittle fracture zone (OL-BFZ045). According to the seismic monitoring the rock mass has been stable in 2013. The local GPS network consists of 18 stations. Six new stations were set up for permanent tracking during 2013 and in total 12 permanent stations are now operating continuously. Manual measurements were carried out twice in 2013. Most of the inner network baselines showed very small motions as in the previous years: 75% of change rates were smaller than 0.10 mm/y. Roughly one third of the change rates are statistically significant. The surface levelling network currently consists of 87 fixed measuring points. During 2013 all the measuring loops were measured. The results indicated local subsidence area in the ONKALO loop and the rising area in the VLJ loop. Mean deformation rate has been +0.05 mm/y. Only elevation of one benchmark in the GPS station loop has changed more than one millimetre. The continuous displacement measurements in the technical rooms of

  6. Results of monitoring at Olkiluoto in 2013, rock mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E. (ed.) [Saanio and Riekkola Oy, Helsinki (Finland)

    2014-10-15

    The rock mechanics monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The rock mechanics monitoring programme 2013 consisted of seismic measurements, GPS measurements, surface levelling measurements and temperature measurements at Olkiluoto and vicinity and displacement measurements, temperature measurements and visual tunnel observations made in the ONKALO. The Posiva's microseismic network consists of 17 seismic stations and 21 triaxial sensors. Five stations are in the ONKALO. In spite of few breaks the network operated continuously and well during 2013. The number of located events (436) was slightly more than in 2012, but much less than in 2011. Nearly half of the observed explosions (237) in 2013 occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (137). One small induced earthquake (M{sub L} = -1.8) was detected at the depth of 429 m and was probably associated with smaller branches of the brittle fracture zone (OL-BFZ045). According to the seismic monitoring the rock mass has been stable in 2013. The local GPS network consists of 18 stations. Six new stations were set up for permanent tracking during 2013 and in total 12 permanent stations are now operating continuously. Manual measurements were carried out twice in 2013. Most of the inner network baselines showed very small motions as in the previous years: 75% of change rates were smaller than 0.10 mm/y. Roughly one third of the change rates are statistically significant. The surface levelling network currently consists of 87 fixed measuring points. During 2013 all the measuring loops were measured. The results indicated local subsidence area in the ONKALO loop and the rising area in the VLJ loop. Mean deformation rate has been +0.05 mm/y. Only elevation of one benchmark in the GPS station loop has changed more than one millimetre. The continuous displacement measurements in the technical rooms

  7. Strategy for a Rock Mechanics Site Descriptive Model. A test case based on data from the Aespoe HRL

    International Nuclear Information System (INIS)

    Hudson, John A

    2002-06-01

    In anticipation of the SKB Site Investigations for radioactive waste disposal, an approach has been developed for the Rock Mechanics Site Descriptive Model. This approach was tested by predicting the rock mechanics properties of a 600 m x 180 m x 120 m rock volume at the Aespoe Hard Rock Laboratory (HRL) using limited borehole data of the type typically obtained during a site investigation. These predicted properties were then compared with 'best estimate' properties obtained from a study of the test rock volume using additional information, mainly tunnel data. The exercise was known as the Test Case, and is the subject of this Report. Three modelling techniques were used to predict the rock properties: the 'empirical approach' - the rock properties were estimated using rock mass classification schemes and empirical correlation formulae; the 'theoretical approach' - the rock properties were estimated using numerical modelling techniques; and the 'stress approach' - the rock stress state was estimated using primary data and numerical modelling. These approaches are described separately and respectively. Following an explanation of the context for the Test Case within the strategy for developing the Rock Mechanics Site Descriptive Model, conditions at the Aespoe HRL are described in Chapter 2. The Test Case organization and the suite of nine Protocols used to ensure that the work was appropriately guided and co-ordinated are described in Chapter 3. The methods for predicting the rock properties and the rock stress, and comparisons with the 'best estimate' properties of the actual conditions, are presented in Chapters 4 and 5. Finally, the conclusions from this Test Case exercise are given in Chapter 6. General recommendations for the management of this type of Test Case are also included

  8. Strategy for a Rock Mechanics Site Descriptive Model. A test case based on data from the Aespoe HRL

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, John A (ed.) [Rock Engineering Consultants, Welwyn Garden City (United Kingdom)

    2002-06-01

    In anticipation of the SKB Site Investigations for radioactive waste disposal, an approach has been developed for the Rock Mechanics Site Descriptive Model. This approach was tested by predicting the rock mechanics properties of a 600 m x 180 m x 120 m rock volume at the Aespoe Hard Rock Laboratory (HRL) using limited borehole data of the type typically obtained during a site investigation. These predicted properties were then compared with 'best estimate' properties obtained from a study of the test rock volume using additional information, mainly tunnel data. The exercise was known as the Test Case, and is the subject of this Report. Three modelling techniques were used to predict the rock properties: the 'empirical approach' - the rock properties were estimated using rock mass classification schemes and empirical correlation formulae; the 'theoretical approach' - the rock properties were estimated using numerical modelling techniques; and the 'stress approach' - the rock stress state was estimated using primary data and numerical modelling. These approaches are described separately and respectively. Following an explanation of the context for the Test Case within the strategy for developing the Rock Mechanics Site Descriptive Model, conditions at the Aespoe HRL are described in Chapter 2. The Test Case organization and the suite of nine Protocols used to ensure that the work was appropriately guided and co-ordinated are described in Chapter 3. The methods for predicting the rock properties and the rock stress, and comparisons with the 'best estimate' properties of the actual conditions, are presented in Chapters 4 and 5. Finally, the conclusions from this Test Case exercise are given in Chapter 6. General recommendations for the management of this type of Test Case are also included.

  9. Rock mechanics and the economics of cut-and-fill mining

    Energy Technology Data Exchange (ETDEWEB)

    Almgren, G.

    1980-05-15

    The application of rock mechanics to mining has great economic potential. Factors such as loss of ore, rock-dilution, possibilities of machanization and rock support are all influenced by the degree of rock mechanics involvement. In particular loss of ore is limited by the correct dimensioning of pillars and remnants. Rock-dilution, depending upon caving, can in the same way be mastered by the right dimensions of stopes and pillars and of rock supporting. Possibilities of mechanization depend upon sizes of drifts and stopes, stope availabilities and access to the stopes, all depending upon a considered rock mechanic investigation. Also shut-downs in the stopes owing to caving can be affected in the same way. Consequences on the mining economy for cut-and-fil mining are illustrated concerning loss of ore, rock-dilution, mechanization levels and rock support. The biggest influence can be made on rock-dilution and mechanization. Under special circumstances loss of ore can be of the same magnitude, namely if the ore production per year is directly influenced by the loss of ore and can not be compensated by other mining activities. Rock support is of less economic importance compared with rock-dilution and mechanization, presupposed no less of ore-production.

  10. A structural behavior study of rock caverns considering the effects of discontinuities

    International Nuclear Information System (INIS)

    Kim, Jhin Wung; Kim, Sun Hoon; Seo, Jeong Moon; Choi, Kyu Seop; Kim, Dae Hong; Lee, Kyung Jin; Choi, In Gil; Lee, Dong Yong

    1990-06-01

    The objective of this study is to understand the effects of discontinuities within rock masses on the structural behavior of underground rock caverns for radioactive waste disposal, and then develop a computer program for the structural analysis of rock caverns considering these effect of discontinuities. The behavior of rock masses, such as strength, deformation modes, ect., is very difficult to predict because discontinuities in the form of microcracks or joints are randomly distributed within rock masses. Discontinuties existing around the rock cavern for underground radioactive waste disposal may become the main transport pathways of radionuclides, and reduce the strength of rock masses eventually causing the rock cavern structure unstable. Therefore, a comprehensive understanding of the mechanical properties and behavior of discontinuous rock masses and an improvement of structural analysis methods are essential in order to understand the behavior of underground rock cavern structures properly in order to design safe and economic understanding the behavior of discontinuous rock masses is essential. Therfore, this study includes literature review on mechanical properties of and computational models for discontinuous rock masses, and on structures. Then, bases on the engineering judgement a suitable selection and slight modifications on computational models and analysis methods have been made before developing the structural analysis computer program for underground radioactive waste disposal structures. (author)

  11. Results of Monitoring at Olkiluoto in 2010. Rock Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Lahti, M [ed.; Siren, T

    2011-12-15

    The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. After that the number of seismic stations has increased gradually. In 2010 the permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2010.

  12. Results of Monitoring at Olkiluoto in 2010. Rock Mechanics

    International Nuclear Information System (INIS)

    Lahti, M.; Siren, T.

    2011-12-01

    The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. After that the number of seismic stations has increased gradually. In 2010 the permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2010

  13. Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction

    OpenAIRE

    Lyu, Qiao; Ranjith, Pathegama Gamage; Long, Xinping; Ji, Bin

    2016-01-01

    The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/supe...

  14. Mechanisms controlling rock coast evolution in paraglacial landscapes - examples from Arctic, Antarctic and Scandinavian regions

    Science.gov (United States)

    Strzelecki, M. C.; Lim, M.; Kasprzek, M.; Swirad, Z. M.; Rachlewicz, G.; Migoń, P.; Pawlowski, L.; Jaskolski, M.

    2017-12-01

    This paper presents the results of an investigation into the processes controlling development of paraglacial rock coast systems in Hornsund, Svalbard, Admiralty Bay, South Shetland Islands and Gotland Island, Scandinavia. A suite of nested geomorphological and geophysical methods have been applied to characterize the functioning of rock cliffs, shore platforms and stacks influenced by lithological control and geomorphic processes driven by paraglacial coast environments - both in glaciated and deglaciated study sites. Rock hardness, quantified by Schmidt hammer rebound tests, demonstrate strong spatial control on the degree of rock weathering (rock strength) along studied rock coasts. Elevation controlled geomorphic zones are identified and linked to distinct processes and mechanisms, transitioning from peak hardness values at the icefoot/sea-ice through the wave and storm dominated scour zones to the lowest values on the cliff tops, where the effects of periglacial weathering dominate. Observations of rock surface change using a traversing micro-erosion meter (TMEM) indicate that significant changes in erosion rates occur at the junction between shore platform and the cliff toe, where rock erosion is facilitated by frequent wetting and drying and operation of nivation and sea ice processes (formation and melting of snow patches and icefoot complexes). Electrical resistivity tomography (ERT) surveys have been used to investigate frozen ground control on rock coast dynamics and reveal the strong interaction with marine processes in polar coastal settings. In Gotland, Scandinavia the morphology of rocky coastal landforms (rauks) bear traces of numerous environmental changes that occurred in Baltic region over the Holocene including salinity, temperature, ice-cover/storminess and relative sea-level. The results are synthesised to propose a new conceptual model of paraglacial rock coast systems, with the aim of contributing towards a unifying concept of cold region

  15. Theoretical Investigations on the Influence of Artificially Altered Rock Mass Properties on Mechanical Excavation

    Science.gov (United States)

    Hartlieb, Philipp; Bock, Stefan

    2018-03-01

    This study presents a theoretical analysis of the influence of the rock mass rating on the cutting performance of roadheaders. Existing performance prediction models are assessed for their suitability for forecasting the influence of pre-damaging the rock mass with alternative methods like lasers or microwaves, prior to the mechanical excavation process. Finally, the RMCR model was chosen because it is the only reported model incorporating a range of rock mass properties into its calculations. The results show that even very tough rocks could be mechanically excavated if the occurrence, orientation and condition of joints are favourable for the cutting process. The calculated improvements in the cutting rate (m3/h) are up to 350% for the most favourable cases. In case of microwave irradiation of hard rocks with an UCS of 200 MPa, a reasonable improvement in the performance by 120% can be achieved with as little as an extra 0.7 kWh/m3 (= 1% more energy) compared to cutting only.

  16. Hydro-mechanically coupled finite-element analysis of the stability of a fractured-rock slope using the equivalent continuum approach: a case study of planned reservoir banks in Blaubeuren, Germany

    Science.gov (United States)

    Song, Jie; Dong, Mei; Koltuk, Serdar; Hu, Hui; Zhang, Luqing; Azzam, Rafig

    2017-12-01

    Construction works associated with the building of reservoirs in mountain areas can damage the stability of adjacent valley slopes. Seepage processes caused by the filling and drawdown operations of reservoirs also affect the stability of the reservoir banks over time. The presented study investigates the stability of a fractured-rock slope subjected to seepage forces in the lower basin of a planned pumped-storage hydropower (PSH) plant in Blaubeuren, Germany. The investigation uses a hydro-mechanically coupled finite-element analyses. For this purpose, an equivalent continuum model is developed by using a representative elementary volume (REV) approach. To determine the minimum required REV size, a large number of discrete fracture networks are generated using Monte Carlo simulations. These analyses give a REV size of 28 × 28 m, which is sufficient to represent the equivalent hydraulic and mechanical properties of the investigated fractured-rock mass. The hydro-mechanically coupled analyses performed using this REV size show that the reservoir operations in the examined PSH plant have negligible effect on the adjacent valley slope.

  17. Hydro-mechanically coupled finite-element analysis of the stability of a fractured-rock slope using the equivalent continuum approach: a case study of planned reservoir banks in Blaubeuren, Germany

    Science.gov (United States)

    Song, Jie; Dong, Mei; Koltuk, Serdar; Hu, Hui; Zhang, Luqing; Azzam, Rafig

    2018-05-01

    Construction works associated with the building of reservoirs in mountain areas can damage the stability of adjacent valley slopes. Seepage processes caused by the filling and drawdown operations of reservoirs also affect the stability of the reservoir banks over time. The presented study investigates the stability of a fractured-rock slope subjected to seepage forces in the lower basin of a planned pumped-storage hydropower (PSH) plant in Blaubeuren, Germany. The investigation uses a hydro-mechanically coupled finite-element analyses. For this purpose, an equivalent continuum model is developed by using a representative elementary volume (REV) approach. To determine the minimum required REV size, a large number of discrete fracture networks are generated using Monte Carlo simulations. These analyses give a REV size of 28 × 28 m, which is sufficient to represent the equivalent hydraulic and mechanical properties of the investigated fractured-rock mass. The hydro-mechanically coupled analyses performed using this REV size show that the reservoir operations in the examined PSH plant have negligible effect on the adjacent valley slope.

  18. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    1997-03-01

    One must consider micro-structures of rock and rock mass in order to predict the long-term behavior for more than ten thousand years. First we observe the micro-crack distribution of granite which is commonly distributed in Japan, and is widely used for several structures. The creep under constant load and the relaxation under constant displacement are typical time dependent phenomena, and we performed a series of relaxation tests under microscope observation in laboratory. The specimen that is preserved in water is granite as mentioned above. The aim of this experiment is to observe the sequential propagation of micro-cracks and its affect to the macroscopic response of the rock material under relaxation state. Next, a viscoelastic homogenization method is applied for analyzing the behavior of granite that is composed of several kinds of minerals (i.e., a polycrystalline material). The homogenization method developed for analyzing mechanics of composite materials is a mathematical theory that can describe the macroscopic behavior accounting for the microscopic characteristics with periodic microstructures. In this study, it is applied to a polycrystalline rock which involves a few minerals and micro-cracks. Furthermore, it is required to apply the homogenization analysis for rock materials which show a nonlinear time dependent behavior, so we develop a new elasto-visco-plastic homogenization theory, and its validity is checked for some ground structures made by clay. (author)

  19. Rock Strength Anisotropy in High Stress Conditions: A Case Study for Application to Shaft Stability Assessments

    Directory of Open Access Journals (Sweden)

    Watson Julian Matthew

    2015-03-01

    Full Text Available Although rock strength anisotropy is a well-known phenomenon in rock mechanics, its impact on geotechnical design is often ignored or underestimated. This paper explores the concept of anisotropy in a high stress environment using an improved unified constitutive model (IUCM, which can account for more complex failure mechanisms. The IUCM is used to better understand the typical responses of anisotropic rocks to underground mining. This study applies the IUCM to a proposed rock shaft located in high stress/anisotropic conditions. Results suggest that the effect of rock strength anisotropy must be taken into consideration when assessing the rock mass response to mining in high stress and anisotropic rock conditions.

  20. Time dependency in the mechanical properties of crystalline rocks. A literature survey

    International Nuclear Information System (INIS)

    Hagros, A.; Johansson, E.; Hudson, J.A.

    2008-09-01

    Because of the long design life, elevated temperatures, and the location at depth (high stresses), time-dependent aspects of the mechanical properties of crystalline rock are potentially important for the design and the long term safety of the radioactive waste repository at Olkiluoto. However, time-dependent effects in rock mechanics are still one of the least understood aspects of the physical behaviour of rock masses, this being partly due to the fact that it is difficult to conduct long-term experimental tests - either in the laboratory or in situ. Yet, the time-dependent mechanical behaviour needs to be characterised so that it can be included in the modelling studies supporting repository design. The Introduction explains the background to the literature survey and includes definitions of the terms 'creep' (increasing strain at constant stress) and 'stress relaxation' (decreasing stress at constant strain). Moreover, it is noted that the rock around an in situ excavation is loaded by the adjacent rock elements and so the timedependent behaviour will depend on the unloading stiffness of these and hence will not actually be either pure creep or pure stress relaxation. The Appendix contains the results of the literature survey of reported time-dependent research as it applies to crystalline rock. A summary of each of the 38 literature items is presented in tabular form covering document number, subject area, document reference, subject matter, objectives, methodology, highlighted figures, conclusions and comments. It is concluded that the time-dependent failure strength of all rocks observed may be interpreted by sub-critical crack growth assisted by the stress corrosion mechanism. Also, certain parameters are known to affect the long-term properties: mineralogy, grain size, water/water chemistry, confining stress and loading history. At some point in the loading history of rock, the state of crack development reaches a point whereby the continued generation of

  1. Mechanism of groundwater inrush hazard caused by solution mining in a multilayered rock-salt-mining area: a case study in Tongbai, China

    Science.gov (United States)

    Zeng, Bin; Shi, Tingting; Chen, Zhihua; Xiang, Liu; Xiang, Shaopeng; Yang, Muyi

    2018-01-01

    The solution mining of salt mineral resources may contaminate groundwater and lead to water inrush out of the ground due to brine leakage. Through the example of a serious groundwater inrush hazard in a large salt-mining area in Tongbai County, China, this study mainly aims to analyse the source and channel of the inrushing water. The mining area has three different types of ore beds including trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, with the formula Na2CO3 × NaHCO3 × 2H2O, it is a non-marine evaporite mineral), glauber (sodium sulfate, it is the inorganic compound with the formula Na2SO4 as well as several related hydrates) and gypsum (a soft sulfate mineral composed of calcium sulfate dihydrate, with chemical formula CaSO4 × 2H2O). Based on characterisation of the geological and hydrogeological conditions, the hydrochemical data of the groundwater at different points and depths were used to analyse the pollution source and the pollutant component from single or mixed brine by using physical-chemical reaction principle analysis and hydrogeochemical simulation method. Finally, a possible brine leakage connecting the channel to the ground was discussed from both the geological and artificial perspectives. The results reveal that the brine from the trona mine is the major pollution source; there is a NW-SE fissure zone controlled by the geological structure that provides the main channels through which brine can flow into the aquifer around the water inrush regions, with a large number of waste gypsum exploration boreholes channelling the polluted groundwater inrush out of the ground. This research can be a valuable reference for avoiding and assessing groundwater inrush hazards in similar rock-salt-mining areas, which is advantageous for both groundwater quality protection and public health.

  2. Mechanical effects associated with surface loading of dry rock due to glaciation

    International Nuclear Information System (INIS)

    Wahi, K.K.; Hunter, R.L.

    1985-01-01

    Many scenarios of interest for a repository in the Pasco Basin begin with glaciation. Loading and unloading of joints and fractures due to the weight of ice sheets could affect the hydrologic properties of the host rock and surrounding units. Scoping calculations performed using two-dimensional numerical models with simplifying assumptions predict stress changes and uplift or subsidence caused by an advancing glacier. The magnitudes of surface uplift and subsidence predicted by the study agree well with previous independent predictions. Peak stress unloading near the repository horizon is a small fraction of the ambient stress. Any resultant aperture increase is likewise small. Based on the results of this study, mechanical loading caused by a glacier is expected to have a minimal effect on rock permeability, assuming that the excess compressive loads do not crush the rock. 13 refs., 3 figs., 1 tab

  3. The validity of generic trends on multiple scales in rock-physical and rock-mechanical properties of the Whitby Mudstone, United Kingdom

    NARCIS (Netherlands)

    Douma, L.A.N.R.; Primarini, M.I.W.; Houben, M.E.; Barnhoorn, A.

    Finding generic trends in mechanical and physical rock properties will help to make predictions of the rock-mechanical behaviour of shales. Understanding the rock-mechanical behaviour of shales is important for the successful development of unconventional hydrocarbon reservoirs. This paper presents

  4. Study on water migration of tunnel surrounding rock in nuclear waste repository based on coupling theory

    International Nuclear Information System (INIS)

    Jiang Zhongming; Zhang Xinmin

    2008-01-01

    Excavation of tunnel changes not only the stresses and deformation of tunnel surrounding rock, but also disturbs the underground water environment in tunnel surrounding rock Water migration happens due to variation of pore water pressure and redistribution. Based on the mechanics of porous media, saturated and unsaturated hydro-mechanical coupling analysis method is employed to study the variation of the stresses, deformation and pore pressure of the surrounding rock. Case study indicates that the excavation of tunnel will induce redistribution of stress and pore water pressure. Redistribution of pore water pressure will seriously affect on evaluation of surrounding rock stability and diffusion of nucleon in the pore water. (authors)

  5. Electrokinetic mechanism of wettability alternation at oil-water-rock interface

    Science.gov (United States)

    Tian, Huanhuan; Wang, Moran

    2017-12-01

    Design of ions for injection water may change the wettability of oil-brine-rock (OBR) system, which has very important applications in enhanced oil recovery. Though ion-tuned wettability has been verified by various experiments, the mechanism is still not clear. In this review paper, we first present a comprehensive summarization of possible wettability alteration mechanisms, including fines migration or dissolution, multicomponent ion-exchange (MIE), electrical double layer (EDL) interaction between rock and oil, and repulsive hydration force. To clarify the key mechanism, we introduce a complete frame of theories to calculate attribution of EDL repulsion to wettability alteration by assuming constant binding forces (no MIE) and rigid smooth surface (no fines migration or dissolution). The frame consists of three parts: the classical Gouy-Chapman model coupled with interface charging mechanisms to describe EDL in oil-brine-rock systems, three methods with different boundary assumptions to evaluate EDL interaction energy, and the modified Young-Dupré equation to link EDL interaction energy with contact angle. The quantitative analysis for two typical oil-brine-rock systems provides two physical maps that show how the EDL interaction influences contact angle at different ionic composition. The result indicates that the contribution of EDL interaction to ion-tuned wettability for the studied system is not quite significant. The classical and advanced experimental work using microfabrication is reviewed briefly on the contribution of EDL repulsion to wettability alteration and compared with the theoretical results. It is indicated that the roughness of real rock surface may enhance EDL interaction. Finally we discuss some pending questions, perspectives and promising applications based on the mechanism.

  6. The Effect of Void Shape on the Mechanical Properties of Rock

    International Nuclear Information System (INIS)

    D.O. Potyondy

    2006-01-01

    The bonded-particle model for rock (Potyondy and Cundall, 2004) represents rock by a dense packing of non-uniform-sized circular or spherical particles that are bonded together at their contact points and whose mechanical behavior is simulated by the distinct-element method using the two- and three-dimensional programs PFC2D and PFC3D. A bonded-particle model of lithophysal tuff has been used to study the effect of lithophysae (hollow, bubble-like voids) on the mechanical properties (Young's modulus and unconfined compressive strength) of this rock, and to quantify the variability of these properties. The model reproduces the failure mechanisms observed in the laboratory and exhibits a reduction of strength and modulus with increasing lithophysal volume fraction. The effect of void shape on mechanical properties is studied by inserting randomly distributed voids of simple shape (circle, triangle and star) and by inserting voids corresponding with lithophysal cavities identified in panel maps of the walls of a tunnel through this material. These studies address tunnel-stability issues associated with mechanical degradation of planned emplacement drifts at Yucca Mountain, which is the designated site for the proposed US high-level nuclear waste repository

  7. Mechanism of groundwater inrush hazard caused by solution mining in a multilayered rock-salt-mining area: a case study in Tongbai, China

    Directory of Open Access Journals (Sweden)

    B. Zeng

    2018-01-01

    Full Text Available The solution mining of salt mineral resources may contaminate groundwater and lead to water inrush out of the ground due to brine leakage. Through the example of a serious groundwater inrush hazard in a large salt-mining area in Tongbai County, China, this study mainly aims to analyse the source and channel of the inrushing water. The mining area has three different types of ore beds including trona (trisodium hydrogendicarbonate dihydrate, also sodium sesquicarbonate dihydrate, with the formula Na2CO3  ×  NaHCO3  ×  2H2O, it is a non-marine evaporite mineral, glauber (sodium sulfate, it is the inorganic compound with the formula Na2SO4 as well as several related hydrates and gypsum (a soft sulfate mineral composed of calcium sulfate dihydrate, with chemical formula CaSO4  ×  2H2O. Based on characterisation of the geological and hydrogeological conditions, the hydrochemical data of the groundwater at different points and depths were used to analyse the pollution source and the pollutant component from single or mixed brine by using physical–chemical reaction principle analysis and hydrogeochemical simulation method. Finally, a possible brine leakage connecting the channel to the ground was discussed from both the geological and artificial perspectives. The results reveal that the brine from the trona mine is the major pollution source; there is a NW–SE fissure zone controlled by the geological structure that provides the main channels through which brine can flow into the aquifer around the water inrush regions, with a large number of waste gypsum exploration boreholes channelling the polluted groundwater inrush out of the ground. This research can be a valuable reference for avoiding and assessing groundwater inrush hazards in similar rock-salt-mining areas, which is advantageous for both groundwater quality protection and public health.

  8. Results of monitoring at Olkiluoto in 2009. Rock mechanics

    International Nuclear Information System (INIS)

    Lahti, M.; Hakala, M.

    2010-09-01

    The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and additionally extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. The number of seismic stations has increased gradually being in 2009 altogether 14. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semi-regional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale. The smaller target area is s called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. All the expected excavation induced events assumingly occur within this volume. At the moment the seismic ONKALO block includes 10 seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. The seismic network has operated continuously in 2009 and during the year altogether 1256 events have been located in the Olkiluoto area. Most of them (1161) are explosions that occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (1135 events)

  9. Study of deep fracturation of granitic rock mass. Documentary study

    International Nuclear Information System (INIS)

    Bles, J.L.; Landry, J.

    1984-01-01

    This documentary study realized with the financial support of the European Communities and the CEA aims at the utilization of available data for the understanding of the evolution of natural fractures in granitic rocks from the surface to deep underground. The Mt Blanc road tunnel, the EDF's Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied because detailed structural and geological studies have been realized these last 20 years. In this study are more particularly analyzed the relationship between small fractures and large faults, evolution with depth of fracture density and direction, consequences of rock decompression and relationship between fracturation and groundwater

  10. Studies of ionic diffusion in crystalline rock

    International Nuclear Information System (INIS)

    Ohlsson, Yvonne

    2001-01-01

    Matrix diffusion is of great importance in delaying radionuclides escaping from a deep geologic repository, on their way to the biosphere. There are, however, poorly understood mechanisms related to transport in pores with charged pore surfaces. Ions are affected by this charge and may be repelled or attracted by it. The rate of transport may be reduced, or even enhanced, as a result of this. Transport of ions is studied by traditional diffusion experiments, but mainly by a faster electrical conductivity method. With this method the pore connectivity, the formation factor variability and its relation to the porosity, as well as the surface conductivity are investigated. The method is compared. with traditional diffusion experiments, and an in-situ application is suggested and qualitatively tested. Furthermore, surface diffusion is studied by evaluating literature data and recently developed diffusion models. The pore connectivity reached to a depth of at least 15 cm in the rocks studied. The formation factor did not generally decrease with increasing sample length. It was also found that not only cations in the free pore water add to the electrical conductivity, but also at least part of those sorbed to the pore surfaces of the minerals. This surface conductivity influences the determination of the formation factor in low ionic strength pore waters, and was also found to be a function of the formation factor. It was furthermore dependent on the type of ion at the surface, giving for example a higher conductivity for Na + than for Cs + . It is not fully understood which part of the sorbed ions that are mobile. A simple model was developed assigning the mobile ions to the diffuse layer, and this model explained experimental data for diffusion of Cs + in clay well. This is contradicted by surface conductivity measurements that have shown that most mobile ions are found behind the Stern layer. The in-situ formation factor determination method seems promising. The most

  11. Geo-Mechanical Characterization of Carbonate Rock Masses by Means of Laser Scanner Technique

    Science.gov (United States)

    Palma, Biagio; Parise, Mario; Ruocco, Anna

    2017-12-01

    Knowledge of the geometrical and structural setting of rock masses is crucial to evaluate the stability and to design the most suitable stabilization works. In this work we use the Terrestrial Laser Scanning (TLS) at the site of the Grave of the Castellana Caves, a famous show cave in southern Italy. The Grave is the natural access to the cave system, produced by collapse of the vault, due to upward progression of instabilities in the carbonate rock masses. It is about 55-m high, bell-shaped, with maximum width of 120 m. Aim of the work is the characterization of carbonate rock masses from the structural and geo-mechanical standpoints through the use of innovative survey techniques. TLS survey provides a product consisting of millions of geo-referenced points, to be managed in space, to become a suitable database for the morphological and geological-structural analysis. Studying by means of TLS a rock face, partly inaccessible or located in very complex environments, allows to investigate slopes in their overall areal extent, thus offering advantages both as regards safety of the workers and time needed for the survey. In addition to TLS, the traditional approach was also followed by performing scanlines surveys along the rims of the Grave, following the ISRM recommendations for characterization of discontinuity in rock masses. A quantitative comparison among the data obtained by TLS technique and those deriving from the classical geo-mechanical survey is eventually presented, to discuss potentiality of drawbacks of the different techniques used for surveying the rock masses.

  12. Exact effective-stress rules in rock mechanics

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1992-01-01

    The standard paradigm for analysis of rock deformation arises from postulating the existence of ''an equivalent homogeneous porous rock.'' However, data on the pore-pressure dependence of fluid permeability for some rocks cannot be explained using any equivalent homogeneous porous medium. In contrast, a positive result shows that deformation measurements on both high-porosity sandstones and low-porosity granites can be explained adequately in terms of an equivalent two-constituent model of porous rocks, for which exact results have recently been discovered

  13. APPLICATIONS OF BOREHOLE-ACOUSTIC METHODS IN ROCK MECHANICS.

    Science.gov (United States)

    Paillet, Frederick L.

    1985-01-01

    Acoustic-logging methods using a considerable range of wavelengths and frequencies have proven very useful in the in situ characterization of deeply buried crystalline rocks. Seismic velocities are useful in investigating the moduli of unfractured rock, and in producing a continuous record of rock quality for comparison with discontinuous intervals of core. The considerable range of frequencies makes the investigation of scale effects possible in both fractured and unfractured rock. Several specific methods for the characterization of in situ permeability have been developed and verified in the field.

  14. Large-Scale True Triaxial Apparatus for Geophysical Studies in Fractured Rock

    KAUST Repository

    Garcia, A. V.

    2018-05-12

    The study of fractured rock masses in the laboratory remains challenging because of the large specimen sizes and bulky loading systems that are required. This article presents the design, structural analysis, and operation of a compact and self-reacting true triaxial device for fractured rock. The frame subjects a 50 cm by 50 cm by 50 cm fractured rock specimen to a maximum stress of 3 MPa along three independent axes. Concurrent measurements include long-wavelength P-wave propagation, passive acoustic emission monitoring, deformations, and thermal measurements. The device can accommodate diverse research, from rock mass properties and geophysical fractured rock characterizations, to coupled hydro-chemo-thermo-mechanical processes, drilling, and grouting. Preliminary wave propagation data gathered under isotropic and anisotropic stress conditions for an assembly of 4,000 rock blocks demonstrate the system’s versatility and provide unprecedented information related to long-wavelength propagation in fractured rock under various stress anisotropies.

  15. Large-Scale True Triaxial Apparatus for Geophysical Studies in Fractured Rock

    KAUST Repository

    Garcia, A. V.; Rached, R. M.; Santamarina, Carlos

    2018-01-01

    The study of fractured rock masses in the laboratory remains challenging because of the large specimen sizes and bulky loading systems that are required. This article presents the design, structural analysis, and operation of a compact and self-reacting true triaxial device for fractured rock. The frame subjects a 50 cm by 50 cm by 50 cm fractured rock specimen to a maximum stress of 3 MPa along three independent axes. Concurrent measurements include long-wavelength P-wave propagation, passive acoustic emission monitoring, deformations, and thermal measurements. The device can accommodate diverse research, from rock mass properties and geophysical fractured rock characterizations, to coupled hydro-chemo-thermo-mechanical processes, drilling, and grouting. Preliminary wave propagation data gathered under isotropic and anisotropic stress conditions for an assembly of 4,000 rock blocks demonstrate the system’s versatility and provide unprecedented information related to long-wavelength propagation in fractured rock under various stress anisotropies.

  16. Evaluation of the basic mechanical and thermal properties of deep crystalline rocks

    International Nuclear Information System (INIS)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    This report provides the mechanical and thermal properties of granitic intact rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are the basic material properties of the core samples from the boreholes drilled up to 500 m depth at the Yusung and Kosung sites. These sites were selected based on the result of preliminary site evaluation study. In this study, the mechanical properties include density, porosity, P-wave velocity, S-wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, and shear strength of fractures, and the thermal properties are heat conductivity, thermal expansion coefficient, specific heat and so on. Those properties were measured through laboratory tests and these data are compared with the existing test results of several domestic rocks

  17. Evaluation of the basic mechanical and thermal properties of deep crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    This report provides the mechanical and thermal properties of granitic intact rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are the basic material properties of the core samples from the boreholes drilled up to 500 m depth at the Yusung and Kosung sites. These sites were selected based on the result of preliminary site evaluation study. In this study, the mechanical properties include density, porosity, P-wave velocity, S-wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, and shear strength of fractures, and the thermal properties are heat conductivity, thermal expansion coefficient, specific heat and so on. Those properties were measured through laboratory tests and these data are compared with the existing test results of several domestic rocks.

  18. Analysis of mechanical behavior of soft rocks and stability control in deep tunnels

    Directory of Open Access Journals (Sweden)

    Hui Zhou

    2014-06-01

    Full Text Available Due to the weakness in mechanical properties of chlorite schist and the high in situ stress in Jinping II hydropower station, the rock mass surrounding the diversion tunnels located in chlorite schist was observed with extremely large deformations. This may significantly increase the risk of tunnel instability during excavation. In order to assess the stability of the diversion tunnels laboratory tests were carried out in association with the petrophysical properties, mechanical behaviors and water-weakening properties of chlorite schist. The continuous deformation of surrounding rock mass, the destruction of the support structure and a large-scale collapse induced by the weak chlorite schist and high in situ stress were analyzed. The distributions of compressive deformation in the excavation zone with large deformations were also studied. In this regard, two reinforcement schemes for the excavation of diversion tunnel bottom section were proposed accordingly. This study could offer theoretical basis for deep tunnel construction in similar geological conditions.

  19. Hydro-thermo-mechanical response of a fractured rock block

    International Nuclear Information System (INIS)

    Kelkar, S.; Zyvoloski, G.

    1990-01-01

    Hydro-thermo-mechanical effects in fractured rocks are important in many engineering applications and geophysical processes. Modeling these effects is made difficult by the fact that the governing equations are nonlinear and coupled, and the problems to be solved are three dimensional. In this paper we describe a numerical code developed for this purpose. The code is finite element based to allow for complicated geometries, and the time differencing is implicit, allowing for large time steps. The use of state-of-the-art equation solvers has resulted in a practical code. The code is capable of fully three dimensional simulations, however, in this paper we consider only the case of two dimensional heat and mass flow coupled to one dimensional deformation. Partial verification of the code is obtained by comparison with published semianalytical results. Several examples are presented to demonstrate the effects of matrix expansion, due to pore pressure and heating, on fracture opening due to fluid injection. 16 refs., 11 figs

  20. Coupled hydro-thermo-mechanical modeling of hydraulic fracturing in quasi-brittle rocks using BPM-DEM

    Directory of Open Access Journals (Sweden)

    Ingrid Tomac

    2017-02-01

    Full Text Available This paper presents an improved understanding of coupled hydro-thermo-mechanical (HTM hydraulic fracturing of quasi-brittle rock using the bonded particle model (BPM within the discrete element method (DEM. BPM has been recently extended by the authors to account for coupled convective–conductive heat flow and transport, and to enable full hydro-thermal fluid–solid coupled modeling. The application of the work is on enhanced geothermal systems (EGSs, and hydraulic fracturing of hot dry rock (HDR is studied in terms of the impact of temperature difference between rock and a flowing fracturing fluid. Micro-mechanical investigation of temperature and fracturing fluid effects on hydraulic fracturing damage in rocks is presented. It was found that fracture is shorter with pronounced secondary microcracking along the main fracture for the case when the convective–conductive thermal heat exchange is considered. First, the convection heat exchange during low-viscosity fluid infiltration in permeable rock around the wellbore causes significant rock cooling, where a finger-like fluid infiltration was observed. Second, fluid infiltration inhibits pressure rise during pumping and delays fracture initiation and propagation. Additionally, thermal damage occurs in the whole area around the wellbore due to rock cooling and cold fluid infiltration. The size of a damaged area around the wellbore increases with decreasing fluid dynamic viscosity. Fluid and rock compressibility ratio was found to have significant effect on the fracture propagation velocity.

  1. Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach

    Science.gov (United States)

    Draebing, D.; Krautblatter, M.; Dikau, R.

    2014-12-01

    Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

  2. U.S. National Committee for Rock Mechanics; and Conceptual model of fluid infiltration in fractured media. Project summary, July 28, 1997--July 27, 1998

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    The title describes the two tasks summarized in this report. The remainder of the report contains information on meetings held or to be held on the subjects. The US National Committee for Rock Mechanics (USNC/RM) provides for US participation in international activities in rock mechanics, principally through adherence to the International Society for Rock Mechanics (ISRM). It also keeps the US rock mechanics community informed about new programs directed toward major areas of national concern in which rock mechanics problems represent critical or limiting factors, such as energy resources, excavation, underground storage and waste disposal, and reactor siting. The committee also guides or produces advisory studies and reports on problem areas in rock mechanics. A new panel under the auspices of the US National Committee for Rock Mechanics has been appointed to conduct a study on Conceptual Models of Fluid Infiltration in Fractured Media. The study has health and environmental applications related to the underground flow of pollutants through fractured rock in and around mines and waste repositories. Support of the study has been received from the US Nuclear Regulatory Commission and the Department of Energy`s Yucca Mountain Project Office. The new study builds on the success of a recent USNC/RM report entitled Rock Fractures and Fluid Flow: Contemporary Understanding and Applications (National Academy Press, 1996, 551 pp.). A summary of the new study is provided.

  3. U.S. National Committee for Rock Mechanics and conceptual model of fluid infiltration in fractured media. Project summary, July 28, 1997 - July 27, 1998

    International Nuclear Information System (INIS)

    1998-01-01

    The title describes the two tasks summarized in this report. The remainder of the report contains information on meetings held or to be held on the subjects. The US National Committee for Rock Mechanics (USNC/RM) provides for US participation in international activities in rock mechanics, principally through adherence to the International Society for Rock Mechanics (ISRM). It also keeps the US rock mechanics community informed about new programs directed toward major areas of national concern in which rock mechanics problems represent critical or limiting factors, such as energy resources, excavation, underground storage and waste disposal, and reactor siting. The committee also guides or produces advisory studies and reports on problem areas in rock mechanics. A new panel under the auspices of the US National Committee for Rock Mechanics has been appointed to conduct a study on Conceptual Models of Fluid Infiltration in Fractured Media. The study has health and environmental applications related to the underground flow of pollutants through fractured rock in and around mines and waste repositories. Support of the study has been received from the US Nuclear Regulatory Commission and the Department of Energy's Yucca Mountain Project Office. The new study builds on the success of a recent USNC/RM report entitled Rock Fractures and Fluid Flow: Contemporary Understanding and Applications (National Academy Press, 1996, 551 pp.). A summary of the new study is provided

  4. Mechanism of rock shattering by explosions, depending on the nature of jointing and the elastic state

    Energy Technology Data Exchange (ETDEWEB)

    Mosinets, V N

    1966-01-01

    For proper use of explosives in shattering rock it is necessary to understand the mechanism of shattering. To a great extent this mechanism of shattering is controlled by fracturing in the rock and by the elastic properties of the rock. The processes of shattering as a result of explosion are analyzed, and the conclusion is made that, in its general interpretation, the mechanism of shattering is merely of theoretical interest. The applicability to actual media changes according to structure of the medium. Relatively massive rocks are characterized by an asymmetrical distribution function of the joints and micro-fractures and other inhomogeneities, the mode being shifted to the left of the asymmetry center. Rocks cut by an extensive network of microfractures and joints are characterized by an approximately normal distribution function; rocks cut by large joints have an asymmetrical distribution function, with the mode shifted to the right of the asymmetry center.

  5. The results of the investigations on rock mechanics in HDB-9-11 boreholes and update of the rock mechanical model around the Horonobe URL construction area

    International Nuclear Information System (INIS)

    Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya

    2008-09-01

    Horonobe URL (Underground Research Laboratory) Project is conducted at Horonobe-cho, Teshio-gun, Hokkaido. This research report shows the result of the rock mechanical investigations which have been carried out from 2004 to 2005 as a part of the project. The objectives of the rock mechanical investigation are as follows: To obtain the data which were necessary for construction design of URL. To confirm the distribution of rock mechanical properties in and around URL construction area. The results of the investigations are summarized as follows: 1) Variation and values of depth direction of physical and mechanical properties in the laboratory construction area corresponded approximately to the results obtained from the rock mechanical investigations of HDB-1-8. 2) The major redesign had been not had about physical and mechanical properties in the laboratory construction area being able to divide into three zones and length of its own zone in updating rock mechanical model. 3) From the results of initial stress measured by hydraulic fracturing, the results that the direction of the maximum principle stress is E-W was no different from results obtained from the investigations of HDB-1-8, but the magnitude correlation among maximum, minimum principle stress and overburden pressure measured around G.L.-927 m showed different trends compared with the results of HDB-1-8. 4) Diatomaceous mudstone was yielded under isotropic compression. Cam-clay model as constitutive law of diatomaceous mudstone should be used for tunnel excavation analysis. 5) Uniaxial compression strength of rock saturated under saline water is larger than that of saturated under freshwater. Poisson's ratio of rock saturated under saline water is smaller than that of saturated under saline water. 6) The effective confining pressure increases with the equivalent opening width and permeability decreases. 7) The value of principle stress obtained from DSCA method is larger than that obtained from hydraulic

  6. Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks - a principal study with application to the Goetemar and Uthammar granites. Site-descriptive modelling SDM-Site Laxemar

    International Nuclear Information System (INIS)

    Cruden, Alexander R.

    2008-12-01

    The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86-1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Goetemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. Field observations and structural measurements indicate that both the Goetemar and the Uthammar granites are discordant and have not imposed any significant ductile deformation on their wall-rocks. The apparent conformity of geological contacts and fabrics in the wall rocks and the southern margin of the Goetemar granite is coincidental and inherited from the pattern of Svecokarelian deformation of the TIB. However, interpretation of regional aeromagnetic data suggests that the granites occur within a broad, NNE-SSW trending linear belt, pointing to deep seated tectonic control on their generation, ascent and emplacement. Thermochronology indicates that the granites were emplaced at depths between 4 and 8 km into brittle wall rocks. The 3-D shape of the Goetemar and Uthammar plutons has been investigated by 2.75D forward modelling of the residual gravity anomalies due to both granites. Both granites are associated with strong residual gravity anomalies of up to -10 mgal. Constraints on the geometry of the plutons at the surface are provided from surface geology maps and several deep boreholes located on or close to the model profiles. A further variable in the gravity modelling is introduced by either allowing the upper contact of the plutons to assume the most suitable orientation to produce the best fit between the modelled and observed gravity ('unconstrained models') or by forcing the near surface orientation of the contacts to be vertical ('constrained

  7. Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks - a principal study with application to the Goetemar and Uthammar granites. Site-descriptive modelling SDM-Site Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Cruden, Alexander R. (Dept. of Geology, Univ. of Toronto (Canada))

    2008-12-15

    The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86-1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Goetemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. Field observations and structural measurements indicate that both the Goetemar and the Uthammar granites are discordant and have not imposed any significant ductile deformation on their wall-rocks. The apparent conformity of geological contacts and fabrics in the wall rocks and the southern margin of the Goetemar granite is coincidental and inherited from the pattern of Svecokarelian deformation of the TIB. However, interpretation of regional aeromagnetic data suggests that the granites occur within a broad, NNE-SSW trending linear belt, pointing to deep seated tectonic control on their generation, ascent and emplacement. Thermochronology indicates that the granites were emplaced at depths between 4 and 8 km into brittle wall rocks. The 3-D shape of the Goetemar and Uthammar plutons has been investigated by 2.75D forward modelling of the residual gravity anomalies due to both granites. Both granites are associated with strong residual gravity anomalies of up to -10 mgal. Constraints on the geometry of the plutons at the surface are provided from surface geology maps and several deep boreholes located on or close to the model profiles. A further variable in the gravity modelling is introduced by either allowing the upper contact of the plutons to assume the most suitable orientation to produce the best fit between the modelled and observed gravity ('unconstrained models') or by forcing the near surface orientation of the contacts to be vertical (&apos

  8. Rock mechanics in the disposal of radioactive wastes by hydraulic fracturing

    Energy Technology Data Exchange (ETDEWEB)

    McClain, W C

    1968-01-01

    The ultimate capacity of a hydraulic-fracturing waste disposal facility is governed primarily by the integrity of the rocks overlying the injected wastes. The objective of this study is to analyze theoretically the stresses and strains generated by the injected wastes in an effort to understand the behavior of the system sufficiently well that the failure mechanism can be predicted and the capacity of the injection well estimated. The surface uplifts at Oak Ridge National Laboratory's fracturing site were compared with theoretical curves obtained by assuming the uplifts to be inversely analogous to the subsidence which occurs over mining excavations. This analysis, based on assumptions of homogeneity, isotropy, and linear elasticity, provided considerable insight into the mechanics of the process. The most probable mechanism of failure of the rock appears to be by the formation of a vertical instead of a horizontal fracture. Fracture orientation is controlled primarily by the orientation of the principal stress field in the rock. Each successive waste injection slightly modifies this stress field toward a condition more favorable to the formation of a vertical fracture. (16 refs.)

  9. Characterization of Rock Mechanical Properties Using Lab Tests and Numerical Interpretation Model of Well Logs

    Directory of Open Access Journals (Sweden)

    Hao Xu

    2016-01-01

    Full Text Available The tight gas reservoir in the fifth member of the Xujiahe formation contains heterogeneous interlayers of sandstone and shale that are low in both porosity and permeability. Elastic characteristics of sandstone and shale are analyzed in this study based on petrophysics tests. The tests indicate that sandstone and mudstone samples have different stress-strain relationships. The rock tends to exhibit elastic-plastic deformation. The compressive strength correlates with confinement pressure and elastic modulus. The results based on thin-bed log interpretation match dynamic Young’s modulus and Poisson’s ratio predicted by theory. The compressive strength is calculated from density, elastic impedance, and clay contents. The tensile strength is calibrated using compressive strength. Shear strength is calculated with an empirical formula. Finally, log interpretation of rock mechanical properties is performed on the fifth member of the Xujiahe formation. Natural fractures in downhole cores and rock microscopic failure in the samples in the cross section demonstrate that tensile fractures were primarily observed in sandstone, and shear fractures can be observed in both mudstone and sandstone. Based on different elasticity and plasticity of different rocks, as well as the characteristics of natural fractures, a fracture propagation model was built.

  10. Effects of Freezing and Thawing Cycle on Mechanical Properties and Stability of Soft Rock Slope

    OpenAIRE

    Chen, Yanlong; Wu, Peng; Yu, Qing; Xu, Guang

    2017-01-01

    To explore the variation laws of mechanical parameters of soft rock and the formed slope stability, an experiment was carried out with collected soft rock material specimens and freezing and thawing cycle was designed. Meanwhile, a computational simulation analysis of the freezing-thawing slope stability was implemented. Key factors that influence the strength of frozen rock specimens were analyzed. Results showed that moisture content and the number of freezing-thawing cycles influenced mech...

  11. Numerical simulation of mechanisms of deformation,failure and energy dissipation in porous rock media subjected to wave stresses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The pore characteristics,mineral compositions,physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan,X-ray diffraction and physical tests.A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed.The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform.The failure processes of the porous rock media loaded by the split Hopkinson pressure bar(SHPB) were simulated by satisfying the elastic wave propagation theory.The dynamic responses,stress transition,deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed.It is shown that an explicit and quantitative analysis of the stress,strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models.With applied wave stresses of certain amplitude and velocity,no evident pore deformation was observed for the rock media with a porosity less than 15%.The deformation is dominantly the combination of microplasticity(shear strain),cracking(tensile strain) of matrix and coalescence of the cracked regions around pores.Shear stresses lead to microplasticity,while tensile stresses result in cracking of the matrix.Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values.The simulation results of stress wave propagation,deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests.The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response,stress transit mode,deformation and failure mechanisms and the disaster

  12. Proceedings of a technical session on rock mechanics ''Advance in laboratory sample testing''

    International Nuclear Information System (INIS)

    Come, B.

    1984-01-01

    This report brings together a series of papers about rock mechanics. The meeting was divided into three sessions, which dealt with the three main types of rock formation currently considered in the CEC Programme: granite, clay and salt. Safe disposal of high-level radioactive waste involves the proper design of deep underground repositories. This necessitates an in-depth knowledge of the mechanical properties of the rock mass. The behaviour of the rock mass must be known both for the construction and the operation (heating effects) of the repository. Usually, the dominant factor for designing an underground structure is the fracturing of the rock mass. In the present case, the rock is chosen with a very low fracturing. Therefore, the mechanical properties of the formation are mainly those of the rock matrix. These properties are obtained, at least in a first exploratory step, by laboratory testing of rock samples obtained by core-drilling from surface. This aspect of rock characterization was thought to deserve a special technical meeting, in order to bring together most of the results obtained in this field by contracting partners of the CEC for the years 1980-82

  13. Experimental study of chemical-mechanical coupling during percolation of reactive fluid through rocks under stress, in the context of the CO{sub 2} geological sequestration; Etude experimentale du couplage chimie-mecanique lors de la percolation d'un fluide reactif dans des roches sous contrainte, dans le contexte de la sequestration geologique du CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Le Guen, Y

    2006-10-15

    CO{sub 2} injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO{sub 2}. Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10{sup -12} s{sup -1} on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO{sub 2}-rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO{sub 2} which increases rock solubility and reaction kinetics. On the opposite, small effect of CO{sub 2} on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)

  14. Mechanical characteristics of fully mechanized top-coal caving face and surrounding rock stress shell

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guang-xiang [Anhui University of Science and Technology, Huainan (China)

    2005-06-15

    The distribution of surrounding rock stress in fully mechanized top-coal caving (FMTC) face was fully researched by large-scale and non-linear three-dimensional numerical simulation and equivalent laboratory. The results show that, there is the structure that is made of macroscopical stress shell composed of high stress binds in overlying strata of FMTC face. Stress shell, which bears and pass load of overlying strata, is primary supporting body. The stress in skewback of stress shell forms abutment pressure of surrounding rock in vicinity of working face. Bond-beam structure lies in reducing zone under stress shell. It only bear partial burden of strata under stress shell. The uppermost mechanical characteristic of FMTC face is lying in the low stress area under stress shell. It is the essential cause of strata behaviors of FMTC face relaxation. On the basis of analyzing stress shell, the mechanical essence that top coal performs a function of bedding is demonstrated. 4 refs., 7 figs.

  15. Microscale experimental investigation of deformation and damage of argillaceous rocks under cyclic hydric and mechanical loads

    International Nuclear Information System (INIS)

    Wang, Linlin; Yang, Diansen; Heripre, Eva; Chanchole, Serge; Bornert, Michel; Pouya, Ahmad; Halphen, Bernard

    2012-01-01

    Document available in abstract form only. Argillaceous rocks are possible host rocks for underground nuclear waste repositories. They exhibit complex coupled thermo-hydro-chemo-mechanical behavior, the description of which would strongly benefit from an improved experimental insight on their deformation and damage mechanisms at microscale. We present some recent observations of the evolution of these rocks at the scale of their composite microstructure, essentially made of a clay matrix with embedded carbonates and quartz particles with sizes ranging from a few to several tens of micrometers, when they are subjected to cyclic variations of relative humidity and mechanical loading. They are based on the combination of high definition and high resolution imaging in an environmental scanning electron microscope (ESEM), in situ hydro-mechanical loading of the samples, and digital image correlation techniques. Samples, several millimeters in diameter, are held at a constant temperature of 2 deg. Celsius while the vapor pressure in the ESEM chamber is varied from a few to several hundreds of Pascals, generating a relative humidity ranging from about 10% up to 90%. Results show a strongly heterogeneous deformation field at microscale, which is the result of complex hydro-mechanical interactions. In particular, it can be shown that local swelling incompatibilities can generate irreversible deformations in the clay matrix, even if the overall hydric deformations seem reversible. In addition, local damage can be generated, in the form of a network of microcracks, located in the bulk of the clay matrix and/or at the interface between clay and other mineral particles. The morphology of this network, described in terms of crack length, orientation and preferred location, has been observed to be dependent on the speed of the variation of the relative humidity, and is different in a saturation or desaturation process. Besides studying the deformation and damage under hydric

  16. Mechanisms and consequences of creep in the nearfield rock of a KBS-3 repository

    International Nuclear Information System (INIS)

    Pusch, R.; Hoekmark, H.

    1992-12-01

    Creep in rock depends on the structure as well as on the stress and temperature. Log time creep is often observed and can be explained on the basis of statistical mechanics. Simple Kelvin behavior can be used as an approximation. The code FLAC is concluded to be useful for predicting creep strain, assuming that the rock obeys the Kelvin law. 22 refs

  17. Mechanical weathering and rock erosion by climate-dependent subcritical cracking

    Science.gov (United States)

    Eppes, Martha-Cary; Keanini, Russell

    2017-06-01

    This work constructs a fracture mechanics framework for conceptualizing mechanical rock breakdown and consequent regolith production and erosion on the surface of Earth and other terrestrial bodies. Here our analysis of fracture mechanics literature explicitly establishes for the first time that all mechanical weathering in most rock types likely progresses by climate-dependent subcritical cracking under virtually all Earth surface and near-surface environmental conditions. We substantiate and quantify this finding through development of physically based subcritical cracking and rock erosion models founded in well-vetted fracture mechanics and mechanical weathering, theory, and observation. The models show that subcritical cracking can culminate in significant rock fracture and erosion under commonly experienced environmental stress magnitudes that are significantly lower than rock critical strength. Our calculations also indicate that climate strongly influences subcritical cracking—and thus rock weathering rates—irrespective of the source of the stress (e.g., freezing, thermal cycling, and unloading). The climate dependence of subcritical cracking rates is due to the chemophysical processes acting to break bonds at crack tips experiencing these low stresses. We find that for any stress or combination of stresses lower than a rock's critical strength, linear increases in humidity lead to exponential acceleration of subcritical cracking and associated rock erosion. Our modeling also shows that these rates are sensitive to numerous other environment, rock, and mineral properties that are currently not well characterized. We propose that confining pressure from overlying soil or rock may serve to suppress subcritical cracking in near-surface environments. These results are applicable to all weathering processes.

  18. Experimental Investigation on the Fatigue Mechanical Properties of Intermittently Jointed Rock Models Under Cyclic Uniaxial Compression with Different Loading Parameters

    Science.gov (United States)

    Liu, Yi; Dai, Feng; Dong, Lu; Xu, Nuwen; Feng, Peng

    2018-01-01

    Intermittently jointed rocks, widely existing in many mining and civil engineering structures, are quite susceptible to cyclic loading. Understanding the fatigue mechanism of jointed rocks is vital to the rational design and the long-term stability analysis of rock structures. In this study, the fatigue mechanical properties of synthetic jointed rock models under different cyclic conditions are systematically investigated in the laboratory, including four loading frequencies, four maximum stresses, and four amplitudes. Our experimental results reveal the influence of the three cyclic loading parameters on the mechanical properties of jointed rock models, regarding the fatigue deformation characteristics, the fatigue energy and damage evolution, and the fatigue failure and progressive failure behavior. Under lower loading frequency or higher maximum stress and amplitude, the jointed specimen is characterized by higher fatigue deformation moduli and higher dissipated hysteresis energy, resulting in higher cumulative damage and lower fatigue life. However, the fatigue failure modes of jointed specimens are independent of cyclic loading parameters; all tested jointed specimens exhibit a prominent tensile splitting failure mode. Three different crack coalescence patterns are classified between two adjacent joints. Furthermore, different from the progressive failure under static monotonic loading, the jointed rock specimens under cyclic compression fail more abruptly without evident preceding signs. The tensile cracks on the front surface of jointed specimens always initiate from the joint tips and then propagate at a certain angle with the joints toward the direction of maximum compression.

  19. United States National Waste Terminal Storage argillaceous rock studies

    International Nuclear Information System (INIS)

    Brunton, G.D.

    1981-01-01

    The past and present argillaceous rock studies for the US National Waste Terminal Storage Program consist of: (1) evaluation of the geological characteristics of several widespread argillaceous formations in the United States; (2) laboratory studies of the physical and chemical properties of selected argillaceous rock samples; and (3) two full-scale in situ surface heater experiments that simulate the emplacement of heat-generating radioactive waste in argillaceous rock

  20. United States National Waste Terminal Storage argillaceous rock studies

    International Nuclear Information System (INIS)

    Brunton, G.D.

    1979-01-01

    The past and present argillaceous rock studies for the US National Waste Terminal Storage Program consist of: (1) evaluation of the geological characteristics of several widespread argillaceous formations in the United States; (2) laboratory studies of the physical and chemical properties of selected argillaceous rock samples; and (3) two full-scale in-situ surface heater experiments that simulate the emplacement of heat-generating radioactive waste in argillaceous rock

  1. Spot testing on mechanical characteristics of surrounding rock in gates of fully mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guang-xiang; Yang Ke; Chang Ju-cai [Anhui University of Science and Technology, Anhui (China). Department of Resource Exploration and Management Engineering

    2006-07-01

    The distribution patterns of mechanical characteristics for surrounding rock in the gateways of fully mechanized top-coal caving (FMTC) face were put forward by analyzing deep displacement, surface displacement, stress distribution and supports loading. The results show that the surrounding rock of the gateways lies in abutment pressure decrease zone near the working face, so that the support load decreases. But the deformations of supports and surrounding rock are very acute. The deformation of surrounding rock appears mainly in abutment pressure influence zone. Reasonable roadway supporting should control the deformation of surrounding rock in intense stage of mining influence. Supporting design ideas of tailentry and head entry should be changed from loading control to deformation control. 8 refs., 10 figs., 1 tab.

  2. A sampling study on rock properties affecting drilling rate index (DRI)

    Science.gov (United States)

    Yenice, Hayati; Özdoğan, Mehmet V.; Özfırat, M. Kemal

    2018-05-01

    Drilling rate index (DRI) developed in Norway is a very useful index in determining the drillability of rocks and even in performance prediction of hard rock TBMs and it requires special laboratory test equipment. Drillability is one of the most important subjects in rock excavation. However, determining drillability index from physical and mechanical properties of rocks is very important for practicing engineers such as underground excavation, drilling operations in open pit mining, underground mining and natural stone production. That is why many researchers have studied concerned with drillability to find the correlations between drilling rate index (DRI) and penetration rate, influence of geological properties on drillability prediction in tunneling, correlations between rock properties and drillability. In this study, the relationships between drilling rate index (DRI) and some physico-mechanical properties (Density, Shore hardness, uniaxial compressive strength (UCS, σc), Indirect tensile strength (ITS, σt)) of three different rock groups including magmatic, sedimentary and metamorphic were evaluated using both simple and multiple regression analysis. This study reveals the effects of rock properties on DRI according to different types of rocks. In simple regression, quite high correlations were found between DRI and uniaxial compressive strength (UCS) and also between DRI and indirect tensile strength (ITS) values. Multiple regression analyses revealed even higher correlations when compared to simple regression. Especially, UCS, ITS, Shore hardness (SH) and the interactions between them were found to be very effective on DRI values.

  3. Mechanics of debris flows and rock avalanches: Chapter 43

    Science.gov (United States)

    Iverson, Richard M.; Fernando, Harindra Joseph

    2012-01-01

    Debris flows are geophysical phenomena intermediate in character between rock avalanches and flash floods. They commonly originate as water-laden landslides on steep slopes and transform into liquefied masses of fragmented rock, muddy water, and entrained organic matter that disgorge from canyons onto valley floors. Typically including 50%–70% solid grains by volume, attaining speeds >10 m/s, and ranging in size up to ∼109 m3, debris flows can denude mountainsides, inundate floodplains, and devastate people and property (Figure 43.1). Notable recent debris-flow disasters resulted in more than 20,000 fatalities in Armero, Colombia, in 1985 and in Vargas state, Venezuela, in 1999.

  4. Basic processes and mechanisms of the water-rock system evolution

    OpenAIRE

    Shvartsev, Stepan Lvovich

    2007-01-01

    A new conception of progressive evolution and self-organizing presence in dead matter is developed; inner mechanisms and processes, realizing this development, are revealed. It is proven that the water-rock system satisfy these requirements

  5. THM-issues in repository rock. Thermal, mechanical, thermo-mechanical and hydro-mechanical evolution of the rock at the Forsmark and Laxemar sites

    Energy Technology Data Exchange (ETDEWEB)

    Hoekmark, Harald; Loennqvist, Margareta; Faelth, Billy (Clay Technology AB, Lund (Sweden))

    2010-05-15

    The present report addresses aspects of the Thermo-Hydro-Mechanical (THM) evolution of the repository host rock that are of potential importance to the SR-Site safety assessment of a KBS-3 type spent nuclear fuel repository. The report covers the evolution of rock temperatures, rock stresses, pore pressures and fracture transmissivities during the excavation and operational phase, the temperate phase and a glacial cycle on different scales. The glacial cycle is assumed to include a period of pre-glacial permafrost with lowered temperatures and with increased pore pressures in the rock beneath the impermeable permafrost layer. The report also addresses the question of the peak temperature reached during the early temperate phase in the bentonite buffer surrounding the spent fuel canisters. The main text is devoted exclusively to the projected THM evolution of the rock at the Forsmark site in central Sweden. The focus is on the potential for stress-induced failures, i.e. spalling, in the walls of the deposition holes and on changes in the transmissivity of fractures and deformation zones. All analyses are conducted by a combination of numerical tools (3DEC) and analytical solutions. All phases are treated separately and independently of each other, although in reality construction will overlap with heat generation because of the step-by-step excavation/deposition approach with some 50 years between deposition of the first and last canisters. It is demonstrated here that the thermal and thermo-mechanical evolution of the near-field will be independent of heat generated by canisters that were deposited in the past, provided that deposition is made in an orderly fashion, deposition area by deposition area. Peak temperatures and near-field stresses can, consequently, be calculated as if all canisters were deposited simultaneously. The canister and tunnel spacing is specified such that the peak buffer temperature will not exceed 100 deg C in any deposition hole, i.e. not

  6. Numerical modelling of fluid-rock interactions: Lessons learnt from carbonate rocks diagenesis studies

    Science.gov (United States)

    Nader, Fadi; Bachaud, Pierre; Michel, Anthony

    2015-04-01

    Quantitative assessment of fluid-rock interactions and their impact on carbonate host-rocks has recently become a very attractive research topic within academic and industrial realms. Today, a common operational workflow that aims at predicting the relevant diagenetic processes on the host rocks (i.e. fluid-rock interactions) consists of three main stages: i) constructing a conceptual diagenesis model including inferred preferential fluids pathways; ii) quantifying the resulted diagenetic phases (e.g. depositing cements, dissolved and recrystallized minerals); and iii) numerical modelling of diagenetic processes. Most of the concepts of diagenetic processes operate at the larger, basin-scale, however, the description of the diagenetic phases (products of such processes) and their association with the overall petrophysical evolution of sedimentary rocks remain at reservoir (and even outcrop/ well core) scale. Conceptual models of diagenetic processes are thereafter constructed based on studying surface-exposed rocks and well cores (e.g. petrography, geochemistry, fluid inclusions). We are able to quantify the diagenetic products with various evolving techniques and on varying scales (e.g. point-counting, 2D and 3D image analysis, XRD, micro-CT and pore network models). Geochemical modelling makes use of thermodynamic and kinetic rules as well as data-bases to simulate chemical reactions and fluid-rock interactions. This can be through a 0D model, whereby a certain process is tested (e.g. the likelihood of a certain chemical reaction to operate under specific conditions). Results relate to the fluids and mineral phases involved in the chemical reactions. They could be used as arguments to support or refute proposed outcomes of fluid-rock interactions. Coupling geochemical modelling with transport (reactive transport model; 1D, 2D and 3D) is another possibility, attractive as it provides forward simulations of diagenetic processes and resulting phases. This

  7. Petrological studies of plutonic rocks of Ecuador

    International Nuclear Information System (INIS)

    Aly, S.

    1980-01-01

    The feldspars of many tonalitic plutonic rocks in the coastal regions and West Andean regions are zoned. This leads to the conclusion that they are relatively flat intrusions and to some extent transition rocks in the subvulcanite direction. This is in accordance with the genetic and chronological relationship between plutonites and the surrounding vulcanites of the Basic Igreous Complex (BIC). The composition of representative minerals, e.g. alkali feldspar, plagioclase feldspar, biotite, chlorite, and amphibole has been determined as well as the age of plutonite samples by the K/Ar dating method. (DG) [de

  8. Study on Monitoring Rock Burst through Drill Pipe Torque

    OpenAIRE

    Zhonghua Li; Liyuan Zhu; Wanlei Yin; Yanfang Song

    2015-01-01

    This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the a...

  9. Petrophysical and rock-mechanics effects of CO2 injection for enhanced oil recovery

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Hjuler, Morten Leth; Christensen, Helle Foged

    2014-01-01

    this issue we studied two types of chalk from South Arne field, North Sea: (1) Ekofisk Formation having >12% non-carbonate and (2) Tor Formation, which has less than 5% non-carbonate. We performed a series of laboratory experiments to reveal the changes in petrophysical and rock-mechanics properties due...... reservoirs. North Sea chalk is characterized by high porosity but also high specific surface causing low permeability. A high porosity provides room for CO2 storage, while a high specific surface causes a high risk for chemical reaction and consequently for mechanical weakening. In order to address...... to the injection of CO2 at supercritical state. We analyzed these changes with respect to the differences in porosity, specific surface, pore stiffness, wettability, mineralogy and mechanical strength. We observed a 2–3% increase in porosity, a minor decrease of specific surface and consequently a small increase...

  10. Consideration on the Mechanism of Microwave Emission Due to Rock Fracture

    Science.gov (United States)

    Takano, Tadashi; Sugita, Seiji; Yoshida, Shingo; Maeda, Takashi

    2010-05-01

    Microwave emission due to rock fracture was found at 300 MHz, 2 GHz, and 22 GHz, and its power was calibrated in laboratory for the first time in the world. The observed waveform is impulsive, and contains correspondent frequency component inside the envelope at each frequency band. At such high frequencies, the electro-magnetic signal power can be calibrated as a radiating wave with high accuracy. Accordingly, it was verified that a substantial power is emitted. The microwave emission phenomena were also observed on occasions of hypervelocity impact, and esteemed as phenomena generally associated with material destruction. Earthquakes and volcanic activities are association with rock fractures so that the microwave is expected to be emitted. Actually, the e emission was confirmed by the data analysis of the brightness temperature obtained by a remote sensing satellite, which flew over great earthquakes of Wuenchan and Sumatra, and great volcanic eruptions of Reventador and Chanten. It is important to show the microwave emission during rock fracture in natural phenomena. Therefore, the field test to detect the microwave due to the collapse of a crater cliff was planned and persecuted at the volcano of Miyake-jima about 100 km south of Tokyo. Volcanic activity may be more convenient than an earthquake because of the known location and time. As a result, they observed the microwave emission which was strongly correlated with the cliff collapses. Despite of the above-mentioned phenomenological fruits, the reason of the microwave emission is not fixed yet. We have investigated the mechanism of the emission in consideration of the obtained data in rock fracture experiments so far and the study results on material destruction by hypervelocity impact. This paper presents the proposal of the hypothesis and resultant discussions. The microwave sensors may be useful to monitor natural hazards such as an earthquake or a volcanic eruption, because the microwave due to rock

  11. Mechanisms of continental subduction and exhumation of HP and UHP rocks

    NARCIS (Netherlands)

    Burov, Evgene; Francois, Thomas; Yamato, Philippe; Wolf, Sylvie

    We discuss possible scenarios of continental collision, and their relation to mechanisms of exhumation of HP and UHP rocks, inferred from thermo-mechanical numerical models accounting for thermo-rheological complexity of the continental lithosphere. Due to this complexity, mechanisms of continental

  12. Dynamic Response and Failure Mechanism of Brittle Rocks Under Combined Compression-Shear Loading Experiments

    Science.gov (United States)

    Xu, Yuan; Dai, Feng

    2018-03-01

    A novel method is developed for characterizing the mechanical response and failure mechanism of brittle rocks under dynamic compression-shear loading: an inclined cylinder specimen using a modified split Hopkinson pressure bar (SHPB) system. With the specimen axis inclining to the loading direction of SHPB, a shear component can be introduced into the specimen. Both static and dynamic experiments are conducted on sandstone specimens. Given carefully pulse shaping, the dynamic equilibrium of the inclined specimens can be satisfied, and thus the quasi-static data reduction is employed. The normal and shear stress-strain relationships of specimens are subsequently established. The progressive failure process of the specimen illustrated via high-speed photographs manifests a mixed failure mode accommodating both the shear-dominated failure and the localized tensile damage. The elastic and shear moduli exhibit certain loading-path dependence under quasi-static loading but loading-path insensitivity under high loading rates. Loading rate dependence is evidently demonstrated through the failure characteristics involving fragmentation, compression and shear strength and failure surfaces based on Drucker-Prager criterion. Our proposed method is convenient and reliable to study the dynamic response and failure mechanism of rocks under combined compression-shear loading.

  13. The Relationship between Mechanical Properties and Gradual Deterioration of Microstructures of Rock Mass Subject to Freeze-thaw Cycles

    Directory of Open Access Journals (Sweden)

    Haibo Jiang

    2018-01-01

    Full Text Available Under freeze-thaw cycles, the relationship between rock microstructure deterioration and its macroscopic mechanical characteristics has drawn extensive attention from engineers. With the objective to incorporate freeze-thaw cycle experiment into headrace tunnel engineering, in the present study two groups of andesite rock samples in different states are tested under the conditions of the lowest freezing temperature of –40 ℃ and the thawing temperature of 20 ℃. Damage detection was performed by magnetic resonance imaging for the interior microstructure of rock samples subject to different freeze-thaw cycles, and the relationship between the sample mechanical properties and gradual deterioration of rock microstructures was discussed. The results demonstrate evident influence of freeze-thaw cycle on the damage and deterioration of internal pore structure in andesite, and the rock uniaxial compressive strength and elasticity modulus exhibit a decreasing trend with the increase of freeze-thaw cycles. After 40 cycles, the strength of naturally saturated rock samples decreases by 39.4% (equivalent to 69.4 MPa and the elasticity modulus drops by 47.46% (equivalent to 3.27 GPa. For rock samples saturated by vacuum, 40 freeze-thaw cycles lead to a decrease of 36.86% (equivalent to 58.2 MPa in rock strength and a drop of 44.85% (equivalent to 2.83 GPa in elasticity modulus. Therefore, the test results quantitatively elucidate the substantial influence of freeze-thaw cycle on the damage and deterioration of internal structure in andesite.

  14. Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone

    Directory of Open Access Journals (Sweden)

    Hongwu Yin

    2017-09-01

    Full Text Available Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China.

  15. Microwave propagation and absorption and its thermo-mechanical consequences in heterogeneous rocks.

    Science.gov (United States)

    Meisels, R; Toifl, M; Hartlieb, P; Kuchar, F; Antretter, T

    2015-02-10

    A numerical analysis in a two-component model rock is presented including the propagation and absorption of a microwave beam as well as the microwave-induced temperature and stress distributions in a consistent way. The analyses are two-dimensional and consider absorbing inclusions (discs) in a non-absorbing matrix representing the model of a heterogeneous rock. The microwave analysis (finite difference time domain - FDTD) is performed with values of the dielectric permittivity typical for hard rocks. Reflections at the discs/matrix interfaces and absorption in the discs lead to diffuse scattering with up to 20% changes of the intensity in the main beam compared to a homogeneous model rock. The subsequent thermo-mechanical finite element (FE) analysis indicates that the stresses become large enough to initiate damage. The results are supported by preliminary experiments on hard rock performed at 2.45 GHz.

  16. 煤岩组合体力学特性与瓦斯渗流规律试验研究%Experimental Study on Mechanical Properties and Permeability Evolution Law of Coal-rock Combination

    Institute of Scientific and Technical Information of China (English)

    常悦; 张雅萍; 栗继祖; 王向玲; 马利云; 李燕

    2017-01-01

    Based on triaxial permeability test system,the strength characteristics and permeability evolution law of coal-rock specimens of different height ratios of rock to coal under the condition of simulating different thicknesses of roof-coal-floor are studied.The results show that the peak strength values for coal-rock specimens are different due to the different height ratios of rock to coal,and the peak stress increases with the height ratio.The broken and failure models of the coal-rock combination specimens show a macroscopic shear fracture surface,and the fracture surface runs through the top and bottom rocks.With the increase of the axial strain,the permeability evolution law of the coal-rock combination specimen shows the "V" shape,which decreases to the lowest point first and then increases rapidly.And the corresponding axial strain of the permeability curve increases with the increase of the height ratio of rock to coal.%利用三轴渗流测试系统,模拟不同厚度的顶板、煤层和底板条件,进行了不同岩煤高度比条件下煤岩组合试件的力学特性与渗流规律的试验研究.结果表明:对于不同岩煤高度比的煤岩组合试件,失稳破坏的峰值强度存在差异,且峰值强度随岩煤高度比的增加呈增大趋势;组合煤岩体的失稳破坏呈现宏观剪切破裂面,且破裂面贯穿顶、底部岩石;组合煤岩体的渗透率随轴向应变的升高呈现先减小到最小值后迅速增加的“V”型变化趋势;且随着岩煤高度比的增加,渗透率曲线反弹点对应的轴向应变呈增大趋势.

  17. A study about long-term deformation of soft rock. 2

    International Nuclear Information System (INIS)

    Inoue, Hiroyuki; Yoshino, Naoto; Miyanomae, Shunichi; Mizutani, Kazuhiko; Noda, Kenji

    2004-02-01

    In this study, the laboratory mechanical tests of sedimentary soft rock sampled at Horonobe area in Hokkaido prefecture were conducted in order to build the confidence of Okubo model for long term deformation of sedimentary rock. And the stability of rock around tunnel in building under the condition assumed the underground of Horonobe area was examined by numerical simulation using information of boring data obtained before 2002 year. As a result, authors could obtain many values of parameter in Okubo model under various conditions. These conditions have the difference of temperature and water saturation. In addition, the life time in creep predicted by Okubo model could be compared with the real one. And numerical simulations, assuming various conditions such as stiffness of buffer material and yielding of support, had been carried out to evaluate the long-term stability of rock surrounding buffer material. Results show the decreasing tendency of time dependency of rock. (author)

  18. Foliation: Geological background, rock mechanics significance, and preliminary investigations at Olkiluoto

    International Nuclear Information System (INIS)

    Milnes, A.G.; Hudson, J.; Wikstroem, L.; Aaltonen, I.

    2006-01-01

    A well developed, pervasive foliation is a characteristic feature of the migmatites and gneisses in the Olkiluoto bedrock, and is expected to have a significant influence on the underground construction, the design and layout and the groundwater flow regime of a deep spent nuclear fuel repository. This Working Report reviews the geological background and rock mechanics significance of foliation, and develops a methodology for the systematic acquisition of foliation data in cored boreholes and in tunnels at the Olkiluoto site, to provide the necessary basis for future geological, rock mechanics and hydrogeological modelling. The first part of the methodology concerns foliation characterisation, and develops a characterisation scheme based on two variables: the foliation type (G = gneissic, B = banded, S = schistose), which is a function of mineral composition and degree of smallscale heterogeneity, and the foliation intensity (1 = low, 2 = intermediate, 3 = high), which is a function of the type and intensity of the deformation by which it was produced (under high-grade metamorphic conditions in the core of the Svecofennian orogenic belt). At the suggested reference scales (1 m length of core, 10 m 2 area of tunnel wall), the most representative foliation type and intensity is assessed using a standard set of core photographs, which are included as an Appendix at the end of the report, providing a systematic description in terms of 9 descriptive types (G1, G2, G3, B1, B2, B3, S1, S2, S3). As a further step, the rock mechanics significance of these types is assessed and a rock mechanics foliation (RMF) number is assigned (RMF 0 = no significance, RMF 1, RMF 2 and RMF 3 = low, intermediate and high significance, respectively). The second part of the methodology concerns the orientations of the foliation within the same 1 m core lengths or 10 m2 wall areas, which have been characterised as above. This combined analysis of foliation character and foliation orientation

  19. Basic rock properties for the thermo-hydro-mechanical analysis of a high-level radioactive waste repository

    International Nuclear Information System (INIS)

    Kim, Jhin Wung; Kang, Chul Hyung

    1999-04-01

    Deep geological radioactive waste disposal is generally based on the isolation of the waste from the biosphere by multiple barriers. The host rock is one of these barriers which should provide a stable mechanical and chemical environment for the engineered barriers. In the evaluation of the safety of the high-level radioactive waste disposal systems, an important part of the safety analysis is an assessment of the coupling or interaction between thermal, hydrological, and mechanical effects. In order to do this assessment, adequate data on the characteristics of different host rocks are necessary. The properties of the rock and rock discontinuity are very complex and their values vary in a wide range. The accuracy of the result of the assessment depends on the values of these properties used. The present study is an attempt to bring together and condense data for the basic properties of various rock masses, which are needed in the thermo-hydro-mechanical analysis for the deep geological radioactive waste repository. The testing and measurement methods for these basic properties are also presented. Domestic data for deep geological media should be supplemented in the future, due to the insufficiency and the lack of accuracy of the data available at present. (author). 28 refs., 21 figs

  20. Basic rock properties for the thermo-hydro-mechanical analysis of a high-level radioactive waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jhin Wung; Kang, Chul Hyung

    1999-04-01

    Deep geological radioactive waste disposal is generally based on the isolation of the waste from the biosphere by multiple barriers. The host rock is one of these barriers which should provide a stable mechanical and chemical environment for the engineered barriers. In the evaluation of the safety of the high-level radioactive waste disposal systems, an important part of the safety analysis is an assessment of the coupling or interaction between thermal, hydrological, and mechanical effects. In order to do this assessment, adequate data on the characteristics of different host rocks are necessary. The properties of the rock and rock discontinuity are very complex and their values vary in a wide range. The accuracy of the result of the assessment depends on the values of these properties used. The present study is an attempt to bring together and condense data for the basic properties of various rock masses, which are needed in the thermo-hydro-mechanical analysis for the deep geological radioactive waste repository. The testing and measurement methods for these basic properties are also presented. Domestic data for deep geological media should be supplemented in the future, due to the insufficiency and the lack of accuracy of the data available at present. (author). 28 refs., 21 figs.

  1. Mechanical characterization of rocks at high strain rate

    Directory of Open Access Journals (Sweden)

    Konstantinov A.

    2012-08-01

    Full Text Available The paper presents the dynamic characterization in tension and compression of three rocks, Carrara marble, Onsernone gneiss and Peccia Marble, at high strain-rates. Two versions of a Split Hopkinson Bar have been used. The version for direct tension tests is installed at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland, while the traditional version in compression is installed at the Laboratory of Dynamic Investigation of Materials of Lobachevsky State University. Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic strength increasing with strain-rate. The experimental research has been developed in the frame of the Swiss-Russian Joint Research Program.

  2. Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

    Science.gov (United States)

    Li, Qinghai; Shi, Weiping; Yang, Renshu

    2016-01-01

    The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

  3. Effects of Freezing and Thawing Cycle on Mechanical Properties and Stability of Soft Rock Slope

    Directory of Open Access Journals (Sweden)

    Yanlong Chen

    2017-01-01

    Full Text Available To explore the variation laws of mechanical parameters of soft rock and the formed slope stability, an experiment was carried out with collected soft rock material specimens and freezing and thawing cycle was designed. Meanwhile, a computational simulation analysis of the freezing-thawing slope stability was implemented. Key factors that influence the strength of frozen rock specimens were analyzed. Results showed that moisture content and the number of freezing-thawing cycles influenced mechanical parameters of soft rock significantly. With the increase of moisture content, cohesion of frozen soft rock specimens presents a quadratic function decrease and the internal friction angle shows a negative exponential decrease. The stability coefficient of soft rock material slope in seasonal freeze soil area declines continuously. With the increase of freezing and thawing cycle, both cohesion and internal friction angle of soft rock decrease exponentially. The higher the moisture content, the quicker the reduction. Such stability coefficient presents a negative exponential reduction. After three freezing and thawing cycles, the slope stability coefficient only changes slightly. Findings were finally verified by the filed database.

  4. Studies on the radiation absorption characteristics of various rocks

    International Nuclear Information System (INIS)

    Rahman, K.N.; Abdullah, S.A.; Gazzaz, M.A.

    1984-05-01

    Radiation absorption characteristics of nine different rocks, namely, ferrugenous quartz, metabasalt, larvikite, coarse grained diorite, coarse grained granite, coarse grained alkali granite, marble, quartz mica schist, and metamorphosed rock are studied. The rocks were collected from Jeddah, Makkah, Mina and Taif areas. Special attention was given on the availability, compactness, physical formation and uniform composition in selecting the rocks. The rocks were identified by optical method and their elemental composition determined by chemical analysis. The data were used to calculate the effective atomic numbers, half value layers mass and linear attenuation coefficients. The half value layers and the linear attenuation coefficientsof these rocks were determined experimentally using Am-241, Cs-137,and Co-60 sources. The results are compared with those obtained by theoretical calculations and agrre within 10%. Most of the rocks show much higher radiation attenuation characteristics than the standard concrete. Rocks containing higher percentage of Fe, Ca, Ti, and Mn show much higher radiation absorption characteristics than concrete. Only granites are found to be almost equivalent to concrete. 12 Ref

  5. Influence of Fissure Number on the Mechanical Properties of Layer-Crack Rock Models under Uniaxial Compression

    Directory of Open Access Journals (Sweden)

    Yun-liang Tan

    2018-01-01

    Full Text Available Many case studies have revealed that rock bursts generally occur in the high stress concentration area where layer-crack structures often exist, especially for brittle coal or rock masses. Understanding the mechanical properties of layer-crack rock models is beneficial for rational design and stability analysis of rock engineering project and rock burst prevention. This study experimentally investigated the influence of fissure number on the mechanical properties of layer-crack rock models through uniaxial compression tests. The digital speckle correlation method (DSCM and acoustic emission (AE techniques were applied to record and analyze the information of deformation and failure processes. Test results show the following: the bearing capacity of layer-crack specimen decreases compared with intact specimen, but their failure modes are similar, which are the splitting failure accompanied with local shear failure; the nonuniform deformation phenomenon begins to appear at the elastic deformation stage for layer-crack specimens; the AE behavior of intact specimens consists of three stages, that is, active stage, quiet stage, and major active stage, but for layer-crack specimens, it is characteristic by three peaks without quiet stage. In addition, as the fissure number of layer-crack specimens increases, the bearing capacity of specimens decreases, the appearing time of nonuniform deformation phenomenon in the specimen surface decreases, the AE events are denser and denser in each peak stage, and the risk of dynamic instability of layer-crack structure increases. At last, the failure mechanism of layer-crack structure and the related mitigation advices were discussed based on the test results. In general, the novelty is that this paper focuses on the failure mechanism of layer-crack structure directly.

  6. Determination of soil mechanics of salt rock as a potential backfilling material in an underground repository

    International Nuclear Information System (INIS)

    Kappei, G.

    1987-09-01

    Within the framework of the research and development project 'Backfilling and sealing of boreholes, chambers and roadways in a final dump', the Institute for Underground Dumping chose - from the broad range of possible stowing materials - the material 'salt spoil' and investigated its soil-mechanical properties in detail. Besides the implementation of soil-mechanical standard analyses (determination of the grain size distribution, bulk density, limits of storage density, proctor density, permeabilities, and shear strength) of two selected salt spoils (heap salt and rock salt spoil), the studies concentrated on the determination of the compression behaviour of salt spoil. In order to obtain data on the compaction behaviour of this material in the case of increasing stress, compression tests with obstructed lateral expansion were carried out on a series of spoil samples differing mainly in the composition of grain sizes. In addition to this, for a small number of samples of rock salt spoil, the creep behaviour at constant stress was determined after the compaction phase. (orig./RB) [de

  7. Assessment of rock mechanical properties and seismic slope stability in variably weathered layered basalts

    Science.gov (United States)

    Greenwood, William; Clark, Marin; Zekkos, Dimitrios; Von Voigtlander, Jennifer; Bateman, Julie; Lowe, Katherine; Hirose, Mitsuhito; Anderson, Suzanne; Anderson, Robert; Lynch, Jerome

    2016-04-01

    A field and laboratory experimental study was conducted to assess the influence of weathering on the mechanical properties of basalts in the region of the Kohala volcano on the island of Hawaii. Through the systematic characterization of the weathering profiles developed in different precipitation regimes, we aim to explain the regional pattern of stability of slopes in layered basalts that were observed during the 2006 Mw 6.7 Kiholo Bay earthquake. While deeper weathering profiles on the wet side of the island might be expected to promote more and larger landslides, the distribution of landslides during the Kiholo Bay earthquake did not follow this anticipated trend. Landslide frequency (defined as number of landslides divided by total area) was similar on the steepest slopes (> 50-60) for both the dry and the wet side of the study area suggesting relatively strong ground materials irrespective of weathering. The study location is ideally suited to investigate the role of precipitation, and more broadly of climate, on the mechanical properties of the local rock units because the presence of the Kohala volcano produces a significant precipitation gradient on what are essentially identical basaltic flows. Mean annual precipitation (MAP) varies by more than an order of magnitude, from 200 mm/year on the western side of the volcano to 4000 mm/year in the eastern side. We will present results of measured shear wave velocities using a seismic surface wave methodology. These results were paired with laboratory testing on selected basalt specimens that document the sample-scale shear wave velocity and unconfined compressive strength of the basaltic rocks. Shear wave velocity and unconfined strength of the rocks are correlated and are both significantly lower in weathered rocks near the ground surface than at depth. This weathering-related reduction in shear wave velocity extends to greater depths in areas of high precipitation compared to areas of lower precipitation

  8. Mineralogical and geological study of fault rocks and associated strata

    International Nuclear Information System (INIS)

    Kim, Jeon Jin; Jeong, Gyo Cheol; Bae, Doo Won; Park, Seong Min; Kim, Jun Yeong

    2007-01-01

    Mineralogical characterizations of fault clay and associated strata in fault zone with field study and analytical methods. Mineral composition and color of fault clay and rock occur in fracture zone different from bed rocks. Fault clay mainly composed of smectite with minor zeolite such as laumontite and stilbite, and halloysite, illite, Illite and halloysite grow on the surface of smectite, and laumontite and stilbite result from precipitation or alteration of Ca rich bed rock. The result of mineralogical study at Ipsil, Wangsan, Gaegok, Yugyeori, Gacheon in Gyeongju area, the detail research of microstructure in the fault clay making it possible for prediction to age of fault activity

  9. Mineralogical and geological study of fault rocks and associated strata

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeon Jin; Jeong, Gyo Cheol; Bae, Doo Won; Park, Seong Min; Kim, Jun Yeong [Andong Univ., Andong (Korea, Republic of)

    2007-01-15

    Mineralogical characterizations of fault clay and associated strata in fault zone with field study and analytical methods. Mineral composition and color of fault clay and rock occur in fracture zone different from bed rocks. Fault clay mainly composed of smectite with minor zeolite such as laumontite and stilbite, and halloysite, illite, Illite and halloysite grow on the surface of smectite, and laumontite and stilbite result from precipitation or alteration of Ca rich bed rock. The result of mineralogical study at Ipsil, Wangsan, Gaegok, Yugyeori, Gacheon in Gyeongju area, the detail research of microstructure in the fault clay making it possible for prediction to age of fault activity.

  10. FE Analysis of Rock with Hydraulic-Mechanical Coupling Based on Continuum Damage Evolution

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2016-01-01

    Full Text Available A numerical finite element (FE analysis technology is presented for efficient and reliable solutions of rock with hydraulic-mechanical (HM coupling, researching the seepage characteristics and simulating the damage evolution of rock. To be in accord with the actual situation, the rock is naturally viewed as heterogeneous material, in which Young’s modulus, permeability, and strength property obey the typical Weibull distribution function. The classic Biot constitutive relation for rock as porous medium is introduced to establish a set of equations coupling with elastic solid deformation and seepage flow. The rock is subsequently developed into a novel conceptual and practical model considering the damage evolution of Young’s modulus and permeability, in which comprehensive utilization of several other auxiliary technologies, for example, the Drucker-Prager strength criterion, the statistical strength theory, and the continuum damage evolution, yields the damage variable calculating technology. To this end, an effective and reliable numerical FE analysis strategy is established. Numerical examples are given to show that the proposed method can establish heterogeneous rock model and be suitable for different load conditions and furthermore to demonstrate the effectiveness and reliability in the seepage and damage characteristics analysis for rock.

  11. Astronaut Neil Armstrong studies rock samples during geological field trip

    Science.gov (United States)

    1969-01-01

    Astronaut Neil Armstrong, commander of the Apollo 11 lunar landing mission, studies rock samples during a geological field trip to the Quitman Mountains area near the Fort Quitman ruins in far west Texas.

  12. Studies about strength recovery and generalized relaxation behavior of rock (4)

    International Nuclear Information System (INIS)

    Sanada, Masanori; Kishi, Hirokazu; Hayashi, Katsuhiko; Takebe, Atsuji; Okubo, Seisuke

    2011-11-01

    Surrounding rock failure occurs due to the increasing stress with tunnel excavation and extent of the failure depends on rock strength and rock stress. The NATM (New Austrian Tunneling Method) assumes that supporting effects by shotcrete and rock bolt prevent rock failure maximizing the potential capability of rock mass. Recently, it was found that failed rock just behind tunnel support recovers its strength. This phenomenon should take into account in evaluation of tunnel stability and long-term mechanical behavior of rock mass after closure of a repository for high-level radioactive waste (HLW). Visco-elastic behavior of rock is frequently studied by creep testing, but creep occasionally occurs together with relaxation in-situ due to the effect of various supports and rock heterogeneity. Therefore generalized stress relaxation in which both load and displacement are controlled is proper to study such behavior under the complicated conditions. It is also important to understand rock behavior in tensile stress field which may be developed in the surrounding rock of deposition hole or tunnel by swelling of bentonite or volume expansion of overpack with corrosion after the repository closure. Cores sampled at 'Horonobe Underground Research Laboratory' has been tested to reveal the above-mentioned behavior. Quantitative evaluation and modeling of the rock behavior, however, have not been established mainly because of large scatter of data. As a factor of the large scatter of data, it was expected that the evaporation of moisture from the surface of the test piece influences the test outcome because it tested in the nature. In this study, strength recovery, generalized stress relaxation and two tensile strength tests were carried out using shale sampled in the Wakkanai-formation. As the results, recovery of failed rocks in strength and hydraulic conductivity were observed under a certain condition. We believe this result is very important for the stability evaluation

  13. Mechanical behaviour and rupture in clayey rocks studied by x-ray micro tomography; Comportement mecanique et rupture dans les roches argileuses etudies par micro tomographie a rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Lenoir, N

    2006-03-15

    Within the framework of feasibility studies of underground repositories for radioactive waste, the study of permeability evolution with damage of the host layer is crucial. The goals of this work were: (i) to characterize experimentally the damage of two clayey rocks (BEAUCAIRE MARL and EAST SHALE) with x-ray micro tomography, (ii) to develop a high pressure triaxial set-up adapted to permeability measurement on very low permeability rocks.A number of original triaxial devices have been realised to characterize damage of clayey rocks, under deviatoric loading, with x-ray micro tomography on a synchrotron beamline at the ESRF (Grenoble). Localized damage and its evolution have been characterized at a fine scale (of order of ten microns). Digital image correlation techniques, extended to 3d images, have been used to measure incremental strain fields from tomographic images. we demonstrated that these techniques are very useful in the study of the localized damage of geo-materials and especially for the initiation. A high pressure triaxial device has been realised to measure permeability evolution of the east shale as a function of applied stress (isotropic and deviatoric). The particularity of this set-up is the small size of the test specimen (cylinder of 10 mm in diameter and 20 mm in height) which allows significant reduction of test duration. (author)

  14. Workshop on rock mechanics issues in repository design and performance assessment

    International Nuclear Information System (INIS)

    1996-04-01

    The Center for Nuclear Waste Regulatory Analyses organized and hosted a workshop on ''Rock Mechanics Issues in Repository Design and Performance Assessment'' on behalf its sponsor the U.S. Nuclear Regulatory Commission (NRC). This workshop was held on September 19- 20, 1994 at the Holiday Inn Crowne Plaza, Rockville, Maryland. The objectives of the workshop were to stimulate exchange of technical information among parties actively investigating rock mechanics issues relevant to the proposed high-level waste repository at Yucca Mountain and identify/confirm rock mechanics issues important to repository design and performance assessment The workshop contained three technical sessions and two panel discussions. The participants included technical and research staffs representing the NRC and the Department of Energy and their contractors, as well as researchers from the academic, commercial, and international technical communities. These proceedings include most of the technical papers presented in the technical sessions and the transcripts for the two panel discussions

  15. STAFAN, Fluid Flow, Mechanical Stress in Fractured Rock of Nuclear Waste Repository

    International Nuclear Information System (INIS)

    Huyakorn, P.; Golis, M.J.

    1989-01-01

    1 - Description of program or function: STAFAN (Stress And Flow Analysis) is a two-dimensional, finite-element code designed to model fluid flow and the interaction of fluid pressure and mechanical stresses in a fractured rock surrounding a nuclear waste repository. STAFAN considers flow behavior of a deformable fractured system with fracture-porous matrix interactions, the coupling effects of fluid pressure and mechanical stresses in a medium containing discrete joints, and the inelastic response of the individual joints of the rock mass subject to the combined fluid pressure and mechanical loading. 2 - Restrictions on the complexity of the problem: STAFAN does not presently contain thermal coupling, and it is unable to simulate inelastic deformation of the rock mass and variably saturated or two-phase flow in the fractured porous medium system

  16. Influence of geological factors on the mechanical properties of rock in the Palo Duro Basin

    International Nuclear Information System (INIS)

    Cregger, D.M.; Corkum, D.H.; Gokce, A.O.; Peck, J.H.

    1985-01-01

    Sedimentary formations in the Palo Duro Basin of the Texas Panhandle exhibit a variety of petrofabrics which contribute to different mechanical behavior. Similarly classified rock core specimens, upon closer inspection, are comprised of different textures and slight compositional variations. The resultant rock mass characteristics interpreted from laboratory tests and deep borehole geophysical logs are seen to be a direct result of the depositional environment and geologic history. Depositional environments include chemical precipitation in shallow brine pools, basin filling with terrigenous or eolian supply of clastics, restricted circulation, and transgression of normal marine waters. Geochemical transformations of the deposits, (diagenesis), can or may result in profound changes to the mechanical properties of the rock. Structural deformation of the bedded salts is slight and may be far less important in its effect on mechanical properties than diagenetic changes

  17. Integrating rock mechanics issues with repository design through design process principles and methodology

    International Nuclear Information System (INIS)

    Bieniawski, Z.T.

    1996-01-01

    A good designer needs not only knowledge for designing (technical know-how that is used to generate alternative design solutions) but also must have knowledge about designing (appropriate principles and systematic methodology to follow). Concepts such as open-quotes design for manufactureclose quotes or open-quotes concurrent engineeringclose quotes are widely used in the industry. In the field of rock engineering, only limited attention has been paid to the design process because design of structures in rock masses presents unique challenges to the designers as a result of the uncertainties inherent in characterization of geologic media. However, a stage has now been reached where we are be able to sufficiently characterize rock masses for engineering purposes and identify the rock mechanics issues involved but are still lacking engineering design principles and methodology to maximize our design performance. This paper discusses the principles and methodology of the engineering design process directed to integrating site characterization activities with design, construction and performance of an underground repository. Using the latest information from the Yucca Mountain Project on geology, rock mechanics and starter tunnel design, the current lack of integration is pointed out and it is shown how rock mechanics issues can be effectively interwoven with repository design through a systematic design process methodology leading to improved repository performance. In essence, the design process is seen as the use of design principles within an integrating design methodology, leading to innovative problem solving. In particular, a new concept of open-quotes Design for Constructibility and Performanceclose quotes is introduced. This is discussed with respect to ten rock mechanics issues identified for repository design and performance

  18. Mechanical and physical properties of hydrothermally altered rocks, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Wyering, L. D.; Villeneuve, M. C.; Wallis, I. C.; Siratovich, P. A.; Kennedy, B. M.; Gravley, D. M.; Cant, J. L.

    2014-11-01

    Mechanical characterization of hydrothermally altered rocks from geothermal reservoirs will lead to an improved understanding of rock mechanics in a geothermal environment. To characterize rock properties of the selected formations, we prepared samples from intact core for non-destructive (porosity, density and ultrasonic wave velocities) and destructive laboratory testing (uniaxial compressive strength). We characterised the hydrothermal alteration assemblage using optical mineralogy and existing petrography reports and showed that lithologies had a spread of secondary mineralisation that occurred across the smectite, argillic and propylitic alteration zones. The results from the three geothermal fields show a wide variety of physical rock properties. The testing results for the non-destructive testing shows that samples that originated from the shallow and low temperature section of the geothermal field had higher porosity (15 - 56%), lower density (1222 - 2114 kg/m3) and slower ultrasonic waves (1925 - 3512 m/s (vp) and 818 - 1980 m/s (vs)), than the samples from a deeper and higher temperature section of the field (1.5 - 20%, 2072 - 2837 kg/m3, 2639 - 4593 m/s (vp) and 1476 - 2752 m/s (vs), respectively). The shallow lithologies had uniaxial compressive strengths of 2 - 75 MPa, and the deep lithologies had strengths of 16 - 211 MPa. Typically samples of the same lithologies that originate from multiple wells across a field have variable rock properties because of the different alteration zones from which each sample originates. However, in addition to the alteration zones, the primary rock properties and burial depth of the samples also have an impact on the physical and mechanical properties of the rock. Where this data spread exists, we have been able to derive trends for this specific dataset and subsequently have gained an improved understanding of how hydrothermal alteration affects physical and mechanical properties.

  19. Rock Mechanics Forsmark. Site descriptive modelling Forsmark stage 2.2

    Energy Technology Data Exchange (ETDEWEB)

    Glamheden, Rune; Fredriksson, Anders (Golder Associates AB (SE)); Roeshoff, Kennert; Karlsson, Johan (Berg Bygg Konsult AB (SE)); Hakami, Hossein (Itasca Geomekanik AB (SE)); Christiansson, Rolf (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE))

    2007-12-15

    The Swedish Nuclear Fuel and Waste Management Company (SKB) is undertaking site characterisation at two different locations, Forsmark and Laxemar/Simpevarp, with the objective of siting a geological repository for spent nuclear fuel. The characterisation of a site is an integrated work carried out by several disciplines including geology, rock mechanics, thermal properties, hydrogeology, hydrogeochemistry and surface systems. This report presents the rock mechanics model of the Forsmark site up to stage 2.2. The scope of work has included compilation and analysis of primary data of intact rock and fractures, estimation of the rock mass mechanical properties and estimation of the in situ state of stress at the Forsmark site. The laboratory results on intact rock and fractures in the target volume demonstrate a good quality rock mass that is strong, stiff and relatively homogeneous. The homogeneity is also supported by the lithological and the hydrogeological models. The properties of the rock mass have been initially estimated by two separate modelling approaches, one empirical and one theoretical. An overall final estimate of the rock mass properties were achieved by integrating the results from the two models via a process termed 'Harmonization'. Both the tensile tests, carried out perpendicular and parallel to the foliation, and the theoretical analyses of the rock mass properties in directions parallel and perpendicular to the major principal stress, result in parameter values almost independent of direction. This indicates that the rock mass in the target volume is isotropic. The rock mass quality in the target volume appears to be of high and uniform quality. Those portions with reduced rock mass quality that do exist are mainly related to sections with increased fracture frequency. Such sections are associated with deformation zones according to the geological description. The results of adjacent rock domains and fracture domains of the target

  20. Mechanical Behavior of Low Porosity Carbonate Rock: From Brittle Creep to Ductile Creep.

    Science.gov (United States)

    Nicolas, A.; Fortin, J.; Gueguen, Y.

    2014-12-01

    Mechanical compaction and associated porosity reduction play an important role in the diagenesis of porous rocks. They may also affect reservoir rocks during hydrocarbon production, as the pore pressure field is modified. This inelastic compaction can lead to subsidence, cause casing failure, trigger earthquake, or change the fluid transport properties. In addition, inelastic deformation can be time - dependent. In particular, brittle creep phenomena have been deeply investigated since the 90s, especially in sandstones. However knowledge of carbonates behavior is still insufficient. In this study, we focus on the mechanical behavior of a 14.7% porosity white Tavel (France) carbonate rock (>98% calcite). The samples were deformed in a triaxial cell at effective confining pressures ranging from 0 MPa to 85 MPa at room temperature and 70°C. Experiments were carried under dry and water saturated conditions in order to explore the role played by the pore fluids. Two types of experiments have been carried out: (1) a first series in order to investigate the rupture envelopes, and (2) a second series with creep experiments. During the experiments, elastic wave velocities (P and S) were measured to infer crack density evolution. Permeability was also measured during creep experiments. Our results show two different mechanical behaviors: (1) brittle behavior is observed at low confining pressures, whereas (2) ductile behavior is observed at higher confining pressures. During creep experiments, these two behaviors have a different signature in term of elastic wave velocities and permeability changes, due to two different mechanisms: development of micro-cracks at low confining pressures and competition between cracks and microplasticity at high confining pressure. The attached figure is a summary of 20 triaxial experiments performed on Tavel limestone under different conditions. Stress states C',C* and C*' and brittle strength are shown in the P-Q space: (a) 20°C and dry

  1. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2004-02-01

    Micro-structure of rock plays an essential role for their long-term behavior. For understanding long-term characteristics of granite we here present the followings: 1) observation of microcrack initiation and propagation by Conforcal Laser Scanning Microscope (CLSM) under uniaxial compression (before loading and at each loading stage), 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, and 3) a study of strong discontinuity analysis included in the homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. First, CLSM was used to acquire clearly focused three-dimensional images of granite specimens, and observed the change of microscale structure including the mineral configuration under applying uniaxial compression stress. Then though microcracks have ever thought to be initiated and propagated on intergranular boundaries, we understand through the CLSM observation that new microcracks are generated from the ends of pre-existing cracks which are distributed in quartz and biotite. Second, we showed the results of stress-relaxation test of granite specimens observed by an optical microscope under water-saturated triaxial compression condition. Since microcrack generation and propagation play an essential role to predict the long-term behavior of rock, we managed the experiments with careful attention of 1) keeping constant edge-displacement and constant strain in the whole specimen accurately, and 2) measuring the relaxed stress exactly. Next, in order to simulate the experimental results which indicate that initiation and propagation of microcracks control the stress-relaxation phenomenon, we introduce a homogenization analysis procedure together with the strong discontinuity analysis which has recently established the mechanical implication and mathematical foundation. The numerical results show that we can

  2. Yucca Mountain Project thermal and mechanical codes first benchmark exercise: Part 3, Jointed rock mass analysis

    International Nuclear Information System (INIS)

    Costin, L.S.; Bauer, S.J.

    1991-10-01

    Thermal and mechanical models for intact and jointed rock mass behavior are being developed, verified, and validated at Sandia National Laboratories for the Yucca Mountain Site Characterization Project. Benchmarking is an essential part of this effort and is one of the tools used to demonstrate verification of engineering software used to solve thermomechanical problems. This report presents the results of the third (and final) phase of the first thermomechanical benchmark exercise. In the first phase of this exercise, nonlinear heat conduction code were used to solve the thermal portion of the benchmark problem. The results from the thermal analysis were then used as input to the second and third phases of the exercise, which consisted of solving the structural portion of the benchmark problem. In the second phase of the exercise, a linear elastic rock mass model was used. In the third phase of the exercise, two different nonlinear jointed rock mass models were used to solve the thermostructural problem. Both models, the Sandia compliant joint model and the RE/SPEC joint empirical model, explicitly incorporate the effect of the joints on the response of the continuum. Three different structural codes, JAC, SANCHO, and SPECTROM-31, were used with the above models in the third phase of the study. Each model was implemented in two different codes so that direct comparisons of results from each model could be made. The results submitted by the participants showed that the finite element solutions using each model were in reasonable agreement. Some consistent differences between the solutions using the two different models were noted but are not considered important to verification of the codes. 9 refs., 18 figs., 8 tabs

  3. Thermo-hydro-mechanical coupling in long-term sedimentary rock response

    Science.gov (United States)

    Makhnenko, R. Y.; Podladchikov, Y.

    2017-12-01

    Storage of nuclear waste or CO2 affects the state of stress and pore pressure in the subsurface and may induce large thermal gradients in the rock formations. In general, the associated coupled thermo-hydro-mechanical effect on long-term rock deformation and fluid flow have to be studied. Principles behind mathematical models for poroviscoelastic response are reviewed, and poroviscous model parameter, the bulk viscosity, is included in the constitutive equations. Time-dependent response (creep) of fluid-filled sedimentary rocks is experimentally quantified at isotropic stress states. Three poroelastic parameters are measured by drained, undrained, and unjacketed geomechanical tests for quartz-rich Berea sandstone, calcite-rich Apulian limestone, and clay-rich Jurassic shale. The bulk viscosity is calculated from the measurements of pore pressure growth under undrained conditions, which requires time scales 104 s. The bulk viscosity is reported to be on the order of 1015 Pa•s for the sandstone, limestone, and shale. It is found to be decreasing with the increase of pore pressure despite corresponding decrease in the effective stress. Additionally, increase of temperature (from 24 ºC to 40 ºC) enhances creep, where the most pronounced effect is reported for the shale with bulk viscosity decrease by a factor of 3. Viscous compaction of fluid-filled porous media allows a generation of a special type of fluid flow instability that leads to formation of high-porosity, high-permeability domains that are able to self-propagate upwards due to interplay between buoyancy and viscous resistance of the deforming porous matrix. This instability is known as "porosity wave" and its formation is possible under conditions applicable to deep CO2 storage in reservoirs and explains creation of high-porosity channels and chimneys. The reported experiments show that the formation of high-permeability pathways is most likely to occur in low-permeable clay-rich materials (caprock

  4. Application of rock mechanics to cut-and-fill mining. Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-15

    The conference on application of rock mechanics to cut-and-fill mining was held June 1-3, 1980, at the University of Luleaa, Luleaa, Sweden. Basic rock mechanics investigations of interest involving improving the support characteristics of backfilling by adding cement, compacting, and water removal have been entered individually into EDB. The papers also cover measurements of the support capability of such fills and the application of deformation measurements and calculations using finite element computer codes to the mining of particular ore bodies, including changes in the calculations as the mining progressed. (LTN)

  5. Rock mechanics. Proceedings of the 33rd U.S. symposium

    International Nuclear Information System (INIS)

    Tillerson, J.R.; Wawersik, W.R.

    1992-01-01

    After giving abstracts of the award winning papers for 1991 and the keynote lecture, papers are presented under the following headings: origin of stresses in the lithosphere; fault mechanics; rock mass monitoring; subsidence and ground motions; blasting; reservoir completion and stimulation; underground storage and sealing; design and supports; fluid and contaminant transport; numerical methods; constitutive modelling and strain localization; nonlinear dynamic systems; geostatistics and reliability; fracture mechanics; physical rock properties; experimental methods; geotechnical design methodology - workshop; and induced seismicity - workshop. Six papers have been abstracted separately

  6. Application of rock mechanics to cut-and-fill mining. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-15

    The conference on application of rock mechanics to cut-and-fill mining was held June 1-3, 1980, at the University of Luleaa, Sweden. The papers in this volume deal almost entirely with the Naesliden project in Sweden. Stress measurements were made on the rock mass before and during mining and complex computer codes using the finite element method developed to calculate the strains and their changes as mining developed. Major problems involved the effects of joints and the mechanical properties of the hydraulic backfill and in corporating these items in the calculations. Most papers were entered individually into EDB. (LTN)

  7. Deformation and damage modes of deep argillaceous rocks under hydro-mechanical stresses

    International Nuclear Information System (INIS)

    Vales, F.

    2008-12-01

    An experimental identification of the hydro-mechanical behaviour of an argillite rock is proposed within a multi-scale approach. In particular, interest is focused on the spatial and temporal localization of strain and damage in a specimen during hydro-mechanical loading. Firstly, we describe the techniques used to follow the rock evolutions under loading, and in particular Digital Images Correlation (DIC), Acoustic Emission, microscopy and mercury intrusion porosimetry. Measurement errors and device limitations are discussed. The studied material is the Callovo-Oxfordian indurated argillaceous rock (or argillite) of the Bure site where ANDRA has built an underground research laboratory to study the radioactive waste storage. Petrophysical characterizations and microstructural observations by optical and scanning electron microscopy provide an identification of the constitutive phase and a characterization of their spatial distribution and typical sizes. Argillite can be described as a composite structure with a continuous clay matrix and embedded mineral particles, essentially quartz and carbonates. The typical size of these particles ranges from a few micrometers to a few hundreds micrometers, with an average close to 50 μ.m. The general experimental procedure combines two steps: in a fist time, imposed suctions bring samples to a given degree of water saturation, and, in a second time, uniaxial mechanical compression tests are performed. To understand the evolutions of the material under hydric and mechanical loading, samples are instrumented with standard measurement techniques, but also with Digital Image Correlation, at both the global scale of the sample and the local scale of the composite microstructure, and with Acoustic Emissions recording. Moisture transfers are imposed by controlled suctions on the range of 150 to 2.8 MPa, corresponding to the relative humidity range of 32 to 98%RH. During pure hydric solicitation, the changes in physical parameters

  8. Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction

    Directory of Open Access Journals (Sweden)

    Qiao Lyu

    2016-08-01

    Full Text Available The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS tests together with an acoustic emission (AE system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young’s modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young’s modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young’s modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO2, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO2. SC-CO2 causes a greater reduction of shale’s mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.

  9. Some Mechanical Properties of Concrete by using Manufactured Blended Cement with Grinded Local Rocks

    Directory of Open Access Journals (Sweden)

    Zena K. Abbas Al-Anbori

    2016-03-01

    Full Text Available he use of blended cement in concrete provides economic, energy savings, and ecological benefits, and also provides. Improvement in the properties of materials incorporating blended cements. The major aim of this investigation is to develop blended cement technology using grinded local rocks . The research includes information on constituent materials, manufacturing processes and performance characteristics of blended cements made with replacement (10 and 20 % of grinded local rocks (limestone, quartzite and porcelinite from cement. The main conclusion of this study was that all types of manufactured blended cement conformed to the specification according to ASTM C595-12 (chemical and physical requirements. The percentage of the compressive strength for blended cement with 10% replacement are (20, 11 and 5 % , (2 , 12 and, 13 % and (18, 15 and 16 % for limestone , quartzite and porcelinite respectively at (7,28 and 90days for each compare to the reference mix, while blended cement with 20% replacement are (-3, -5 and -11 ,(6, -4% and -5 and (6, 4 and 6 % for limestone , quartzite and porcelinite respectively at (7, 28 and 90days compare to the reference mix .The other mechanical properties (flexural tensile strength and splitting tensile strength are the same phenomena of increase and decrease in compressive strength. The results indicated that the manufacture Portland-limestone cement, Portland-quartzite cement and Portland-porcelinite cement with 10% replacement of cement with improvable mechanical properties while the manufacture Portland-porcelinite cement with 20% replacement of cement with slight improvable mechanical properties and more economical cost.

  10. Mechanical Assessment of the Drip Shield Subject to Vibratory Motion and Dynamic and Static Rock Loading

    International Nuclear Information System (INIS)

    R.C. Quittmeyer

    2005-01-01

    The purpose of the drip shield (DS) is to divert water that may seep into emplacement drifts from contacting the waste packages, and to protect the waste packages from impact or static loading from rockfall. The objective of this document is to summarize, into one location, the results of a series of supporting engineering calculations that were developed to study the effect of static and dynamic loads on the mechanical performance of the DS. The potential DS loads are a result of: (1) Potential earthquake vibratory ground motion, and resulting interaction of the DS, waste package and pallet, and drift invert; (2) Dynamic impacts of rockfall resulting from emplacement drift damage as a result of earthquake vibratory motion; and (3) Static load of the caved rock rubble that may come to rest on the DS as a result of vibratory motion or from time-dependent yielding of the rock mass surrounding the emplacement drift. The potential mechanical failure mechanisms that may result from these loads include: (1) Overturning and/or separation of the interlocking DS segments; (2) Loss of structural integrity and stability of the DS, including excessive deformation or buckling; and (3) Localized damage to the top and side-wall plates of the DS. The scope of this document is limited to summarizing results presented in the supporting calculations in the areas of analysis of the potential for DS collapse, and determination of the damaged surface area of the DS plates. New calculations are presented to determine whether or not separation of DSs occur under vibratory motion

  11. Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction

    Science.gov (United States)

    Lyu, Qiao; Ranjith, Pathegama Gamage; Long, Xinping; Ji, Bin

    2016-01-01

    The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young’s modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young’s modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young’s modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO2, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO2). SC-CO2 causes a greater reduction of shale’s mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation. PMID:28773784

  12. Experimental Investigation of Mechanical Properties of Black Shales after CO₂-Water-Rock Interaction.

    Science.gov (United States)

    Lyu, Qiao; Ranjith, Pathegama Gamage; Long, Xinping; Ji, Bin

    2016-08-06

    The effects of CO₂-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO₂ in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO₂. According to the experimental results, the values of UCS, Young's modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO₂. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young's modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young's modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO₂, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO₂). SC-CO₂ causes a greater reduction of shale's mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO₂. The EDS results show that CO₂-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.

  13. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2002-03-01

    Micro-structure of rock plays a essential role for their long-term behavior. For elucidating long-term characteristics of granite we here present the followings: 1) Conforcal Laser Scanning Microscope (LSM) observation of joint surfaces of granite and Fourier analysis, 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, 3) observation of microcrack initiation and propagation by LSM under uniaxial compression, and 4) a viscoelastic homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. Rock image processing and analysis become a fundamental procedure to determine rock surface discontinuities. But the complexity of rock surface discontinuities seems beyond the manual image processing method. In Chapter 2 a Conforcal Laser Scanning Microscope that can acquire three-dimensional images is introduced to observe the rock roughness of a discontinuity. Then, scanning three-dimensional images are changed its data form in order to adapt various image analysis programs, and granitic rock roughness of discontinuities are displayed by graphic images. For example, these datas are analyzed by Discrete Fourier Transformation (DFT) program and Inverse Discrete Fourier Transformation (IDFT) program. Microcrack generation and propagation play an essential role to predict the long-term behavior of rock. In Chapter 3 a progressive development of cracking in granite is revealed by using stereoscopic microscope under triaxial compression condition and by using LSM under uniaxial compression condition. With a viscoelastic theory applied in homogenization method, we can calculate macro behavior of medium influenced by its micro structure by analyse the long-term time-dependent behavior of granite under the same condition to the relaxation experiment. (author)

  14. Natural analogue and microstructural studies in relation to radionuclide retardation by rock matrix diffusion in granite

    International Nuclear Information System (INIS)

    Montoto, M.; Rodriguez Rey, A.; Ruiz de Argandona, V.G.; Calleja, L.; Menendez, B.

    1992-01-01

    The possibility that radionuclide retardation by rock matrix diffusion will be limited in granitic rocks by geological factors is studied, as well as the possibility that diffusion will be confined to a narrow zone from water-conducting fractures. Petrophysical measurements, uranium series and geochemical analyses in the rock adjacent to fractures, have been performed to establish the extent of fracture-related microstructural changes that might influence the potential for diffusion and whether or not there is any record of diffusion of uranium, its daughters, or other elements. The results obtained from El Berrocal (Spain), Stripa (Sweden) and White-shell (Canada) granites, suggest that: (a) there is a zone adjacent to the fractures (generally less than 100 mm) where microstructural changes and enhanced uranium mobility exist; (b) the evidence for diffusion having taken place in the rock is confined largely to this zone. So, it appears that diffusivity determinations on rock collected away from the influence of fractures will not give representative data for diffusion modelling, in addition to the effect of distressing after removing rocks from depth. It is suggested that diffusion will be of limited effectiveness as a retardation mechanism in many granitic rocks, particularly in water movement confined to narrow channels where access by nuclides to the fracture walls is restricted. 51 refs., 56 figs., 9 tabs., 9 appendices

  15. Application of rock mechanics to cut-and-fill mining. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-15

    The conference on application of rock mechanics to cut-and-fill mining was held June 1-3, 1980, at the University of Luleaa, Sweden. The conference began with reviews of the application of rock mechanics to mining and back filling in Australia, Canada and the USA. More particular papers involved mines in Sweden, Italy, Australia (pre reinforcement of walls with steel cables cemented in) and at the Con Mine in Canada. Two papers involved backfill material and specifications. Eight papers involved the use of the mathematical models for calculating the stresses developed in the rock mass by computer calculations and therefore, the probable stability. Such calculations are particularly necessary in deep mines. Papers of general interest were entered individually into EDB. (LTN)

  16. A probabilistic approach to rock mechanical property characterization for nuclear waste repository design

    International Nuclear Information System (INIS)

    Kim, Kunsoo; Gao, Hang

    1996-01-01

    A probabilistic approach is proposed for the characterization of host rock mechanical properties at the Yucca Mountain site. This approach helps define the probability distribution of rock properties by utilizing extreme value statistics and Monte Carlo simulation. We analyze mechanical property data of tuff obtained by the NNWSI Project to assess the utility of the methodology. The analysis indicates that laboratory measured strength and deformation data of Calico Hills and Bullfrog tuffs follow an extremal. probability distribution (the third type asymptotic distribution of the smallest values). Monte Carlo simulation is carried out to estimate rock mass deformation moduli using a one-dimensional tuff model proposed by Zimmermann and Finley. We suggest that the results of these analyses be incorporated into the repository design

  17. Study on Monitoring Rock Burst through Drill Pipe Torque

    Directory of Open Access Journals (Sweden)

    Zhonghua Li

    2015-01-01

    Full Text Available This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the analysis, a new device for testing drill pipe torque is developed and a series of experiments is performed under different conditions; the results show that drill pipe torque linearly increases with the increase of coal stress and coal strength; the faster the drilling speed, the larger the drill pipe torque, and vice versa. When monitoring rock burst by drill pipe torque method, the index of rock burst is regarded as a function in which coal stress index and coal strength index are principal variables. The results are important for the forecast of rock burst in coal mine.

  18. Temperature loading and rocks mechanics at final storage of radioactive waste

    International Nuclear Information System (INIS)

    Leijon, B.; Stephansson, O.

    1979-01-01

    This report describes the rock mechanical effects - in the far field - from the thermal loading at a final storage of radioactive waste in crystalline rocks. The stress distribution of a two-storey storage is described in more details. The temperature rise in a final storage of radiactive waste will create thermal stresses which may cause a failure of the rock mass, and thereby an increase of its permeability. However, the state of stress in the Earth's crust is able to neutralize the thermal stresses. By this analysis we have been able to demonstrate that the thermal stresses due to heat conduction from the final storage are compensated by the state of stress in the upper part of the crust. The absolute stress, which is the superposition of thermal stress and virgin rock stress, is in all cases found to be below the limit of failure due to frictional resistance between surfaces of constituent blocks in the rock mass. Failure by sliding friction is the most conservative failure criterion for a rock mass. (author)

  19. Analysis of the rock mechanics properties of volcanic tuff units from Yucca Mountain, Nevada Test Site

    International Nuclear Information System (INIS)

    Price, R.H.

    1983-08-01

    Over two hundred fifty mechanical experiments have been run on samples of tuff from Yucca Mountain, Nevada Test Site. Cores from the Topopah Spring, Calico Hills, Bullfrog and Tram tuff units were deformed to collect data for an initial evaluation of mechanical (elastic and strength) properties of the potential horizons for emplacement of commercial nuclear wastes. The experimental conditions ranged in sample saturation from room dry to fully saturated, confining pressure from 0.1 to 20 MPa, pore pressure from 0.1 to 5 MPa, temperature from 23 to 200 0 C, and strain rate from 10 -7 to 10 -2 s -1 . These test data have been analyzed for variations in elastic and strength properties with changes in test conditions, and to study the effects of bulk-rock characteristics on mechanical properties. In addition to the site-specific data on Yucca Mountain tuff, mechanical test results on silicic tuff from Rainier Mesa, Nevada Test Site, are also discussed. These data both overlap and augment the Yucca Mountain tuff data, allowing more definitive conclusions to be reached, as well as providing data at some test conditions not covered by the site-specific tests

  20. Hydraulic and mechanical properties of natural fractures in low-permeability rock

    International Nuclear Information System (INIS)

    Pyrack-Nolte, L.J.; Myer, L.R.; Cook, N.G.W.; Witherspoon, P.A.

    1987-01-01

    The results of a comprehensive laboratory study of the mechanical displacement, permeability, and void geometry of single rock fractures in a quartz monzonite are summarized and analyzed. A metal-injection technique was developed that provided quantitative data on the precise geometry of the void spaces between the fracture surfaces and the areas of contact at different stresses. At effective stresses of less than 20 MPa fluid flow was proportional to the mean fracture aperture raised to a power greater than 3. As stress was increased, contact area was increased and void spaces become interconnected by small tortuous channels that constitute the principal impediment to fluid flow. At effective stresses higher than 20 MPa, the mean fracture aperture continued to diminish with increasing stress, but this had little effect on flow because the small tortuous flow channels deformed little with increasing stress

  1. Study on crystalline rock for evaluating method of long-term behavior. FY2012 (Contract research)

    International Nuclear Information System (INIS)

    Fukui, Katsunori; Hashiba, Kimihiro; Tanno, Takeo; Hikima, Ryoichi; Sanada, Hiroyuki; Sato, Toshinori

    2013-12-01

    Rock shows time-dependent behavior such as creep/relaxation. With respect to high-level radioactive waste disposal, knowledge of the long-term mechanical stability of shafts and galleries excavated in rock are required, over a period of thousands of years after closure as well as during construction and operation. Therefore, it is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. The purpose of this study is to determine the mechanisms of time-dependent behavior of rock by the precise test (e.g. laboratory creep test), observation and measurement and to develop methods for evaluating long-term mechanical stability. In previous works, testing techniques were established and basic evaluation methods were developed. Recently, some parameters, which required for simulation of time-dependent behavior, were determined for the modeling of biotite granite (Toki granite) distributed around the Mizunami underground research laboratory. However, we were not able to obtain enough data to assess the reliability of the method to evaluate these parameters. This report describes the results of the research activities carried out in fiscal year 2012. In Chapter 1, we provide background and an overview of this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in fiscal year 1997, are described. In Chapter 3, the experimental results concerning the loading-rate dependency of rock strength were examined to understand the time-dependent behavior of rock. In Chapter 4, the stability of tunnels, under conditions which rock stress is larger than that around a circular tunnel, were examined to obtain useful information on the future plan for in-situ tests in the underground research laboratory. (author)

  2. A 3D Analysis of Rock Block Deformation and Failure Mechanics Using Terrestrial Laser Scanning

    Science.gov (United States)

    Rowe, Emily; Hutchinson, D. Jean; Kromer, Ryan A.; Edwards, Tom

    2017-04-01

    planes on the slope that were confining the block. It is concluded that rock blocks in White Canyon may be classified as one of five main failure mechanisms based on their pre-failure deformation and structure: planar slide, topple, rotation, wedge, and overhang, with overhang failures representing a large portion of rockfalls in this area. Overhang rockfalls in the White Canyon are characterized by blocks that (a) are not supported by an underlying discontinuity plane, and (b) generally do not exhibit pre-failure deformation. Though overhanging rock blocks are a structural subset of toppling failure, their behavior suggests a different mechanism of detachment. Future work will further populate the present database of rockfalls in White Canyon and will expand the study to include other sites along this corridor. The ultimate goal of this research is to establish warning thresholds based on deformation magnitudes for rockfalls in White Canyon to assist Canadian railways in better understanding and managing these slopes.

  3. Investigation on the oxygen transport mechanisms in the Sarcheshmeh waste rock dumps

    Directory of Open Access Journals (Sweden)

    Saeed Yousefi

    2015-04-01

    Full Text Available Introduction Pyrite oxidation and acid mine drainage (AMD are the serious environmental problems associated with the mining activities in sulphide ores. The rate of pyrite oxidation is governed by the availability of oxygen (Borden, 2003. Therefore, the identifying oxygen supplying mechanism is one of the most important issues related to the environmental assessment of waste rock dumps (Cathles and Apps, 1975; Jaynes et al., 1984; Davis and Ritchie, 1986. Although comprehensive researches were performed on the mathematical description of oxygen transport processes using the numerical modeling (Morin et al., 1988; Blowes et al., 1991; Wunderly et al., 1986; Elberling et al., 1994; Jannesar Malakooti et al., 2014, so far, the interactions between these processes and geochemical and mineralogical characteristics has not been studied especially in waste rock dumps. Therefore the main objective of this study is to identify the evidences for knowing the oxygen transport mechanisms in the waste dumps and also, its role in intensity of pyrite oxidation. It is expected that such these structural studies could be useful for better understanding of dominant processes in numerical modeling and also providing environmental management strategies in the study area and other sites by similar characteristics. Materials and Methods In this study, thirty solid samples were collected from six excavated trenches in the waste rock dumps No. 19 and 31 of the Sarcheshmeh porphyry copper mine. Collected samples were studied using several methods such as XRD, ASTM-D2492, paste pH and grain size distribution. The results obtained from these methods were used with the field observations in order to characterize some detail information about oxygen supplying mechanisms for oxidation reactions in the waste rock dumps. Result The main minerals found by the XRD analysis were quartz and muscovite which were present in all samples. Pyrite, orthose, albite, and chlorite were also

  4. Study of rock structures by geotomography 5

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Yul; Kim, Yoo Sung; Hyun, Hye Ja [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

    1995-12-01

    Since computerized axial tomography has revolutionized medical x-ray imaging, geotomography has found its big impact in the field of seismic exploration because of its ability to clearly image subsurface velocity structures and attenuation characteristics of the formations. For example, lateral or vertical inhomogeneities may generate distortions in the observed arrival time and/or amplitude of seismic waves. By evaluating such distortions, one can locate the inhomogeneities which may not be detected easily by the conventional surface seismic survey. Recently, seismic geotomography has been used as an efficient aid for solving various, geophysical problems such as evaluating radioactive waste repository, detecting fracture zones in crystalline rocks, dam site investigation, cavity detection and so on. However, application of seismic methods to such environmental problems as above has rarely been conducted, thus many problems including development of suitable equipment and processing facilities still to be attacked. The objectives of this project can be categorized in three major parts. The first is an establishment of the geotomographical processing system on personal computers. This includes the development of an effective routines useful for the first onsets picking. The second is associated with the development of borehole source and receiver systems which provide meaningful data for geotomography. The small and light but powerful borehole acquisition system which is suitable for our field environment is needed to be developed. The third is concerned with the establishment of borehole scanner (televiewer) system for obtaining detailed information about fractures, bedding planes, geothermal reservoirs etc. It is evident that the above mentioned developments should represent our potential of crosshole seismic methods for the exploration of subsurface. The purpose of this investigation is to realize the highly efficient seismic methods i.e. (Abstract Truncated)

  5. Rock mechanics site descriptive model-theoretical approach. Preliminary site description Forsmark area - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Fredriksson, Anders; Olofsson, Isabelle [Golder Associates AB, Uppsala (Sweden)

    2005-12-15

    The present report summarises the theoretical approach to estimate the mechanical properties of the rock mass in relation to the Preliminary Site Descriptive Modelling, version 1.2 Forsmark. The theoretical approach is based on a discrete fracture network (DFN) description of the fracture system in the rock mass and on the results of mechanical testing of intact rock and on rock fractures. To estimate the mechanical properties of the rock mass a load test on a rock block with fractures is simulated with the numerical code 3DEC. The location and size of the fractures are given by DFN-realisations. The rock block was loaded in plain strain condition. From the calculated relationship between stresses and deformations the mechanical properties of the rock mass were determined. The influence of the geometrical properties of the fracture system on the mechanical properties of the rock mass was analysed by loading 20 blocks based on different DFN-realisations. The material properties of the intact rock and the fractures were kept constant. The properties are set equal to the mean value of each measured material property. The influence of the variation of the properties of the intact rock and variation of the mechanical properties of the fractures are estimated by analysing numerical load tests on one specific block (one DFN-realisation) with combinations of properties for intact rock and fractures. Each parameter varies from its lowest values to its highest values while the rest of the parameters are held constant, equal to the mean value. The resulting distribution was expressed as a variation around the value determined with mean values on all parameters. To estimate the resulting distribution of the mechanical properties of the rock mass a Monte-Carlo simulation was performed by generating values from the two distributions independent of each other. The two values were added and the statistical properties of the resulting distribution were determined.

  6. Rock mechanics site descriptive model-theoretical approach. Preliminary site description Forsmark area - version 1.2

    International Nuclear Information System (INIS)

    Fredriksson, Anders; Olofsson, Isabelle

    2005-12-01

    The present report summarises the theoretical approach to estimate the mechanical properties of the rock mass in relation to the Preliminary Site Descriptive Modelling, version 1.2 Forsmark. The theoretical approach is based on a discrete fracture network (DFN) description of the fracture system in the rock mass and on the results of mechanical testing of intact rock and on rock fractures. To estimate the mechanical properties of the rock mass a load test on a rock block with fractures is simulated with the numerical code 3DEC. The location and size of the fractures are given by DFN-realisations. The rock block was loaded in plain strain condition. From the calculated relationship between stresses and deformations the mechanical properties of the rock mass were determined. The influence of the geometrical properties of the fracture system on the mechanical properties of the rock mass was analysed by loading 20 blocks based on different DFN-realisations. The material properties of the intact rock and the fractures were kept constant. The properties are set equal to the mean value of each measured material property. The influence of the variation of the properties of the intact rock and variation of the mechanical properties of the fractures are estimated by analysing numerical load tests on one specific block (one DFN-realisation) with combinations of properties for intact rock and fractures. Each parameter varies from its lowest values to its highest values while the rest of the parameters are held constant, equal to the mean value. The resulting distribution was expressed as a variation around the value determined with mean values on all parameters. To estimate the resulting distribution of the mechanical properties of the rock mass a Monte-Carlo simulation was performed by generating values from the two distributions independent of each other. The two values were added and the statistical properties of the resulting distribution were determined

  7. Anisotropy of magnetic susceptibility of silicic rocks from quarries in the vicinity of São Marcos, Rio Grande do Sul, South Brazil: Implications for emplacement mechanisms

    Science.gov (United States)

    Cañón-Tapia, Edgardo; Raposo, M. Irene B.

    2018-04-01

    The Paraná-Etendeka Large Igneous Province includes acid volcanic rocks that can be found throughout its extension. Several aspects concerning those rocks remain controversial, including their mechanism of emplacement and location of their eruptive sources. Opening of several quarries of dimension stone near the city of Sao Marcos, Rio Grande do Sul, Brazil, offers a unique opportunity to study in detail the acid products. Here, we present the results of a study of the anisotropy of magnetic susceptibility (AMS) completed in some rocks that had been interpreted as the roots of volcanic conduits. Our results, and reexamination of the textural features of the rocks, lead to a reinterpretation that suggests that these rocks were emplaced subaerially, and involved assimilation and remelting of clastic components of previous products. Due to the inferred conditions of emplacement, it is unlikely that the eruptive vents are located far from the area of study, therefore ruling out the long-travelled nature of these products.

  8. Rock fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W.S.; Green, S.J.; Hakala, W.W.; Hustrulid, W.A.; Maurer, W.C. (eds.)

    1976-01-01

    Experts in rock mechanics, mining, excavation, drilling, tunneling and use of underground space met to discuss the relative merits of a wide variety of rock fragmentation schemes. Information is presented on novel rock fracturing techniques; tunneling using electron beams, thermocorer, electric spark drills, water jets, and diamond drills; and rock fracturing research needs for mining and underground construction. (LCL)

  9. Mechanisms of recharge in a fractured porous rock aquifer in a semi-arid region

    Science.gov (United States)

    Manna, Ferdinando; Walton, Kenneth M.; Cherry, John A.; Parker, Beth L.

    2017-12-01

    Eleven porewater profiles in rock core from an upland exposed sandstone vadose zone in southern California, with thickness varying between 10 and 62 m, were analyzed for chloride (Cl) concentration to examine recharge mechanisms, estimate travel times in the vadose zone, assess spatial and temporal variability of recharge, and determine effects of land use changes on recharge. As a function of their location and the local terrain, the profiles were classified into four groups reflecting the range of site characteristics. Century- to millennium-average recharge varied from 4 to 23 mm y-1, corresponding to different average Cl concentrations in the vadose zone and in groundwater, the contribution of diffuse flow (estimated at 80%) and preferential flow (20%) to the total recharge was quantified. This model of dual porosity recharge was tested by simulating transient Cl transport along a physically based narrow column using a discrete fracture-matrix numerical model. Using a new approach based on partitioning both water and Cl between matrix and fracture flow, porewater was dated and vertical displacement rates estimated to range in the sandstone matrix from 3 to 19 cm y-1. Moreover, the temporal variability of recharge was estimated and, along each profile, past recharge rates calculated based on the sequence of Cl concentrations in the vadose zone. Recharge rates increased at specific times coincident with historical changes in land use. The consistency between the timing of land use modifications and changes in Cl concentration and the match between observed and simulated Cl concentration values in the vadose zone provide confidence in porewater age estimates, travel times, recharge estimates, and reconstruction of recharge histories. This study represents an advancement of the application of the chloride mass balance method to simultaneously determine recharge mechanisms and reconstruct location-specific recharge histories in fractured porous rock aquifers. The

  10. Adsorption mechanisms of radioactive cesium and selenium in rocks

    Energy Technology Data Exchange (ETDEWEB)

    Fujikawa, Yoko; Fukui, Masami [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.

    1996-04-01

    The effect of Cl{sup -}, SO{sub 4}{sup 2-}, HCO{sub 3}{sup -}, CO{sub 3}{sup 2-} and pH on adsorption kinetics of {sup 75}Se and {sup 137}Cs was studied. Surface chelate model was applied to interprete adsorption experiment. (J.P.N.)

  11. Moessbauer Study of Sedimentary Rocks from King George Island, Antarctica

    International Nuclear Information System (INIS)

    Kuzmann, E.; Souza, P. A. de; Schuch, L. A.; Oliveira, A. C. de; Garg, R.; Garg, V. K.

    2002-01-01

    The separation of continents at the periphery of Antarctica occurred about 180 ma ago due to volcanic activity. Geological faults can be very important in the study of geological occurrences. Such geological faults occur across the Admiralty Bay, King George Island, and have been studied in detail previously. Controversial statements were given in earlier works, based on conventional geological investigations, as to whether altered 'Jurassic' and unaltered Tertiary rocks were separated by a major fault which goes across the Admiralty Bay, or whether there is no difference in the alteration of the rocks located at either side of the fault. The aim of our work is to investigate rock samples from the Admiralty Bay of King George Island, Antarctica, from different locations on both sides of the geological fault. For these investigations 57 Fe Moessbauer spectroscopy and X-ray diffractometry were used. We have found that the phase composition, and the iron distribution among the crystallographic sites of iron-bearing minerals, are characteristic of the location of the rock samples from the Admiralty Bay of King George Island. There is a much higher amount of iron oxides in the rocks from the south part of the geological fault than in the north part. The differences in the mineral composition and iron distribution showed that the rocks in the southern part of the geological fault of King George Island are significantly altered compared to the rocks in the northern part. Our present results support and complement well the results obtained earlier on soils from King George Island.

  12. micro-mechanical experimental investigation and modelling of strain and damage of argillaceous rocks under combined hydric and mechanical loads

    International Nuclear Information System (INIS)

    Wang, L.

    2012-01-01

    The hydro-mechanical behavior of argillaceous rocks, which are possible host rocks for underground radioactive nuclear waste storage, is investigated by means of micro-mechanical experimental investigations and modellings. Strain fields at the micrometric scale of the composite structure of this rock, are measured by the combination of environmental scanning electron microscopy, in situ testing and digital image correlation technique. The evolution of argillaceous rocks under pure hydric loading is first investigated. The strain field is strongly heterogeneous and manifests anisotropy. The observed nonlinear deformation at high relative humidity (RH) is related not only to damage, but also to the nonlinear swelling of the clay mineral itself, controlled by different local mechanisms depending on RH. Irreversible deformations are observed during hydric cycles, as well as a network of microcracks located in the bulk of the clay matrix and/or at the inclusion-matrix interface. Second, the local deformation field of the material under combined hydric and mechanical loadings is quantified. Three types of deformation bands are evidenced under mechanical loading, either normal to stress direction (compaction), parallel (microcracking) or inclined (shear). Moreover, they are strongly controlled by the water content of the material: shear bands are in particular prone to appear at high RH states. In view of understanding the mechanical interactions a local scale, the material is modeled as a composite made of non-swelling elastic inclusions embedded in an elastic swelling clay matrix. The internal stress field induced by swelling strain incompatibilities between inclusions and matrix, as well as the overall deformation, is numerically computed at equilibrium but also during the transient stage associated with a moisture gradient. An analytical micro-mechanical model based on Eshelby's solution is proposed. In addition, 2D finite element computations are performed. Results

  13. Multi-scale modelling of the hydro-mechanical behaviour of argillaceous rocks

    International Nuclear Information System (INIS)

    Van den Eijnden, Bram

    2015-01-01

    Feasibility studies for deep geological radioactive waste disposal facilities have led to an increased interest in the geomechanical modelling of its host rock. In France, a potential host rock is the Callovo-Oxfordian clay-stone. The low permeability of this material is of key importance, as the principle of deep geological disposal strongly relies on the sealing capacity of the host formation. The permeability being coupled to the mechanical material state, hydro-mechanical coupled behaviour of the clay-stone becomes important when mechanical alterations are induced by gallery excavation in the so-called excavation damaged zone (EDZ). In materials with microstructure such as the Callovo-Oxfordian clay-stone, the macroscopic behaviour has its origin in the interaction of its micromechanical constituents. In addition to the coupling between hydraulic and mechanical behaviour, a coupling between the micro (material microstructure) and macro scale will be made. By means of the development of a framework of computational homogenization for hydro-mechanical coupling, a double-scale modelling approach is formulated, for which the macro-scale constitutive relations are derived from the microscale by homogenization. An existing model for the modelling of hydro-mechanical coupling based on the distinct definition of grains and intergranular pore space is adopted and modified to enable the application of first order computational homogenization for obtaining macro-scale stress and fluid transport responses. This model is used to constitute a periodic representative elementary volume (REV) that allows the representation of the local macroscopic behaviour of the clay-stone. As a response to deformation loading, the behaviour of the REV represents the numerical equivalent of a constitutive relation at the macro-scale. For the required consistent tangent operators, the framework of computational homogenization by static condensation is extended to hydro-mechanical coupling. The

  14. Flexible parallel implicit modelling of coupled thermal-hydraulic-mechanical processes in fractured rocks

    Science.gov (United States)

    Cacace, Mauro; Jacquey, Antoine B.

    2017-09-01

    Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracture-solid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment) which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton-Raphson or by free Jacobian inexact Newton-Krylow schemes) on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres) and temporal scales (from minutes to hundreds of years).

  15. Flexible parallel implicit modelling of coupled thermal–hydraulic–mechanical processes in fractured rocks

    Directory of Open Access Journals (Sweden)

    M. Cacace

    2017-09-01

    Full Text Available Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracture–solid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton–Raphson or by free Jacobian inexact Newton–Krylow schemes on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres and temporal scales (from minutes to hundreds of years.

  16. Investigations into stress shell characteristics of surrounding rock in fully mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Xie, G.X.; Chang, J.C.; Yang, K. [Anhui University of Science and Technology, Huainan (China)

    2009-01-15

    A key issue in underground mining is to understand and master the evolving patterns of stress induced by mining, and to control and utilize the action of rock pressure. Numerical and physical modeling tests have been carried out to investigate the distribution patterns of stress in the rock surrounding a fully mechanized top-coal caving (FMTC) face. The results showed that a macro-stress shell composed of high stress exists in the rock surrounding an FMTC face. The stress of the shell is higher than its internal and external stress and the stresses at its skewback producing abutment pressure for the surrounding rock. The stress shell lies in the virgin coal and rock mass in the vicinity of the face and its sagging zone. The stress shell, which bears and transfers the loads of overlying strata, acts as the primary supporting system of forces, and is the corpus of characterizing three-dimensional and macro-rock pressure distribution of mining face. Its external and internal shape changes with the variations in the working face structure as the face advances. Within the low-stress zone inside the stress shell, another structure, i.e. voussoir beam, which only bears parts of the load from the lower-lying strata, will produce periodic pressures on the face instead of great dynamic pressure even if the beam ruptures and loses stability. The results show that the FMTC face is situated within the lower-stress zone, which is protected by the stress shell of the overlying surrounding rock. We give an explanation of lower occurrence of rock pressure on FMTC faces, and reveal the mechanical nature of the top coal of an FMTC face acting as a 'cushion'. The strata behaviors of the face and its neighboring gates are under control of the stress shell. Drastic rock pressure in mine may occur when the balance of the stress shell is destruction or the forces system of the stress shell transfers. Crown Copyright

  17. Phenomenological study on crystalline rock aiming at evaluation of long-term behaviour of rock mass

    International Nuclear Information System (INIS)

    Okubo, Seisuke

    2005-02-01

    This study was started on the basis of the outcomes of the research project conducted between 1994 and 2003. In the fiscal year of 1994 when this project was started, a pneumatic creep testing machine was modified. At the end of the fiscal year of 1994, Inada granite was purchased, and the preliminary tests such as P-wave velocity measurement and Schmidt hammer testing were carried out. Through the fiscal year of 1995, a specimen of Tage tuff under water-saturated condition had been loaded in uniaxial condition in the pneumatic creep testing machine. In the fiscal year of 1995, the uniaxial compression and tension tests, and the short-term creep test of Inada granite were also carried out in the servo-controlled testing machines to obtain the complete stress-strain curves. A hydraulic creep testing machine which was planned to use in the next year was modified for long-term creep testing. Finally, a constitutive equation of variable compliance type was examined based on the experimental results. In the fiscal year of 1996, creep, compression and tension tests were carried out. Two types of pressure maintenance equipment (hydraulic and pneumatic types) were developed and examined. In the fiscal year of 1997, creep, compression and tension tests etc. were again carried out on the basis of the results heretofore. The experimental results of long-term creep testing of Tage tuff, middle-term creep testing of Inada granite were described. In both creep tests, samples were submerged in water. In the fiscal year of 1998, creep testing of Tage tuff was conducted. Results of relatively short-term (middle-term) creep conducted on a servo-controlled testing machine were also described. Sample rock was Sirahama sandstone that showed a considerably large creep strain in low stress level such as 17 % of the uniaxial compression strength. Results of triaxial compression test and uniaxial tension test including unloading-reloading tests were described. In the fiscal years of 1999

  18. Coupled hydrological-mechanical effects due to excavation of underground openings in unsaturated fractured rocks

    International Nuclear Information System (INIS)

    Montazer, P.

    1985-01-01

    One of the effects of excavating an underground opening in fractured rocks is a modification of the state of the stress in the rock mass in the vicinity of the opening. This effect causes changes in the geometry of the cross sections of the fracture planes, which in turn results in modification of the hydrologic properties of the fractures of the rock mass. The significance of the orientation of the fractures and their stiffness on the extent of the modification of the hydrologic properties as a result of excavation of underground openings is demonstrated. A conceptual model is presented to illustrate the complexity of the coupled hydrological-mechanical phenomena in the unsaturated zone. This conceptual model is used to develop an investigative program to assess the extent of the effect at a proposed repository site for storing high-level nuclear wastes

  19. Results of monitoring at Olkiluoto in 2006. Rock mechanics

    International Nuclear Information System (INIS)

    Mattila, J.

    2007-07-01

    Posiva Oy has operated a local microseismic at Olkiluto network since February 2002. During the monitoring in 2006, altogether 2041 events have been located in the Olkiluoto area, in the reported time period. The magnitudes of the observed events range from ML = -1.1 to 3.1 (ML = magnitude in local Richter's scale). Most of the events are construction-related explosions but two of them are recorded as microearthquakes. Evidence of seismic activity that would have influence on the safety of the ONKALO, have not been observed. The observed earthquakes that occurred in 2006 were small, with a magnitude of ML -0.6 and ML= -0.9. The earthquakes relate to small movements in brittle deformation zones OL-BFZ043 and OL-BFZ034. Estimated peak slip values of the earthquakes are 14 μm and 4 μm and the source radiuses 11 and 8 meters, respectively. The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Since then, altogether 22 GPS measurement campaigns have been carried out at Olkiluoto. According to the time series of the GPS results, 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.23 mm/a ± 0.023 mm/a) (orig.)

  20. Rock-Mechanics Research. A Survey of United States Research to 1965, with a Partial Survey of Canadian Universities.

    Science.gov (United States)

    National Academy of Sciences - National Research Council, Washington, DC.

    The results of a survey, conducted by the Committee on Rock Mechanics, to determine the status of training and research in rock mechanics in presented in this publication. In 1964 and 1965 information was gathered by questionnaires sent to industries, selected federal agencies, and universities in both the United States and Canada. Results are…

  1. A Coupled Thermo-Hydro-Mechanical Model of Jointed Hard Rock for Compressed Air Energy Storage

    Directory of Open Access Journals (Sweden)

    Xiaoying Zhuang

    2014-01-01

    Full Text Available Renewable energy resources such as wind and solar are intermittent, which causes instability when being connected to utility grid of electricity. Compressed air energy storage (CAES provides an economic and technical viable solution to this problem by utilizing subsurface rock cavern to store the electricity generated by renewable energy in the form of compressed air. Though CAES has been used for over three decades, it is only restricted to salt rock or aquifers for air tightness reason. In this paper, the technical feasibility of utilizing hard rock for CAES is investigated by using a coupled thermo-hydro-mechanical (THM modelling of nonisothermal gas flow. Governing equations are derived from the rules of energy balance, mass balance, and static equilibrium. Cyclic volumetric mass source and heat source models are applied to simulate the gas injection and production. Evaluation is carried out for intact rock and rock with discrete crack, respectively. In both cases, the heat and pressure losses using air mass control and supplementary air injection are compared.

  2. Results of Monitoring at Olkiluoto in 2007. Rock Mechanics

    International Nuclear Information System (INIS)

    Mattila, J.; Hakala, M.

    2008-06-01

    Posiva Oy has operated a local microseismic at Olkiluoto network since February 2002. During the monitoring in 2007, altogether 2207 events have been located in the Olkiluoto area, in the reported time period. The magnitudes of the observed events range from ML = -2.1 to 1.5 (ML = magnitude in local Richter's scale). All these events are explosions. Evidence of seismic activity that would have influence on the safety of the ONKALO, have not been observed. One recorded event was a microearthquake of magnitude ML 1.9, which occurred in Laitila, approximately 40 km from Olkiluoto. The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Since then, altogether 24 GPS measurement campaigns have been carried out at Olkiluoto. According to the time series of the GPS results, 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.21 mm/a ± 0.02 mm/a) In order to monitor vertical movements at Olkiluoto, precise leveling campaigns of the GPS stations were started in the area in autumn 2003. Since then, leveling campaigns have taken place in 2005 and 2007, including the leveling of the existing GPS network and line from Olkiluoto Island to Lapijoki at the main land. Additional smaller leveling campaigns took place in 2006. The campaign in autumn 2007 consisted of the levellings of all measured and undestroyed points of the earlier campaigns. Compared to the mean theoretical land uplift, the nodal bench mark near the crossing of Olkiluodontie and Satamatie had risen in four years 2.6 mm more than the nodal bench

  3. Study of the radioactivity of rocks by the photographic method

    Energy Technology Data Exchange (ETDEWEB)

    Picciotto, E E

    1949-08-16

    The use of photographic plates, and especially of the new Ilford and Kodak plates, in nuclear physics is briefly described. In particular, the application of these methods to the study of the radioactivity of rocks is discussed. In a series of studies made by the authors, the photographic plates were placed in close contact with a thin, highly polished sheet of the rock sample and then developed under specified conditions. This method was used to determine the concentration of U and Th in two radioactive rock samples and the results are given. The samples were then reduced to powder form and the concentrations were again determined. Work on dissolved samples has not yet been completed. In conclusion, the relative merits of these different techniques are indicated.

  4. Multi-scale investigation into the mechanisms of fault mirror formation in seismically active carbonate rocks

    Science.gov (United States)

    Ohl, Markus; Chatzaras, Vasileios; Niemeijer, Andre; King, Helen; Drury, Martyn; Plümper, Oliver

    2017-04-01

    Mirror surfaces along principal slip zones in carbonate rocks have recently received considerable attention as they are thought to form during fault slip at seismic velocities and thus may be a marker for paleo-seismicity (Siman-Tov et al., 2013). Therefore, these structures represent an opportunity to improve our understanding of earthquake mechanics in carbonate faults. Recent investigations reported the formation of fault mirrors in natural rocks as well as in laboratory experiments and connected their occurrence to the development of nano-sized granular material (Spagnuolo et al., 2015). However, the underlying formation and deformation mechanisms of these fault mirrors are still poorly constrained and warrant further research. In order to understand the influence and significance of these fault products on the overall fault behavior, we analysed the micro-, and nanostructural inventory of natural fault samples containing mirror slip surfaces. Here we present first results on the possible formation mechanisms of fault mirrors and associated deformation mechanisms operating in the carbonate fault gouge from two seismically active fault zones in central Greece. Our study specifically focuses on mirror slip surfaces obtained from the Arkitsa fault in the Gulf of Evia and the Schinos fault in the Gulf of Corinth. The Schinos fault was reactivated by a magnitude 6.7 earthquake in 1981 while the Arkitsa fault is thought to have been reactivated by a magnitude 6.9 earthquake in 1894. Our investigations encompass a combination of state-of-the-art analytical techniques including X-ray computed tomography, focused ion beam scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Using this multiscale analytical approach, we report decarbonation-reaction structures, considerable calcite twinning and grain welding immediately below the mirror slip surface. Grains or areas indicating decarbonation reactions show a foam

  5. Processes and mechanisms governing hard rock cliff erosion in western Brittany, France

    Science.gov (United States)

    Laute, Katja; Letortu, Pauline; Le Dantec, Nicolas

    2017-04-01

    The evolution of rocky coasts is controlled by the interplay between subaerial, marine as well as biological processes, and the geological context. In times of ongoing climate change it is difficult to predict how these erosional landscapes will respond for example to anticipated sea-level rise or to an increase in storminess. However, it can be expected that changes in the morphodynamics of rocky coasts will have a noticeable effect on society and infrastructure. Recent studies have proven that monitoring cliff micro-seismic ground motion has been very effective in exploring both marine and atmospheric actions on coastal cliffs. But only few studies have focused so far on the effects of wave loading and water circulation (runoff, infiltration, water table variations) on cliff stability and subsequent erosion, considering the interaction between subaerial and marine processes. This project focuses on the identification and quantification of environmental controls on hard rock cliff erosion with an emphasis on discriminating the relative contributions of subaerial and marine processes. We aim at relating different sources of mechanical stress (e.g. wave loading, direct wave impact, hydrostatic pressure, thermal expansion) to cliff-scale strain (cliff-top swaying and shaking) and micro-fracturing (generation, expansion and contraction of micro-cracks) with the objective to unravel and discriminate triggering mechanisms of cliff failure. A four-month monitoring field experiment during the winter period (February-May) of 2017 is carried out at a cliff face located in Porsmilin beach (western Brittany, France). The selected cliff section is exposed to Atlantic swell from the south/southwest with a significant wave height of ca. 1.5 m on average and, reaching up to 4 m during storm events. The cliff rises ca. 20 m above the beach and is mainly formed of orthogneiss with intrusions of granodiorite. The entire cliff is highly fractured and altered, which can promote slope

  6. A Study on the Fracture Control of Rock Bolts in High Ground Pressure Roadways of Deep Mines

    Directory of Open Access Journals (Sweden)

    Wen Jinglin

    2015-01-01

    Full Text Available According to the frequent fractures of rock bolts in high ground pressure roadways of deep mines, this paper analyzes the mechanism of fractures and concludes that high ground pressure and material de-fects are main reasons for the fracture of rock bolts. The basic idea of fracture control of rock bolts in high ground pressure roadways of deep mines is to increase the yield load and the limit load of rock bolt materials and reduce the actual load of rock bolts. There are four ways of controlling rock bolt fracture: increasing the rock bolt diameter, strengthening bolt materials, weakening support rigidity and the implementation of double supporting. With the roadway support of the 2302 working face of a coal mine as the project background, this paper carries out a study on the effect of two schemes, increasing the rock bolt diameter and the double supporting technique through methods of theoretical analysis, numerical simulation and so on. It determines the most reasonable diam-eter of rock bolts and the best delay distance of secondary support. Practices indicate that rock bolt fracture can be effectively controlled through the double supporting technique, which strengthens the roof and two sides through the first supporting technique and strengthens side angles through the secondary supporting technique.

  7. Experimental Study on Water Sensitivity Difference Based on Oiliness of Porous Medium Rock

    Directory of Open Access Journals (Sweden)

    Jie Li

    2017-01-01

    Full Text Available This study presents the differences of water sensitivity experiment of porous medium rock between conventional dry core samples and oil-bearing core. The comparison was made to analyze the impact of single-phase fluid and multiphase fluid on the actual sensitivity of rock. The nuclear magnetic resonance (NMR test was carried out to reveal the distribution of oil in porous medium and the microscopic influence mechanism of oil phase. The study shows that the initial oil in place could isolate the clay from water, and then the expansion and the migration of the clay were prevented to reduce the decrease of degree of damage.

  8. Studies on groundwater transport in fractured crystalline rock under controlled conditions using nonradioactive tracers

    International Nuclear Information System (INIS)

    Gustafsson, E.; Klockars, C.-E.

    1981-04-01

    The purpose of the investigation has been study the following parameters along existing fractures between two boreholes: hydraulic properties of rock mass and fractures; adsorptive properties of some selected tracers during transport along fractures; dispersivity and dilution of tracers during transport in fractures; kinematic porosity of fractured bedrock. The procedure has been to determine the hydraulic properties of a rock mass by means of conventional hydraulic testing methods in 100 m deep boreholes, and to study transport mechanisms and properties of selected tracers in a selected fracture zone between two boreholes. (Auth.)

  9. The Experimental Study of the Temperature Effect on the Interfacial Properties of Fully Grouted Rock Bolt

    Directory of Open Access Journals (Sweden)

    Fuhai Li

    2017-03-01

    Full Text Available This study analyzes the phenomenon of performance deterioration in fully grouted rock bolts in tunnels with a dry, hot environment and high geothermal activity with a focus on temperature effects on interfacial bond performance. Three groups of fully grouted rock bolt specimens were designed based on similar mechanical principles. They were produced and maintained at 20 °C, 35 °C, and 50 °C. Through the indoor gradual loading tensile test of specimens, variations of axial force and shear stress between the rock bolt and mortar adhesive interface were obtained under different environmental temperatures. Distribution of the axial force and shear stress on the anchorage section were found under different tensile forces. Results showed that, with an increase in specimen environmental temperature, maximum shear stress of the rock bolt section became smaller, while shear stress distribution along the rock bolt segment became more uniform. In addition, the axial force value at the same position along the pull end was greater, while axial stress along the anchorage’s length decayed faster. With an increase in tensile force under different temperatures, the axial force and maximum shear stress of rock bolt specimens along the anchorage section has a corresponding increase.

  10. The paleomagnetic field and possible mechanisms for the formation of reversed rock magnetization

    International Nuclear Information System (INIS)

    Trukhin, Vladimir I.; Bezaeva, Natalia; Kurochkina, Evgeniya

    2006-01-01

    Investigations of ancient magnetized rocks show that their natural remanent magnetization (NRM) can be oriented in the direction of modern geomagnetic field (GMF) as well as in the opposite direction. It is supposed that reversed NRM is related to reversals of the GMF in the past geological periods. During reversals, the strength of the GMF is near zero and can cause the destruction of living organisms as a result of powerful space and solar radiation, which, in the absence of the GMF, can reach the Earth's surface. That is why the question of reality of the GMF reversals is of global ecological importance. There is also another natural mechanism for the formation of reversed NRM-the self-reversal of magnetization as a result of thermomagnetization of rocks. In the paper, both natural processes for the formation of reversed NRM in rocks are discussed, and the results of experimental research on the physical mechanism of self-reversal of magnetization in continental and oceanic rocks are presented. The results of computer modeling of the self-reversal phenomenon are also presented

  11. The paleomagnetic field and possible mechanisms for the formation of reversed rock magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Trukhin, Vladimir I. [Faculty of Physics, Moscow State University, 119992 Moscow (Russian Federation)]. E-mail: trukhin@phys.msu.ru; Bezaeva, Natalia [Faculty of Physics, Moscow State University, 119992 Moscow (Russian Federation); Kurochkina, Evgeniya [Faculty of Physics, Moscow State University, 119992 Moscow (Russian Federation)

    2006-05-15

    Investigations of ancient magnetized rocks show that their natural remanent magnetization (NRM) can be oriented in the direction of modern geomagnetic field (GMF) as well as in the opposite direction. It is supposed that reversed NRM is related to reversals of the GMF in the past geological periods. During reversals, the strength of the GMF is near zero and can cause the destruction of living organisms as a result of powerful space and solar radiation, which, in the absence of the GMF, can reach the Earth's surface. That is why the question of reality of the GMF reversals is of global ecological importance. There is also another natural mechanism for the formation of reversed NRM-the self-reversal of magnetization as a result of thermomagnetization of rocks. In the paper, both natural processes for the formation of reversed NRM in rocks are discussed, and the results of experimental research on the physical mechanism of self-reversal of magnetization in continental and oceanic rocks are presented. The results of computer modeling of the self-reversal phenomenon are also presented.

  12. Phenomenological study on crystalline rock for evaluating of long-term behavior (Contract research)

    International Nuclear Information System (INIS)

    Okubo, Seisuke; Fukui, Katsunori; Hashiba, Kimihiro; Hikima, Ryoichi; Tanno, Takeo; Sanada, Hiroyuki; Matsui, Hiroya; Sato, Toshinori

    2012-02-01

    Rock, under in situ conditions, shows time-dependent behavior such as creep/relaxation. With respect to high-level radioactive waste disposal, knowledge of the long-term mechanical stability of shafts and galleries excavated in rock is required, not only during construction and operation but also over a period of thousands of years after closure. Therefore, it is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. The purpose of this study is determining the mechanisms of time-dependent behavior of rock by precise testing, observation and measurement in order to develop methods for evaluating long-term mechanical stability of a rock mass. In the previous work, testing techniques have been established and basic evaluation methods were developed. Recently, some parameters needed for simulation of time-dependent behavior were determined at the Mizunami underground research facilities. However, sufficient data to check the reliability of the evaluation method for these parameters were not available. This report describes the results of the activities in fiscal year 2010. In Chapter 1, we provide an overview and the background to this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in fiscal year 1997 are described. In Chapter 3, the relation of loading-rate dependency of strength and stress dependency of creep life, the relation of time dependency, probability distribution and size effects are discussed to indicate more clearly the meaning of the value of 'n' to express the degree of time dependency of the rock. Furthermore, past studies concerning the value of 'n' are reviewed and the tests that could be carried out in future studies of mechanical properties and time dependency of Toki granite are considered in this Chapter. In Chapter 4, failure criterions of a rock mass considering time dependency are discussed. In Chapter 5, the FEM analysis implemented with a generalized

  13. Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions

    Science.gov (United States)

    Pei, Liang; Blöcher, Guido; Milsch, Harald; Zimmermann, Günter; Sass, Ingo; Huenges, Ernst

    2018-01-01

    The present study aims to quantify the thermo-mechanical properties of Neuburger Bankkalk limestone, an outcrop analog of the Upper Jurassic carbonate formation (Germany), and to provide a reference for reservoir rock deformation within future enhanced geothermal systems located in the Southern German Molasse Basin. Experiments deriving the drained bulk compressibility C were performed by cycling confining pressure p c between 2 and 50 MPa at a constant pore pressure p p of 0.5 MPa after heating the samples to defined temperatures between 30 and 90 °C. Creep strain was then measured after each loading and unloading stage, and permeability k was obtained after each creep strain measurement. The drained bulk compressibility increased with increasing temperature and decreased with increasing differential pressure p d = p c - p p showing hysteresis between the loading and unloading stages above 30 °C. The apparent values of the indirectly calculated Biot coefficient α ind containing contributions from inelastic deformation displayed the same temperature and pressure dependencies. The permeability k increased immediately after heating and the creep rates were also temperature dependent. It is inferred that the alteration of the void space caused by temperature changes leads to the variation of rock properties measured under isothermal conditions while the load cycles applied under isothermal conditions yield additional changes in pore space microstructure. The experimental results were applied to a geothermal fluid production scenario to constrain drawdown and time-dependent effects on the reservoir, overall, to provide a reference for the hydromechanical behavior of geothermal systems in carbonate, and more specifically, in Upper Jurassic lithologies.

  14. Hydrogeology of rocks of low permeability: region studies

    International Nuclear Information System (INIS)

    Llamas, M.R.

    1985-01-01

    Hydrogeological regional studies on low permeability rocks are rather scarce in comparison to similar studies on normal permeability rocks. Economic and technological difficulties to develop ground water from these terrains may be the main cause of this scarcity. Several facts may indicate that these studies will increase in the near future. First, the need to supply water to the people living in underdeveloped arid zones over extensive areas of low permeability rocks. Second, the relevant role that some low permeability large groundwater basins may play in conjunctive ground and surface-water use. And last but not least the feasibility of some low permeability rock areas as sites for nuclear waste repositories. Some specific difficulties in these regional studies may be: a) intrinsic difficulties in obtaining representative water samples and measuring hydraulic heads; b) scarcity of observation and/or pumping wells; c) important hydraulic head and chemical properties variations in a vertical direction; d) old groundwater ages; this may require paleohydrological considerations to understand certain apparent anomalies. In most of these regional studies hydrogeochemical methods and modelling (flow and mass transport) may be very valuable tools. 77 references, 7 figures

  15. Colloid and radionuclide retention mechanisms in fractured rock under near-natural flow conditions

    International Nuclear Information System (INIS)

    Delos, A.; Schaefer, T.; Geckeis, H.; Guimera, J.; Carrera, J.; Fanghaenel, T.

    2005-01-01

    Full text of publication follows: Experiments in fractured host rock (Grimsel Test Site, GTS, Switzerland) revealed that the colloid relevance for actinide migration is high due to the specific geochemical groundwater conditions [1]. However, even under such conditions it is found that retention of colloids and colloid-borne actinides becomes significant under near-natural groundwater flow rates (1-10 m/a) [2]. Underlying mechanisms of colloid and radionuclide retention are not well understood up to now. The present study co-funded by the NoE ACTINET-6 focuses on (i) the kinetics of actinide-colloid interactions and (ii) the relevance of matrix diffusion as a competition process to other retention mechanisms which affect the actinides behavior in fractured rock systems such as the Grimsel granodiorite. Colloid migration is studied with well defined model colloids as e.g. fluorescence dyed carboxylated polystyrene particles, and natural colloids extracted from bentonite (FEBEX) and from fracture filling material (GTS). In order to study the influence of matrix porosity on actinides migration, those experiments are performed in columns of well defined geometry filled with microporous unmodified silica spheres, porous ceramic material and natural fracture filling material from the GTS. The behaviour of actinides (Pu(IV) and Am(III)) sorbed onto bentonite colloids is investigated in column and batch experiments. All experiments are performed under anoxic conditions. Colloid characterization methods used in this study include the combination of photon correlation spectroscopy (PCS), laser-induced breakdown detection (LIBD), fluorimetry and field flow fractionation (FFF). Experimental results and their application to the parametrisation of reactive colloid transport models are discussed. [1] Geckeis H, Schaefer T, Hauser W, Rabung T, Missana T, Degueldre C, Moeri A, Eikenberg J, Fierz T, Alexander WR (2004) Results of the Colloid and Radionuclide Retention experiment

  16. Moessbauer study of rock paintings from Minas Gerais (Brazil)

    International Nuclear Information System (INIS)

    Costa, G.M. da; Jesus Filho, M.F. de; Cruz Souza, L.A.

    1991-01-01

    Four samples of a wall containing rock paintings have been studied by Moessbauer spectroscopy in combination with optical microscopy analysis and X-ray diffraction. Hematite and goethite were identified as the pigments responsible for the colors and the mineral tinsleyite, as the principal component of a light pink layer that is present in some parts of the wall. (orig.)

  17. Astronauts Armstrong and Aldrin study rock samples during field trip

    Science.gov (United States)

    1969-01-01

    Astronaut Neil Armstrong, commander of the Apollo 11 lunar landing mission, and Astronaut Edwin Aldrin, Lunar module pilot for Apollo 11, study rock samples during a geological field trip to the Quitman Mountains area near the Fort Quitman ruins in far west Texas.

  18. Mechanical behavior of host rock close to H.L.W. disposal cavities in a deep granitic formation

    International Nuclear Information System (INIS)

    Hoorelbeke, J.M.; Dourthe, M.

    1986-01-01

    The construction of a H.L.W. repository in a deep granitic formation creates mechanical disturbances in the rock on the scale of the massif and in the nearfield. Amongst all the disturbances noted in the nearfield, this study is concerned with examining the evolution of stresses linked with the excavation of the rock and the rise in temperature in the proximity of the waste packages. Several linear elasticity calculations were made using on the one hand finite element models and on the other simple analytical models. These calculations concern two different storage concepts - in room concept and in floor concept- whose differences in mechanical behavior are analyzed. A study of sensitivity with regard to the characteristics of the rock and to the initial geostatic stresses is presented. The comparison of the calculated stresses with three-dimensional failure criteria gives a clear indication of the satisfactory behavior of granite for final storage. However, the need for experimental study and complementary calculation must be emphasized

  19. Temperature effect on the poro-mechanical or hydraulic behaviour of a carbonated rock and a mortar: experimental studies; Influence de la temperature sur le comportement poromecanique ou hydraulique d'une roche carbonatee et d'un mortier: etudes experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Lion, M

    2004-07-15

    The main objective of this study is to evaluate the temperature effect on the hydraulic and poro-mechanical behaviour of a limestone. Many experimental tests (porosity and permeability measurements, uniaxial and hydrostatic compressions tests) were carried out in order to study the thermal treatments effect and so the thermal microcracking effect on rock behaviour. Moreover, an experimental device for permeability measurements under high temperatures (until 200 C) was realized. This experimental device permitted to study the permeability variation of the limestone under thermal stresses. Finally, the behaviour of cementitious materials was studied; the temperature effect on the permeability of a mortar was examined. (author)

  20. High strain rate studies in rock

    International Nuclear Information System (INIS)

    Grady, D.

    1977-01-01

    Dynamic compression studies using high velocity impact are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brough to a shock compressed state. Although this is frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate of these methods makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates in the range of 10 4 /s to 10 6 /s for final stress states of approximately 3.9 GPa or less.Ramp wave compression experiments have been conducted on dolomite at strain rates of 3 x 10 4 /s. Both initial yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (epsilon-dotapprox.10 6 /s) and differs substantially from quasi-static measurements (epsilon-dotapprox.10 -4 /s). The ramp wave studies have also uncovered a pressure-induced phase transition in dolomite initiating at 4.0 GPa

  1. Rock Abrasion and Ventifact Formation on Mars from Field Analog, Theoretical, and Experimental Studies

    Science.gov (United States)

    Bridges, N. T.; Laity, J. E.

    2001-01-01

    Rocks observed by the Viking Landers and Pathfinder Lander/Sojourner rover exhibit a suite of perplexing rock textures. Among these are pits, spongy textures, penetrative flutes, lineaments, crusts, and knobs Fluvial, impact, chemical alteration, and aeolian mechanisms have been proposed for many of these. In an effort to better understand the origin and characteristics of Martian rock textures, abraded rocks in the Mojave Desert and other regions have been studied. We find that most Martian rock textures, as opposed to just a few, bear close resemblance to terrestrial aeolian textures and can most easily be explained by wind, not other, processes. Flutes, grooves, and some pits on Mars are consistent with abrasion by saltating particles, as described previously. However, many other rock textures probably also have an aeolian origin. Sills at the base of rocks that generally lie at high elevations, such as Half Dome, are consistent with such features on Earth that are related to moats or soil ramps that shield the basal part of the rock from erosion. Crusts consisting of fluted fabrics, such as those on Stimpy and Chimp, are similar to fluted crusts on Earth that spall off over time. Knobby and lineated rocks are similar to terrestrial examples of heterogeneous rocks that differentially erode. The location of specific rock textures on Mars also gives insight into their origin. Many of the most diagnostic ventifacts found at the Pathfinder site are located on rocks that lie near the crests or the upper slopes of ridges. On Earth, the most active ventifact formation occurs on sloped or elevated topography, where windflow is accelerated and particle kinetic energy and flux are increased. Integrated 0 together, these observations point to significant aeolian 0 modification of rocks on Mars and cast doubt on whether many primary textures resulting from other processes are preserved. Experimental simulations of abrasion in the presence of abundant sand indicate that

  2. Mechanics of graben formation in crustal rocks - A finite element analysis

    Science.gov (United States)

    Melosh, H. J.; Williams, C. A., Jr.

    1989-01-01

    The mechanics of the initial stages of graben formation are examined, showing that the configuration of a graben (a pair of antithetically dipping normal faults) is the most energetically favorable fault configuration in elastic-brittle rocks subjected to pure extension. The stress field in the vicinity of a single initial normal fault is computed with a two-dimensional FEM. It is concluded that the major factor controlling graben width is the depth of the initial fault.

  3. Determination of the mechanical parameters of rock mass based on a GSI system and displacement back analysis

    Science.gov (United States)

    Kang, Kwang-Song; Hu, Nai-Lian; Sin, Chung-Sik; Rim, Song-Ho; Han, Eun-Cheol; Kim, Chol-Nam

    2017-08-01

    It is very important to obtain the mechanical paramerters of rock mass for excavation design, support design, slope design and stability analysis of the underground structure. In order to estimate the mechanical parameters of rock mass exactly, a new method of combining a geological strength index (GSI) system with intelligent displacment back analysis is proposed in this paper. Firstly, average spacing of joints (d) and rock mass block rating (RBR, a new quantitative factor), surface condition rating (SCR) and joint condition factor (J c) are obtained on in situ rock masses using the scanline method, and the GSI values of rock masses are obtained from a new quantitative GSI chart. A correction method of GSI value is newly introduced by considering the influence of joint orientation and groundwater on rock mass mechanical properties, and then value ranges of rock mass mechanical parameters are chosen by the Hoek-Brown failure criterion. Secondly, on the basis of the measurement result of vault settlements and horizontal convergence displacements of an in situ tunnel, optimal parameters are estimated by combination of genetic algorithm (GA) and numerical simulation analysis using FLAC3D. This method has been applied in a lead-zinc mine. By utilizing the improved GSI quantization, correction method and displacement back analysis, the mechanical parameters of the ore body, hanging wall and footwall rock mass were determined, so that reliable foundations were provided for mining design and stability analysis.

  4. Workshop on rock mechanics issues in repository design and performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    The Center for Nuclear Waste Regulatory Analyses organized and hosted a workshop on ``Rock Mechanics Issues in Repository Design and Performance Assessment`` on behalf its sponsor the U.S. Nuclear Regulatory Commission (NRC). This workshop was held on September 19- 20, 1994 at the Holiday Inn Crowne Plaza, Rockville, Maryland. The objectives of the workshop were to stimulate exchange of technical information among parties actively investigating rock mechanics issues relevant to the proposed high-level waste repository at Yucca Mountain and identify/confirm rock mechanics issues important to repository design and performance assessment The workshop contained three technical sessions and two panel discussions. The participants included technical and research staffs representing the NRC and the Department of Energy and their contractors, as well as researchers from the academic, commercial, and international technical communities. These proceedings include most of the technical papers presented in the technical sessions and the transcripts for the two panel discussions. Selected papers have been indexed separately for inclusion the Energy Science and Technology Database.

  5. Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

    Directory of Open Access Journals (Sweden)

    Baoyun Zhao

    2018-01-01

    Full Text Available In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

  6. Analysis on the Rock-Cutter Interaction Mechanism During the TBM Tunneling Process

    Science.gov (United States)

    Yang, Haiqing; Wang, He; Zhou, Xiaoping

    2016-03-01

    The accurate prediction of rock cutting forces of disc cutters is crucial for tunnel boring machine (TBM) design and construction. Disc cutter wear, which affects TBM penetration performance, has frequently been found at TBM sites. By considering the operating path and wear of the disc cutter, a new model is proposed for evaluating the cutting force and wear of the disc cutter in the tunneling process. The circular path adopted herein, which is the actual running path of the TBM disc cutter, shows that the lateral force of the disc cutter is asymmetric. The lateral forces on the sides of the disc cutter are clearly different. However, traditional solutions are obtained by assuming a linear path, where the later forces are viewed as equal. To simulate the interaction between the rock and disc cutter, a simple brittle damage model for rock mass is introduced here. Based on the explicit dynamic finite element method, the cutting force acting on the rock generated by a single disc cutter is simulated. It is shown that the lateral cutting force of the disc cutter strongly affects the wear extent of disc cutter. The wear mechanism is thus underestimated by the classical model, which was obtained by linear cutting tests. The simulation results are discussed and compared with other models, and these simulation results agree well with the results of present ones.

  7. Slope Stability Analysis Based on Type, Physical And Mechanical Properties Rock in Teluk Pandan District, East Kutai Regency, East Kalimantan

    Directory of Open Access Journals (Sweden)

    Sujiman Kusnadi

    2017-12-01

    Full Text Available Research was located In Teluk Pandan District, East Kutai Regency, East Kalimantan Province.  It’s aimed to determine the lithology in the  research area and to find out how the amount of slope that will be a landslide at that location. The research conducted with the analysis of coring drilling results and then analyzed in the laboratory of rock mechanics to get the characteristic of physical and mechanical properties of the rocks. The data analysis using Hoek and Bray Method. The results showed that in the area study has a sedimentary rock lithology fine to medium detritus, such as claystone, siltstone and sandstone, as well as inserts are coal and shale. Based on the results of laboratory analysis of rock mechanics obtained density between 2,648 to 2,770. While the test results obtained value triaxial cohesion between (6.66 - 9:05 Kg / cm2, friction angle in between (37.19 - 44.08o, cohesion residual (2.72 - 3.10 Kg / cm2, residual friction angle (27.22 - 32.44o. While the direct shear test the cohesion of the summit between (6.66 - 9:05 Kg / cm2, friction angle in the cohesion peak (36.15 - 43.00o, cohesion residual (2:22 to 3:10 Kg / cm2, friction angle in the cohesion residual (37.22 - 33.85o. The simulation results stability of the slope stability Hoek and Bray using rockslide software, the result is that if the slope with a single slope stability, the stability of the slope is 60o, and if the slope with the stability of the slope overall stability of the slope is 48o.

  8. Stress-Dependent Voltage Offsets From Polymer Insulators Used in Rock Mechanics and Material Testing

    Science.gov (United States)

    Carlson, G. G.; Dahlgren, Robert; Gray, Amber; Vanderbilt, V. C.; Freund, F.; Johnston, M. J.; Dunson, C.

    2013-01-01

    Dielectric insulators are used in a variety of laboratory settings when performing experiments in rock mechanics, petrology, and electromagnetic studies of rocks in the fields of geophysics,material science, and civil engineering. These components may be used to electrically isolate geological samples from the experimental equipment, to perform a mechanical compliance function between brittle samples and the loading equipment, to match ultrasonic transducers, or perform other functions. In manyexperimental configurations the insulators bear the full brunt of force applied to the sample but do not need to withstand high voltages, therefore the insulators are often thin sheets of mechanically tough polymers. From an instrument perspective, transduction from various types of mechanical perturbation has beenqualitatively compared for a number of polymers [1, 2] and these error sources are readily apparent duringhigh-impedance measurements if not mitigated. However even when following best practices, a force dependent voltage signal still remains and its behavior is explored in this presentation. In this experimenttwo thin sheets (0.25 mm) of high-density polyethylene (HDPE) were set up in a stack, held alternatelybetween three aluminum bars; this stack was placed on the platen of a 60T capacity hydraulic testingmachine. The surface area, A, over which the force is applied to the PE sheets in this sandwich is roughly 40 square cm, each sheet forming a parallel-plate capacitor having roughly 320 pF [3], assuming therelative dielectric permittivity of PE is approximately 2.3. The outer two aluminum bars were connected to the LO input ofthe electrometer and the central aluminum bar was connected to the HI input of a Keithley model 617 electrometer. Once the stack is mechanically well-seated with no air gaps, the voltage offset is observed tobe a linear function of the baseline voltage for a given change in applied force. For a periodically appliedforce of 66.7 kN the

  9. Experimental Investigation of the Influence of Joint Geometric Configurations on the Mechanical Properties of Intermittent Jointed Rock Models Under Cyclic Uniaxial Compression

    Science.gov (United States)

    Liu, Yi; Dai, Feng; Fan, Pengxian; Xu, Nuwen; Dong, Lu

    2017-06-01

    Intermittent joints in rock mass are quite sensitive to cyclic loading conditions. Understanding the fatigue mechanical properties of jointed rocks is beneficial for rational design and stability analysis of rock engineering projects. This study experimentally investigated the influences of joint geometry (i.e., dip angle, persistency, density and spacing) on the fatigue mechanism of synthetic jointed rock models. Our results revealed that the stress-strain curve of jointed rock under cyclic loadings is dominated by its curve under monotonic uniaxial loadings; the terminal strain in fatigue curve is equal to the post-peak strain corresponding to the maximum cyclic stress in the monotonic stress-strain curve. The four joint geometrical parameters studied significantly affect the fatigue properties of jointed rocks, including the irreversible strains, the fatigue deformation modulus, the energy evolution, the damage variable and the crack coalescence patterns. The higher the values of the geometrical parameters, the lower the elastic energy stores in this jointed rock, the higher the fatigue damage accumulates in the first few cycles, and the lower the fatigue life. The elastic energy has certain storage limitation, at which the fatigue failure occurs. Two basic micro-cracks, i.e., tensile wing crack and shear crack, are observed in cyclic loading and unloading tests, which are controlled principally by joint dip angle and persistency. In general, shear cracks only occur in the jointed rock with higher dip angle or higher persistency, and the jointed rock is characterized by lower fatigue strength, larger damage variable and lower fatigue life.

  10. Research of long-term mechanical displaced behavior of soft rock

    International Nuclear Information System (INIS)

    Inoue, Hiroyuki; Minami, Kosuke

    2003-01-01

    When it thinks about a stratum disposition system of high-level radioactive waste, it is important to evaluate the long-term mechanical displaced behavior of the near field bedrock which is boundary condition of the engineered barrier that should be evaluated based on the reality. In this research, three following examination was carried out for reliability improvement of long-term dynamic deformation behavior estimate. 1) We evaluated the sedimentary rock of Horonobe where we used Okubo model as while changing hydraulic condition and temperature condition. 2) We carried out the model experiment that inner pressure acted on in order to grasp a movement of near field bedrock. 3) We examined model to evaluate that. As a result, the following things were provided. 1) Sedimentary rock of Horonobe is easy to cause strength degradation for being wet and dry cycles. When the rock is saturated after drying, it is broken along potential cracking. The rock reacts for a change of moisture content sensitively. In addition, a variation of the strength occurs in a little depth remainder. This diffuseness gave the strong influence on failure time. 2) Big plastic deformation may not do elasto-plasticity behavior according to theory for stress modification of rock mass. 3) We think with one of the factor that it produces remainder in prediction and real creep hour that these is as 'm = n (conatnt of Okubo model)' simply. Therefore we collect data after peak, and it is necessary to grasp 'm/n'. In addition, it is necessary to improve 'n' in the model which we can change by environment and stress state on the way. (author)

  11. Research on Formation Mechanisms of Hot Dry Rock Resources in China

    Science.gov (United States)

    Wang, G.; Xi, Y.

    2017-12-01

    As an important geothermal resource, hot dry rock(HDR) reserves have been studied in many countries. HDR resources in China have huge capacity and have become one of the most important resources for the potential replacement of fossil fuels. However, HDR resources are difficult to develop and utilise. Technologies for use with HDR, such as high-temperature drilling, reservoir characterisation, reservoir fracturing, microseismic monitoring and high-temperature power stations, originate from the field of oil and drilling. Addressing how to take advantage of these developed technologies is a key factor in the development of HDR reserves. Based on the thermal crustal structure in China, HDR resources can be divided into four types: high radioactive heat production, sedimentary basin, modern volcano and the inner-plate active tectonic belt. The prospective regions of HDR resources are located in South Tibet, West Yunnan, the southeast coast of China, Bohai Rim, Songliao Basin and Guanzhong Basin. The related essential technologies are relatively mature, and the prospect of HDR power generation is promising. Therefore, analysing the formation mechanisms of HDR resources and promoting the transformation of technological achievements, large-scale development and the utilisation of HDR resources can be achieved in China.

  12. Fracturing Fluid Leak-off for Deep Volcanic Rock in Zhungeer Basin: Mechanism and Control Method

    Directory of Open Access Journals (Sweden)

    Huang Bo

    2017-01-01

    Full Text Available The deep volcanic reservoir in Zhungeer Basin is buried in over 4000m depth, which is characterized by complex lithology (breccia, andesite, basalt, etc., high elastic modulus and massive natural fractures. During hydraulic fracturing, hydraulic fracture will propagate and natural fractures will be triggered by the increasing net pressure. However, the extension of fractures, especially natural fractures, would aggravate the leak-off effect of fracturing fluid, and consequently decrease the fracturing success rate. 4 out of 12 fracturing wells in the field have failed to add enough proppants due to fluid loss. In order to increase the success rate and efficiency of hydraulic fracturing for deep volcanic reservoir, based on theoretical and experimental method, the mechanism of fracturing fluid leak-off is deeply studied. We propose a dualistic proppant scheme and employ the fluid loss reducer to control the fluid leak-off in macro-fractures and micro-fractures respectively. The proposed technique remarkably improved the success rate in deep volcanic rock fracturing. It bears important theoretical value and practical significance to improve the hydraulic fracturing design for deep volcanic reservoir.

  13. Experimental Study and Numerical Modeling of Fracture Propagation in Shale Rocks During Brazilian Disk Test

    Science.gov (United States)

    Mousavi Nezhad, Mohaddeseh; Fisher, Quentin J.; Gironacci, Elia; Rezania, Mohammad

    2018-06-01

    Reliable prediction of fracture process in shale-gas rocks remains one of the most significant challenges for establishing sustained economic oil and gas production. This paper presents a modeling framework for simulation of crack propagation in heterogeneous shale rocks. The framework is on the basis of a variational approach, consistent with Griffith's theory. The modeling framework is used to reproduce the fracture propagation process in shale rock samples under standard Brazilian disk test conditions. Data collected from the experiments are employed to determine the testing specimens' tensile strength and fracture toughness. To incorporate the effects of shale formation heterogeneity in the simulation of crack paths, fracture properties of the specimens are defined as spatially random fields. A computational strategy on the basis of stochastic finite element theory is developed that allows to incorporate the effects of heterogeneity of shale rocks on the fracture evolution. A parametric study has been carried out to better understand how anisotropy and heterogeneity of the mechanical properties affect both direction of cracks and rock strength.

  14. Modelling of thermo-hydro-mechanical couplings and damage of viscoplastic rocks in the context of radioactive waste storage

    International Nuclear Information System (INIS)

    Kharkhour, H.

    2002-12-01

    Trying to develop a model taking into account the complex rheology of a geologic media characterized by visco-plasticity, damage and thermo-hydro-mechanical couplings is unusual in geotechnics. This is not the case for radioactive waste storage that presents specificities from several viewpoints. Indeed, the scales of time and space concerned by this type of storage are disproportionate to those of civil engineering works or mines. Another specificity of the radioactive waste storage lies in the coupled processes involved. No effect likely to compromise the long-term security of the storage could be ignored. For example this is the case of damage, a phenomenon which does not necessarily lead to a major change of the mechanical behavior of the works but can influence the permeability of the medium in relation with a migration of radionuclides. It can be conceived that this phenomenon finds all its importance in the context of the thermo-hydro-mechanical couplings of a waste storage with high activity. However, the interaction between the damage and the THM coupled processes was the object of very few research subject up to now. This. is even more true for viscoplastic media considered as ductile, and therefore, less prone to cracking than brittle media. It is exactly in this 'original' but difficult context that took place the research presented in this report. This study was dedicated to the analysis of the phenomena and the thermal, hydraulic and mechanical couplings occurring in the near and far field of a high activity radioactive waste storage. Two examples of geological media were considered in this report: the clayey rock of Callovo-Oxfordian, called ' Argilites de l'Est ', target rock of the ANDRA project to carry out a subterranean laboratory for the study of long life radioactive waste storage; and the salt rock of the. subterranean laboratory in the old salt mine of Asse in Germany. (author)

  15. Rock Physics and Petrographic Parameters Relationship Within Siliciclastic Rocks: Quartz Sandstone Outcrop Study Case

    Science.gov (United States)

    Syafriyono, S.; Caesario, D.; Swastika, A.; Adlan, Q.; Syafri, I.; Abdurrokhim, A.; Mardiana, U.; Mohamad, F.; Alfadli, M. K.; Sari, V. M.

    2018-03-01

    Rock physical parameters value (Vp and Vs) is one of fundamental aspects in reservoir characterization as a tool to detect rock heterogenity. Its response is depend on several reservoir conditions such as lithology, pressure and reservoir fluids. The value of Vp and Vs is controlled by grain contact and contact stiffness, a function of clay mineral content and porosity also affected by mineral composition. The study about Vp and Vs response within sandstone and its relationship with petrographic parameters has become important to define anisotrophy of reservoir characteristics distribution and could give a better understanding about local diagenesis that influence clastic reservoir properties. Petrographic analysis and Vp-Vs calculation was carried out to 12 core sample which is obtained by hand-drilling of the outcrop in Sukabumi area, West Java as a part of Bayah Formation. Data processing and interpretation of sedimentary vertical succession showing that this outcrop comprises of 3 major sandstone layers indicating fluvial depositional environment. As stated before, there are 4 petrographic parameters (sorting, roundness, clay mineral content, and grain contact) which are responsible to the differences of shear wave and compressional wave value in this outcrop. Lithology with poor-sorted and well- roundness has Vp value lower than well-sorted and poor-roundness (sub-angular) grain. For the sample with high clay content, Vp value is ranging from 1681 to 2000 m/s and could be getting high until 2190 to 2714 m/s in low clay content sample even though the presence of clay minerals cannot be defined neither as matrix nor cement. The whole sample have suture grain contact indicating telogenesis regime whereas facies has no relationship with Vp and Vs value because of the different type of facies show similar petrographic parameters after diagenesis.

  16. Prediction of thermal conductivity of rock through physico-mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, T.N. [Department of Earth Sciences, Indian Institute of Technology, Bombay 400 076 (India); Sinha, S.; Singh, V.K. [Institute of Technology, Banaras Hindu University, Varanasi 221 005 (India)

    2007-01-15

    The transfer of energy between two adjacent parts of rock mainly depends on its thermal conductivity. Present study supports the use of artificial neural network (ANN) and adaptive neuro fuzzy inference system (ANFIS) in the study of thermal conductivity along with other intrinsic properties of rock due to its increasing importance in many areas of rock engineering, agronomy and geo environmental engineering field. In recent years, considerable effort has been made to develop techniques to determine these properties. Comparative analysis is made to analyze the capabilities among six different models of ANN and ANFIS. ANN models are based on feedforward backpropagation network with training functions resilient backpropagation (RP), one step secant (OSS) and Powell-Beale restarts (CGB) and radial basis with training functions generalized regression neural network (GRNN) and more efficient design radial basis network (NEWRB). A data set of 136 has been used for training different models and 15 were used for testing purposes. A statistical analysis is made to show the consistency among them. ANFIS is proved to be the best among all the networks tried in this case with average absolute percentage error of 0.03% and regression coefficient of 1, whereas best performance shown by the FFBP (RP) with average absolute error of 2.26%. Thermal conductivity is predicted using P-wave velocity, porosity, bulk density, uniaxial compressive strength of rock as input parameters. (author)

  17. Study on long-term behavior of weak rock

    International Nuclear Information System (INIS)

    Okubo, Seisuke

    2003-03-01

    Using the boring core obtained in the Horonobe region, the beta in triaxial compression stress state was acquired, and the examination was carried out on the effect of the confirming pressure on long-term deformation or stability of the sample rock. At first, triaxial compression tests were carried out. In the test, loading rate (strain rate) was changed several times to obtain viscoelastic properties of the sample rock. Multi-stage creep tests were also performed in triaxial compression stress. The parameter set of a constitutive equation of variable compliance type was obtained based on the testing results. In this study, a transparent triaxial cell recently developed by this author was used. The external cylinder of this vessel was made of the transparent acrylic resin. Therefore, gradual deformation of the sample under testing was easily and clearly observed. (author)

  18. Aespoe Pillar Stability Experiment. Geology and mechanical properties of the rock in TASQ

    International Nuclear Information System (INIS)

    Staub, Isabelle; Andersson, J. Christer; Magnor, Bjoern

    2004-03-01

    An extensive characterization programme has been performed in the drift, TASQ, excavated for the Aespoe Pillar Stability Experiment, APSE, including the rock volume that will host the experiment pillar between the two deposition holes. The two major objectives with the characterization has been to 1) derive material properties for the final numerical modelling of the experiment and 2) to ensure that the pillar location is suitable from a structural and rock mechanical point of view. In summary the following activities have been performed: Geological mapping of the drift, the pilot holes cores and deposition hole DQ0066G01. 3D-visualisation of the geological mapping in the experiment (pillar) volume of TASQ. Convergence measurements during the excavation and back calculation of the results for determination of the stress tensor and the rock mass Young's modulus. Laboratory tests on core samples from the 15Φ76 mm core boreholes drilled around the pillar volume for determination of: compressive strength, thermal properties and fracture properties. P-wave velocity measurements on core samples and between boreholes for estimation of the excavation damaged zone and rock mass properties. The geological mapping and the 3D-visualisation gives a good description of the TASQ drift in general and the experiment volume in the drift in particular. The fracturing of the drift follows the pattern of the rest of Aespoe. Three fracture sets have been mapped in TASQ. The major fracture set is sub-vertical and trending NW, in principle parallel to σ 1 . This set is the most conductive at Aespoe and is the only water bearing set in TASQ. A second less pronounced set is trending NE, parallel to TASQ, and is also sub-vertical. The third set is sub-horizontal. It is interesting to note that the third set is the only one that almost completely consists of sealed fractures. The first two sets have mostly open fractures. One unique feature in the drift is a heavily oxidized brittle

  19. Aespoe Pillar Stability Experiment. Geology and mechanical properties of the rock in TASQ

    Energy Technology Data Exchange (ETDEWEB)

    Staub, Isabelle [Golder Associates AB, Uppsala (Sweden); Andersson, J. Christer; Magnor, Bjoern

    2004-03-01

    An extensive characterization programme has been performed in the drift, TASQ, excavated for the Aespoe Pillar Stability Experiment, APSE, including the rock volume that will host the experiment pillar between the two deposition holes. The two major objectives with the characterization has been to 1) derive material properties for the final numerical modelling of the experiment and 2) to ensure that the pillar location is suitable from a structural and rock mechanical point of view. In summary the following activities have been performed: Geological mapping of the drift, the pilot holes cores and deposition hole DQ0066G01. 3D-visualisation of the geological mapping in the experiment (pillar) volume of TASQ. Convergence measurements during the excavation and back calculation of the results for determination of the stress tensor and the rock mass Young's modulus. Laboratory tests on core samples from the 15{phi}76 mm core boreholes drilled around the pillar volume for determination of: compressive strength, thermal properties and fracture properties. P-wave velocity measurements on core samples and between boreholes for estimation of the excavation damaged zone and rock mass properties. The geological mapping and the 3D-visualisation gives a good description of the TASQ drift in general and the experiment volume in the drift in particular. The fracturing of the drift follows the pattern of the rest of Aespoe. Three fracture sets have been mapped in TASQ. The major fracture set is sub-vertical and trending NW, in principle parallel to {sigma}{sub 1}. This set is the most conductive at Aespoe and is the only water bearing set in TASQ. A second less pronounced set is trending NE, parallel to TASQ, and is also sub-vertical. The third set is sub-horizontal. It is interesting to note that the third set is the only one that almost completely consists of sealed fractures. The first two sets have mostly open fractures. One unique feature in the drift is a heavily

  20. Mechanical behavior of New Mexico rock salt in triaxial compression up to 2000C

    International Nuclear Information System (INIS)

    Wawersik, W.R.; Hannum, D.W.

    1978-01-01

    An extensive experimental program is being conducted to determine the mechanical behavior of New Mexico rock salt in support of the structural design of a Radioactive Waste Isolation Pilot Plant (WIPP). In this initial report, three groups of tests are discussed to identify the relative and site-specific importance of deviator stress, confining pressure (mean stress), temperature, time (loading rate), and stress path. The three groups of experiments consist of (1) hydrostatic loading, (2) conventional triaxial compression tests (sigma 1 > sigma 2 = sigma 3 = const.), and (3) variable stress path tests including experiments at approximately constant sigma 1 and at constant mean stress. All data were generated on 100 mm diameter specimens. The rock salt exhibited nonlinear response under all loading conditions, practically zero initial elastic limit and an apparent inseparability of permanent deformations into time-independent and time-dependent components. Pressure and temperature did not alter the elastic constants but affected the principal strain ratio, the ratio volumetric strain/shear strain, rock salt ductility, and the ultimate stress. In particular, low pressure and temperature permitted pronounced dilatancy and loss in load bearing ability. Under such conditions the volumetric strains reach sizable fractions of the shear strains. Pressure remained important even at high temperature because it influenced the rate of shearing. Load path and stress history may be significant under deviatoric loading conditions and for large variations in pressure

  1. Mechanical and Thermophysical Properties of Cubic Rock-Salt AlN Under High Pressure

    Science.gov (United States)

    Lebga, Noudjoud; Daoud, Salah; Sun, Xiao-Wei; Bioud, Nadhira; Latreche, Abdelhakim

    2018-03-01

    Density functional theory, density functional perturbation theory, and the Debye model have been used to investigate the structural, elastic, sound velocity, and thermodynamic properties of AlN with cubic rock-salt structure under high pressure, yielding the equilibrium structural parameters, equation of state, and elastic constants of this interesting material. The isotropic shear modulus, Pugh ratio, and Poisson's ratio were also investigated carefully. In addition, the longitudinal, transverse, and average elastic wave velocities, phonon contribution to the thermal conductivity, and interesting thermodynamic properties were predicted and analyzed in detail. The results demonstrate that the behavior of the elastic wave velocities under increasing hydrostatic pressure explains the hardening of the corresponding phonons. Based on the elastic stability criteria under pressure, it is found that AlN with cubic rock-salt structure is mechanically stable, even at pressures up to 100 GPa. Analysis of the Pugh ratio and Poisson's ratio revealed that AlN with cubic rock-salt structure behaves in brittle manner.

  2. Rock properties influencing impedance spectra (IS) studied by lab measurements on porous model systems

    Energy Technology Data Exchange (ETDEWEB)

    Volkmann, J.; Klitzsch, N.; Mohnke, O. [RWTH Aachen Univ. (Germany). Applied Geophysics and Geothermal Energy; Schleifer, N. [Wintershall Holding GmbH, Barnstorf (Germany)

    2013-08-01

    The wetting condition of reservoir rocks is a crucial parameter for the estimation of reservoir characteristics like permeability and saturation with residual oil or water. Since standard methods are often costly, at least in terms of time, we aim at assessing wettability of reservoir rocks using impedance spectroscopy (IS), a frequency dependent measurement of complex electric resistivity. This approach is promising, because IS is sensitive to the electrochemical properties of the inner surface of rocks which, on the other hand, are decisively influencing wettability. Unfortunately, there is large number of rock parameters - besides wettability - influencing the impedance spectra often not exactly known for natural rock samples. Therefore, we study model systems to improve the understanding of the underlying mechanisms and to quantify the influencing parameters. The model systems consist of sintered porous silica beads of different sizes leading to samples with different pore sizes. The main advantage of these samples compared to natural rocks is their well-defined and uniform mineralogical composition and thus their uniform electrochemical surface property. In order to distinguish pore geometry and fluid electrochemistry effects on the IS properties we measured the IS response of the fully water saturated model systems in a wide frequency range - from 1 mHz to 35 MHz - to capture different often overlapping polarization processes. With these measurements we study the influence of pore or grain size, fluid conductivity, and wettability (contact angle) on the impedance spectra. The influence of wettability was studied by modifying the originally hydrophilic inner surface into a hydrophobic state. The wettability change was verified by contact angle measurements. As results, we find pore size dependent relaxation times and salinity dependent chargeabilities for the hydrophilic samples in the low frequency range (< 10 kHz), whereas for the hydrophobic samples

  3. Rock avalanche and rock glacier: A compound landform study from Hornsund, Svalbard

    Czech Academy of Sciences Publication Activity Database

    Hartvich, Filip; Blahůt, Jan; Stemberk, Josef

    2017-01-01

    Roč. 276, JAN 1 (2017), s. 244-256 ISSN 0169-555X R&D Projects: GA MŠk(CZ) LM2015079; GA MŠk(CZ) LG15007 Institutional support: RVO:67985891 Keywords : ERT * TLS (LiDAR) * lichenometry * morphometry * rock avalanche * rock glacier * Schmidt hammer * Svalbard * Hornsund Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.958, year: 2016

  4. Field and in-situ rock-mechanics testing manual. Technical report

    International Nuclear Information System (INIS)

    Shuri, F.S.; Feves, M.L.; Peterson, G.L.; Foster, K.M.; Kienle, C.F. Jr.

    1981-10-01

    Standardized field and in situ rock mechanics testing procedures have been prepared for use in the National Terminal Waste Storage Program. The procedures emphasize equipment performance specifications, documentation and reporting, and Quality Assurance acceptance criteria. Sufficient theoretical background is included to allow the user to perform the necessary data reduction. These procedures incorporate existing standards when possible, otherwise they represent the current state of the art. Maximum flexibility in equipment design has been incorporated to allow use of this manual by existing groups and to encourage future improvements

  5. Critical issues in soft rocks

    OpenAIRE

    Milton Assis Kanji

    2014-01-01

    This paper discusses several efforts made to study and investigate soft rocks, as well as their physico-mechanical characteristics recognized up to now, the problems in their sampling and testing, and the possibility of its reproduction through artificially made soft rocks. The problems in utilizing current and widespread classification systems to some types of weak rocks are also discussed, as well as other problems related to them. Some examples of engineering works in soft rock or in soft ...

  6. Hydro-mechanical modelling of a shaft seal in crystalline and sedimentary host rock media using COMSOL

    Energy Technology Data Exchange (ETDEWEB)

    Priyanto, D.G. [Atomic Energy of Canada Limited, Pinawa, MB (Canada)

    2011-07-01

    Shaft seals are components of the engineered barriers system considered for closure of a Deep Geological Repository (DGR). These seals would be installed in strategic locations of the shafts, where significant fracture zones (FZ) are located and would serve to limit upward flow of groundwater from the repository level towards the surface. This paper presents the results of hydro-mechanical (HM) numerical modelling exercises to evaluate the performance of a shaft seal using a finite element computer code, COMSOL. This study considered a variety of host geological media as part of generic assessments of system evolution in a variety of environments including five hypothetical sedimentary and crystalline host rock conditions. Four simulations of a shaft seal in different sedimentary rocks were completed, including: shale with isotropic permeability; shale with anisotropic permeability; limestone with isotropic permeability; and limestone with anisotropic permeability. The other simulation was a shaft seal in crystalline rock with isotropic permeability. Two different stages were considered in these HM simulations. Stages 1 and 2 simulated the groundwater flow into an open shaft and after installation of shaft sealing components, respectively. As expected, the models were able to simulate that installation of the shaft seal limits groundwater flow through the shaft. Based on the conditions and assumptions defined for the host media and fracture features examined in this study, the following conclusions can be drawn from the results of the numerical modelling exercises. A shaft that remained open for a longer time was beneficial with respect to delaying of seal saturation because it could reduce the groundwater flow rate around the fracture zone. Delaying saturation time indicates slower movement of the groundwater or other substances that may be transported with the groundwater. The core of the shaft seal (i.e., the bentonite-sand mixture (BSM)) became fully saturated

  7. Red Rock Canyon National Conservation Area Transportation Feasibility Study

    Science.gov (United States)

    2012-07-31

    Red Rock Canyon National Conservation Area is a popular Bureau of Land Management natural area located near Las Vegas, Nevada. Red Rock Canyon experiences heavy congestion on its Scenic Drive and associated parking areas, due to high volumes of visit...

  8. Thermo-hydro-mechanical modelling of fractured rock masses application to radioactive wastes storage

    International Nuclear Information System (INIS)

    Vuillod, E.

    1995-01-01

    This work belongs to the Decovalex project (international cooperative project for the development of coupled models and their validation against experiments in nuclear waste isolation) of thermo-hydro-mechanical (THM) modeling of fractured rock massifs inside which high level radioactive waste disposal sites are simulated. The mathematical laws controlling the behaviour of the environment are resolved analytically in the case of a continuous environment (definition of an equivalent environment) and numerically if the environment is discontinuous (modeling of joints behaviour). The coupled THM models strongly influence the behaviour of a model. Modeling performed with the UDEC code shows the importance of HM couplings depending on whether the calculations are made in permanent or transient regime, and the influence of the loading path in the case of TM modeling. The geometry of fractures also influences the behaviour of the model. Studying the connexity of a fractures network allows to determine its degree of homogeneity. The comparison between two methods, continuous environment and discontinuous environment, has been carried out by determining the permeability tensor and the stress-deformation relations on fractured test-samples. It shows the differences in behaviour between an homogenized environment and a discrete environment. Finally two exercises of THM modeling of radioactive waste disposal sites illustrate the researches carried out. A far field model has permitted to compare the results obtained with calculation codes using different logics. The second model, a near field one, focusses more on the importance played by fracturing on the behaviour of the massif. The high density of the reference network has required some mathematical developments, in order to determine the representative equivalent volume (continuous approaches), and some mathematical analyses, to correctly simplify the environment (discontinuous approaches). These methods and analyses are

  9. Leaching of boron, arsenic and selenium from sedimentary rocks: II. pH dependence, speciation and mechanisms of release

    Energy Technology Data Exchange (ETDEWEB)

    Tabelin, Carlito Baltazar, E-mail: carlito@trans-er.eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Hashimoto, Ayaka, E-mail: a.hashimoto@diaconsult.co.jp [DIA Consultants Co. Ltd., Sapporo (Japan); Igarashi, Toshifumi, E-mail: tosifumi@eng.hokudai.ac.jp [Laboratory of Groundwater and Mass Transport, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Yoneda, Tetsuro, E-mail: yonet@eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan)

    2014-03-01

    Sedimentary rocks excavated in Japan from road- and railway-tunnel projects contain relatively low concentrations of hazardous trace elements like boron (B), arsenic (As) and selenium (Se). However, these seemingly harmless waste rocks often produced leachates with concentrations of hazardous trace elements that exceeded the environmental standards. In this study, the leaching behaviors and release mechanisms of B, As and Se were evaluated using batch leaching experiments, sequential extraction and geochemical modeling calculations. The results showed that B was mostly partitioned with the residual/crystalline phase that is relatively stable under normal environmental conditions. In contrast, the majority of As and Se were associated with the exchangeable and organics/sulfides phases that are unstable under oxidizing conditions. Dissolution of water-soluble phases controlled the leaching of B, As and Se from these rocks in the short term, but pyrite oxidation, calcite dissolution and adsorption/desorption reactions became more important in the long term. The mobilities of these trace elements were also strongly influenced by the pH of the rock-water system. Although the leaching of Se only increased in the acidic region, those of B and As were enhanced under both acidic and alkaline conditions. Under strongly acidic conditions, the primarily release mechanism of B, As and Se was the dissolution of mineral phases that incorporated and/or adsorbed these elements. Lower concentrations of these trace elements in the circumneutral pH range could be attributed to their strong adsorption onto minerals like Al-/Fe-oxyhydroxides and clays, which are inherently present and/or precipitated in the rock-water system. The leaching of As and B increased under strongly alkaline conditions because of enhanced desorption and pyrite oxidation while that of Se remained minimal due to its adsorption onto Fe-oxyhydroxides and co-precipitation with calcite. - Highlights: • The bulk of

  10. Fundamental Research on Percussion Drilling: Improved rock mechanics analysis, advanced simulation technology, and full-scale laboratory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Michael S. Bruno

    2005-12-31

    This report summarizes the research efforts on the DOE supported research project Percussion Drilling (DE-FC26-03NT41999), which is to significantly advance the fundamental understandings of the physical mechanisms involved in combined percussion and rotary drilling, and thereby facilitate more efficient and lower cost drilling and exploration of hard-rock reservoirs. The project has been divided into multiple tasks: literature reviews, analytical and numerical modeling, full scale laboratory testing and model validation, and final report delivery. Literature reviews document the history, pros and cons, and rock failure physics of percussion drilling in oil and gas industries. Based on the current understandings, a conceptual drilling model is proposed for modeling efforts. Both analytical and numerical approaches are deployed to investigate drilling processes such as drillbit penetration with compression, rotation and percussion, rock response with stress propagation, damage accumulation and failure, and debris transportation inside the annulus after disintegrated from rock. For rock mechanics modeling, a dynamic numerical tool has been developed to describe rock damage and failure, including rock crushing by compressive bit load, rock fracturing by both shearing and tensile forces, and rock weakening by repetitive compression-tension loading. Besides multiple failure criteria, the tool also includes a damping algorithm to dissipate oscillation energy and a fatigue/damage algorithm to update rock properties during each impact. From the model, Rate of Penetration (ROP) and rock failure history can be estimated. For cuttings transport in annulus, a 3D numerical particle flowing model has been developed with aid of analytical approaches. The tool can simulate cuttings movement at particle scale under laminar or turbulent fluid flow conditions and evaluate the efficiency of cutting removal. To calibrate the modeling efforts, a series of full-scale fluid hammer

  11. Strategy for a numerical Rock Mechanics Site Descriptive Model. Further development of the theoretical/numerical approach

    International Nuclear Information System (INIS)

    Olofsson, Isabelle; Fredriksson, Anders

    2005-05-01

    The Swedish Nuclear and Fuel Management Company (SKB) is conducting Preliminary Site Investigations at two different locations in Sweden in order to study the possibility of a Deep Repository for spent fuel. In the frame of these Site Investigations, Site Descriptive Models are achieved. These products are the result of an interaction of several disciplines such as geology, hydrogeology, and meteorology. The Rock Mechanics Site Descriptive Model constitutes one of these models. Before the start of the Site Investigations a numerical method using Discrete Fracture Network (DFN) models and the 2D numerical software UDEC was developed. Numerical simulations were the tool chosen for applying the theoretical approach for characterising the mechanical rock mass properties. Some shortcomings were identified when developing the methodology. Their impacts on the modelling (in term of time and quality assurance of results) were estimated to be so important that the improvement of the methodology with another numerical tool was investigated. The theoretical approach is still based on DFN models but the numerical software used is 3DEC. The main assets of the programme compared to UDEC are an optimised algorithm for the generation of fractures in the model and for the assignment of mechanical fracture properties. Due to some numerical constraints the test conditions were set-up in order to simulate 2D plane strain tests. Numerical simulations were conducted on the same data set as used previously for the UDEC modelling in order to estimate and validate the results from the new methodology. A real 3D simulation was also conducted in order to assess the effect of the '2D' conditions in the 3DEC model. Based on the quality of the results it was decided to update the theoretical model and introduce the new methodology based on DFN models and 3DEC simulations for the establishment of the Rock Mechanics Site Descriptive Model. By separating the spatial variability into two parts, one

  12. Mechanical Aqueous Alteration Dominates Textures of Gale Crater Rocks: Mars Hand Lens Imager (MAHLI) Results

    Science.gov (United States)

    Aileen Yingst, R.; Minitti, Michelle; Edgett, Kenneth; McBride, Marie; Stack, Kathryn

    2015-04-01

    The Mars Hand Lens Imager (MAHLI) acquired sub-mm/pixel scale color images of over 70 individual rocks and outcrops during Curiosity's first year on Mars, permitting the study of textures down to the distinction between silt and very fine sand. We group imaged rock textures into classes based on their grain size, sorting, matrix characteristics, and abundance of pores. Because the recent campaign at Pahrump Hills acquired many more MAHLI images than elsewhere along the rover traverse [6], textural analysis there is more detailed and thus types observed there are sub-divided. Mudstones: These rocks contain framework grains smaller than the highest resolution MAHLI images (16 μm/pixel), and thus are interpreted to consist of grains that are silt-sized or smaller. Some rocks contain nodules, sulfate veins, and Mg-enriched erosionally-resistant ridges. The Pahrump Hills region contains mudstones of at least four different sub-textures: recessive massive, recessive parallel-laminated, resistant laminated-to-massive, and resistant cross-stratified. Recessive mudstones are slope-forming; parallel-laminated recessive mudstones display mm-scale parallel (and in some cases rhythmic) lamination that extends laterally for many meters, and are interbedded with recessive massive mudstones. Coarse cm- to mm-scale laminae appear within resistant mudstones though some portions are more massive; laminae tend to be traceable for cm to meters. Well-sorted sandstones: Rocks in this class are made of gray, fine-to-medium sand and exhibit little to no porosity. Two examples of this class show fine lineations with sub-mm spacing. Aillik, a target in the Shaler outcrop, shows abundant cross-lamination. The Pahrump Hills region contains a sub-texture of well-sorted, very fine to fine-grained cross-stratified sandstone at the dune and ripple-scale. Poorly-sorted sandstones. This class is subdivided into two sub-classes: rounded, coarse-to-very coarse sand grains of variable colors and

  13. A Comprehensive Study on Dielectric Properties of Volcanic Rock/PANI Composites

    Science.gov (United States)

    Kiliç, M.; Karabul, Y.; Okutan, M.; İçelli, O.

    2016-05-01

    Basalt is a very well-known volcanic rock that is dark colored and relatively rich in iron and magnesium, almost located each country in the world. These rocks have been used in the refused rock industry, to produce building tiles, construction industrial, highway engineering. Powders and fibers of basalt rocks are widely used of radiation shielding, thermal stability, heat and sound insulation. This study examined three different basalt samples (coded CM-1, KYZ-13 and KYZ-24) collected from different regions of Van province in Turkey. Polyaniline (PANI) is one of the representative conductive polymers due to its fine environmental stability, huge electrical conductivity, as well as a comparatively low cost. Also, the electrical and thermal properties of polymer composites containing PANI have been widely studied. The dielectric properties of Basalt/Polyaniline composites in different concentrations (10, 25, 50 wt.% PANI) have been investigated by dielectric spectroscopy method at the room temperature. The dielectric parameters (dielectric constants, loss and strength) were measured in the frequency range of 102 Hz-106 Hz at room temperature. The electrical mechanism change with PANI dopant. A detailed dielectrically analysis of these composites will be presented.

  14. Application feasibility study of evaluation technology for long-term rock behavior. 2. Parameter setting of variable compliance type model and application feasibility study for rock behavior evaluation

    International Nuclear Information System (INIS)

    Sato, Shin; Noda, Masaru; Niunoya, Sumio; Hata, Koji; Matsui, Hiroya; Mikake, Shinichiro

    2012-01-01

    Creep phenomenon is one of the long-term rock behaviors. In many of rock-creep studies, model and parameter have been verified in 2D analysis using model parameter acquired by uniaxial compression test etc considering rock types. Therefore, in this study model parameter was set by uniaxial compression test with classified rock samples which were taken from pilot boring when the main shaft was constructed. Then, comparison between measured value and 3D excavation analysis with identified parameter was made. By and large, the study showed that validity of identification methodology of parameter to identify reproduction of measured value and analysis method. (author)

  15. Beyond Tree Throw: Wind, Water, Rock and the Mechanics of Tree-Driven Bedrock Physical Weathering

    Science.gov (United States)

    Marshall, J. A.; Anderson, R. S.; Dawson, T. E.; Dietrich, W. E.; Minear, J. T.

    2017-12-01

    Tree throw is often invoked as the dominant process in converting bedrock to soil and thus helping to build the Critical Zone (CZ). In addition, observations of tree roots lifting sidewalk slabs, occupying cracks, and prying slabs of rock from cliff faces have led to a general belief in the power of plant growth forces. These common observations have led to conceptual models with trees at the center of the soil genesis process. This is despite the observation that tree throw is rare in many forested settings, and a dearth of field measurements that quantify the magnitude of growth forces. While few trees blow down, every tree grows roots, inserting many tens of percent of its mass below ground. Yet we lack data quantifying the role of trees in both damaging bedrock and detaching it (and thus producing soil). By combing force measurements at the tree-bedrock interface with precipitation, solar radiation, wind speed, and wind-driven tree sway data we quantified the magnitude and frequency of tree-driven soil-production mechanisms from two contrasting climatic and lithologic regimes (Boulder and Eel Creek CZ Observatories). Preliminary data suggests that in settings with relatively thin soils, trees can damage and detach rock due to diurnal fluctuations, wind response and rainfall events. Surprisingly, our data suggests that forces from roots and trunks growing against bedrock are insufficient to pry rock apart or damage bedrock although much more work is needed in this area. The frequency, magnitude and style of wind-driven tree forces at the bedrock interface varies considerably from one to another species. This suggests that tree properties such as mass, elasticity, stiffness and branch structure determine whether trees respond to gusts big or small, move at the same frequency as large wind gusts, or are able to self-dampen near-ground sway response to extended wind forces. Our measurements of precipitation-driven and daily fluctuations in root pressures exerted on

  16. The Rho GTPase Effector ROCK Regulates Cyclin A, Cyclin D1, and p27Kip1 Levels by Distinct Mechanisms

    OpenAIRE

    Croft, Daniel R.; Olson, Michael F.

    2006-01-01

    The members of the Rho GTPase family are well known for their regulation of actin cytoskeletal structures. In addition, they influence progression through the cell cycle. The RhoA and RhoC proteins regulate numerous effector proteins, with a central and vital signaling role mediated by the ROCK I and ROCK II serine/threonine kinases. The requirement for ROCK function in the proliferation of numerous cell types has been revealed by studies utilizing ROCK-selective inhibitors such as Y-27632. H...

  17. Rock foundations of hydroengineering structures: mechanical properties and calculations. Skal'nye osnovaniya gidrotekhnicheskikh sooruzhenii: mekhanicheskie svoistva i raschety

    Energy Technology Data Exchange (ETDEWEB)

    Ukhov, S B

    1975-01-01

    This book presents the analytical methods which are used to describe the processes of the deformation and collapse of the rock-dirt foundations of dams, and techniques are presented for experimentally determining the mechanical properties of fissured rock-dirt under natural conditions. A determination is made of the required complex of engineering-geological, geophysical and geomechanical methods of investigation for calculating the interaction of the structure and the foundation, and a report is also given on the main assumptions of such calculations by using the method of finite elements. Methods are recommended for estimating the effect of engineering actions on the change in mechanical properties of the rock-dirt foundation. The book is intended for engineering dealing with the search and design of dam structures constructed on rock foundations. 126 refs.

  18. Rock mechanical, thermomechanical and hydraulic behaviour of the near field for spent nuclear fuel

    International Nuclear Information System (INIS)

    Johansson, E.; Hakala, M.; Lorig, L.J.

    1991-10-01

    Teollisuuden Voima Oy (TVO) is investigating the feasibility of disposing high level nuclear waste in crystalline rock at depths of 400 to 600 meters below the ground surface. Two explicit distinct element computer codes UDEC and 3DEC were used to simulate the mechanical response associated with excavation and the thermomechanical response associated with waste emplacement. Model input data are mostly based on preliminary design of the repository and on field data from on-going site investigations in Finland. The results showed that the overall stability of the repository near-field appears to be good during the studied time period 0 - 900 years. The maximum displacements after excavation are about 2 mm on the walls of the disposal tunnel. Joint openings are only a few micrometers. The hydraulic conductivity increases by 4 to 6 times within the zone of 0,3 m around the tunnel and emplacement hole, and farther away the average increase in conductivity is 1,2 to 1,7 times. After 60 years the heating increases the stresses in the vicinity of the excavated rooms, and closes the joints decreasing the hydraulic conductivity by 93 - 99 % when assuming 10 μm in-situ hydraulic aperture. However, when assuming 50 μm in-situ hydraulic aperture the hydraulic conductivity increases 10 - 40 % because the change in dynamic viscosity of water has a larger effect than the joint aperture change. After 900 years in the cooling stage the stresses and displacements come back almost to the same level as after the excavation. Some permanent displacements remain in the joints due to the shearing. The hydraulic conductivity at 900 years is 10 - 70 % of the conductivity after the excavation. The comparisons between the 2-D and 3-D results show that the two-dimensional modeling, if sufficient cross-sections have been analyzed, is enough to describe mechanical behaviour of the near-field, whereas the three-dimensional modeling is needed in some cases to assess the thermomechanical behaviour

  19. Mechanisms of hydrothermal alteration in a granitic rock. Consequences for high-level radioactive waste disposal

    International Nuclear Information System (INIS)

    Parneix, J.C.

    1987-06-01

    The study of hydrothermal alteration in the Auriat granitic rock (France, Massif-Central) has evidenced three main events: - a pervasive chloritisation of biotites in some parts of the drill-core, - an alteration localized around subvertical cracks and superimposed on previously chloritized or unaltered granite, - an alteration localized around subhorizontal cracks cross-cutting the preceding ones. The second type of alteration, produced by a geothermal system, gives the most interesting results to be applied to the nuclear radwaste disposal problem. Among primary minerals of granite, only biotite (or chlorite) and oligoclase are intensively altered. Therefore, the chemical composition of these minerals induces the nature of secondary parageneses. These, associated to the subvertical cracks network, indicate a thermal gradient of 150 C/Km. The geochemical code has allowed to corroborate that the thermal gradient was responsible for the occurrence of different parageneses with depth. Moreover, it was shown that the variable mineralogy around cracks was due to a thermal profile established at equilibrium between the rock and the fluid. Therefore, the extent of the alteration was proportional to the thermal power of the fluid. A dissolution and next a precipitation phase of new minerals characterize hydrothermal alteration, which is due to the thermal power emitted by radioactive waste and linked with the evolution of temperature during time. This alteration provokes two favourable events to storage: decrease of rock porosity and increase of sorption capacity [fr

  20. Mechanical and bulk properties of intact rock collected in the laboratory in support of the Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Price, R.H.; Martin, R.J. III; Boyd, P.J.; Boinott, G.N.

    1994-01-01

    A comprehensive laboratory investigation is determining the mechanical properties of tuffs for the Yucca Mountain Site Characterization Project (YMP). Most recently, experiments have been performed on tuff samples from a series of drill holes along the planned alignment of the Exploratory Study Facilities (ESF) north ramp. Unconfined compression and indirect tension experiments were performed and the results are being analyzed with the help of bulk property information. The results on samples from eight of the drill holes are presented. In general, the properties vary widely, but are highly dependent on the sample porosity. The developed relationships between mechanical properties and porosity are powerful tools in the effort to model the rock mass response of Yucca Mountain to the emplacement of the potential high-level radioactive waste repository

  1. Phenomenological study on crystalline rock for evaluating of long-term behavior (Contract research)

    International Nuclear Information System (INIS)

    Okubo, Seisuke; Seno, Yasuhiro; Hirano, Toru; Matsui, Hiroya; Nakama, Shigeo

    2008-08-01

    The Japan Atomic Energy Agency (JAEA) is conducting the Mizunami Underground Research Laboratory (MIU) Project in order to develop comprehensive geological investigation and engineering techniques for deep underground applications (e.g. repository of HLW). The purpose of this study is to contribute to the evaluation of the mechanical stability of a research drift and to plan the future studies. Rock shows time-dependent behavior such as creep/relaxation. For the shaft and gallery of the geological disposal for the radioactive waste, the mechanical stability over a period of thousands of years is demanded not only during construction and operation but also after back-filling. So, to understand the time-dependent behavior of rock is very important for evaluating the long-term mechanical stability. This study is aiming to find out the mechanism of time-dependent behavior of rock such as creep by the precision test, observation and measurement, to develop the evaluating method of long-term behavior of rock mass, and to get the information for planning the study of the Phase III (Operation Phase) at the Mizunami URL. In the previous work conducted before this fiscal year 2007, we improved the testing technique and started test of Toki granite sampled from target site. Furthermore we studied the in-situ measurement method for evaluating the scatter of rock properties. This report describes the results of the works in the fiscal year 2007. In Chapter 1, we described the overview and background of this study. In Chapter 2, the result of continuing creep test of Tage tuff which was started from the fiscal year 1997 was described. Although there was some annual variability, the precious data were obtained. In Chapter 3, the control program for the generalized relaxation test was developed. The generalized relaxation test of Toki granite was conducted in order to get basically data. In Chapter 4, the extended constitutive equation of variable compliance was analytically

  2. Acoustic and mechanical response of reservoir rocks under variable saturation and effective pressure.

    Science.gov (United States)

    Ravazzoli, C L; Santos, J E; Carcione, J M

    2003-04-01

    We investigate the acoustic and mechanical properties of a reservoir sandstone saturated by two immiscible hydrocarbon fluids, under different saturations and pressure conditions. The modeling of static and dynamic deformation processes in porous rocks saturated by immiscible fluids depends on many parameters such as, for instance, porosity, permeability, pore fluid, fluid saturation, fluid pressures, capillary pressure, and effective stress. We use a formulation based on an extension of Biot's theory, which allows us to compute the coefficients of the stress-strain relations and the equations of motion in terms of the properties of the single phases at the in situ conditions. The dry-rock moduli are obtained from laboratory measurements for variable confining pressures. We obtain the bulk compressibilities, the effective pressure, and the ultrasonic phase velocities and quality factors for different saturations and pore-fluid pressures ranging from normal to abnormally high values. The objective is to relate the seismic and ultrasonic velocity and attenuation to the microstructural properties and pressure conditions of the reservoir. The problem has an application in the field of seismic exploration for predicting pore-fluid pressures and saturation regimes.

  3. Naesliden Project: rock mechanics observations and measurements in the Naesliden mine

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, G.; Krauland, N.

    1980-05-15

    Observations and measurements of the reaction of the rock mass to mining have been made in the Naesliden Mine since the very start of mining operations in 1970. This observation program originated in the need of better understanding of the rock mechanics of cut-and-fill mining. The program comprises the following types of measurement - in the backfilled excavation convergence of the sidewalls pressure in the fill - in the orebody and alteration zones above the stopes horizontal deformation of the orebody and of the adjoining alteration zones horizontal stresses changes in horizontal stresses - in the stope amount and direction of roof and sidewall displacements convergence and sidewall deformation successively in roof and floor - in the sidewall surface subsidence horizontal displacements at 260 m level. Purpose, extent, methods and results of measurements are described. Qualitative observations concerning fracture processes due to mining are reported. The results are discussed and used for estimation of in situ modulus of elasticity of the orebody as well as the ratio of the modulus of elasticity of the orebody to the modulus of the alteration zone.

  4. Microscopic study of rock for estimating long-term behavior. Research document

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2003-02-01

    Micro-structure of rock plays an essential role for their long-term behavior. For elucidating long-term characteristics of granite we here present the followings: 1) Conformal Lase Scanning Microscope (LSM) observation of configuration of a joint in granite, its Fourier analysis and the change under uniaxial stress condition, 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, 3) observation of microcrack initiation and propagation by LSM under uniaxial compression, and 4) a study of strong discontinuity analysis included in the homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. Rock image processing and analysis become a fundamental procedure to determine rock surface discontinuities. In Chapter 2 LSM that can acquire three-dimensional images is introduced to observe the roughness of discontinuity in a rock specimen. Then, discontinuities appeared on circular sections are identified by LSM and characterized by a Discrete Fourier Transform (DFT) analysis. The change of discontinuities is observed under applying stress. Microcrack generation and propagation play an essential role to predict the long-term behavior of rock. In Chapter 3 a progressive development of cracking in granite is revealed by using stereoscopic microscope under water-saturated triaxial compression condition. Next by using LSM observe the procedure of micro-cracking under uniaxial compression condition. Obviously the micro-crack initiation and propagation controls the time-dependent behavior of granite. We have analysed the behavior by a viscoelastic theory applied in homogenization method. However since it is difficult to determine the inter-granular properties of constituent crystals and to represent the stress-dependent nonlinear characteristics by this method, we study a strong discontinuity analysis included in the

  5. Study on effects of coupled phenomenon on long-term behavior for crystalline rock (Joint research)

    International Nuclear Information System (INIS)

    Kimoto, Kazushi; Ichikawa, Yasuaki; Matsui, Hiroya

    2017-11-01

    It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior such as creep and stress relaxation. On the other hand, it was revealed that chemical reaction of groundwater in rock has an influence on the long-term behavior. Therefore, an evaluation of the microcracks influencing on rock mechanical and chemical coupled phenomena is the issue to understand the past long-term behavior of rock mass. In view of above points, this study has been started as joint research with Okayama University from Fiscal Year 2016. In Fiscal Year 2016, several kinds of elastic wave velocity were measured using ultra sonic sensors and laser Doppler vibrometer to evaluate the anisotropy of different elastic wave in granite. The velocity measurements were carried out focused on transmitted wave and surface wave. The results showed that strong anisotropy was observed in transmitted P-wave velocity while weak anisotropy was observed in transmitted S-wave and group velocity estimated by surface velocity measurement. In addition, data obtained from surface velocity measurement was partitioned into transmitted and reflected waves and analyzed them in detail. It resulted that elastic wave due to mineral particles to compose granite was dispersed; however, significant dispersion was only observed at specific location. For the future study, understanding of the relationship between density and anisotropy of micro cracks also anisotropy and strong dispersion of group velocity is important subject to estimate the geometrical distribution of micro cracks in granitic rock. (author)

  6. Usage of energy- dispersial analysis in studying rocks melts

    Directory of Open Access Journals (Sweden)

    Kudelas Dušan

    2001-09-01

    Full Text Available EDS analysis of constituent minerals of nefelitic basanite from locality Konrádovce – lava stream of ceric basalt formation of upper Phocene-Pleistocene age was carried out using the electron microscope JEOL JSM-840 and the energy-dispersive microanalyser KEVEX DELTA+ with MIRROR QUANTEX+ software.Based on the results of EDS microanalysis, the primary rock can be, from the petrographic point of view, described as nefelitic basanite. The following substances were determined in the primer matter and porfiric phenocrysts:- isometric grainsof pyroxene-augite (point A1,- grainsof nepheline-kalsite (point A2,- cryptocrystallic glassy matter (point A3,- grainsof olivine (point A4,- microlite of basic plagioclase (point A5.The energy-dispersive analysis is fast and full spectrum is taken at the same time. In common, a required time is less than one minute. Results of the measurement donot depend significantly on the topography of sample and it is also possible to analyze a rough surface which makes easier the preparation of samples. A very important aspect of the mentioned method is the precision of obtained results in order to identify the chemical composition of analyzed point which, in a subsequent step, allows to determine the type of mineral. EDS is a convenient and powerful supplement of microscopic studies which are, sometime, unable to distinguish exactly the complete composition of the analyzed rocks.

  7. Numerical studies of rock-gas flow in Yucca Mountain

    International Nuclear Information System (INIS)

    Ross, B.; Amter, S.; Lu, Ning

    1992-02-01

    A computer model (TGIF -- Thermal Gradient Induced Flow) of two-dimensional, steady-state rock-gas flow driven by temperature and humidity differences is described. The model solves for the ''fresh-water head,'' a concept that has been used in models of variable-density water flow but has not previously been applied to gas flow. With this approach, the model can accurately simulate the flows driven by small differences in temperature. The unsaturated tuffs of Yucca Mountain, Nevada, are being studied as a potential site for a repository for high-level nuclear waste. Using the TGIF model, preliminary calculations of rock-gas flow in Yucca Mountain are made for four east-west cross-sections through the mountain. Calculations are made for three repository temperatures and for several assumptions about a possible semi-confining layer above the repository. The gas-flow simulations are then used to calculate travel-time distributions for air and for radioactive carbon-14 dioxide from the repository to the ground surface

  8. The geology and mechanics of formation of the Fort Rock Dome, Yavapai County, Arizona

    Science.gov (United States)

    Fuis, Gary S.

    1996-01-01

    The Fort Rock Dome, a craterlike structure in northern Arizona, is the erosional product of a circular domal uplift associated with a Precambrian shear zone exposed within the crater and with Tertiary volcanism. A section of Precambrian to Quaternary rocks is described, and two Tertiary units, the Crater Pasture Formation and the Fort Rock Creek Rhyodacite, are named. A mathematical model of the doming process is developed that is consistent with the history of the Fort Rock Dome.

  9. Strain localisation in mechanically layered rocks beneath detachment zones: insights from numerical modelling

    Directory of Open Access Journals (Sweden)

    L. Le Pourhiet

    2013-04-01

    Full Text Available We have designed a series of fully dynamic numerical simulations aimed at assessing how the orientation of mechanical layering in rocks controls the orientation of shear bands and the depth of penetration of strain in the footwall of detachment zones. Two parametric studies are presented. In the first one, the influence of stratification orientation on the occurrence and mode of strain localisation is tested by varying initial dip of inherited layering in the footwall with regard to the orientation of simple shear applied at the rigid boundary simulating a rigid hanging wall, all scaling and rheological parameter kept constant. It appears that when Mohr–Coulomb plasticity is being used, shear bands are found to localise only when the layering is being stretched. This corresponds to early deformational stages for inital layering dipping in the same direction as the shear is applied, and to later stages for intial layering dipping towards the opposite direction of shear. In all the cases, localisation of the strain after only γ=1 requires plastic yielding to be activated in the strong layer. The second parametric study shows that results are length-scale independent and that orientation of shear bands is not sensitive to the viscosity contrast or the strain rate. However, decreasing or increasing strain rate is shown to reduce the capacity of the shear zone to localise strain. In the later case, the strain pattern resembles a mylonitic band but the rheology is shown to be effectively linear. Based on the results, a conceptual model for strain localisation under detachment faults is presented. In the early stages, strain localisation occurs at slow rates by viscous shear instabilities but as the layered media is exhumed, the temperature drops and the strong layers start yielding plastically, forming shear bands and localising strain at the top of the shear zone. Once strain localisation has occured, the deformation in the shear band becomes

  10. A coupled mechanical-hydrological investigation of crystalline rocks: Annual technical progress report, proposed test matrix, and preliminary results

    International Nuclear Information System (INIS)

    Bastian, R.J.; Voss, C.F.; Apted, M.J.; Shotwell, L.R.

    1988-02-01

    This report reviews the Fracture Flow Behavior in Rock Study being performed at the Pacific Northwest Laboratory. The study's objective is to determine the feasibility of predicting mechanical-hydrological behavior of natural rock fractures by accurately characterizing fracture surface topography and mineralization. A laboratory-scale facility is currently being used to ensure optimum control of variables. Devising a technique to study small-scale samples is the first step to understanding the complex coupled processes encountered in geomechanics and hydrology. The major accomplishments during fiscal year 1987 were initial development of the innovative testing method, identification of appropriate specimens, substantial renovation to the facility, completion of several sets of experiments, and procurement of hardware components for a laser-imaging device used to characterize fracture surfaces. A complete set of preliminary results and findings is presented in this report. These results, gathered from a basalt core with a natural fracture, have demonstrated that the methodology is valid, and definite trends in the data are readily apparent. 10 refs., 14 figs., 1 tab

  11. Elastic-plastic mechanical constitutive description for rock salt triaxial compression

    International Nuclear Information System (INIS)

    Butcher, B.M.

    1981-06-01

    A model for the time-independent part of the mechanical deformation of rock salt from the Waste Isolation Pilot Plant Site in southeastern New Mexico is presented. A recently published creep model was first used to correct conventional triaxial compression data for time-dependent deformation. The experimental data was from tests at a loading rate of approximately 11.9 N/s, 23 0 C, and confining pressures from 0 to -20.7 MPa. The corrected time-independent curves were then used to determine material constants for the model. Generalization to a three-dimensional plasticity-failure theory using a general constitutive relation proposed by Rudnicki and Rice was also performed. 7 figures, 3 tables

  12. Choosing the function of mechanical properties of grounds and rock formations due to their heterogeneity

    Science.gov (United States)

    Frolova, Irina; Agakhanov, Murad

    2018-03-01

    The development of computing techniques to analyze underground structures, buildings in high-rise construction that would fully take account of the conditions of their design and operation, as well as the real material properties, is one of the important trends in structural mechanics. For the territory in high-rise construction it is necessary to monitor the deformations of the soil surface. When high-rise construction is recommended to take into account the rheological properties and temperature deformations of the soil, the effect of temperature on the mechanical characteristics of the surrounding massif. Similar tasks also arise in the creation and operation of underground parts of high-rise construction, which are used for various purposes. These parts of the structures are surrounded by rock massifs of various materials. The actual mechanical characteristics of such materials must be taken into account. The objective property of nearly all materials is their non-homogeneity, both natural and technological. The work addresses the matters of building nonhomogeneous media initial models based on the experimental evidence. This made it possible to approximate real dependencies and obtain the appropriate functions in a simple and convenient way.

  13. Retrievability of high-level nuclear waste from geologic repositories - Regulatory and rock mechanics/design considerations

    International Nuclear Information System (INIS)

    Tanious, N.S.; Nataraja, M.S.; Daemen, J.J.K.

    1987-01-01

    Retrievability of nuclear waste from high-level geologic repositories is one of the performance objectives identified in 10CFR60 (Code of Federal Regulations, 1985). 10CFR60.111 states that the geologic repository operations area shall be designed to preserve the option of waste retrieval. In designing the repository operations area, rock mechanics considerations play a major role especially in evaluating the feasibility of retrieval operations. This paper discusses generic considerations affecting retrievability as they relate to repository design, construction, and operation, with emphasis on regulatory and rock mechanics aspects

  14. Programme of research into the disposal of radioactive waste into geological formations. Studies on crystalline rock. Contract 059-78-1 WASUK. Final report: General studies of physical properties

    International Nuclear Information System (INIS)

    1981-11-01

    This report covers the following topics: groundwater dating; heat transfer and associated thermal studies (in-situ heat transfer experiment; thermal rock and fluid mechanics studies; thermal convection; hydraulic permeability experiments; laboratory studies); corrosion and chemical compatibility studies (field and laboratory corrosion studies; waste - rock interactions). (U.K.)

  15. Particulate Matter and Noise Impact Studies of Waste Rock Dump ...

    African Journals Online (AJOL)

    Adansi Gold Company Limited identified an economically viable gold deposit at Nkran in the Amansie West District of Ghana. Mining of this deposit requires the disposal of waste rock materials at a proposed waste rock dump near Nkran and Koninase communities. Since particulates and noise emissions from the ...

  16. A seismic study on cracks in crystalline rock

    International Nuclear Information System (INIS)

    Israelsson, H.

    1981-07-01

    This report summarizes results from a field study with in-situ seismic measurements in crystalline rock. It was found that among a few potential seismic techniques the so called cross hole method would probably provide the most powerful capability for detecting cracks and fracture zones. By this method the area between two holes are systematically scanned by seismic raypaths. Seismic signals are generated in one hole by micro explosions and recorded in the other at various combinations of depths. A test sample of scanning data showed a rather dramatic variation of the seismic P-wave velocity (5-6 km/s). Analysis procedures like tomographic imaging was applied to this data set primarily to illustrate the kind of structural mapping such procedures can provide. (Author)

  17. Prediction of mining conditions from bore core information: rock mechanics investigations in the Whybrow Seam at Wambo Colliery

    Energy Technology Data Exchange (ETDEWEB)

    Richmond, A.; Levers, R.; Smith, K.

    1979-12-01

    Rock mechanics investigations were conducted at Wambo Colliery as part of the series designed to study the stability of mining structures and obtain geomechanical properties. The roof and floor were drilled in order to obtain core for rock testing and samples of coal were collected to measure the coal properties. A successful overcoring of a CSIR strain cell was achieved to determine the absolute stress field. The core which was recovered was logged prior to laboratory testing to determine a C index (modified RQD index based on core fragmentation). This was used to estimate the in-situ strata properties from the laboratory results. The roof material was found to consist predominantly of a competent laminite. The Whybrow seam above the Cow Manure band had an average uniaxial strength of 26 MPa. The Cow Manure band was extremely weak with a strength of 1 MPa, while the coal below this band was much weaker than the upper section coal with a strength of 7 MPa. The floor strata was made up of competent carbonaceous siltstone and alternate bands of shale and sandstone. Finite element analyses indicate very stable roof, floor and rib, corresponding closely to the in-situ conditions.

  18. Plant- and microbial-based mechanisms to improve the agronomic effectiveness of phosphate rock: a review

    Directory of Open Access Journals (Sweden)

    Melissa M. Arcand

    2006-12-01

    Full Text Available Deficiency in plant-available phosphorus is considered to be a major limiting factor to food production in many agricultural soils. Mineral resources are necessary to restore soil phosphorus content. In regions where conventional fertilizers are not used due to cost limitations or to mitigate adverse environmental effects, local sources of phosphate rock are being increasingly recognized for potential use as alternative phosphorus fertilizers. The main obstacle associated with using directly applied ground phosphate rock is that the phosphate released is often unable to supply sufficient plant-available phosphorus for crop uptake. Plantand microbial-based mechanisms are low-cost, appropriate technologies to enhance the solubilization and increase the agronomic effectiveness of phosphate rock. Common mechanisms of phosphate rock dissolution including proton and organic acid production will be reviewed for both plants and microorganisms. This review will also address possibilities for future research directions and applications to agriculture, as well as highlight ongoing research at the University of Guelph, Guelph, Canada.A deficiência de fósforo disponível nas plantas é considerada o maior fator de limitação na produção de alimentos em diversos solos agrícolas. São necessários recursos minerais para restaurar o conteúdo de fósforo no solo. Em regiões onde fertilizantes convencionais nãosão utilizados devido às limitações de custo ou de seus efeitos ambientais adversos, fontes locais de rocha fosfática estão sendo crescentemente reconhecidas por seu uso potencial como alternativa aos fertilizantes solúveis de fósforo. O principal obstáculo associado ao uso daaplicação direta da rocha fosfática no solo é que o fósforo liberado é, muitas vezes, incapaz de suprir as necessidades das plantas de forma a aumentar a produção. Mecanismos baseados no uso de plantas e micro-organismos são consideradas tecnologias

  19. Geological site selection studies in Precambrian crystalline rocks in Finland

    International Nuclear Information System (INIS)

    Vuorela, P.

    1988-01-01

    In general geological investigations made since 1977 the Finnish crystalline bedrock has been determined to be suitable for the final disposal of the spent nuclear fuel. Regional investigations have been mainly based on already existing geological studies. Special attention has been paid on the international geological Finland as the Baltic Shield is stiff and stable and situated far outside the zones of volcanic and seismic activity. The present day crustal movements in Finland are related to landuplift process. Movements and possible faults in the bedrock follow fracture zones which devide the bedrock into mosaiclike blocks. As compared to small scale geological maps the bedrock blocks are often indicated as large granite rock formations which are less broken than the surrounding rocks, though the age of granite formations is at least 1500 millions of years. The large bedrock blocks (20-300 km 2 ) are divided to smaller units by different magnitudes of fractures and these smaller bedrock units (5-20 km 2 ) have been selected for further site selection investigations. At the first stage of investigations 327 suitable regional bedrock blocks have been identified on the basis of Landsat-1 winter and summer mosaics of Finland. After two years of investigations 134 investigation areas were selected inside 61 bedrock blocks and classified to four priority classes, the three first of which were redommended for further investigations. Geological criteries used in classification indicated clear differences between the classes one and three, however all classified areas are situated in large rather homogenous bedrock blocks and more exact three dimensional suitability errors may not be observed until deep bore holes have been made

  20. Thermal-chemical-mechanical feedback during fluid-rock interactions: Implications for chemical transport and scales of equilibria in the crust

    International Nuclear Information System (INIS)

    Dutrow, Barbara

    2008-01-01

    Our research evaluates the hypothesis that feedback amongst thermal-chemical-mechanical processes operative in fluid-rock systems alters the fluid flow dynamics of the system which, in turn, affects chemical transport and temporal and spatial scales of equilibria, thus impacting the resultant mineral textural development of rocks. Our methods include computational experimentation and detailed analyses of fluid-infiltrated rocks from well-characterized terranes. This work focuses on metamorphic rocks and hydrothermal systems where minerals and their textures are utilized to evaluate pressure (P), temperature (T), and time (t) paths in the evolution of mountain belts and ore deposits, and to interpret tectonic events and the timing of these events. Our work on coupled processes also extends to other areas where subsurface flow and transport in porous media have consequences such as oil and gas movement, geothermal system development, transport of contaminants, nuclear waste disposal, and other systems rich in fluid-rock reactions. Fluid-rock systems are widespread in the geologic record. Correctly deciphering the products resulting from such systems is important to interpreting a number of geologic phenomena. These systems are characterized by complex interactions involving time-dependent, non-linear processes in heterogeneous materials. While many of these interactions have been studied in isolation, they are more appropriately analyzed in the context of a system with feedback. When one process impacts another process, time and space scales as well as the overall outcome of the interaction can be dramatically altered. Our goals to test this hypothesis are: to develop and incorporate algorithms into our 3D heat and mass transport code to allow the effects of feedback to be investigated numerically, to analyze fluid infiltrated rocks from a variety of terranes at differing P-T conditions, to identify subtle features of the infiltration of fluids and/or feedback, and

  1. Vapour loss (``boiling'') as a mechanism for fluid evolution in metamorphic rocks

    Science.gov (United States)

    Trommsdorff, Volkmar; Skippen, George

    1986-11-01

    The calculation of fluid evolution paths during reaction progress is considered for multicomponent systems and the results applied to the ternary system, CO2-H2O-NaCl. Fluid evolution paths are considered for systems in which a CO2-rich phase of lesser density (vapour) is preferentially removed from the system leaving behind a saline aqueous phase (liquid). Such “boiling” leads to enrichment of the residual aqueous phase in dissolved components and, for certain reaction stoichiometries, to eventual saturation of the fluids in salt components. Distinctive textures, particularly radiating growths of prismatic minerals such as tremolite or diopside, are associated with saline fluid inclusions and solid syngenetic salt inclusions at a number of field localities. The most thoroughly studied of these localities is Campolungo, Switzerland, where metasomatic rocks have developed in association with fractures and veins at 500° C and 2,000 bars of pressure. The petrography of these rocks suggests that fluid phase separation into liquid and vapour has been an important process during metasomatism. Fracture systems with fluids at pressure less than lithostatic may facilitate the loss of the less dense vapour phase to conditions of the amphibolite facies.

  2. Rock mass mechanical property estimation strategy for the Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Lin, M.; Brechtel, C.E.; Hardy, M.P.; Bauer, S.J.

    1992-01-01

    This paper presents a method of estimating the rock mass properties for the welded and nonwelded tuffs based on currently available information on intact rock and joint characteristics at the Yucca Mountain site. Variability of the expected ground conditions at the potential repository horizon (the TSw2 thermomechanical unit) and in the Calico Hills nonwelded tuffs is accommodated by defining five rock mass quality categories in each unit based upon assumed and observed distributions of the data

  3. Impact of solid second phases on deformation mechanisms of naturally deformed salt rocks (Kuh-e-Namak, Dashti, Iran) and rheological stratification of the Hormuz Salt Formation

    Science.gov (United States)

    Závada, P.; Desbois, G.; Urai, J. L.; Schulmann, K.; Rahmati, M.; Lexa, O.; Wollenberg, U.

    2015-05-01

    Viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between 'weak' second phase bearing rock salt and 'strong' pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study. While the solid inclusions rich ("dirty") rock salts contain disaggregated siltstone and dolomite interlayers, "clean" salts reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although the flow in both, the recrystallized "dirty" and "clean" salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS), transgranular microcracking and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts observed in the field outcrops are explained by: 1) enhanced ductility of "dirty" salts due to increased diffusion rates along the solid inclusion-halite contacts than along halite-halite contacts, and 2) slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for "clean" salt types Rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the "dirty" salt forming Lower Hormuz and the "clean" salt forming the Upper Hormuz of the Hormuz Formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure.

  4. Displaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake

    Science.gov (United States)

    Michael, Andrew J.; Ross, Stephanie L.; Stenner, Heidi D.

    2002-01-01

    The paucity of strong-motion stations near the 1999 Hector Mine earthquake makes it impossible to make instrumental studies of key questions about near-fault strong-motion patterns associated with this event. However, observations of displaced rocks allow a qualitative investigation of these problems. By observing the slope of the desert surface and the frictional coefficient between these rocks and the desert surface, we estimate the minimum horizontal acceleration needed to displace the rocks. Combining this information with observations of how many rocks were displaced in different areas near the fault, we infer the level of shaking. Given current empirical shaking attenuation relationships, the number of rocks that moved is slightly lower than expected; this implies that slightly lower than expected shaking occurred during the Hector Mine earthquake. Perhaps more importantly, stretches of the fault with 4 m of total displacement at the surface displaced few nearby rocks on 15?? slopes, suggesting that the horizontal accelerations were below 0.2g within meters of the fault scarp. This low level of shaking suggests that the shallow parts of this rupture did not produce strong accelerations. Finally, we did not observe an increased incidence of displaced rocks along the fault zone itself. This suggests that, despite observations of fault-zone-trapped waves generated by aftershocks of the Hector Mine earthquake, such waves were not an important factor in controlling peak ground acceleration during the mainshock.

  5. A laboratory study of supercritical CO2 adsorption on cap rocks in the geological storage conditions

    Science.gov (United States)

    Jedli, Hedi; Jbara, Abdessalem; Hedfi, Hachem; Bouzgarrou, Souhail; Slimi, Khalifa

    2017-04-01

    In the present study, various cap rocks have been experimentally reacted in water with supercritical CO2 in geological storage conditions ( P = 8 × 106 Pa and T = 80 °C) for 25 days. To characterize the potential CO2-water-rock interactions, an experimental setup has been built to provide additional information concerning the effects of structure, thermal and surface characteristics changes due to CO2 injection with cap rocks. In addition, CO2 adsorption capacities of different materials (i.e., clay evaporate and sandstone) are measured. These samples were characterized by XRD technique. The BET specific surface area was determined by nitrogen isotherms. In addition, thermal characteristics of untreated adsorbents were analyzed via TGA method and topography surfaces are identified by Scanning Electron Microscope (SEM). Taking into account pressure and temperature, the physical as well as chemical mechanisms of CO2 retention were determined. Isotherm change profiles of samples for relative pressure range indicate clearly that CO2 was adsorbed in different quantities. In accordance with the X-ray diffraction, a crystalline phase was formed due to the carbonic acid attack and precipitation of some carbonate.

  6. Design of Rock Slope Reinforcement: An Himalayan Case Study

    Science.gov (United States)

    Tiwari, Gaurav; Latha, Gali Madhavi

    2016-06-01

    The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from site-specific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

  7. Criticism of Levantine Rock Art studies from a bibliometric perspective

    Directory of Open Access Journals (Sweden)

    Berrocal, María Cruz

    1999-06-01

    Full Text Available A historiographic analysis of Levantine rock art studies from their origins to the present using a bibliometric study is presented. The research is based on a bibliographic data base integrated by 521 records (notes, reports, papers, chapters of books and monographs and 235 authors. Three periods (1907-1960, 1960-1980, 1980-1995 have been defined on the basis of the production, themes and characteristics of the authors. The institutionalization of Spanish archaeology, and the partiality and localism of current research are stressed. The huge activity of local scholars is remarkable in the first period. In the second one the number of authors and they monopolise a large part of the research. The foreign contribution disappears, and female researchers appear Finally, in the third period the percentage of publications increases and the descentralization of the study of Levantine rock art takes place. The independent authors as well as researchers assigned to regional administrations prevail over the academic researchers. The most relevant conclusion of this study is the persistence of iconography and simple description as the main aims of research on Levantine rock art during the entire century.

    Presentamos un análisis historiográfico de la investigación del arte levantino desde su comienzo hasta nuestros días, a través de un estudio bibliométrico basado en una muestra de 521 registros (notas, comunicaciones en congresos, artículos, capítulos de libros y monografías y 235 autores, que consideramos suficientemente representativa. Hemos definido tres períodos (1907-1960, 1960-1980, 1980-1995 a partir de la producción, la temática y las características de autor. Hacemos hincapié en la institucionalización de la arqueología española, el personalismo y el actual localismo de la investigación. La primera etapa destaca por la gran actividad de eruditos locales, mientras que en la segunda el número de autores se reduce

  8. TL studies of calcareous rocks of Danta area, North Gujarat

    International Nuclear Information System (INIS)

    Limaye, M.A.; Desai, S.J.; Murthy, K.V.R.; Joshi, T.R.

    1992-01-01

    The lithounits exposed around Danta in Banaskantha district of North Gujarat belong to Ajabgarh Group, the upper division of the Delhi super group. These rocks are intruded by syn to late kinematic basic rocks and by Erinpura granites of post Delhi age. The Ajabgarh group consists of pelitic and calcareous components. Mineralogically the pelitic rocks comprise cordierite, almandine garnet, k-feldspar, sillimanite, quartz and mica in variable proportions. The calcareous rocks are seen to contain dominantly calcite, scapolite, forsterite, sphene, k-feldspar. These mineral assemblages correspond to upper Amphibolite to lower Granulite facies of regional metamorphism. The chemistry of the calcareous rocks show predominance of CaO over MgO. The glow curves obtained from virgin samples (NTL) as well as artificial beta irradiated indicate glow peaks at 140 o C, 290 o C, 310 o C and 390 o C. The TL glow peak temperatures are in general agreement with those reported by Borsi and Rinaldi and Medlin. The pronounced peak at 390 o C and 290 o C are suggestive of their high irradiation sensitivity and also probably reflect variation in the Mn content of the rocks. (author). 9 refs., 16 tabs., 2 figs

  9. Using Neutrons to Study Fluid-Rock Interactions in Shales

    Science.gov (United States)

    DiStefano, V. H.; McFarlane, J.; Anovitz, L. M.; Gordon, A.; Hale, R. E.; Hunt, R. D.; Lewis, S. A., Sr.; Littrell, K. C.; Stack, A. G.; Chipera, S.; Perfect, E.; Bilheux, H.; Kolbus, L. M.; Bingham, P. R.

    2015-12-01

    Recovery of hydrocarbons by hydraulic fracturing depends on complex fluid-rock interactions that we are beginning to understand using neutron imaging and scattering techniques. Organic matter is often thought to comprise the majority of porosity in a shale. In this study, correlations between the type of organic matter embedded in a shale and porosity were investigated experimentally. Selected shale cores from the Eagle Ford and Marcellus formations were subjected to pyrolysis-gas chromatography, Differential Thermal Analysis/Thermogravimetric analysis, and organic solvent extraction with the resulting affluent analyzed by gas chromatography-mass spectrometry. The pore size distribution of the microporosity (~1 nm to 2 µm) in the Eagle Ford shales was measured before and after solvent extraction using small angle neutron scattering. Organics representing mass fractions of between 0.1 to 1 wt.% were removed from the shales and porosity generally increased across the examined microporosity range, particularly at larger pore sizes, approximately 50 nm to 2 μm. This range reflects extraction of accessible organic material, including remaining gas molecules, bitumen, and kerogen derivatives, indicating where the larger amount of organic matter in shale is stored. An increase in porosity at smaller pore sizes, ~1-3 nm, was also present and could be indicative of extraction of organic material stored in the inter-particle spaces of clays. Additionally, a decrease in porosity after extraction for a sample was attributed to swelling of pores with solvent uptake. This occurred in a shale with high clay content and low thermal maturity. The extracted hydrocarbons were primarily paraffinic, although some breakdown of larger aromatic compounds was observed in toluene extractions. The amount of hydrocarbon extracted and an overall increase in porosity appeared to be primarily correlated with the clay percentage in the shale. This study complements fluid transport neutron

  10. An Improved Computing Method for 3D Mechanical Connectivity Rates Based on a Polyhedral Simulation Model of Discrete Fracture Network in Rock Masses

    Science.gov (United States)

    Li, Mingchao; Han, Shuai; Zhou, Sibao; Zhang, Ye

    2018-06-01

    Based on a 3D model of a discrete fracture network (DFN) in a rock mass, an improved projective method for computing the 3D mechanical connectivity rate was proposed. The Monte Carlo simulation method, 2D Poisson process and 3D geological modeling technique were integrated into a polyhedral DFN modeling approach, and the simulation results were verified by numerical tests and graphical inspection. Next, the traditional projective approach for calculating the rock mass connectivity rate was improved using the 3D DFN models by (1) using the polyhedral model to replace the Baecher disk model; (2) taking the real cross section of the rock mass, rather than a part of the cross section, as the test plane; and (3) dynamically searching the joint connectivity rates using different dip directions and dip angles at different elevations to calculate the maximum, minimum and average values of the joint connectivity at each elevation. In a case study, the improved method and traditional method were used to compute the mechanical connectivity rate of the slope of a dam abutment. The results of the two methods were further used to compute the cohesive force of the rock masses. Finally, a comparison showed that the cohesive force derived from the traditional method had a higher error, whereas the cohesive force derived from the improved method was consistent with the suggested values. According to the comparison, the effectivity and validity of the improved method were verified indirectly.

  11. The influence of water on the mechanical behaviour of argillaceous rocks

    International Nuclear Information System (INIS)

    Freissmuth, H.J.

    2002-12-01

    This thesis was done in collaboration with the French national radioactive waste agency ANDRA. The aim is to contribute to a better understanding of the mechanical behaviour of argillaceous rocks under the influence of aqueous solutions, as they are considered to be a possible host rock for a nuclear waste disposal site. Shale, can depending on the composition, change its mechanical and petrophysical properties in a wide range due to fluid-clay mineral interactions. One and the same shale can be soft or hard, ductile or rigid, permeable or sealing - depending on the environmental conditions the sample is exposed to. Shale can be very sensitive to a change of conditions such as humidity, stress state, temperature, and chemical potential gradients. One of the most obvious shale reactions is the swelling and shrinking as a function of it's saturation and the chemical potential gradient in the fluid system. Theses volume changes also sometimes alter other properties. Depending on the nature and the concentration of a liquid, a shale can either shrink or swell when in contact with a liquid. The material may sometimes also disperse in the liquid and deteriorate completely.An understandable description of the clay-minerals from the site of Est is given. The physicochemical micro mechanism of the fluid solid interaction such as adsorption, absorption, capillarity and osmosis are also presented. The possible consequences of these mechanisms on the macro mechanical behaviour, such as swelling and shrinking, crack induction and others was analysed. X-ray microfocus technology was introduced and used to analyse shale under different environmental conditions. The advantage of this technology is it's non-destructive character. The preparation of classical thin cross section is a rather inappropriate method, concerning micro cracks and deterioration in shale, because of the grinding of the material. A solution test was conducted to qualitatively observe the real-time reaction of

  12. Mechanical interaction between swelling compacted clay and fractured rock, and the leaching of clay colloids

    NARCIS (Netherlands)

    Grindrod, P.; Peletier, M.A.; Takase, H.

    1999-01-01

    We consider the interaction between a saturated clay buffer layer and a fractured crystalline rock engineered disturbed zone. Once saturated, the clay extrudes into the available rock fractures, behaving as a compressible non-Newtonian fluid. We discuss the modelling implications of published

  13. Theoretical and numerical aspects of the calculation of thermo-mechanical creep processes in rock salt

    International Nuclear Information System (INIS)

    Stein, E.; Wetjen, D.; Mahnken, R.; Heemann, U.

    1987-01-01

    This paper is a step in the development of thermodynamically consistent material equations for inelastic materials, such as polycrystalline rock salt. In this context it is of particular importance to reduce the number and the structure of the internal variables, in order to allow for a fit with available experimental data. As an example this is demonstrated in detail in the case of the so-called dislocation model. As physical non-linearities and in addition also geometrical non-linearities lead to an inhomogeneous deformation - and stress state even in the case of simple samples, boundary value problems have to be studied, in order to test the material equations. For this purpose the finite element method has been used. (orig.) [de

  14. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1997-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  15. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1996-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  16. Oxygen and hydrogen isotope studies of plutonic granitic rocks

    International Nuclear Information System (INIS)

    Taylor, H.P. Jr.

    1978-01-01

    The primary deltaD values of the biotites and hornblendes in granitic batholiths are remarkably constant at about -50 to -85, identical to the values in regional metamorphic rocks, marine sediments and greenstones, and most weathering products in temperate climates. Therefore the primary water in these igneous rocks is probably not 'juvenile', but is ultimately derived by dehydration and/or partial melting of the lower crust or subducted lithosphere. Most granitic rocks have delta 18 O = +7.0 to +10.0, probably indicating significant involvment of high- 18 O metasedimentary or altered volcanic rocks in the melting process; such an origin is demanded for many other granodiorites and tonalites that have delta 18 O = +10 to +13. Gigantic meteoric-hydrothermal convective circulation systems were established in the epizonal portions of all batholiths, locally producing very low delta 18 O values (particularly in feldspars) during subsolidus exchange. Some granitic plutons in such environments also were emplaced as low- 18 O magmas probably formed by melting or assimilation of hydrothermally altered roof rocks. However, the water/rock ratios were typically low enough that over wide areas the only evidence for meteoric water exchange in the batholiths is given by low D/H ratios (deltaK as low as -180); for example, because of latitudinal isotopic variations in meteoric waters, as one moves north through the Cordilleran batholiths of western North America an increasingly higher proportion of the granitic rocks have deltaD values lower than -120. The lowering of deltaD values commonly corelates with re-setting of K-Ar ages. (Auth.)

  17. Numerical simulation for the coupled thermo-mechanical performance of a lined rock cavern for underground compressed air energy storage

    Science.gov (United States)

    Zhou, Shu-Wei; Xia, Cai-Chu; Zhao, Hai-Bin; Mei, Song-Hua; Zhou, Yu

    2017-12-01

    Compressed air energy storage (CAES) is a technology that uses compressed air to store surplus electricity generated from low power consumption time for use at peak times. This paper presents a thermo-mechanical modeling for the thermodynamic and mechanical responses of a lined rock cavern used for CAES. The simulation was accomplished in COMSOL Multiphysics and comparisons of the numerical simulation and some analytical solutions validated the thermo-mechanical modeling. Air pressure and temperatures in the sealing layer and concrete lining exhibited a similar trend of ‘up-down-down-up’ in one cycle. Significant temperature fluctuation occurred only in the concrete lining and sealing layer, and no strong fluctuation was observed in the host rock. In the case of steel sealing, principal stresses in the sealing layer were larger than those in the concrete and host rock. The maximum compressive stresses of the three layers and the displacement on the cavern surface increased with the increase of cycle number. However, the maximum tensile stresses exhibited the opposite trend. Polymer sealing achieved a relatively larger air temperature and pressure compared with steel and air-tight concrete sealing. For concrete layer thicknesses of 0 and 0.1 m and an initial air pressure of 4.5 MPa, the maximum rock temperature could reach 135 °C and 123 °C respectively in a 30 day simulation.

  18. The migration law of overlay rock and coal in deeply inclined coal seam with fully mechanized top coal caving.

    Science.gov (United States)

    Liu, Jian; Chen, Shan-Le; Wang, Hua-Jun; Li, Yu-Cheng; Geng, Xiaowei

    2015-07-01

    In a mine area, some environment geotechnics problems always occure, induced by mined-out region such as the subsidence and cracks at ground level, deformation and destruction of buildings, landslides destruction of water resources and the ecological environment. In order to research the migration of surrounding rock and coal in steeply inclined super high seams which used fully mechanized top coal caving, a working face of a certain mine was made as an example, analyzed the migration law of the overlay rock and coal under different caving ratio of fully mechanized top coal caving with numerical simulation analysis. The results suggest that the laws of overlay rock deformation caused by deeply inclined coal seam were different from horizontal coal seam. On the inclined direction, with an increase of dip angle and caving ratio, the vertical displacement of overlay rock and coal became greater, the asymmetric phenomenon of vertical displacement became obvious. On the trend direction, active region and transition region in goaf became smaller along with the increase of mining and caving ratio. On the contrary, the stable region area became greater. Therefore, there was an essential difference between the mechanism of surface movement deformation with deeply inclined coal seam and that with horizontal coal seam.

  19. A numerical study on the structural behavior of underground rock caverns for radioactive waste disposal

    International Nuclear Information System (INIS)

    Kim, Sun Hoon; Choi, Kyu Sup; Lee, Kyung Jin; Kim, Dae Hong

    1991-01-01

    In order to design safe and economical underground disposal structures for radioactive wastes, understanding the behavior of discontinuous rock masses is essential. This study includes discussions about the computational model for discontinuous rock masses and the structural analysis method for underground storage structures. Then, based on an engineering judgement a suitable selection and slight modifications on computational models and analysis methods have been made in order to analyze and understand the structural behavior of the rock cavern with discontinuities

  20. I. Some results from a field investigation of thermo-mechanical loading of a rock mass when heaters are emplaced in the rock

    International Nuclear Information System (INIS)

    Hood, M.

    1979-01-01

    Results are presented of a field experiment to monitor the response of a rock mass to thermomechanical loading from electrically heated canisters emplaced in the rock at a depth of 340 m. Measurements made to date of temperature, displacement, and stress fields indicate that heat is transferred through the rock mainly by conduction; discontinuities within the rock mass have a minimal effect on the heat flow. Displacements within the rock from thermal expansion are shown to be much less than those predicted by linear thermoelastic theory. A plausible, though not complete, reason for these reduced displacements is the absorption of the initial rock expansions into discontinuities within the rock mass. Difficulties have been experienced in obtaining reliable stress measurement data using borehole deformation gauges to monitor changes in rock stress. Some data have been obtained and are being analyzed. Rock decrepitation in the heater boreholes is discussed

  1. Computational method for thermoviscoelasticity with application to rock mechanics. [Ph. D. Thesis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.C.

    1984-01-01

    Large-scale numerical computations associated with rock mechanics problems have required efficient and economical models for predicting temperature, stress, failure, and deformed structural configuration under various loading conditions. To meet this requirement, the complex dependence of the properties of geological materials on the time and temperature is modified to yield a reduced time scale as a function of time and temperature under the thermorheologically simple material (TSM) postulate. The thermorheologically linear concept is adopted in the finite element formulation by uncoupling thermal and mechanical responses. The thermal responses, based on transient heat conduction or convective-diffusion, are formulated by using the two-point recurrence scheme and the upwinding scheme, respectively. An incremental solution procedure with the implicit time stepping scheme is proposed for the solution of the thermoviscoelastic response. The proposed thermoviscoelastic solution algorithm is based on the uniaxial creep experimental data and the corresponding temperature shift functions, and is intended to minimize computational efforts by allowing large time step size with stable solutions. A thermoelastic fracture formulation is also presented by introducing the degenerate quadratic isoparametric singular element for the thermally-induced line crack problems. The stress intensity factors are computed by use of the displacement method. Efficiency of the presented formulation and solution algorithm is initially demonstrated by comparison with other available solutions for a variety of problems. Subsequent field applications are made to simulate the post-burn and post-repose phases of an underground coal conversion (UCC) experiment and in-situ nuclear waste disposal management problems. 137 references, 48 figures, 6 tables.

  2. Rock mechanics observations pertinent to the rheology of the continental lithosphere and the localization of strain along shear zones

    Science.gov (United States)

    Kirby, S.H.

    1985-01-01

    Emphasized in this paper are the deformation processes and rheologies of rocks at high temperatures and high effective pressures, conditions that are presumably appropriate to the lower crust and upper mantle in continental collision zones. Much recent progress has been made in understanding the flexure of the oceanic lithosphere using rock-mechanics-based yield criteria for the inelastic deformations at the top and base. At mid-plate depths, stresses are likely to be supported elastically because bending strains and elastic stresses are low. The collisional tectonic regime, however, is far more complex because very large permanent strains are sustained at mid-plate depths and this requires us to include the broad transition between brittle and ductile flow. Moreover, important changes in the ductile flow mechanisms occur at the intermediate temperatures found at mid-plate depths. Two specific contributions of laboratory rock rheology research are considered in this paper. First, the high-temperature steady-state flow mechanisms and rheology of mafic and ultramafic rocks are reviewed with special emphasis on olivine and crystalline rocks. Rock strength decreases very markedly with increases in temperature and it is the onset of flow by high temperature ductile mechanisms that defines the base of the lithosphere. The thickness of the continental lithosphere can therefore be defined by the depth to a particular isotherm Tc above which (at geologic strain rates) the high-temperature ductile strength falls below some arbitrary strength isobar (e.g., 100 MPa). For olivine Tc is about 700??-800??C but for other crustal silicates, Tc may be as low as 400??-600??C, suggesting that substantial decoupling may take place within thick continental crust and that strength may increase with depth at the Moho, as suggested by a number of workers on independent grounds. Put another way, the Moho is a rheological discontinuity. A second class of laboratory observations pertains to

  3. 40Ar/39Ar studies of deep sea igneous rocks

    International Nuclear Information System (INIS)

    Seidemann, D.

    1978-01-01

    An attempt to date deep-sea igneous rocks reliably was made using the 40 Ar/ 39 Ar dating technique. It was determined that the 40 Ar/ 39 Ar incremental release technique could not be used to eliminate the effects of excess radiogenic 40 Ar in deep-sea basalts. Excess 40 Ar is released throughout the extraction temperature range and cannot be distinguished from 40 Ar generated by in situ 40 K decay. The problem of the reduction of K-Ar dates associated with sea water alteration of deep-sea igneous rocks could not be resolved using the 40 Ar/ 39 Ar technique. Irradiation induced 39 Ar loss and/or redistribution in fine-grained and altered igneous rocks results in age spectra that are artifacts of the experimental procedure and only partly reflect the geologic history of the sample. Therefore, caution must be used in attributing significance to age spectra of fine grained and altered deep-sea igneous rocks. Effects of 39 Ar recoil are not important for either medium-grained (or coarser) deep-sea rocks or glasses because only a small fraction of the 39 Ar recoils to channels of easy diffusion, such as intergranular boundaries or cracks, during the irradiation. (author)

  4. Principles of safe mechanization of operations in seams with hazards of rock and gas outbursts

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, B; Siarkiewicz, R

    1976-10-01

    Rock burst hazards in Lower Silesia, Poland, and methods for rock burst forecasting are discussed. From 1894 to 1974, 1403 rock bursts occurred in the basin; five were accompanied by emission of methane, the rest with emission of carbon dioxide. Use of the GMA-030 sensor system (type GfG) for detecting increasing emission of carbon dioxide at longwall faces mined by coal plows is analyzed. Site selection for sensors at longwall faces (retreat or advance) in mines with ascending or descending ventilation, with blowing or exhaust ventilation systems and in mine drivage is analyzed. Examples of sensor installation at face ends are evaluated. Recommendations for sensor installation are made. 2 references.

  5. A Study of Analytical Solution for the Special Dissolution Rate Model of Rock Salt

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2017-01-01

    Full Text Available By calculating the concentration distributions of rock salt solutions at the boundary layer, an ordinary differential equation for describing a special dissolution rate model of rock salt under the assumption of an instantaneous diffusion process was established to investigate the dissolution mechanism of rock salt under transient but stable conditions. The ordinary differential equation was then solved mathematically to give an analytical solution and related expressions for the dissolved radius and solution concentration. Thereafter, the analytical solution was fitted with transient dissolution test data of rock salt to provide the dissolution parameters at different flow rates, and the physical meaning of the analytical formula was also discussed. Finally, the influential factors of the analytical formula were investigated. There was approximately a linear relationship between the dissolution parameters and the flow rate. The effects of the dissolution area and initial volume of the solution on the dissolution rate equation of rock salt were computationally investigated. The results showed that the present analytical solution gives a good description of the dissolution mechanism of rock salt under some special conditions, which may provide a primary theoretical basis and an analytical way to investigate the dissolution characteristics of rock salt.

  6. A study about the long-term stability of sedimentary rock

    International Nuclear Information System (INIS)

    Yoshino, Naoto; Miyanomae, Shun-ichi; Inoue, Hiroyuki; Nashimoto, Yutaka

    2005-02-01

    In this paper, following two issues were examined and estimated, (1) the influence of near field condition factor to the dynamical behavior of sedimentary soft rock, (2) the long term estimation of the dynamical behavior considering the condition of Horonobe area. As the study about the influence of near field condition factor to the dynamical behavior of sedimentary soft rock, the thermal factor was focused on and the laboratory tests using test pieces which were sampled in Horonobe area were carried out under the water temperature were 20 degrees and 80 degrees. As a result, the time dependence parameter in variable-compliance-type constitutive-equation could be obtained. And comparison between creep property under 20 degrees and 80 degrees was conducted. In addition, the general properties of sedimentary soft rock under several conditions were identified by the survey of the literature. And the way how to confirm the dynamical properties of sedimentary soft rock with in-situ test were presented. For the study on the short-term and long-term stability of rock surrounding buffer materials, numerical simulations were carried out assuming several conditions. The direction of disposal tunnels and the ratio of rock strength by initial stress were estimated to be the main factor affecting the short-term stability of rock. Time dependency of rock and the stiffness of buffer material were estimated to be the main factor affecting the long-term stability of rock. (author)

  7. WIPP air-intake shaft disturbed-rock zone study

    International Nuclear Information System (INIS)

    Dale, T.; Hurtado, L.D.

    1996-01-01

    The disturbed-rock zone surrounding the air-intake shaft at the Waste Isolation Pilot Plant (WIPP) site was investigated to determine the extent and the permeability of the disturbed-rock zone as a function of radial distance from the 6.1 m diameter shaft, at different elevations within the Salado. Gas- and brine-permeability tests were performed in the bedded halite of the Salado formation at two levels within the air-intake shaft. The gas- and brine-permeability test results demonstrated that the radial distance to an undisturbed formation permeability of 1 x 10 -21 m 2 was less than 3.0 m

  8. Geochronological studies on some rocks and minerals from selected areas

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, J N [Department of Atomic Energy, Hyderabad (India). Atomic Minerals Div.

    1979-01-01

    Ages obtained at the Atomic Minerals Division laboratory, Hyderabad on a number of rock and mineAal samples are presented. Rb-Sr mineral ages from Pungurthy (Tamil Nadu), Sarguja (Madhya Pradesh), Hazaribagh (Bihar) and whole rock isochron age of the granitic bodies surrounding the Kolar schist belt are reported. Discordant U-Pb ages obtained on the uraninites from Kulu (H.P.) and its interpretation in terms of episodic loss has been discussed. Further facilities that are being set up for undertaking other isotopic analysis work for various geoscientific investigations are outtined.

  9. Study on the constitutive model for jointed rock mass.

    Directory of Open Access Journals (Sweden)

    Qiang Xu

    Full Text Available A new elasto-plastic constitutive model for jointed rock mass, which can consider the persistence ratio in different visual angle and anisotropic increase of plastic strain, is proposed. The proposed the yield strength criterion, which is anisotropic, is not only related to friction angle and cohesion of jointed rock masses at the visual angle but also related to the intersection angle between the visual angle and the directions of the principal stresses. Some numerical examples are given to analyze and verify the proposed constitutive model. The results show the proposed constitutive model has high precision to calculate displacement, stress and plastic strain and can be applied in engineering analysis.

  10. Study on flow and mass transport through fractured soft sedimentary rocks (Contact research)

    International Nuclear Information System (INIS)

    Shimo, Michito; Kumamoto, Sou; Maekawa, Keisuke

    2007-03-01

    It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of Koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Pottasium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock. (author)

  11. Theoretical study on crystalline rock for evaluating of long-term behavior (Contract research)

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki; Seno, Yasuhiro; Sato, Toshinori; Nakama, Shigeo

    2008-03-01

    The Japan Atomic Energy Agency (JAEA) is working on the Project of Mizunami Underground Research Laboratory (MIU). The project aims at developing comprehensive techniques of geological investigation and of construction of deep underground space for a repository of HLW and/or TRU. This study contributes to an estimation of long-term stability of underground spaces. Rock materials commonly show time-dependent behavior such as creep and relaxation. The underground structures for geological disposal of radioactive wastes must keep stable not only during construction and operation but also after closing, and then the long-term stability of rock structures (over thousands of years) is essentially important for designing the structures. The true mechanism of time-dependent behavior of rock materials is not yet clearly understood, though the phenomena are widely known. This study aims at elucidating the scientific truth involved in the time-dependent behavior of rock showing creep and relaxation. We used samples of Toki granite and performed precise tests under laser microscope observation, and then developed theories representing the experimental results. These experimental and theoretical results will be served for the design and construction of the Phase III (Operation Phase) of the MIU Project. This is the report worked out in the fiscal year 2006. In this work we performed the following subjects: 1) Uniaxial and stress relaxation tests under observation of a confocal laser scanning microscope (CLSM) by using granite specimens of MIU. 2) Pressure dissolution experiment by using specimens of single crystal quartz and glass beads. 3) Development of the rate of pressure dissolution of quartz and a homogenization analysis for quartz dissolution. In Chapter 2 CLSM was used to acquire clear three-dimensional images of Mizunami granite specimens for uniaxial and stress relaxation tests, and observed the change of microscale structure including the mineral configuration under

  12. An experimental study of pressure shadows in partially molten rocks

    Science.gov (United States)

    Qi, Chao; Zhao, Yong-Hong; Kohlstedt, David L.

    2013-11-01

    As a two-phase, solid-melt material flows around rigid particles, melt-depleted and melt-enriched regions (i.e., pressure shadows) develop due to the coupled fluxes of melt and solid driven by pressure gradients around the particles. To study this compaction-decompaction process, samples composed of fine-grained San Carlos olivine plus mid-ocean ridge basalt containing dispersed sub-millimeter-sized, single crystal beads of olivine were deformed in torsion at a temperature of 1473 K and a confining pressure of 300 MPa. Indicated by melt distribution maps obtained from reflected-light optical and backscattered electron microscopy, melt-enriched and melt-depleted regions around the beads became observable at a local shear strain of γ≈1 in samples with an initially homogeneously distributed melt fraction of ϕ≈0.05. The melt-enriched regions (ϕbarhigh≈0.06 to 0.10) and the melt-depleted regions (ϕbarlow≈0.02 to 0.04), extending as far as one radius of the bead, were symmetrically distributed around the bead. The flow field of the olivine matrix determined from crystallographic preferred orientations agrees with theoretical predictions based on two-phase flow analysis. These experiments are the first to produce pressure shadows in partially molten rocks. One implication of this study is that it will be possible to constrain the ratio of bulk to shear viscosity, which is inferred from the distribution of melt using a combination of experimental observations and numerical simulations.

  13. Rock stresses (Grimsel rock laboratory)

    International Nuclear Information System (INIS)

    Pahl, A.; Heusermann, S.; Braeuer, V.; Gloeggler, W.

    1989-01-01

    On the research and development project 'Rock Stress Measurements' the BGR has developed and tested several test devices and methods at GTS for use in boreholes at a depth of 200 m and has carried out rock mechanical and engineering geological investigations for the evaluation and interpretation of the stress measurements. The first time a computer for data processing was installed in the borehole together with the BGR-probe. Laboratory tests on hollow cylinders were made to study the stress-deformation behavior. To validate and to interprete the measurement results some test methods were modelled using the finite-element method. The dilatometer-tests yielded high values of Young's modulus, whereas laboratory tests showed lower values with a distinct deformation anisotropy. Stress measurements with the BGR-probe yielded horizontal stresses being higher than the theoretical overburden pressure and vertical stresses which agree well with the theoretical overburden pressure. These results are comparable to the results of the hydraulic fracturing tests, whereas stresses obtained with CSIR-triaxial cells are generally lower. The detailed geological mapping of the borehole indicated relationships between stress and geology. With regard to borehole depth different zones of rock structure joint frequency, joint orientation, and orientation of microfissures as well as stress magnitude, stress direction, and degree of deformation anisotropy could be distinguished. (orig./HP) [de

  14. Overview of OWI waste/rock interaction studies

    International Nuclear Information System (INIS)

    Jenks, G.H.

    1977-01-01

    A review is presented of office of waste isolation (OWI) programs which fall within the waste/rock categories. Discussions are included on salt repository design, thermal powers and radiation intensities, maximum temperatures and gamma doses, salt temperatures around high level waste cannisters, projects concerned with radiation and thermal effects, projects concerned with long term interactions, and waste isolation safety assessment tasks

  15. Petrological and geochemical studies of ultramafic–mafic rocks from ...

    Indian Academy of Sciences (India)

    rocks from the North Puruliya Shear Zone (eastern India). Aditi Mandal∗ ..... quently replaced by hornblende along margin and are greater in ...... tion and accumulation. ..... J. Petrol. 43(2) 219–241. Das D K 1977 A review on sulphide zone around Belamu hill, ... implication for trans-continental Gondwanaland correla-.

  16. Organic richness and organic matter quality studies of source rocks ...

    African Journals Online (AJOL)

    The hydrocarbon potential of the Upper Cretaceous units (Maastrichtian Mamu Formation) exposed at Imiegba and environs of the Benin Flank, Western Anambra Basin was assessed by Total Organic Carbon (TOC) and Rock-Eval Pyrolysis Analyses. The investigated sections of the Mamu Formation consist of dark grey to ...

  17. Analytical, Experimental, and Modelling Studies of Lunar and Terrestrial Rocks

    Science.gov (United States)

    Haskin, Larry A.

    1997-01-01

    The goal of our research has been to understand the paths and the processes of planetary evolution that produced planetary surface materials as we find them. Most of our work has been on lunar materials and processes. We have done studies that obtain geological knowledge from detailed examination of regolith materials and we have reported implications for future sample-collecting and on-surface robotic sensing missions. Our approach has been to study a suite of materials that we have chosen in order to answer specific geologic questions. We continue this work under NAG5-4172. The foundation of our work has been the study of materials with precise chemical and petrographic analyses, emphasizing analysis for trace chemical elements. We have used quantitative models as tests to account for the chemical compositions and mineralogical properties of the materials in terms of regolith processes and igneous processes. We have done experiments as needed to provide values for geochemical parameters used in the models. Our models take explicitly into account the physical as well as the chemical processes that produced or modified the materials. Our approach to planetary geoscience owes much to our experience in terrestrial geoscience, where samples can be collected in field context and sampling sites revisited if necessary. Through studies of terrestrial analog materials, we have tested our ideas about the origins of lunar materials. We have been mainly concerned with the materials of the lunar highland regolith, their properties, their modes of origin, their provenance, and how to extrapolate from their characteristics to learn about the origin and evolution of the Moon's early igneous crust. From this work a modified model for the Moon's structure and evolution is emerging, one of globally asymmetric differentiation of the crust and mantle to produce a crust consisting mainly of ferroan and magnesian igneous rocks containing on average 70-80% plagioclase, with a large

  18. An experimental study of velocities under pressure for ancient oceanic rocks

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, K.V.L.N.S.

    Seismic velocities of Indus suture rock types from Dras-Sanko-Kargil, Kashmir Himalaya, as a function of pressure up to 10 kbar were studied. The high-pressure measurements on the rocks reflect the depthwise increase in velocity, and in general...

  19. Rock Physics

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2017-01-01

    Rock physics is the discipline linking petrophysical properties as derived from borehole data to surface based geophysical exploration data. It can involve interpretation of both elastic wave propagation and electrical conductivity, but in this chapter focus is on elasticity. Rock physics is based...... on continuum mechanics, and the theory of elasticity developed for statics becomes the key to petrophysical interpretation of velocity of elastic waves. In practice, rock physics involves interpretation of well logs including vertical seismic profiling (VSP) and analysis of core samples. The results...

  20. Coupled Large Scale Hydro-mechanical Modelling for cap-rock Failure Risk Assessment of CO2 Storage in Deep Saline Aquifers

    International Nuclear Information System (INIS)

    Rohmer, J.; Seyedi, D.M.

    2010-01-01

    This work presents a numerical strategy of large scale hydro-mechanical simulations to assess the risk of damage in cap-rock formations during a CO 2 injection process. The proposed methodology is based on the development of a sequential coupling between a multiphase fluid flow (TOUGH2) and a hydro-mechanical calculation code (Code-Aster) that enables us to perform coupled hydro-mechanical simulation at a regional scale. The likelihood of different cap-rock damage mechanisms can then be evaluated based on the results of the coupled simulations. A scenario based approach is proposed to take into account the effect of the uncertainty of model parameters on damage likelihood. The developed methodology is applied for the cap-rock failure analysis of deep aquifer of the Dogger formation in the context of the Paris basin multilayered geological system as a demonstration example. The simulation is carried out at a regional scale (100 km) considering an industrial mass injection rate of CO 2 of 10 Mt/y. The assessment of the stress state after 10 years of injection is conducted through the developed sequential coupling. Two failure mechanisms have been taken into account, namely the tensile fracturing and the shear slip reactivation of pre-existing fractures. To deal with the large uncertainties due to sparse data on the layer formations, a scenario based strategy is undertaken. It consists in defining a first reference modelling scenario considering the mean values of the hydro-mechanical properties for each layer. A sensitivity analysis is then carried out and shows the importance of both the initial stress state and the reservoir hydraulic properties on the cap-rock failure tendency. On this basis, a second scenario denoted 'critical' is defined so that the most influential model parameters are taken in their worst configuration. None of these failure criteria is activated for the considered conditions. At a phenomenological level, this study points out three key

  1. Effects of non-linearity of material properties on the coupled mechanical-hydraulic-thermal behavior in rock mass

    International Nuclear Information System (INIS)

    Kobayashi, Akira; Ohnishi, Yuzo

    1986-01-01

    The nonlinearity of material properties used in the coupled mechanical-hydraulic-thermal analysis is investigated from the past literatures. Some nonlinearity that is respectively effective for the system is introduced into our computer code for analysis such a coupling problem by using finite element method. And the effects of nonlinearity of each material property on the coupled behavior in rock mass are examined for simple model and Stripa project model with the computer code. (author)

  2. Study of natural radioactivity in the rocks of Coorg District, Karnataka State

    International Nuclear Information System (INIS)

    Prakash, M.M; KaliPrasad, C.S.; Narayana, Y.

    2016-01-01

    The paper deals with the study of natural radioactivity in the rocks of Coorg district, Karnataka state. The level of terrestrial radiation are related to the geological composition of the region, and to the concentration of 226 Ra, 232 Th and 40 K in rock. Rocks are used in various construction activities, which also have these natural radionuclides. Hence, a study was done to assess the concentration of these radionuclides in rock samples. Coorg lies along the eastern slopes of Western Ghats, which is in the south western side of Karnataka state. The rock samples were collected from different locations of Coorg. The samples were crushed, ovendried and sieved through 240µm sieve. The sieved samples were sealed in a plastic container of 300ml and stored for 30 days

  3. Waste/Rock Interactions Technology Program: the status of radionuclide sorption-desorption studies performed by the WRIT program

    International Nuclear Information System (INIS)

    Serne, R.J.; Relyea, J.F.

    1982-04-01

    The most credible means for radionuclides disposed as solid wastes in deep-geologic repositories to reach the biosphere is through dissolution of the solid waste and subsequent radionuclide transport by circulating ground water. Thus safety assessment activities must consider the physicochemical interactions between radionculides present in ground water with package components, rocks and sediments since these processes can significantly delay or constrain the mass transport of radionuclides in comparison to ground-water movement. This paper focuses on interactions between dissolved radiouclides in ground water and rocks and sediments away from the near-field repository. The primary mechanism discussed is adsorption-desorption, which has been studied using two approaches. Empirical studies of adsorption-desorption rely on distribution coefficient measurements while mechanism studies strive to identify, differentiate and quantify the processes that control nuclide retardation

  4. Experimental study of dielectric characteristics of rocks in a high-frequency field

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, S.

    1982-01-01

    Dielectric permeability (epsilon) as an electrical property of rocks has been used in recent years as the new parameter of well logging. Consequently a study was made of the dependence of epsilon of rocks on different factors. It was found that epsilon of rocks depends not only on minerals contained in them, their properties and distribution, but also on the frequency of the field, temperature and content of the mineralized water in the bed. It was indicated that for sedimentary rocks with low content of clay, their epsilon depends mainly on the content of water, and between epsilon and water saturation there is an approximately rectilinear relationship. The epsilon of dry and wet rocks differs 3-5-fold, so that with the help of epsilon one can determine flooding of the bed. Since epsilon increases with a rise in the content of clay in the rocks, with dielectric logging of the flooded bed it is necessary to make the corresponding correction. Under conditions of frequency of the field 60 Mz, epsilon in the NaCl solution decreases with an increase in mineralization, but the epsilon of the soda-containing rocks increases with an increase in mineralization. However, with mineralization less than 1 x 10/sup -2/, its influence on epsilon does not exceed 10%. The epsilon of water containing rocks diminishes with a rise in temperature. In addition, the epsilon of rocks drops with an increase in field frequency. With an increase in frequency, there is a decrease in influence of different factors (mineralization, distribution of minerals, content of clay, etc.) on the epsilon of rocks. At high frequencies, a distinct relationship is observed only between the epsilon and the water content of the rocks. Consequently it is expedient to improve the frequency of measurement to reveal the flooded beds. According to the data of dispersion of epsilon with different frequencies, one can determine the content of quality of the bed using electromagnetic logging.

  5. Coupled thermo-hydro-mechanical calculations of the water saturation phase of a KBS-3 deposition hole. Influence of hydraulic rock properties on the water saturation phase

    International Nuclear Information System (INIS)

    Boergesson, Lennart; Hernelind, J.

    1999-12-01

    The wetting process in deposition holes designed according to the KBS-3-concept has been simulated with finite element calculations of the thermo-hydro-mechanical processes in the buffer, backfill and surrounding rock. The buffer material has been modelled according to the preliminary material models developed for swelling clay. The properties of the rock have been varied in order to investigate the influence of the rock properties and the hydraulic conditions on the wetting processes. In the modelling of the test holes the permeability of the rock matrix, the water supply from the backfill, the water pressure in the surrounding rock, the permeability of the disturbed zone around the deposition hole, the water retention properties of the rock, and the transmissivity of two fractures intersecting the deposition hole have been varied. The calculations indicate that the wetting takes about 5 years if the water pressure in the rock is high and if the permeability of the rock is so high that the properties of the bentonite determine the wetting rate. However, it may take considerably more than 30 years if the rock is very tight and the water pressure in the rock is low. The calculations also show that the influence of the rock structure is rather large except for the influence of the transmissivity T of the fractures, which turned out to be insignificant for the values used in the calculations

  6. Influence of scale-dependent fracture intensity on block size distribution and rock slope failure mechanisms in a DFN framework

    Science.gov (United States)

    Agliardi, Federico; Galletti, Laura; Riva, Federico; Zanchi, Andrea; Crosta, Giovanni B.

    2017-04-01

    An accurate characterization of the geometry and intensity of discontinuities in a rock mass is key to assess block size distribution and degree of freedom. These are the main controls on the magnitude and mechanisms of rock slope instabilities (structurally-controlled, step-path or mass failures) and rock mass strength and deformability. Nevertheless, the use of over-simplified discontinuity characterization approaches, unable to capture the stochastic nature of discontinuity features, often hampers a correct identification of dominant rock mass behaviour. Discrete Fracture Network (DFN) modelling tools have provided new opportunities to overcome these caveats. Nevertheless, their ability to provide a representative picture of reality strongly depends on the quality and scale of field data collection. Here we used DFN modelling with FracmanTM to investigate the influence of fracture intensity, characterized on different scales and with different techniques, on the geometry and size distribution of generated blocks, in a rock slope stability perspective. We focused on a test site near Lecco (Southern Alps, Italy), where 600 m high cliffs in thickly-bedded limestones folded at the slope scale impend on the Lake Como. We characterized the 3D slope geometry by Structure-from-Motion photogrammetry (range: 150-1500m; point cloud density > 50 pts/m2). Since the nature and attributes of discontinuities are controlled by brittle failure processes associated to large-scale folding, we performed a field characterization of meso-structural features (faults and related kinematics, vein and joint associations) in different fold domains. We characterized the discontinuity populations identified by structural geology on different spatial scales ranging from outcrops (field surveys and photo-mapping) to large slope sectors (point cloud and photo-mapping). For each sampling domain, we characterized discontinuity orientation statistics and performed fracture mapping and circular

  7. The quantitative studies on gas explosion suppression by an inert rock dust deposit.

    Science.gov (United States)

    Song, Yifan; Zhang, Qi

    2018-07-05

    The traditional defence against propagating gas explosions is the application of dry rock dust, but not much quantitative study on explosion suppression of rock dust has been made. Based on the theories of fluid dynamics and combustion, a simulated study on the propagation of premixed gas explosion suppressed by deposited inert rock dust layer is carried out. The characteristics of the explosion field (overpressure, temperature, flame speed and combustion rate) at different deposited rock dust amounts are investigated. The flame in the pipeline cannot be extinguished when the deposited rock dust amount is less than 12 kg/m 3 . The effects of suppressing gas explosion become weak when the deposited rock dust amount is greater than 45 kg/m 3 . The overpressure decreases with the increase of the deposited rock dust amounts in the range of 18-36 kg/m 3 and the flame speed and the flame length show the same trends. When the deposited rock dust amount is 36 kg/m 3 , the overpressure can be reduced by 40%, the peak flame speed by 50%, and the flame length by 42% respectively, compared with those of the gas explosion of stoichiometric mixture. In this model, the effective raised dust concentrations to suppress explosion are 2.5-3.5 kg/m 3 . Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Study on flow and mass transport through fractured sedimentary rocks (2)

    International Nuclear Information System (INIS)

    Shimo, Michito; Kumamoto, Sou; Karasaki, Kenzi; Sato, Hisashi; Sawada, Atsushi

    2009-03-01

    It is important for safety assessment of HLW geological disposal to understand hydro-geological conditions at the investigation area, and to evaluate groundwater flow and mass transport model and parameters, at each investigation phase. Traditionally, for Neogene sedimentary rock, the grain spacing of sediments has been considered as the dominant migration path. However, fractures of sedimentary rock could act as dominant paths, although they were soft sedimentary rocks. In this study, as part of developing groundwater flow and mass transport evaluation methodologies of such a fractured sedimentary rock' distributed area, we conducted two different scale of studies; 1) core rock sample scale and 2) several kilometer scale. For the core rock sample scale, some of laboratory hydraulic and tracer experiments have conducted using the rock cores with tailored parallel fracture, obtained at pilot borehole drilled in the vicinity of ventilation shaft. From the test results, hydraulic conductivity, diffusion coefficient, transport aperture, dispersion length and etc. was evaluated. Based on these test results, the influence of these parameters onto mass transport behavior of fractures sedimentary rocks was examined. For larger scale, such as several kilometer scale, the regional scale groundwater flow was examined using temperature data observed along the boreholes at Horonobe site. The results show that the low permeable zone between the boreholes might be estimated. (author)

  9. Tests of Rock Cores Scott Study Area, Missouri

    Science.gov (United States)

    1970-05-01

    little potassium feldspar is present in these cores. The bulk composition of this rock is quartz, plagio - clase feldspar (near oligoclase), chlorite...rhyolite porphyry, containing quartz and equal amounts of potassium and plagio - clase feldspar. Piece 22 of PC-2 (Figure 4.8) and Piece 22 of DC-5 (Figure...representative of this type. The bulk composition was Plagio - clase, orthoclase, quartz, biotite, and chlorite. About one-third of the pieces of the core

  10. The Ypresian clays as alternative host rock for radioactive waste disposal in Belgium. A transferability study

    International Nuclear Information System (INIS)

    Van Baelen, Herve; Wouters, Laurent; Brassinnes, Stephane; Van Geet, Maarten; Vandenberghe, Noel

    2012-01-01

    adaptations to the current design might be necessary due to the dissimilarities with Boom Clay. From our analysis of the available data, it is remarkable that for a number of parameters, the Ypresian clays appear to be less homogeneous than Boom Clay. Therefore special research efforts will be needed to get a hold on this spatial variability. Additionally, there are indications that the precision and accuracy of measurements are low for some of the parameters, which might explain a part of the heterogeneity observed. This seems to be the case for the pore-water chemistry, which will, given the impact it might have on corrosion, the durability of cementitious phases and the retention mechanisms within the host rock, be one of the major issues in future research and one of the reasons to adapt the design. Another important issue to be studied specifically for the Ypresian clays will be its mechanical behaviour at the conditions prevailing at excavation, exploitation and after closure of the disposal system. This might again, in the light of feasibility as well as safety issues, have an impact on the design. Apart from these major research questions arising from dissimilarities between both potential host rocks, a number of research questions are host-rock independent or can, at this stage of research, be treated as similar or followed-up by small-scale studies, because of comparable host rock properties. On the basis of the current knowledge it is concluded that the Ypresian clays remain a valuable alternative to Boom Clay as potential host rock for the geological disposal of high-level and/or long-lived radioactive waste

  11. Interpretation of stress measurements around mining cavities in rock salt - a finite-element study

    International Nuclear Information System (INIS)

    Heusermann, S.

    1986-01-01

    Finite-element studies of stress measurements using the overcoring method and of large drift fields in rock salt show that the measurements are affected by local stress relaxation occurring near the test borehole and by general time-dependent stress redistribution in the marginal zones of adjacent drifts. Analysis of the overcoring method indicates that the following local effects have to be considered in the interpretation of the test results as opposed to measurements in elastic rock: The inelastic deformation behaviour of rock salt causes stress relaxation at the pilot borehole which can lead to an underestimation of the actual stress state in rock. During overcoring considerable inelastic deformations occur in rock salt which demand a modified interpretation of the measurements and as a result of stress relaxation at the borehole various tests conditions, such as overcoring diameter, pilot borehole diameter and time between drilling and overcoring, have an effect on the test results. (orig./PW)

  12. Study of the method to estimate the hydraulic characteristics in rock masses by using elastic wave

    International Nuclear Information System (INIS)

    Katsu, Kenta; Ohnishi, Yuzo; Nishiyama, Satoshi; Yano, Takao; Ando, Kenichi; Yoshimura, Kimitaka

    2008-01-01

    In the area of radioactive waste repository, estimating radionuclide migration through the rock mass is an important factor for assessment of the repository. The purpose of this study is to develop a method to estimate hydraulic characteristics of rock masses by using elastic wave velocity dispersion. This method is based on dynamics poroelastic relations such as Biot and BISQ theories. These theories indicate relations between velocity dispersion and hydraulic characteristics. In order to verify the validity of these theories in crystalline rocks, we performed laboratory experiments. The results of experiments show the dependency of elastic wave velocity on its frequency. To test the applicability of this method to real rock masses, we performed in-situ experiment for tuff rock masses. The results of in-situ experiment show the possibility as a practical method to estimate the hydraulic characteristics by using elastic wave velocity dispersion. (author)

  13. Role of HHM coupling mechanisms on the evolution of rock masses around nuclear waste disposals in the context of gas generation

    International Nuclear Information System (INIS)

    Hoxha, D.; Do, D.-P.; Wendling, J.; Poutrel, A.

    2010-01-01

    Document available in extended abstract form only. This paper aims at modelling of long term evolution of hydro-mechanical state of rock masses around sealing nuclear waste disposals. In the principles of nuclear waste disposals the geological barrier must play a long term confining role in respect with nuclide transport. In terms of hydro-mechanical properties this calls for managing the damage around the underground workings of the waste disposals. In particular the seal buffers and barrier rock will support the generation of hydrogen of different origins, mainly from the corrosion of steals used in various elements of a nuclear waste disposal. This generation would generate gas pressures sufficiently high to partially dry seal or barrier rock leading to a redistribution of stress around underground openings, to a reactivation of the rock damage and finally could put in question the concept of geological barrier itself. The object of this paper is to shed light in the mechanisms of HHM coupling in rocks around a repository by comparative numerical analyses. Basically, we chose two configurations to proceed with analyses: one in plan strain conditions and the other an axial symmetric configuration. The goal of the first configuration is the assessment of gas pressure evolution in the openings of a repository. The principal input of the problem is the kinetics of gas generation (H 2 generation) given by a step-wise function of time describing the gas generation of one single nuclear waste coli. Then known the repository architecture one could easily calculate the mass of gas generated on one access gallery. Since extreme scenario is studied, we suppose that the gas generated by the set of alveoli is fully located in the access gallery and only a radial gas flux is possible.The hydro mechanical properties of rocks up to the surface were taken into account. For the callovo-Oxfordian clay that constitutes barrier rock in immediate neighbouring of the gallery a model

  14. The rock art of Mwana wa Chentcherere II rock shelter, Malawi : a site-specific study of girls' initiation rock art

    NARCIS (Netherlands)

    Zubieta, L.F.

    2006-01-01

    Mwana wa Chentcherere II, or Chentcherere Rock Shelter II, the name by which it was more generally known when it was excavated in 1972, is one of the largest rock painting sites in Malawi. It has been a national monument since 1972 and has been the subject of extensive archaeological research. This

  15. Study on characteristics of sedimentary rock at the Horonobe site. Report of collaboration research between CRIEPI and JAEA

    International Nuclear Information System (INIS)

    Kiho, Kenzo; Oyama, Takahiro; Suzuki, Koichi; Nakata, Eiji; Tanaka, Shiro; Miyakawa, Kimio; Ishii, Eiichi; Takahashi, Kazuharu; Kunimaru, Takanori; Tsukui, Rota; Fukushima, Tatsuo; Seya, Masami; Hama, Katsuhiro; Aoki, Kazuhiro

    2006-01-01

    CRIEPI (Central Research Institute of Electric Power Industry) and JAEA (Japan Atomic Energy Agency) have been conducting a collaboration research to develop methodology for the characterization of geological environment since FY 2002. This report describes the results of the collaboration research in mainly FY 2003. As the collaboration research, the following research results were obtained. (1) Study on the diagenesis of the sedimentary rock of the Noegene Tertiary. The maximum burial depth of the formation can be estimated. (2) Study on the chemical weathering of the soft sedimentary rock. The acidic water can be caused by the chemical weathering of the rock in the Koetoi formation. (3) Study on the pore water extraction. The hydrochemical condition at the Horonobe site can be estimated by the results of the chemical analyses of extracted pore water, and the different pressure of the extraction results the different chloride contents of the pore water. (4) Study on exploration method considering the physical property of the rock. The depth profile of the mechanical properties can be estimated by the results of physical logging in the borehole. (5) Study on the applicability of the controlled drilling system to the Horonobe site. The controlled drilling system can be applicable to drill the directional borehole. (author)

  16. Study on crystalline rock aiming at evaluation method of long-term behavior of rock mass (Joint research)

    International Nuclear Information System (INIS)

    Fukui, Katsunori; Hashiba, Kimihiro; Matsui, Hiroya

    2017-11-01

    It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior such as creep and stress relaxation. Therefore, development of methodology to evaluate the past long-term behavior of rock mass is considered to be an issue. In view of above points, this study has been started as a collaboration study with the University of Tokyo from Fiscal Year 2016. In FY 2016, creep testing on Tage tuff was continuously conducted. Existing theory of rate process and stochastic process was modified to be applied to evaluate effects of water, and then the modified theory was validated based on the results of strength and creep tests performed under dry and wet conditions. Furthermore, effects of water contents on stress-strain curves were examined by uniaxial compression testing under various water content conditions. (author)

  17. Experimental studies of the deformation of carbonated rocks by dissolution crystallization under stress

    International Nuclear Information System (INIS)

    Zubtsov, Sergey

    2003-01-01

    The first part of this research thesis reports the experimental investigation and the modelling of the deformation of poly-mineral rocks under the influence of mechanism of dissolution-crystallization under stress. This mechanism has a significant role in the compaction of sedimentary rocks, in the folding process of the earth's crust. The author notably reports the results of the experimental deformation of calcite in presence of water (calcite is present in marls in which the deposit of nuclear wastes in planned in France). The second part deals with the fact that healing is possible between two grains of similar mineralogy, and slows down or even stops deformation

  18. Nanoscale Properties of Rocks and Subduction Zone Rheology: Inferences for the Mechanisms of Deep Earthquakes

    Science.gov (United States)

    Riedel, M. R.

    2007-12-01

    Grain boundaries are the key for the understanding of mineral reaction kinetics. More generally, nanometer scale processes involved in breaking and establishing bonds at reaction sites determine how and at which rate bulk rock properties change in response to external tectonic forcing and possibly feed back into various geodynamic processes. A particular problem is the effects of grain-boundary energy on the kinetics of the olivine-spinel phase transformation in subducting slabs. Slab rheology is affected in many ways by this (metastable) mineral phase change. Sluggish kinetics due to metastable hindrance is likely to cause particular difficulties, because of possible strong non-linear feedback loops between strain-rate and change of creep properties during transformation. In order to get these nanoscale properties included into thermo-mechanical models, reliable kinetic data is required. The measurement of grain-boundary energies is, however, a rather difficult problem. Conventional methods of grain boundary surface tension measurement include (a) equilibrium angles at triple junction (b) rotating ball method (c) thermal groove method, and others (Gottstein & Shvindlerman, 1999). Here I suggest a new method that allows for the derivation of grain-boundary energies for an isochemical phase transformation based on experimental (in-situ) kinetic data in combination with a corresponding dynamic scaling law (Riedel and Karato, 1997). The application of this method to the olivine-spinel phase transformation in subducting slabs provides a solution to the extrapolation problem of measured kinetic data: Any kinetic phase boundary measured at the laboratory time scale can be "scaled" to the correct critical isotherm at subduction zones, under experimentelly "forbidden" conditions (Liou et al., 2000). Consequences for the metastability hypothesis that relates deep seismicity with olivine metastability are derived and discussed. References: Gottstein G, Shvindlerman LS (1999

  19. Detailed rock failure susceptibility mapping in steep rocky coasts by means of non-contact geostructural surveys: the case study of the Tigullio Gulf (Eastern Liguria, Northern Italy

    Directory of Open Access Journals (Sweden)

    P. De Vita

    2012-04-01

    Full Text Available In this study, an engineering geological analysis for the assessment of the rock failure susceptibility of a high, steep, rocky coast was developed by means of non-contact geostructural surveys. The methodology was applied to a 6-km coastal cliff located in the Gulf of Tigullio (Northern Tyrrhenian Sea between Rapallo and Chiavari.

    The method is based on the geostructural characterisation of outcropping rock masses through meso- and macroscale stereoscopic analyses of digital photos that were taken continuously from a known distance from the coastline. The results of the method were verified through direct surveys of accessible sample areas. The rock failure susceptibility of the coastal sector was assessed by analysing the fundamental rock slope mechanisms of instability and the results were implemented into a Geographic Information System (GIS.

    The proposed method is useful for rock failure susceptibility assessments in high, steep, rocky coastal areas, where accessibility is limited due to cliffs or steep slopes. Moreover, the method can be applied to private properties or any other area where a complete and systematic analysis of rock mass structural features cannot be achieved.

    Compared to direct surveys and to other non-contact methods based on digital terrestrial photogrammetry, the proposed procedure provided good quality data of the structural features of the rock mass at a low cost. Therefore, the method could be applied to similar coastal areas with a high risk of rock failure occurrence.

  20. Qualitative evaluation of various models for mechanical analysis of nuclear wastes storage in brittle rocks

    International Nuclear Information System (INIS)

    Millard, A.

    1994-01-01

    In order to appraise the large scale behaviour of high level nuclear wastes underground repositories in brittle rocks, basic models are presented and evaluated in the case of generic repository configurations. Predictive Capabilities of the models are briefly discussed. 7 figs

  1. X-ray Micro Tomography as a Tool for Studying Localized Damage / Deformation in Clay Rock

    International Nuclear Information System (INIS)

    Viggiani, Gioacchino; Besuelle, Pierre; Desrues, Jacques

    2013-01-01

    Deformation in geo-materials (soils, rocks, concrete, etc.) is often localized, e.g., in the form of shear bands or fractures. In experimental analysis of the mechanical behavior of such materials, standard laboratory methods are insufficient as the majority of measurements are made at the sample scale and rarely at a local scale. X-ray tomography monitoring during loading allows high-resolution full-field observation of the development of deformation. However, such images only indicate clearly the de-formation when there are significant changes in material density (i.e., volume changes) that produce a change in x-ray absorption. As such 3D Digital Image Correlation (DIC) approaches have been developed that allow quantification of the full strain tensor field throughout the imaged volume. This paper presents results from triaxial compression tests on a clay rock (Callovo-Oxfordian argillite) with in situ synchrotron x-ray micro tomography imaging providing complete 3D images of the specimen at several stages throughout the test. These images have been analyzed using 3D DIC to provide full-field displacement and strain measurements, which allowed the detection of the onset of strain localization and its timing relative to the load peak plus insight into the 3D structure of the localized zone. The paper concludes with a few general remarks concerning the lessons learned from this study and perspectives for current and future work. (authors)

  2. Study on dynamic behavior of a shaft excavation through a faulted crystalline rock mass

    International Nuclear Information System (INIS)

    Hashizume, Shigeru; Matsui, Hiroya; Horiuchi, Yasuharu; Hata, Koji; Akiyoshi, Kenji; Sato, Shin; Shibata, Chihoko; Niunoya, Sumio; Noda, Masaru

    2013-01-01

    The 'Mizunami Underground Research Laboratory' has been studying and developing engineering technology for deep underground applications. These applications are multifaceted and are categorized as development of design and construction planning technology, development construction technology, development of countermeasure technology, and development of technology for construction and operation security. In this report, the dynamic behavior of shaft and the surrounding rock mass has been studied with respect to rock mass displacement and stress, the effect of using a concrete liner and excavating through faulted crystalline rock. (author)

  3. Experimental Study of Bilinear Initiating System Based on Hard Rock Pile Blasting

    Directory of Open Access Journals (Sweden)

    Yusong Miao

    2017-01-01

    Full Text Available It is difficult to use industrial explosives to excavate hard rock and achieve suitable blasting effect due to the low energy utilization rate resulting in large rocks and short blasting footage. Thus, improving the utilization ratio of the explosive energy is important. In this study, a novel bilinear initiation system based on hard rock blasting was proposed to improve the blasting effects. Furthermore, on the basis of the detonation wave collision theory, frontal collision, oblique reflection, and Mach reflection during detonation wave propagation were studied. The results show that the maximum detonation pressure at the Mach reflection point where the incident angle is 46.9° is three times larger than the value of the explosive complete detonation. Then, in order to analyze the crack propagation in different initiation forms, a rock fracture test slot was designed, and the results show that bilinear initiating system can change the energy distribution of explosives. Finally, field experiment was implemented at the hard rock pile blasting engineering, and experimental results show that the present system possesses high explosive energy utilization ratio and low rock fragments size. The results of this study can be used to improve the efficiency in hard rock blasting.

  4. Study on epigenetic alterations of ore-enclosing sedimentary rocks

    International Nuclear Information System (INIS)

    Kondrat'eva, I.A.; Komarova, G.V.

    1985-01-01

    Epigenetic alterations of sedimentary rocks under effect of exogenous undeground waters of various types: near-surface, ground, stratum, and deep circulation waters, are considered. Association to postsedimentary tectonic structures, confinement of neogenesis to areas of high permeability (porous or crack one), geochemical contradictions between mineral neogenis and facial outlook of deposits, noncoincidence of variability gradient of authigenous mineral associations with variability of primary facial signs of deposits, regular position of mineral formations and ore concentrations in epigenetic mineralogo-geochemical zonation are referred to epigenetic criteria. The complex of epigenetic alterations accompanying mineralization is frequently used as a search sign of uranium deposit of a certain type

  5. A Micromechanics-Based Elastoplastic Damage Model for Rocks with a Brittle-Ductile Transition in Mechanical Response

    Science.gov (United States)

    Hu, Kun; Zhu, Qi-zhi; Chen, Liang; Shao, Jian-fu; Liu, Jian

    2018-06-01

    As confining pressure increases, crystalline rocks of moderate porosity usually undergo a transition in failure mode from localized brittle fracture to diffused damage and ductile failure. This transition has been widely reported experimentally for several decades; however, satisfactory modeling is still lacking. The present paper aims at modeling the brittle-ductile transition process of rocks under conventional triaxial compression. Based on quantitative analyses of experimental results, it is found that there is a quite satisfactory linearity between the axial inelastic strain at failure and the confining pressure prescribed. A micromechanics-based frictional damage model is then formulated using an associated plastic flow rule and a strain energy release rate-based damage criterion. The analytical solution to the strong plasticity-damage coupling problem is provided and applied to simulate the nonlinear mechanical behaviors of Tennessee marble, Indiana limestone and Jinping marble, each presenting a brittle-ductile transition in stress-strain curves.

  6. Interaction between rock, bentonite buffer and canister. FEM calculations of some mechanical effects on the canister in different disposal concepts

    International Nuclear Information System (INIS)

    Boergesson, L.

    1992-07-01

    An important task of the buffer of highly compacted bentonite is to offer a mechanical protection to the canister. This role has been investigated by a number of finite element calculations using the complex elasto plastic material models for the bentonite that have been developed on the basis of laboratory tests and adapted to the code ABAQUS. The following main functions and scenarios have been investigated for some different canister types and repository concepts: - The effect of the water and swelling pressure, - The effect of a rock shear perpendicular to the canister axis, - The effect of creep in the copper after a rock shear displacement, - The thermomechanical effects when an initially saturated buffer is used

  7. An experimental study of the nonlinear dynamic phenomenon known as wing rock

    Science.gov (United States)

    Arena, A. S., Jr.; Nelson, R. C.; Schiff, L. B.

    1990-01-01

    An experimental investigation into the physical phenomena associated with limit cycle wing rock on slender delta wings has been conducted. The model used was a slender flat plate delta wing with 80-deg leading edge sweep. The investigation concentrated on three main areas: motion characteristics obtained from time history plots, static and dynamic flow visualization of vortex position, and static and dynamic flow visualization of vortex breakdown. The flow visualization studies are correlated with model motion to determine the relationship between vortex position and vortex breakdown with the dynamic rolling moments. Dynamic roll moment coefficient curves reveal rate-dependent hysteresis, which drives the motion. Vortex position correlated with time and model motion show a time lag in the normal position of the upward moving wing vortex. This time lag may be the mechanism responsible for the hysteresis. Vortex breakdown is shown to have a damping effect on the motion.

  8. Rock cliffs hazard analysis based on remote geostructural surveys: The Campione del Garda case study (Lake Garda, Northern Italy)

    Science.gov (United States)

    Ferrero, A. M.; Migliazza, M.; Roncella, R.; Segalini, A.

    2011-02-01

    The town of Campione del Garda (located on the west coast of Lake Garda) and its access road have been historically subject to rockfall phenomena with risk for public security in several areas of the coast. This paper presents a study devoted to the determination of risk for coastal cliffs and the design of mitigation measures. Our study was based on statistical rockfall analysis performed with a commercial code and on stability analysis of rock slopes based on the key block method. Hazard from block kinematics and rock-slope failure are coupled by applying the Rockfall Hazard Assessment Procedure (RHAP). Because of the huge dimensions of the slope, its morphology and the geostructural survey were particularly complicated and demanding. For these reasons, noncontact measurement methods, based on aerial photogrammetry by helicopter, were adopted. A special software program, developed by the authors, was applied for discontinuity identification and for their orientation measurements. The potentially of aerial photogrammetic survey in rock mechanic application and its improvement in the rock mass knowledge is analysed in the article.

  9. Studies of electrical properties of low-resistivity sandstones based on digital rock technology

    Science.gov (United States)

    Yan, Weichao; Sun, Jianmeng; Zhang, Jinyan; Yuan, Weiguo; Zhang, Li; Cui, Likai; Dong, Huaimin

    2018-02-01

    Electrical properties are important parameters to quantitatively calculate water saturation in oil and gas reservoirs by well logging interpretation. It is usual that oil layers show high resistivity responses, while water layers show low-resistivity responses. However, there are low-resistivity oil zones that exist in many oilfields around the world, leading to difficulties for reservoir evaluation. In our research, we used digital rock technology to study different internal and external factors to account for low rock resistivity responses in oil layers. We first constructed three-dimensional digital rock models with five components based on micro-computed tomography technology and x-ray diffraction experimental results, and then oil and water distributions in pores were determined by the pore morphology method. When the resistivity of each component was assigned, rock resistivities were calculated by using the finite element method. We collected 20 sandstone samples to prove the effectiveness of our numerical simulation methods. Based on the control variate method, we studied the effects of different factors on the resistivity indexes and rock resistivities. After sensitivity analyses, we found the main factors which caused low rock resistivities in oil layers. For unfractured rocks, influential factors arranged in descending order of importance were porosity, clay content, temperature, water salinity, heavy mineral, clay type and wettability. In addition, we found that the resistivity index could not provide enough information to identify a low-resistivity oil zone by using laboratory rock-electric experimental results. These results can not only expand our understandings of the electrical properties of low-resistivity rocks from oil layers, but also help identify low-resistivity oil zones better.

  10. EXPERIMENTAL STUDY OF DECOMPRESSION, PERMEABILITY AND HEALING OF SILICATE ROCKS IN FAULT ZONES

    Directory of Open Access Journals (Sweden)

    V. Ya. Medvedev

    2014-01-01

    Full Text Available The article presents results of petrophysical laboratory experiments in studies of decompression phenomena associated with consequences of abrupt displacements in fault zones. Decompression was studied in cases of controlled pressure drop that caused sharp changes of porosity and permeability parameters, and impacts of such decompression were analyzed. Healing of fractured-porous medium by newly formed phases was studied. After experiments with decompression, healing of fractures and pores in silicate rock samples (3×2×2 cm, 500 °C, 100 MPa took about 800–1000 hours, and strength of such rocks was restored to 0.6–0.7 of the original value. In nature, fracture healing is influenced by a variety of factors, such as size of discontinuities in rock masses, pressure and temperature conditions, pressure drop gradients, rock composition and saturation with fluid. Impacts of such factors are reviewed.

  11. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion

    Czech Academy of Sciences Publication Activity Database

    Slavík, M.; Bruthans, J.; Filippi, Michal; Schweigstillová, Jana; Falteisek, L.; Řihošek, J.

    2017-01-01

    Roč. 278, FEB 1 (2017), s. 298-313 ISSN 0169-555X R&D Projects: GA ČR GA13-28040S; GA ČR(CZ) GA16-19459S Institutional support: RVO:67985831 ; RVO:67985891 Keywords : biofilm * biocrust * biologically-initiated rock crust * sandstone protection * case hardening Subject RIV: DB - Geology ; Mineralogy; DB - Geology ; Mineralogy (USMH-B) OBOR OECD: Geology; Geology (USMH-B) Impact factor: 2.958, year: 2016

  12. Rock mechanics research in the Coeur d'Alene mining district

    Energy Technology Data Exchange (ETDEWEB)

    Corp, E. L.

    1980-05-15

    Over the past 20 years, the Bureau of Mines and mining companies of the Coeur d'Alene district have conducted cooperative research on problems of ground control. For the past six years emphasis has been placed on research to improve deep shaft design and to control rock bursts during cut-and-fill stoping. Factors contributing to ground control problems include: depth of mining ranging to 8000 feet; local tectonic activity that in many instances has produced horizontal stresses exceeding the vertical; unequal horizontal stresses at ratios ranging between 1.25 and 2.73; major faults, joints, and bedding planes; and hard, brittle quartzite rock capable of concentrating high levels of stress. Finite-element modeling and construction of small-scale circular and rectangular test shafts have shown that circular openings are stable only when stresses are hydrostatic or weakly biaxial. Under a strongly-biaxial horizontal stress field, a rectangular shaft has a greater depth capabiity if its long axis can be oriented parallel to the major stress and normal to the bedding and joint system. Steel sets appear preferable to wood sets or concrete lining. Based on underground tests at Hecla's Star mine, destressing or preconditioning of the vein rock prior to mining was shown to be an effective means of controlling rock bursts. Drilling and shooting a radial pattern of longholes before stope mining starts has preconditioned or softened the vein material to the extent that seismic energy release during mining is reduced and no bursting occurred. Increased burst and seismic activity while mining above the preconditioned zone points out the need to precondition an entire stope block before mining.

  13. Technical summary of geological, hydrological, and engineering studies at the Slick Rock Uranium Mill Tailings sites, Slick Rock, Colorado

    International Nuclear Information System (INIS)

    1990-12-01

    The purpose of this document is to provide the Colorado Department of Health (CDH) with a summary of the technical aspects of the proposed remedial action for the Slick Rock tailings near Slick Rock, Colorado. The technical issues summarized in this document are the geology and groundwater at the Burro Canyon disposal site and preliminary engineering considerations for the disposal cell

  14. A transformation for predicting mechanical changes resulting from time-dependent microcracking in plutonic rock

    International Nuclear Information System (INIS)

    Heinrich, W.F.

    1987-01-01

    A transformation for a simple phenomenological model of microcracking is proposed. It relates the evolution of microcrack size in an elastic solid (plutonic rock) under different temporal macro- and microstresses. In this model, for a rock property that changes as a result of microcracking, both the calculated and the experimentally determined evolution of that property for a given stress history can be used to determine the evolution of that property (for the same range) for any other stress history. For example, the transformation can be used to extrapolate the short-term extent of microcracking due to thermally induced stresses to time scales too long for experimental determination. This is of interest in assessing the long-term behaviour of rock surrounding a high level nuclear waste vault, where thermally induced microcracking may take tens of thousands of years to develop. Experimental strategies are suggested for validation of the phenomenological model. Where results are obtained from the corresponding mathematical models, the transformation facilitates the efficient calculation of functions that depend only on the state of microcrack size once the functions have been calculated for any convenient stress history

  15. Rock mechanics research in the Coeur d'Alene mining district

    Energy Technology Data Exchange (ETDEWEB)

    Corp, E. L.

    1980-05-15

    Over the past 20 years, the Bureau of Mines and mining companies of the Coeur d'Alene district have conducted cooperative research on problems of ground control. For the past six years emphasis has been placed on research to improve deep shaft design and to control rock bursts during cut-and-fill stoping. Finite-element modeling and construction of small-scale circular and rectangular test shafts have shown that circular openings are stable only when stresses are hydrostatic or weakly biaxial. Under a strongly-biaxial horizontal stress field, a rectangular shaft has a greater depth capability if its long axis can be oriented parallel to the major stress and normal to the bedding and joint system. Steel sets appear preferable to wood sets or concrete lining. Based on underground tests at Hecla's Star mine, destressing or preconditioning of the vein rock prior to mining was shown to be an effective means of controlling rock bursts. Drilling and shooting a radial pattern of longholes before stope mining starts has preconditioned or softened the vein material to the extent that seismic energy release during mining is reduced and no bursting occurred. Increased burst and seismic activity while mining about the preconditioned zone points out the need to precondition an entire stope block before mining.

  16. Predicting Folding Sequences Based on the Maximum Rock Strength and Mechanical Equilibrium

    Science.gov (United States)

    Cubas, N.; Souloumiac, P.; Maillot, B.; Leroy, Y. M.

    2007-12-01

    The objective is to propose and validate simple procedures, compared to the finite-element method, to select and optimize the dominant mode of folding in fold-and-thrust belts and accretionary wedges, and to determine its stress distribution. Mechanical equilibrium as well as the constraints due to the limited rock strength of the bulk material and of major discontinuities, such as décollements, are accounted for. The first part of the proposed procedure, which is at the core of the external approach of classical limit analysis, consists in estimating the least upper bound on the tectonic force by minimisation of the internal dissipation and part of the external work. The new twist to the method is that the optimization is also done with respect to the geometry of the evolving fold. If several folding events are possible, the dominant mode is the one leading to the least upper bound. The second part of the procedure is based on the Equilibrium Element Method, which is an application of the internal approach of limit analysis. The optimum stress field, obtained by spatial discretisation of the fold, provides the best lower bound on the tectonic force. The difference between the two bounds defines an error estimate of the exact unknown tectonic force. To show the merits of the proposed procedure, its first part is applied to predict the life span of a thrust within an accretionary prism, from its onset, its development with a relief build up and its arrest because of the onset of a more favorable new thrust (Cubas et al., 2007). This life span is sensitive to the friction angles over the ramp and the décollement. It is shown how the normal sequence of thrusting in a supercritical wedge is ended with the first out-of sequence event. The second part of the procedure provides the stress state over each thrust showing that the active back thrust is a narrow fan which dip is sensitive to the friction angle over the ramp and the amount of relief build up (Souloumiac et

  17. Geophysical study in waste landfill localized above fractured rocks

    Directory of Open Access Journals (Sweden)

    Ariveltom Cosme da Silva

    2011-08-01

    Full Text Available Geophysical survey is an important method for investigation of contaminated areas used in the characterization of contrasting physical properties in the presence of pollutants. This work applied the geophysical methods of Electrical Resistivity and Self Potential in waste landfill, located in Caçapava do Sul city, RS. The landfill is located over fractured metamorphic rocks. Eight lines of electrical profiling with 288 measures of self potential were done. In addition, 83 measurements of direction and dip of fractures were taken. The application of spontaneous potential method permitted to detect the direction of groundwater flow. The electrical resistivity measurements allowed the identification of low-intensity anomalies associated with the presence of leachate. There is a relationship between anomalous zones and the directions of fractures.

  18. Assessment of dynamic material properties of intact rocks using seismic wave attenuation: an experimental study.

    Science.gov (United States)

    Wanniarachchi, W A M; Ranjith, P G; Perera, M S A; Rathnaweera, T D; Lyu, Q; Mahanta, B

    2017-10-01

    The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of reservoir rocks under different conditions. The attenuation characteristics of five different rock types, siltstone, shale, Australian sandstone, Indian sandstone and granite, were investigated in the laboratory using ultrasonic and acoustic emission instruments in a frequency range of 0.1-1 MHz. The pulse transmission technique and spectral ratios were used to calculate the attenuation coefficient ( α ) and quality factor ( Q ) values for the five selected rock types for both primary ( P ) and secondary ( S ) waves, relative to the reference steel sample. For all the rock types, the attenuation coefficient was linearly proportional to the frequency of both the P and S waves. Interestingly, the attenuation coefficient of granite is more than 22% higher than that of siltstone, sandstone and shale for both P and S waves. The P and S wave velocities were calculated based on their recorded travel time, and these velocities were then used to calculate the dynamic mechanical properties including elastic modulus ( E ), bulk modulus ( K ), shear modulus ( µ ) and Poisson's ratio ( ν ). The P and S wave velocities for the selected rock types varied in the ranges of 2.43-4.61 km s -1 and 1.43-2.41 km h -1 , respectively. Furthermore, it was observed that the P wave velocity was always greater than the S wave velocity, and this confirmed the first arrival of P waves to the sensor. According to the experimental results, the dynamic E value is generally higher than the static E value obtained by unconfined compressive strength tests.

  19. Performance characteristics of tunnel boring machine in basalt and pyroclastic rocks of Deccan traps – A case study

    Directory of Open Access Journals (Sweden)

    Prasnna Jain

    2014-02-01

    Full Text Available A 12.24 km long tunnel between Maroshi and Ruparel College is being excavated by tunnel boring machine (TBM to improve the water supply system of Greater Mumbai, India. In this paper, attempt has been made to establish the relationship between various litho-units of Deccan traps, stability of tunnel and TBM performances during the construction of 5.83 km long tunnel between Maroshi and Vakola. The Maroshi–Vakola tunnel passes under the Mumbai Airport and crosses both runways with an overburden cover of around 70 m. The tunneling work was carried out without disturbance to the ground. The rock types encountered during excavation are fine compacted basalt, porphyritic basalt, amygdaloidal basalt, pyroclastic rocks with layers of red boles and intertrappean beds consisting of various types of shales. Relations between rock mass properties, physico-mechanical properties, TBM specifications and the corresponding TBM performance were established. A number of support systems installed in the tunnel during excavation were also discussed. The aim of this paper is to establish, with appropriate accuracy, the nature of subsurface rock mass condition and to study how it will react to or behave during underground excavation by TBM. The experiences gained from this project will increase the ability to cope with unexpected ground conditions during tunneling using TBM.

  20. Control Mechanism of Rock Burst in the Floor of Roadway Driven along Next Goaf in Thick Coal Seam with Large Obliquity Angle in Deep Well

    Directory of Open Access Journals (Sweden)

    Yunhai Cheng

    2015-01-01

    Full Text Available This paper deals with the theoretical aspects combined with stress analysis over the floor strata of coal seam and the calculation model for the stress on the coal floor. Basically, this research presents the relevant results obtained for the rock burst prevention in the floor of roadway driven along next goaf in the exploitation of thick coal seam with large obliquity in deep well and rock burst tendency. The control mechanism of rock burst in the roadway driven along next goaf is revealed in the present work. That is, the danger of rock burst can be removed by changing the stress environment for the energy accumulation of the floor and by reducing the impact on the roadway floor from the strong dynamic pressure. This result can be profitable being used at the design stage of appropriate position of roadway undergoing rock burst tendency in similar conditions. Based on the analysis regarding the control mechanism, this paper presents a novel approach to the prevention of rock burst in roadway floor under the above conditions. That is, the return airway is placed within the goaf of the upper working face that can prevent the rock burst effectively. And in this way, mining without coal pillar in the thick coal seam with large obliquity and large burial depth (over a thousand meters is realized. Practice also proves that the rock burst in the floor of roadway driven along next goaf is controlled and solved.

  1. Multi-component observation in deep boreholes, and its applications to earthquake prediction research and rock mechanics

    International Nuclear Information System (INIS)

    Ishii, Hiroshi

    2014-01-01

    The Tono Research Institute of Earthquake Science (TRIES) has developed a multicomponent instrument that can be operated in deep boreholes (e.g., those one km in depth). It is equipped with stress meters, strain meters, tilt meters, seismometers, magnetometers, and thermometers; in addition, these sensors can be arbitrarily combined. The stress meters, which were developed recently, can observe stress and strain; in the future, data obtained from these sensors will offer new information on seismology and rock mechanics. The size of typical probe is 12 cm diameter 7.8 m total length and 290 kg total weight. It consists of many meters in tandem connection. (authors)

  2. Experimental simulation of the geological storage of CO2: particular study of the interfaces between well cement, cap-rock and reservoir rock

    International Nuclear Information System (INIS)

    Jobard, Emmanuel

    2013-01-01

    The geological storage of the CO 2 is envisaged to mitigate the anthropogenic greenhouse gas emissions in the short term. CO 2 is trapped from big emitters and is directly injected into a reservoir rock (mainly in deep salty aquifers, depleted hydrocarbon oil fields or unexploited charcoal lodes) located at more than 800 m deep. In the framework of the CO 2 storage, it is crucial to ensure the integrity of the solicited materials in order to guarantee the permanent confinement of the sequestrated fluids. Using experimental simulation the purpose of this work is to study the mechanisms which could be responsible for the system destabilization and could lead CO 2 leakage from the injection well. The experimental simulations are performed under pressure and temperature conditions of the geological storage (100 bar and from 80 to 100 deg. C). The first experimental model, called COTAGES (for 'Colonne Thermoregulee A Grains pour Gaz a Effet de Serre') allows studying the effects of the thermal destabilisation caused by the injection of a fluid at 25 deg. C in a hotter reservoir (submitted to the geothermal gradient). This device composed of an aqueous saline solution (4 g.L -1 of NaCl), crushed rock (Lavoux limestone or Callovo-Oxfordian argillite) and gas (N 2 or CO 2 ) allows demonstrating an important matter transfer from the cold area (30 deg. C) toward the hot area (100 deg. C). The observed dissolution/precipitation phenomena leading to changes of the petro-physical rocks properties occur in presence of N 2 or CO 2 but are significantly amplified by the presence of CO 2 . Concerning the experiments carried out with Lavoux limestone, the dissolution in the cold zone causes a raise of porosity of about 2% (initial porosity of 8%) due to the formation of about 500 pores/mm 2 with a size ranging between 10 and 100 μm 2 . The precipitation in the hot zone forms a micro-calcite fringe on the external part of the grains and fills the intergrain porosity

  3. THE STUDY OF GAS MIGRATION IN CRYSTALLINE ROCK USING INJECTION TESTS

    Directory of Open Access Journals (Sweden)

    Jiří Svoboda

    2012-07-01

    Full Text Available The study of gas migration in crystalline rock using injection tests is being carried out in the frame of the FORGE (Fate of Repository Gases project. The Czech Technical University in Prague (CTU, Centre of Experimental Geotechnics (CEG is participating in WP4 which is focused on disturbed host rock formations with respect to radioactive waste deep repositories. A series of in-situ tests is being conducted at the Josef Underground Laboratory. The aim of the testing is to simulate and study phenomena that might lead to gas-driven radionuclide transport in fractured crystalline rock. The in-situ tests combine migration and large-scale gas injection measurements; gas injection tests are being employed for the study of gas transport. For the purposes of comparison of the behaviour of the rock mass with regard to air and water a series of water pressure tests are also being carried out. The quality of the rock mass is assessed using rock mass classification systems.

  4. Inherent wettability of different rock surfaces at nanoscale: a theoretical study

    Science.gov (United States)

    Chang, Xiao; Xue, Qingzhong; Li, Xiaofang; Zhang, Jianqiang; Zhu, Lei; He, Daliang; Zheng, Haixia; Lu, Shuangfang; Liu, Zilong

    2018-03-01

    Investigating the inherent wettability of rock surfaces at nanoscale is of great importance in ore floatation and oil recovery field. Using molecular dynamics simulations, we systematically study the wetting behavior of water on different rock surfaces (silica, calcite, gypsum, halite and graphite) at nanoscale. It is demonstrated that the inherent rock wettability follows the order of gypsum > calcite > halite > silica > graphite. Remarkably, we also manifest that the polarity of oil molecules can affect the water contact angles on silica surface. For example, the water contact angles on silica surface in hexane, dodecane, thiophene and toluene are 58 ± 2°, 63 ± 3°, 90 ± 1°, 118 ± 1°, respectively. Furthermore, we investigate the wetting behavior of water on heterogeneous rock surfaces and find that water molecules can move from hydrophobic surface to hydrophilic surface.

  5. Study on structural plane characteristics of deep rock mass based on acoustic borehole TV

    International Nuclear Information System (INIS)

    Wang Xiyong; Su Rui; Chen Liang; Tian Xiao

    2014-01-01

    Deep rock mass structural plane characteristics are one of the basic data for evaluating the quality of rock mass. Based on acoustic borehole TV, the structural plane quantity, density, attitude, dominant set, structural plane aperture of deep rock mass in boreholes BS15 # and BS16 # located in Beishan granite rock mass of Gansu Province have been calculated and compared with the results of geological documentation of drill core. The results indicate that acoustic borehole TV has the effect in study on characteristics of structural plane. But as a kind of technique of geophysical logging, the acoustic borehole TV has certain defect, and need to combine with the analysis of the other geological materials in applications. (authors)

  6. Experimental study of polyurethane foam reinforced soil used as a rock-like material

    Directory of Open Access Journals (Sweden)

    Eren Komurlu

    2015-10-01

    Full Text Available In this study, polyurethane foam type thermoset polymerizing, due to chemical reaction between its liquid ingredients, was tested as binder after solidifying and then a rock-like material mixing with a sandy silt type soil was prepared. The uniaxial compressive strengths (UCSs of polyurethane foam reinforced soil specimens were determined for different polyurethane ratios in the mixture. Additionally, a series of tests on slake durability, impact value, freezing–thawing resistance, and abrasion resistance of polyurethane reinforced soil (PRS mixture was conducted. The UCS values over 3 MPa were measured from the PRS specimens. The testing results showed that treated soil can economically become a desirable rock-like material in terms of slake durability and resistances against freezing–thawing, impact effect and abrasion. As another characteristic of the rock-like material made with polyurethane foam, unit volume weight was found to be quite lower than those of natural rock materials.

  7. Prediction of Brittle Failure for TBM Tunnels in Anisotropic Rock: A Case Study from Northern Norway

    Science.gov (United States)

    Dammyr, Øyvind

    2016-06-01

    Prediction of spalling and rock burst is especially important for hard rock TBM tunneling, because failure can have larger impact than in a drill and blast tunnel and ultimately threaten excavation feasibility. The majority of research on brittle failure has focused on rock types with isotropic behavior. This paper gives a review of existing theory and its application before a 3.5-m-diameter TBM tunnel in foliated granitic gneiss is used as a case to study brittle failure characteristics of anisotropic rock. Important aspects that should be considered in order to predict brittle failure in anisotropic rock are highlighted. Foliation is responsible for considerable strength anisotropy and is believed to influence the preferred side of v-shaped notch development in the investigated tunnel. Prediction methods such as the semi- empirical criterion, the Hoek- Brown brittle parameters, and the non-linear damage initiation and spalling limit method give reliable results; but only as long as the angle between compression axis and foliation in uniaxial compressive tests is relevant, dependent on the relation between tunnel trend/plunge, strike/dip of foliation, and tunnel boundary stresses. It is further demonstrated that local in situ stress variations, for example, due to the presence of discontinuities, can have profound impact on failure predictions. Other carefully documented case studies into the brittle failure nature of rock, in particular anisotropic rock, are encouraged in order to expand the existing and relatively small database. This will be valuable for future TBM planning and construction stages in highly stressed brittle anisotropic rock.

  8. Study on natural radioactive elements in soil and rock samples around Mandya district, India

    International Nuclear Information System (INIS)

    Shivakumara, B.C.; Paramesh, L.; Shashikumar, T.S.; Chandrashekara, M.S.

    2012-01-01

    The soil is a complex mixture of different compounds and rocks. In the natural environment, it is an important source of exposure to radiation due to naturally occurring, gamma emitting radionuclides which include 226 Ra, 232 Th and 40 K present in the soil. The study of distribution of these radionuclides in soil and rock is of great importance for radiation protection and measurements. The activity concentrations of 226 Ra, 232 Th, and 40 K in soil and rock samples collected in Mandya District, Karnataka state, India have been measured by gamma ray spectrometry. The average activity concentrations of 226 Ra, 232 Th, and 40 K (Bq/kg) are found to be 40.2, 62.3, and 317.5 Bq/kg, respectively, in soil samples and 30.5, 34.4, and 700.2 Bq/kg, respectively, in rock samples. The concentrations of radionuclides in soil samples are found to higher than in rock samples. The concentrations of radionuclides in soil and rock samples in the study area are slightly higher than Indian average and world average values. (author)

  9. Water - rock interaction in different rock environments

    International Nuclear Information System (INIS)

    Lamminen, S.

    1995-01-01

    The study assesses the groundwater geochemistry and geological environment of 44 study sites for radioactive waste disposal. Initially, the study sites were divided by rock type into 5 groups: (1) acid - intermediate rocks, (2) mafic - ultramafic rocks, (3) gabbros, amphibolites and gneisses that contain calc-silicate (skarn) rocks, (4) carbonates and (5) sandstones. Separate assessments are made of acid - intermediate plutonic rocks and of a subgroup that comprises migmatites, granite and mica gneiss. These all belong to the group of acid - intermediate rocks. Within the mafic -ultramafic rock group, a subgroup that comprises mafic - ultramafic plutonic rocks, serpentinites, mafic - ultramafic volcanic rocks and volcanic - sedimentary schists is also evaluated separately. Bedrock groundwaters are classified by their concentration of total dissolved solids as fresh, brackish, saline, strongly saline and brine-class groundwaters. (75 refs., 24 figs., 3 tabs.)

  10. Hydrogeologic controls imposed by mechanical stratigraphy in layered rocks of the Chateauguay River Basin, a U.S.-Canada transborder aquifer

    Science.gov (United States)

    Morin, Roger H.; Godin, Rejean; Nastev, Miroslav; Rouleau, Alain

    2007-01-01

    [1] The Châteauguay River Basin delineates a transborder watershed with roughly half of its surface area located in northern New York State and half in southern Québec Province, Canada. As part of a multidisciplinary study designed to characterize the hydrogeologic properties of this basin, geophysical logs were obtained in 12 wells strategically located to penetrate the four major sedimentary rock formations that constitute the regional aquifers. The layered rocks were classified according to their elastic properties into three primary units: soft sandstone, hard sandstone, and dolostone. Downhole measurements were analyzed to identify fracture patterns associated with each unit and to evaluate their role in controlling groundwater flow. Fracture networks are composed of orthogonal sets of laterally extensive, subhorizontal bedding plane partings and bed-delimited, subvertical joints with spacings that are consistent with rock mechanics principles and stress models. The vertical distribution of transmissive zones is confined to a few select bedding plane fractures, with soft sandstone having the fewest (one per 70-m depth) and hard sandstone the most (five per 70-m depth). Bed-normal permeability is examined using a probabilistic model that considers the lengths of flow paths winding along joints and bedding plane fractures. Soft sandstone has the smallest bed-normal permeability primarily because of its wide, geomechanically undersaturated joint spacing. Results indicate that the three formations have similar values of bulk transmissivity, within roughly an order of magnitude, but that each rock unit has its own unique system of groundwater flow paths that constitute that transmissivity.

  11. VISCOT: a two-dimensional and axisymmetric nonlinear transient thermoviscoelastic and thermoviscoplastic finite-element code for modeling time-dependent viscous mechanical behavior of a rock mass

    International Nuclear Information System (INIS)

    1983-04-01

    VISCOT is a non-linear, transient, thermal-stress finite-element code designed to determine the viscoelastic, fiscoplastic, or elastoplastic deformation of a rock mass due to mechanical and thermal loading. The numerical solution of the nonlinear incremental equilibrium equations within VISCOT is performed by using an explicit Euler time-stepping scheme. The rock mass may be modeled as a viscoplastic or viscoelastic material. The viscoplastic material model can be described by a Tresca, von Mises, Drucker-Prager or Mohr-Coulomb yield criteria (with or without strain hardening) with an associated flow rule which can be a power or an exponential law. The viscoelastic material model within VISCOT is a temperature- and stress-dependent law which has been developed specifically for salt rock masses by Pfeifle, Mellegard and Senseny in ONWI-314 topical report (1981). Site specific parameters for this creep law at the Richton, Permian, Paradox and Vacherie salt sites have been calculated and are given in ONWI-314 topical report (1981). A major application of VISCOT (in conjunction with a SCEPTER heat transfer code such as DOT) is the thermomechanical analysis of a rock mass such as salt in which significant time-dependent nonlinear deformations are expected to occur. Such problems include room- and canister-scale studies during the excavation, operation, and long-term post-closure stages in a salt repository. In Section 1.5 of this document the code custodianship and control is described along with the status of verification, validation and peer review of this report

  12. Mechanical behavior of New Mexico rock salt in triaxial compression up to 2000C

    International Nuclear Information System (INIS)

    Wawersik, W.R.; Hannum, D.W.

    1979-07-01

    Three groups of tests are discussed to identify the relative and site-specific importance of deviator stress, confining pressure (mean stress), temperature, time (loading rate), and stress path. The three groups of experiments consist of (1) hydrostatic loading, (2) conventional triaxial compression tests (sigma 1 > sigma 2 = sigma 3 = const.), and (3) variable stress path tests including experiments at approximately constant sigma 1 and at constant mean stress. All data were generated on 100 mm-diameter specimens. The rock salt exhibited nonlinear response under all loading conditions, practically zero initial elastic limit and an apparent inseparability of permanent deformations into time-independent and time-dependent components. Pressure and temperature did not alter the elastic constants but affected the principal strain ratio, the ratio of volumetric to shear strain, rock salt ductility, and the ultimate stress. In particular, low pressure and temperature permitted pronounced dilatancy and loss in load bearing ability. Under such conditions the volumetric strains reached sizable fractions of the shear strains. Pressure remained important even at high temperature because it influenced the rate of shearing. Load path and stress history may be significant under deviatoric loading conditions and for large variations in pressure. 17 figures

  13. Experiments on thermo-hydro-mechanical behaviour of Opalinus Clay at Mont Terri rock laboratory, Switzerland

    Directory of Open Access Journals (Sweden)

    Paul Bossart

    2017-06-01

    Full Text Available Repositories for deep geological disposal of radioactive waste rely on multi-barrier systems to isolate waste from the biosphere. A multi-barrier system typically comprises the natural geological barrier provided by the repository host rock – in our case the Opalinus Clay – and an engineered barrier system (EBS. The Swiss repository concept for spent fuel and vitrified high-level waste (HLW consists of waste canisters, which are emplaced horizontally in the middle of an emplacement gallery and are separated from the gallery wall by granular backfill material (GBM. We describe here a selection of five in-situ experiments where characteristic hydro-mechanical (HM and thermo-hydro-mechanical (THM processes have been observed. The first example is a coupled HM and mine-by test where the evolution of the excavation damaged zone (EDZ was monitored around a gallery in the Opalinus Clay (ED-B experiment. Measurements of pore-water pressures and convergences due to stress redistribution during excavation highlighted the HM behaviour. The same measurements were subsequently carried out in a heater test (HE-D where we were able to characterise the Opalinus Clay in terms of its THM behaviour. These yielded detailed data to better understand the THM behaviours of the granular backfill and the natural host rock. For a presentation of the Swiss concept for HLW storage, we designed three demonstration experiments that were subsequently implemented in the Mont Terri rock laboratory: (1 the engineered barrier (EB experiment, (2 the in-situ heater test on key-THM processes and parameters (HE-E experiment, and (3 the full-scale emplacement (FE experiment. The first demonstration experiment has been dismantled, but the last two ones are on-going.

  14. Isotope techniques in the study of the hydrology of fractured and fissured rocks

    International Nuclear Information System (INIS)

    1989-01-01

    It is generally agreed that the hydrology of fractured rocks refers to the occurrence and movement of groundwater in rocks whose porosity is due to cracks, fissures and fractures in compact rocks. Until recently, crystalline rocks were considered to be impervious (the role of karst reservoirs for groundwater storage is already known). Thus, although fractured rocks cover approximately one-third of the Earth's surface, knowledge of groundwater flow dynamics still needs to be substantively improved. The Proceedings include the papers presented at the Advisory Group Meeting on the Application of Isotope Techniques in the Study of the Hydrology of Fractured and Fissured Rocks, which took place in Vienna from 17 to 21 November 1986. The meeting was attended by 21 scientists from 10 Member States. The Group agreed that the following topics should be given the highest priority: (1) Protection of groundwater resources should be incorporated into all future activities. This implies that recharge areas have to be delineated, not only using nuclear techniques but also other hydrogeological and geochemical methods. Research efforts in this direction should be intensified. (2) The Group was aware that new isotope techniques are being developed in hydrogeology and agreed that their application in fractured and fissured rocks showed promise. It was therefore suggested that information on new isotopes such as 36 Cl and 129 I should be gathered, either in the form of the various techniques currently being used by different laboratories or through the various activities that are being undertaken. Ways of co-ordinating the work being done and exchanging information at the international level should be encouraged. The Proceedings should be of interest to scientists responsible for the evaluation of water resources in crystalline rocks. It is hoped that hydrologists and hydrogeologists working in such terrains who are not familiar with the use of isotope techniques will find ideas and

  15. Surface morphology of active normal faults in hard rock: Implications for the mechanics of the Asal Rift, Djibouti

    Science.gov (United States)

    Pinzuti, Paul; Mignan, Arnaud; King, Geoffrey C. P.

    2010-10-01

    Tectonic-stretching models have been previously proposed to explain the process of continental break-up through the example of the Asal Rift, Djibouti, one of the few places where the early stages of seafloor spreading can be observed. In these models, deformation is distributed starting at the base of a shallow seismogenic zone, in which sub-vertical normal faults are responsible for subsidence whereas cracks accommodate extension. Alternative models suggest that extension results from localised magma intrusion, with normal faults accommodating extension and subsidence only above the maximum reach of the magma column. In these magmatic rifting models, or so-called magmatic intrusion models, normal faults have dips of 45-55° and root into dikes. Vertical profiles of normal fault scarps from levelling campaign in the Asal Rift, where normal faults seem sub-vertical at surface level, have been analysed to discuss the creation and evolution of normal faults in massive fractured rocks (basalt lava flows), using mechanical and kinematics concepts. We show that the studied normal fault planes actually have an average dip ranging between 45° and 65° and are characterised by an irregular stepped form. We suggest that these normal fault scarps correspond to sub-vertical en echelon structures, and that, at greater depth, these scarps combine and give birth to dipping normal faults. The results of our analysis are compatible with the magmatic intrusion models instead of tectonic-stretching models. The geometry of faulting between the Fieale volcano and Lake Asal in the Asal Rift can be simply related to the depth of diking, which in turn can be related to magma supply. This new view supports the magmatic intrusion model of early stages of continental breaking.

  16. Paleomagnetic and Rock Magnetic Study of Oligocene-Holocene Sedimentary Rocks from Northern Dominican Republic: Evidence of Vertical Axis Rotations

    Science.gov (United States)

    Anson Sanchez, M.; Kodama, K. P.; Pueyo, E. L.; Soto, R.; Garcia-Senz, J.; Escuder-Viruete, J.; Pastor-Galan, D.

    2017-12-01

    A paleomagnetic and rock magnetic study was conducted in the northern Dominican Republic to detect vertical axis rotations in an active left-lateral, strike slip fault zone. 191 samples from 21 sites were collected from a variety of lithologies including limestones, conglomerates, calcarenites and marls that ranged in age from the Oligocene to the Holocene. The rock magnetic portion of the study focused on the identification of magnetic minerals using coercivity, and Curie temperature (c vs temperature) measurement, modeling of IRM acquisition curves, and thermal demagnetization of IRMs (Lowrie, 19901). In the paleomagnetic portion of the study characteristic remanences (ChRMs) were isolated using thermal demagnetization (19 steps up to 680ºC) and alternating field (AF) demagnetization (17 steps up to 100 mT). In most cases the characteristic remanence is carried by magnetite, with peak unblocking temperatures of 575ºC. This interpretation was supported by c vs. T results that yielded Curie temperatures of 580˚C. In only a few cases (7 samples) higher unblocking temperatures suggested hematite as the magnetic carrier. The modeling of IRM acquisition curves, that shows two coercivity components, further supports the presence of magnetite. 75% of the IRM is carried by the low-coercivity component (100-300 mT, magnetite). 25% of the IRM is carried by the high-coercivity component (1.2-1.6T) characteristic of hematite. The IRM acquisition data was collected from 24 samples (3-4 from each of the lithologies sampled). IRMs were acquired in fields from 4mT to 1T in 23 steps. The paleomagnetic results show a grouping by tectonic blocks with one group having westerly ChRM declinations (268˚-295˚) and a second group having northerly ChRM declinations (357˚-035˚). In most cases, inclinations are intermediate ( 35˚), in agreement with the 24˚-31˚ expected inclinations for Dominican Republic in the period Oligocene to Holocene. The rotation of the tectonic blocks, as

  17. The analysis of creep characteristics of the surrounding rock of the carbonaceous rock tunnel based on Singh-Mitchell model

    Science.gov (United States)

    Luo, Junhui; Mi, Decai; Ye, Qiongyao; Deng, Shengqiang; Zeng, Fuquan; Zeng, Yongjun

    2018-01-01

    Carbonaceous rock has the characteristics of easy disintegration, softening, swelling and environmental sensitivity, which belongs to soft surrounding rock, and the deformation during excavation and long-term stability of the surrounding rock of carbonaceous rock tunnel are common problems in the construction of carbonaceous rock tunnel. According to the above, the Monitor and measure the displacement, temperature and osmotic pressure of the surrounding carbonaceous rock of the tunnel of Guangxi Hebai highway. Then it based on the obtaining data to study the creep mechanism of surrounding rock using Singh-Mitchell model and predict the deformation of surrounding rock before the tunnel is operation. The results show that the Singh-Mitchell creep model can effectively analyse and predict the deformation development law of surrounding rock of tunnel without considering temperature and osmotic pressure, it can provide reference for the construction of carbonaceous rock tunnel and the measures to prevent and reinforce it..

  18. Theoretical and numerical studies of crack initiation and propagation in rock masses under freezing pressure and far-field stress

    Directory of Open Access Journals (Sweden)

    Yongshui Kang

    2014-10-01

    Full Text Available Water-bearing rocks exposed to freezing temperature can be subjected to freeze–thaw cycles leading to crack initiation and propagation, which are the main causes of frost damage to rocks. Based on the Griffith theory of brittle fracture mechanics, the crack initiation criterion, propagation direction, and crack length under freezing pressure and far-field stress are analyzed. Furthermore, a calculation method is proposed for the stress intensity factor (SIF of the crack tip under non-uniformly distributed freezing pressure. The formulae for the crack/fracture propagation direction and length of the wing crack under freezing pressure are obtained, and the mechanism for coalescence of adjacent cracks is investigated. In addition, the necessary conditions for different coalescence modes of cracks are studied. Using the topology theory, a new algorithm for frost crack propagation is proposed, which has the capability to define the crack growth path and identify and update the cracked elements. A model that incorporates multiple cracks is built by ANSYS and then imported into FLAC3D. The SIFs are then calculated using a FISH procedure, and the growth path of the freezing cracks after several calculation steps is demonstrated using the new algorithm. The proposed method can be applied to rocks containing fillings such as detritus and slurry.

  19. Study of uranium mineralization in rock samples from marwat range bannu basin by fission track analysis technique

    International Nuclear Information System (INIS)

    Qureshi, A.Z.; Ullah, K.; Ullah, N.; Akram, M.

    2004-07-01

    The Geophysics Division, Atomic Energy Minerals Centre (AEMC), Lahore has planned a uranium exploration program in Marwat Range, Bannu Basin. In this connection 30 thin sections of rock samples, collected from four areas; namely, Darra Tang, Simukili, Karkanwal and Sheikhillah from Marwat Range, and one from Salt Range were provided to Nuclear Geology Group of Physics Research Division, PINSTECH for the study of nature and mechanism of uranium mineralization These studies are aimed to help in designing uranium exploration strategy by providing the loci of uranium sources in the Marwat and Salt Ranges. The samples have been studied using fission track analysis technique. (author)

  20. Surrounding rock abutment pressure distribution and thickness effect of dynamic catastrophic in fully mechanized sublevel mining stope

    Energy Technology Data Exchange (ETDEWEB)

    Xie, G.; Yang, K.; Chang, J.; Wang, L. [Anhui University of Science and Technology, Huainan (China)

    2006-12-15

    Numerical simulation was carried out to analyse the distribution of surrounding rock stress with coal seams of different thickness (3.0, 5.4, 8.0, 12.0 m) based on engineering geology and exploitation technology of the 151(3) fully mechanized sublevel caving face in Xieqiao colliery. The research indicates that the variation of abutment pressure has obvious difference in coal seams of different thickness. The effect of abutment pressure distribution in seams of different thickness on coal-methane outbursts was analysed. With an increase in thickness of the caving seam, the research illustrates that the elastic energy resilience is reduced and the capability of resisting damage and deformation is strengthened in coal around the stope. The results show that fully mechanized sublevel caving slows down dynamic catastrophes. 7 refs., 4 figs.