Numerical Simulation of Blast Vibration and Crack Forming Effect of Rock-Anchored Beam Excavation in Deep Underground Caverns

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XinPing Li

2017-01-01

Full Text Available Aiming at surrounding rock damage induced by dynamic disturbance from blasting excavation of rock-anchored beam in rock mass at moderate or far distance in underground cavern, numerical model of different linear charging density and crustal stress in underground cavern is established by adopting dynamic finite element software based on borehole layout, charging, and rock parameter of the actual situation of a certain hydropower station. Through comparison in vibration velocity, contour surface of rock mass excavation, and the crushing extent of excavated rock mass between calculation result and field monitoring, optimum linear charging density of blast hole is determined. Studies are also conducted on rock mass vibration in moderate or far distance to blasting source, the damage of surrounding rock in near-field to blasting source, and crushing degree of excavated rock mass under various in situ stress conditions. Results indicate that, within certain range of in situ stress, the blasting vibration is independent of in situ stress, while when in situ stress is increasing above certain value, the blasting vibration velocity will be increasing and the damage of surrounding rock and the crushing degree of excavated rock mass will be decreasing.

Time-Dependent Damage Investigation of Rock Mass in an In Situ Experimental Tunnel

Science.gov (United States)

Jiang, Quan; Cui, Jie; Chen, Jing

2012-01-01

In underground tunnels or caverns, time-dependent deformation or failure of rock mass, such as extending cracks, gradual rock falls, etc., are a costly irritant and a major safety concern if the time-dependent damage of surrounding rock is serious. To understand the damage evolution of rock mass in underground engineering, an in situ experimental testing was carried out in a large belowground tunnel with a scale of 28.5 m in width, 21 m in height and 352 m in length. The time-dependent damage of rock mass was detected in succession by an ultrasonic wave test after excavation. The testing results showed that the time-dependent damage of rock mass could last a long time, i.e., nearly 30 days. Regression analysis of damage factors defined by wave velocity, resulted in the time-dependent evolutional damage equation of rock mass, which corresponded with logarithmic format. A damage viscoelastic-plastic model was developed to describe the exposed time-dependent deterioration of rock mass by field test, such as convergence of time-dependent damage, deterioration of elastic modules and logarithmic format of damage factor. Furthermore, the remedial measures for damaged surrounding rock were discussed based on the measured results and the conception of damage compensation, which provides new clues for underground engineering design.

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

Structural characterization of the rock mass of the underground mine Oro Descanso

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Adeoluwa Olajesu Oluwaseyi

2017-10-01

Full Text Available In the rocky massif where the Oro Descanso underground mine is located, an assessment was made of the physical-mechanical properties of rocks, cracking and blocking, in order to propose safe tillage measures for underground mining excavations using appropriate empirical methods. From the evaluation made it was concluded that the massif is composed of areas of rocks of different quality: good, fair and poor. It is proposed for the area of good quality to work excavations with complete advance, of free length 1.0-1.5 m, using in the crown the support of cemented anchors of diameter 20 mm, length 3 m and spaced 2.5 m and apply concrete released 50 mm thick. For the zone of bad and regular quality, it is suggested to work in stepwise progression, of free length of 1-3 m and after each blasting, to install in the crown, cemented anchors of diameter 20 mm, length 4-5 m and spacing 1-2 m, placing on the sides metallic mesh, with concrete cast 50-150 mm thick.

A new design concept of fully grouted rock bolts in underground construction

Science.gov (United States)

Phich Nguyen, Quang; Nguyen, Van Manh; Tuong Nguyen, Ke

2018-04-01

The main problem after excavating an underground excavation is to maintain the stability of the excavation for a certain period of time. Failure in meeting this demand is a threat to safety of men and equipment. Support and reinforcement are different instruments with different mechanisms. Among the common support systems in tunnelling and mining, rock bolts have been widely used to reinforce rock mass and also to reduce geological hazards. Furthermore rock bolts can be applied under varying different geological conditions with cost-effectiveness. Although different methods are developed for grouted rock bolts design until now, the interaction mechanism of the rock bolts and rock mass is still very complicated issue. The paper addresses an analytical model for the analysis and design of fully grouted rock bolts based on the reinforcement principle. According to this concept the jointed rock mass reinforced by grouted rock bolts is considered as composite material which includes rock mass, the grout material and the bolt shank. The mechanical properties of this composite material depend on the ratio of the components. The closed-form solution was developed based on the assumption that the rock mass arround a circular tunnel remained elastic after installing fully grouted rock bolts. The main parameters of the rock-bolt system (the diameter and length of bolt shank, the space between the bolts) are then easily estimated from the obtained solution.

Dynamic response of underground openings in discontinuous rock

International Nuclear Information System (INIS)

Asmis, H.W.

1984-02-01

This report examines the behaviour of underground openings in discontinuous rock in response to seismic waves associated with either earthquakes or rock bursts. A literature search revealed that well-constructed underground structures, such as would be expected for nuclear fuel waste disposal vaults, underground pumped-storage or nuclear plants, have an extremely high resistance to damage from seismic motion. To complement these qualitative results, it was necessary to examine the basic mechanisms of the entire progression of seismic motion, from wave generation and propagation, to wave interaction with the underground opening. From these investigations, it was found that unless a seismic event occurs very close to the installation, the stresses generated will be low with respect to the excavation stresses, because high stress waves are rapidly attenuated in travelling through rock. As well, an earthquake may generate extremely high accelerations, but is limited in the maximum amount of stress that it can create. The question, however, of the actual specific nature of underground seismic motions still remains essentially unanswered, although it is expected that there is a reduction in peak motions with depth due to the effect of the free surface of the earth

Hydrogeology of the rock mass encountered at the 240 level of Canada's Underground Research Laboratory

International Nuclear Information System (INIS)

Kozak, E.T.; Davison, C.C.

1992-09-01

The rock mass surrounding the 240 level of Canada's Underground Research Laboratory (URL) has been hydrogeologically characterized through observations made in the tunnel and room excavations and from a network of radiating low-dipping boreholes. The 240 level complex sits in a wedge of grey-to-pink granite between two important, low-dipping, hydraulically active fracture zones, known as Fracture Zone 2 (FZ2) and Fracture Zone 2.5 (FZ2.5), a splay of FZ2. There is no apparent seepage into the 240 level room and tunnel network from the surrounding rock mass except from a vertical fracture intersected by the Room 209 tunnel. Extensive hydraulic and geomechanical tests have been conducted in boreholes intersecting the Room 209 vertical fracture, and transmissivities were found to range from 10 -10 to 10 -6 m 2 /s. FZ2 and FZ2.5 occur at the 240 m depth approximately 10 m to the west and 100 m to the south respectively of the 240 level tunnel network. Hydraulic testing within packer-isolated boreholes intersecting these fracture zones showed that transmissivities ranged from 10 -7 to 10 -5 m 2 /s in FZ2, and 10 -9 to 10 -7 m 2 /s in FZ2.5. No naturally-occurring fractures were encountered east of the 240 level complex up to 300 m away. The rock mass to the north of the 240 level is dominated by the Room 209 vertical fracture, which tends to splay with distance and has been intersected 95 m from the Room 209 tunnel. (Author) (50 figs., 5 tabs., 10 refs.)

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)

Reinforcement of Underground Excavation with Expansion Shell Rock Bolt Equipped with Deformable Component

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Korzeniowski Waldemar

2017-03-01

Full Text Available The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod. There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.

Rock index properties for geoengineering in underground development

International Nuclear Information System (INIS)

O'Rourke, J.E.

1989-01-01

This paper describes the use of index testing to obtain rock properties that are useful in the design and construction planning of an underground development for civil engineering or mining projects. The index properties discussed include: point load; Schmidt hammer hardness; abrasion hardness; and total hardness. The first two index properties correlate to uniaxial compressive strength (UCS) and Young's modulus. Discussions are given on empirical, normalized relationships of UCS to rock mass properties and the integrated use with semi-empirical, geotechnical design methods. The hardness property indices correlate to construction performance parameters and some relevant experience is cited. Examples of data are presented from an index testing program carried out primarily on siltstone, sandstone and limestone rock core samples retrieved from depths up to 1005 m (3300 ft) in a borehole drilled in the Paradox Basin in eastern Utah. The borehole coring was done for a nuclear waste repository site investigation

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)

Underground Research Laboratories for Crystalline Rock and Sedimentary Rock in Japan

Energy Technology Data Exchange (ETDEWEB)

Shigeta, N.; Takeda, S.; Matsui, H.; Yamasaki, S.

2003-02-27

The Japan Nuclear Cycle Development Institute (JNC) has started two off-site (generic) underground research laboratory (URL) projects, one for crystalline rock as a fractured media and the other for sedimentary rock as a porous media. This paper introduces an overview and current status of these projects.

Effects of statistical distribution of joint trace length on the stability of tunnel excavated in jointed rock mass

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Kayvan Ghorbani

2015-12-01

Full Text Available The rock masses in a construction site of underground cavern are generally not continuous, due to the presence of discontinuities, such as bedding, joints, faults, and fractures. The performance of an underground cavern is principally ruled by the mechanical behaviors of the discontinuities in the vicinity of the cavern. During underground excavation, many surrounding rock failures have close relationship with joints. The stability study on tunnel in jointed rock mass is of importance to rock engineering, especially tunneling and underground space development. In this study, using the probability density distribution functions of negative exponential, log-normal and normal, we investigated the effect of joint trace length on the stability parameters such as stress and displacement of tunnel constructed in rock mass using UDEC (Universal Distinct Element Code. It was obtained that normal distribution function of joint trace length is more critical on the stability of tunnel, and exponential distribution function has less effect on the tunnel stability compared to the two other distribution functions.

Deep fracturation of granitic rock mass

International Nuclear Information System (INIS)

Bles, J.L.; Blanchin, R.; Bonijoly, D.; Dutartre, P.; Feybesse, J.L.; Gros, Y.; Landry, J.; Martin, P.

1986-01-01

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, in various feasibility studies dealing with radioactive wastes disposal. The Mont Blanc road tunnel, the EDF Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied. 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 [fr

A three-dimensional back-analysis of the collapse of an underground cavity in soft rocks

Science.gov (United States)

Fazio, Nunzio Luciano; Lollino, Piernicola; Perrotti, Michele; Parise, Mario; Bonamini, Marco; Di Maggio, Cipriano; Madonia, Giuliana; Vattano, Marco

2016-04-01

Anthropogenic sinkholes have recently occurred in built-up areas of Sicily (southern Italy) and are generally associated with the presence of ancient underground quarries for the extraction of soft calcarenite rock, used as building material. These quarries were poorly excavated and then were abandoned in the following decades; urban expansion has recently enlarged to involve the areas affected by presence of the cavities, so that the likely collapse of the underground systems poses serious risks to people, buildings and infrastructures. The present work focuses on the case of the town of Marsala, where in 2003 a sinkhole opened at the outskirts of town, near peri-urban buildings. Field surveys, structural analysis of the joint networks in the rock mass and numerical modeling were carried out in order to investigate the most significant factors responsible of the instability processes of the underground quarry. In particular, a geotechnical three-dimensional model has been defined based on in-situ measurements and surveys. The FEM analyses have been performed with the code Plaxis-3D, by using initially the Mohr-Coulomb elasto-plastic model and then assessing the influence of the joint systems on the rock-mass stability with a jointed rock anisotropic model. Discrete planar bands have been also used to simulate the effect of specific joints, as an alternative to the jointed rock model. The results are in good agreement with the failure mechanism generated during the 2003 sinkhole event, and confirm that reliable analyses of these problems requires 3-D sophisticated tools.

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

Assessment of rock mass quality based on rock quality designation and rock block index. Taking the Borehole BS01 in Beishan HLW disposal repository as example

International Nuclear Information System (INIS)

Xu Jian; Wang Ju

2006-01-01

Rock mass quality assessment plays an important role in the security for all kinds of large-scale buildings, especially for the underground buildings. In this paper, based on two parameters of RQD and RBI, taking the Borehole BS01 as example, lots of measured data prove that the rock block index can reflect the integrity and corresponding variation of mechanical properties of core from Borehole BS01 to some extent. Meanwhile, the rock mass classification around the Borehole BS01 is given in this paper. Finally, comparison of the results for rock mass assessment between RBI and RQD is made. The research result shows that the rock block index has remarkable significance in engineering and advantages in rock mass quality assessment. (authors)

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)

Modelling of Gas Flow in the Underground Coal Gasification Process and its Interactions with the Rock Environment

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Tomasz Janoszek

2013-01-01

Full Text Available The main goal of this study was the analysis of gas flow in the underground coal gasification process and interactions with the surrounding rock mass. The article is a discussion of the assumptions for the geometric model and for the numerical method for its solution as well as assumptions for modelling the geochemical model of the interaction between gas-rock-water, in terms of equilibrium calculations, chemical and gas flow modelling in porous mediums. Ansys-Fluent software was used to describe the underground coal gasification process (UCG. The numerical solution was compared with experimental data. The PHREEQC program was used to describe the chemical reaction between the gaseous products of the UCG process and the rock strata in the presence of reservoir waters.

Engineering rock mass classification of the Olkiluoto investigation site

Energy Technology Data Exchange (ETDEWEB)

Aeikaes, K. [ed.; Hagros, A.; Johansson, E. [Saanio and Riekkola Consulting Engineers, Helsinki (Finland)] [and others

2000-06-01

Olkiluoto in Eurajoki is being investigated as a possible site for the final disposal of spent nuclear fuel from the Finnish nuclear power plants. The selection of the depth, placement and layout of the repository is affected by the constructability of the bedrock. The constructability, in turn, is influenced by several properties of the host rock, such as its Ethology, the extent of fracturing, its hydrogeological properties and rock engineering characteristics and also by the magnitude and orientation of the in situ stresses and the chemistry of the groundwater. The constructability can be evaluated by the application of a rock classification system in which the properties of the host rock are assessed against common rock engineering judgements associated with underground construction. These judgements are based partly on measurements of in situ stresses and the properties of the bedrock determined from rock samples, but an important aspect is also the practical experience which has been gained during underground excavation in similar conditions and rock types. The aim of the engineering rock mass classification was to determine suitable bedrock volumes for the construction of the repository and has used data from the site characterisation programme carried out at Olkiluoto, which consisted of both surface studies and borehole investigations. The classification specifies three categories of constructability - normal, demanding and very demanding. In addition, rock mass quality has also been classified according to the empirical Q-system to enable a comparison to be made. The rock mass parameters that determine the constructability of the bedrock at Olkiluoto depend primarily on the depth and the Ethology, as well as on whether construction takes place in intact or in fractured rock. The differences in the characteristics of intact rock within a single rock type have been shown to be small. The major lithological unit at Olkiluoto, the mica gneiss, lies in the

Examining the relation between rock mass cuttability index and rock drilling properties

Science.gov (United States)

Yetkin, Mustafa E.; Özfırat, M. Kemal; Yenice, Hayati; Şimşir, Ferhan; Kahraman, Bayram

2016-12-01

Drilling rate is a substantial index value in drilling and excavation operations at mining. It is not only a help in determining physical and mechanical features of rocks, but also delivers strong estimations about instantaneous cutting rates. By this way, work durations to be finished on time, proper machine/equipment selection and efficient excavation works can be achieved. In this study, physical and mechanical properties of surrounding rocks and ore zones are determined by investigations carried out on specimens taken from an underground ore mine. Later, relationships among rock mass classifications, drillability rates, cuttability, and abrasivity have been investigated using multi regression analysis. As a result, equations having high regression rates have been found out among instantaneous cutting rates and geomechanical properties of rocks. Moreover, excavation machine selection for the study area has been made at the best possible interval.

ROCK MASS DAMAGED ZONE CAUSED BY BLASTING DURING TUNNEL EXCAVATION

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Hrvoje Antičević

2012-07-01

Full Text Available Design of underground spaces, including tunnels, and repositories for radioactive waste include the application of the same or similar technologies. Tunnel excavation by blasting inevitably results in the damage in the rock mass around the excavation profile. The damage in the rock mass immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and-mechanical properties of the rock mass. Concerning the design of deep geological repositories, requirements in terms of damaged rock are the same or more rigorous than for the design of tunnel. The aforementioned research is directed towards determining the depth of damage zone caused by blasting. The depth of the damage zone is determined by measuring the changes of physical and-mechanical properties of the rock mass around the tunnel excavation profile. By this research the drilling and blasting parameters were correlated with the depth and size of the damage zone (the paper is published in Croatian.

Correlation between Rock mass rating, Q-system and Rock mass index based on field data

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Soufi Amine

2018-01-01

The proposed regression models reveal strong correlations between RMR, Q and RMi indexes with high values of accuracy coefficients so that they can be used to estimate the “CPB3” underground rock mass quality for the range of RMR between 30% and 80%. The developed mathematical formulations of the geomechanicalindexes will certainly offer an effective tool to geologist and geotechnical professionals in the decision-making process, preliminary design phase, stability problems and suggestions of the required supporting system and techniques without the expense of more resources or time.

Reducing rock fall injuries in underground US coal mines

Energy Technology Data Exchange (ETDEWEB)

Robertson, S.B.; Molinda, G.M.; Pappas, D.M. [Pittsburgh Research Laboratory, Pittsburgh, PA (United States)

2005-07-01

A continuing risk to underground US coal miners is rock falling from the mine roof. Almost 99% of injuries caused by rock falls are not from a major roof collapse, but from smaller rock that fall from between roof bolts. Installing roof screen provides excellent overhead roof coverage and dramatically reduces the potential for rock fall injuries, especially to roof bolted operators. The National Institute for Occupational Safety and Health (NIOSH) has explored different installation techniques and roof screening options along with machine design innovations that make roof screening easier and safer. Applying ergonomic principles to roof screening will offer insight and direction for better material handling. Other techniques for controlling rock falls and roof falls for long-term stability include the application of surface support liners and polyurethane (PUR) injection. An ongoing study at the NIOSH Lake Lynn Laboratory of various types of spray-on liner and shotcrete materials is providing a unique opportunity to evaluate the long-term behaviour of liners in an underground environment. In-mine studies of PUR have involved pre- and post-injection core drilling and video borecole logging. The results have provided insights into how PUR penetrates and reinforces weak and highly fractured rock. 11 refs., 8 figs., 1 tab.

Material constitutive model for jointed rock mass behavior

International Nuclear Information System (INIS)

Thomas, R.K.

1980-11-01

A material constitutive model is presented for jointed rock masses which exhibit preferred planes of weakness. This model is intended for use in finite element computations. The immediate application is the thermomechanical modelling of a nuclear waste repository in hard rock, but the model seems appropriate for a variety of other static and dynamic geotechnical problems as well. Starting with the finite element representations of a two-dimensional elastic body, joint planes are introduced in an explicit manner by direct modification of the material stiffness matrix. A novel feature of this approach is that joint set orientations, lengths and spacings are readily assigned through the sampling of a population distribution statistically determined from field measurement data. The result is that the fracture characteristics of the formations have the same statistical distribution in the model as is observed in the field. As a demonstration of the jointed rock mass model, numerical results are presented for the example problem of stress concentration at an underground opening

Interim rock mass properties and conditions for analyses of a repository in crystalline rock

International Nuclear Information System (INIS)

Tammemagi, H.Y.; Chieslar, J.D.

1985-03-01

A summary of rock properties for generic crystalline rock is compiled from literature sources to provide the input data for analyses of a conceptual repository in crystalline rock. Frequency histograms, mean values and ranges of physical, mechanical, thermal, and thermomechanical properties, and the dependence of these properties on temperature are described. A description of the hydrogeologic properties of a crystalline rock mass and their dependence on depth is provided. In addition, the temperature gradients, mean annual surface temperature, and in situ stress conditions are summarized for the three regions of the United States currently under consideration to host a crystalline repository; i.e., the North Central, Northeastern, and Southeastern. Brief descriptions of the regional geology are also presented. Large-scale underground experiments in crystalline rock at Stripa, Sweden, and in Climax Stock in Nevada, are reviewed to assess whether the rock properties presented in this report are representative of in situ conditions. The suitability of each rock property and the sufficiency of its data base are described. 110 refs., 27 figs., 4 tabs

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

A proposal of constitutive creep model for soft rock to be applied to numerical analysis for mechanical interaction in the underground facilities

International Nuclear Information System (INIS)

Sawada, Masataka; Okada, Tetsuji

2005-01-01

In the case that the underground facilities of high-level nuclear waste disposal are constructed in soft rock mass, it is predicted that time-dependent behavior of rock has an important role both on the stability of surrounding rock mass after excavation and on the super long-term stability of barrier system. Existing creep model that has been applied to excavation problems in electric power industry is not sufficient in order to evaluate long-term behavior of the facility constructed in soft rock mass. Therefore, it is necessary to develop an appropriate creep model for soft rock. In this research, we try to develop a prototype of numerical tool for evaluating the stability during and after the excavation and super long-term stability after back-filling. Firstly, a simple rheological model for time-dependent behavior of soft rock is proposed. It is the key feature of this model that two different types of rheological model can be selected in order to describe both failure and non-failure processes. Rock continues to deform until failure in the case where stress applied to the rock exceeds its residual strength, although deformation of the rock finally ceases in the other cases. The applicability of this model is investigated by comparing the calculated results with those in laboratory test results. The proposed model can describe the time-dependent and dilatancy behavior of mudstone of Tertiary period observed in the drained triaxial creep test. Next, we apply the proposed model to the problem of time-dependent behavior of rock mass around a deposition hole. Numerical simulation of excavation problem and long-term mechanical interaction between buffer material and surrounding rock mass is carried out using a hydrological - mechanical coupled FEM code that includes the proposed model. Several mechanical models can be selected in order to apply to the mechanical behavior of materials consisting of underground facility. The main results obtained from this simulation

Neutrons from rock radioactivity in the new Canfranc underground laboratory

International Nuclear Information System (INIS)

Amare, J; Bauluz, B; Beltran, B; Carmona, J M; Cebrian, S; GarcIa, E; Gomez, H; Irastorza, I G; Luzon, G; MartInez, M; Morales, J; Solorzano, A Ortiz de; Pobes, C; Jpuimedon; RodrIguez, A; Ruz, J; Sarsa, M L; Torres, L; Villar, J A

2006-01-01

Measurements of radioactivity and composition of rock from the main hall of the new Canfranc underground laboratory are reported. Estimates of neutron production by spontaneous fission and (α, n) reactions are given

A Model of Anisotropic Property of Seepage and Stress for Jointed Rock Mass

Directory of Open Access Journals (Sweden)

Pei-tao Wang

2013-01-01

Full Text Available Joints often have important effects on seepage and elastic properties of jointed rock mass and therefore on the rock slope stability. In the present paper, a model for discrete jointed network is established using contact-free measurement technique and geometrical statistic method. A coupled mathematical model for characterizing anisotropic permeability tensor and stress tensor was presented and finally introduced to a finite element model. A case study of roadway stability at the Heishan Metal Mine in Hebei Province, China, was performed to investigate the influence of joints orientation on the anisotropic properties of seepage and elasticity of the surrounding rock mass around roadways in underground mining. In this work, the influence of the principal direction of the mechanical properties of the rock mass on associated stress field, seepage field, and damage zone of the surrounding rock mass was numerically studied. The numerical simulations indicate that flow velocity, water pressure, and stress field are greatly dependent on the principal direction of joint planes. It is found that the principal direction of joints is the most important factor controlling the failure mode of the surrounding rock mass around roadways.

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)

Characterization of the fracturation of rock masses for determining flow

International Nuclear Information System (INIS)

Derlich, S.

1984-02-01

Flow in a rock mass is the consequence of the permeability of the rock, which can be roughly separated into matrix permeability and fissure permeability. In crystalline rocks fissure permeability is dominant, especially where the rocks are extensively fractured. It is thus essential, by means of studies either at the surface or underground, to characterize the volume fracturation in the mass considered. The purpose of this paper is to illustrate the methodology for analysing fracturation at a site by the studies performed on the granite mass of Auriat in the French Massif Central. A number of geology laboratories have participated in this study and a broad spectrum of observations has been made which can be used for determining the various stages of a study with a view to selection of a site, the advantages and limitations of each method or study plan and additional methods which need to be used for gaining as complete a picture as possible of the fracturation. A brief examination of the results obtained at Auriat enables the relative advantages of using these various methods at a particular site to be compared

Back-analysing rock mass modulus from monitoring data of two tunnels in Sydney, Australia

Directory of Open Access Journals (Sweden)

Robert Bertuzzi

2017-10-01

Full Text Available This paper presents two case studies where the rock mass modulus and in situ stress are estimated from the monitoring data obtained during the construction of underground excavations in Sydney, Australia. The case studies comprise the widening of existing twin road tunnels within Hawkesbury sandstone and the excavation of a large cavern within Ashfield shale. While back-analysis from detailed systematic monitoring has been previously published, this paper presents a relatively simple methodology to derive rock mass modulus and in situ stress from the relatively simple displacement data routinely recorded during tunnelling.

Sensitivity analysis of efficiency thermal energy storage on selected rock mass and grout parameters using design of experiment method

International Nuclear Information System (INIS)

Wołoszyn, Jerzy; Gołaś, Andrzej

2014-01-01

Highlights: • Paper propose a new methodology to sensitivity study of underground thermal storage. • Using MDF model and DOE technique significantly shorter of calculations time. • Calculation of one time step was equal to approximately 57 s. • Sensitivity study cover five thermo-physical parameters. • Conductivity of rock mass and grout material have a significant impact on efficiency. - Abstract: The aim of this study was to investigate the influence of selected parameters on the efficiency of underground thermal energy storage. In this paper, besides thermal conductivity, the effect of such parameters as specific heat, density of the rock mass, thermal conductivity and specific heat of grout material was investigated. Implementation of this objective requires the use of an efficient computational method. The aim of the research was achieved by using a new numerical model, Multi Degree of Freedom (MDF), as developed by the authors and Design of Experiment (DoE) techniques with a response surface. The presented methodology can significantly reduce the time that is needed for research and to determine the effect of various parameters on the efficiency of underground thermal energy storage. Preliminary results of the research confirmed that thermal conductivity of the rock mass has the greatest impact on the efficiency of underground thermal energy storage, and that other parameters also play quite significant role

Applicability of initial stress measurement methods to Horonobe Siliceous rocks and initial stress state around Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya; Fujii, Yoshiaki

2009-01-01

Understanding initial stress condition in deep underground is important for such construction as rock cavern for geological disposal of HLW and underground power plant. Neogene sedimentary rock is widely distributed in Japan. There are only a few studies of initial stress measurement in Neogene sedimentary rock mass in Japan due to difficulty of measurement. Evaluation of initial stress condition around Horonobe Underground Research Laboratory Project was carried out in order to understand initial stress condition and applicability of AE, DSCA and hydraulic fracturing (HF) methods to Neogene sedimentary rock. Initial stress values obtained from AE method is smaller than overburden pressure due to time dependency of Kaizer effect. It would be difficult to use AE method as initial stress measurement method for Horonobe Siliceous rocks. Principal stress values by DSCA are similar to those by HF tests. Directions of maximum horizontal principal stresses are approximately in E-W and corresponded to HF results. In HF, rod type and wire-line type systems were compared. Workability of rod type was much better than wire-line type. However, re-opening pressure were not able to be precisely measured in case of rod type system due to the large compliance of the packers and rods. Horizontal maximum and minimum principal stresses increase linearly in HF results. Deviatoric stress is acting at shallow depth. Initial stress condition approaches hydrostatic condition with depth. Direction of maximum horizontal principal stress was in E-W direction which was similar to tectonic movement around Horonobe URL by triangular surveying. (author)

Computer programs for the numerical modelling of water flow in rock masses

International Nuclear Information System (INIS)

Croney, P.; Richards, L.R.

1985-08-01

Water flow in rock joints provides a very important possible route for the migration of radio-nuclides from radio-active waste within a repository back to the biosphere. Two computer programs DAPHNE and FPM have been developed to model two dimensional fluid flow in jointed rock masses. They have been developed to run on microcomputer systems suitable for field locations. The fluid flows in a number of jointed rock systems have been examined and certain controlling functions identified. A methodology has been developed for assessing the anisotropic permeability of jointed rock. A number of examples of unconfined flow into surface and underground openings have been analysed and ground water lowering, pore water pressures and flow quantities predicted. (author)

Numerical experiments on the probability of seepage into underground openings in heterogeneous fractured rock

International Nuclear Information System (INIS)

Birkholzer, J.; Li, G.; Tsang, C.F.; Tsang, Y.

1998-01-01

An important issue for the performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of this rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, because it is located in thick, unsaturated, fractured tuff formations. Underground opening in unsaturated media might act as capillary barriers, diverting water around them. In the present work, they study the potential rate of seepage into drifts as a function of the percolation flux at Yucca Mountain, based on a stochastic model of the fractured rock mass in the drift vicinity. A variety of flow scenarios are considered, assuming present-day and possible future climate conditions. They show that the heterogeneity in the flow domain is a key factor controlling seepage rates, since it causes channelized flow and local ponding in the unsaturated flow field

A Copula-Based Method for Estimating Shear Strength Parameters of Rock Mass

Directory of Open Access Journals (Sweden)

Da Huang

2014-01-01

Full Text Available The shear strength parameters (i.e., the internal friction coefficient f and cohesion c are very important in rock engineering, especially for the stability analysis and reinforcement design of slopes and underground caverns. In this paper, a probabilistic method, Copula-based method, is proposed for estimating the shear strength parameters of rock mass. The optimal Copula functions between rock mass quality Q and f, Q and c for the marbles are established based on the correlation analyses of the results of 12 sets of in situ tests in the exploration adits of Jinping I-Stage Hydropower Station. Although the Copula functions are derived from the in situ tests for the marbles, they can be extended to be applied to other types of rock mass with similar geological and mechanical properties. For another 9 sets of in situ tests as an extensional application, by comparison with the results from Hoek-Brown criterion, the estimated values of f and c from the Copula-based method achieve better accuracy. Therefore, the proposed Copula-based method is an effective tool in estimating rock strength parameters.

Deep fracturation of granitic rock mass. Fracturation profonde des massifs rocheux granitiques

Energy Technology Data Exchange (ETDEWEB)

Bles, J L; Blanchin, R; Bonijoly, D; Dutartre, P; Feybesse, J L; Gros, Y; Landry, J; Martin, P

1986-01-01

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, in various feasibility studies dealing with radioactive wastes disposal. The Mont Blanc road tunnel, the EDF Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied. 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.

Appraisal of hard rock for potential underground repositories of radioactive wastes. LBL-7004

International Nuclear Information System (INIS)

Cook, N.G.W.

1978-01-01

Underground burial of radioactive wastes in hard rock may be an effective and safe means of isolating them from the environment and from man. The mechanical safety and stability of such an underground repository depends largely on the virgin state of stress in the rock, groundwater pressures, the strengths of the rocks, heating by the decay of the radioactive wastes, and the layout of the excavations and the disposition of waste cannisters within them. A large body of pertinent data exists in the literature, and each of these factors has been analyzed in the light of this information. The results indicate that there are no fundamental geological nor mechanical reasons why repositories capable of storing radioactive wastes should not be excavated at suitable sites in hard rock. However, specific tests to determine the mechanical and thermal properties of the rocks at a site would be needed to provide the data for the engineering design of a repository. Also, little experience exists of the effects on underground excavations of thermal loads, so that this aspect requires theoretical study and experimental validation. The depths of these potential repositories would lie in the range from 0.5 km to 2.0 km below surface, depending upon the strength of the rock. Virgin states of stress have been measured at such depths which would retard the ingress of groundwater and obviate the incidence of faulting. A typical repository comprising three horizons each with a total area of 5 km 2 would have the capacity to store wastes with thermal output of 240 MW

The Gran Sasso underground laboratories (measurements of rock radioactivity and neutron fluxes)

International Nuclear Information System (INIS)

Bellotti, E.; Buraschi, M.; Fiorini, E.; Liguori, C.

1985-01-01

The authors report on measurements of rock radioactivity and neutron flux performed in the Gran Sasso underground laboratories of the INFN in Italy. The Gran Sasso' Laboratories of the INFN are located underground, in galleries which have been excavated under the Gran Sasso mountain range. The minimum rock thickness covering the laboratories is about 1400 m of rock of average density 2.8 g cm/sup -3/, corresponding to a thickness of some 4000 m of water equivalent. The laboratories are located at about 1000 m above sea level. The main destination of these laboratories is to shelter very huge particle detectors which shall detect extremely rare nuclear events of extraordinary interest for particle physics as well as for astrophysics and cosmology. In these laboratories, the radiation background is expected to be extremely low, which is the main condition for performing the proposed experiments

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)

Prediction of Underground Cavity Roof Collapse using the Hoek–Brown Failure Criterion

DEFF Research Database (Denmark)

Suchowerska, A. M.; Merifield, R. S.; Carter, J. P.

2012-01-01

Preventing roof collapse in underground cavities is a challenge to geotechnical engineering. In this study, three independent methods have been used to evaluate the roof collapse of underground rectangular cavities for a range of geometries and rock properties. The rock mass strength has been des...

Classification Identification of Acoustic Emission Signals from Underground Metal Mine Rock by ICIMF Classifier

Directory of Open Access Journals (Sweden)

Hongyan Zuo

2014-01-01

Full Text Available To overcome the drawback that fuzzy classifier was sensitive to noises and outliers, Mamdani fuzzy classifier based on improved chaos immune algorithm was developed, in which bilateral Gaussian membership function parameters were set as constraint conditions and the indexes of fuzzy classification effectiveness and number of correct samples of fuzzy classification as the subgoal of fitness function. Moreover, Iris database was used for simulation experiment, classification, and recognition of acoustic emission signals and interference signals from stope wall rock of underground metal mines. The results showed that Mamdani fuzzy classifier based on improved chaos immune algorithm could effectively improve the prediction accuracy of classification of data sets with noises and outliers and the classification accuracy of acoustic emission signal and interference signal from stope wall rock of underground metal mines was 90.00%. It was obvious that the improved chaos immune Mamdani fuzzy (ICIMF classifier was useful for accurate diagnosis of acoustic emission signal and interference signal from stope wall rock of underground metal mines.

Appraisal of hard rock for potential underground repositories of radioactive wastes

International Nuclear Information System (INIS)

Cook, N.G.W.

1977-10-01

The mechanical safety and stability of such an underground repository depends largely on the virgin state of stress in the rock, groundwater pressures, the strengths of the rocks, heating by the decay of the radioactive wastes, and the layout of the excavations and the disposition of waste cannisters within them. A large body of pertinent data exists in the literature, and each of these factors has been analyzed in the light of this information. The results indicate that there are no fundamental geological nor mechanical reasons why repositories capable of storing radioactive wastes should not be excavated at suitable sites in hard rock. However, specific tests to determine the mechanical and thermal properties of the rocks at a site would be needed to provide the data for the engineering design of a repository. Also, little experience exists of the effects on underground excavations of thermal loads, so that this aspect requires theoretical study and experimental validation. The depths of these potential repositories would lie in the range from 0.5 to 2.0 km below surface, depending upon the strength of the rock. Virgin states of stress have been measured at such depths which would retard the ingress of groundwater and obviate the incidence of faulting. A typical repository comprising three horizons each with a total area of 5 km 2 would have the capacity to store wastes with thermal output of 240 MW

MBC model analysis for predicting the rock behavior in excavating the Mizunami Underground Research Laboratory

International Nuclear Information System (INIS)

Mori, Takayuki; Iwano, Keita; Nakajima, Makoto; Morikawa, Seiji; Tabei, Kazuto

2005-03-01

As a Phase 1 of MIU project (Mizunami Underground Research Laboratory project), through the laboratory and borehole in-situ tests, JNC Tono Geoscience Center plans to constitute the comprehensive geological model and predicts the rock behaviors in excavating the shaft and gallery. These model and results leads to be reflected by the next step research projects. So far, the Phase 1 of MIU project is coming to final stage, and the Phase 2 will start at next year in which the in-situ researches are planned through the excavation. In this study, the comprehensive geometrical model was drawn out through the Phase 1 data, and MBC model analysis was carried out to predict the rock mass behavior around the shaft and gallery. The following results are obtained. 1. With MIZ-1 borehole core, artificial joints, which are assumed to be produced by rock blasting, were formed through the Brazilian test. And through the rock shear test for these joints, these mechanical properties were obtained. 2. By examining the MIZ-1 borehole research data, Mizunami site was classified by mechanical and joint properties and the Geomechanical model were made up. 3. Through the MBC model, the shaft and gallery cases were analyzed which depend on the rock mass classification, Excavation Damaged Zone, and the direction of the galleries. These results showed that in most cases, the joint opening were little because of the rock stiffness, but by the existence of high inclined joints, the side wall of the galleries were damaged by the excavation. (author)

In situ determination of a rock mass modulus using a high resolution tiltmeter

Energy Technology Data Exchange (ETDEWEB)

Saleh, B.; Husein Malkawi, A.I. [University of Jordan, Amman (Jordan); Blum, P.A. [Universite Pierre et Marie Curie, 75 - Paris (France)

1996-04-01

A very sensitive, compact tiltmeter made of melted silica, developed for the measurement of small deformations of various civil engineering structures, was described. The instrument is capable of giving a continuous record and was used to establish a new approach to directly evaluating the in situ average elastic rock mass modulus. Such information is important in decision making during the design stages of large civil engineering works, such as dams, nuclear plant facilities, and underground structures. Five tiltmeters were installed on the facades of the Louvre in Paris to study the deformation induced by internal structural work and by the impact of the Paris metro traffic movement. The data was used to determine displacement using the Boussinesq equation. Results were consistent with typical elastic rock-mass modulus for the rock found in the museum`s foundations. 13 refs., 1 tab., 10 figs.

Model test study on propagation law of plane stress wave in jointed rock mass under different in-situ stresses

Science.gov (United States)

Dong, Qian

2017-12-01

The study of propagation law of plane stress wave in jointed rock mass under in-situ stress has important significance for safety excavation of underground rock mass engineering. A model test of the blasting stress waves propagating in the intact rock and jointed rock mass under different in-situ stresses was carried out, and the influencing factors on the propagation law, such as the scale of static loads and the number of joints were studied respectively. The results show that the transmission coefficient of intact rock is larger than that of jointed rock mass under the same loading condition. With the increase of confining pressure, the transmission coefficients of intact rock and jointed rock mass both show an trend of increasing first and then decreasing, and the variation of transmission coefficients in intact rock is smaller than that of jointed rock mass. Transmission coefficient of jointed rock mass decreases with the increase of the number of joints under the same loading condition, when the confining pressure is relatively small, the reduction of transmission coefficients decreases with the increasing of the number of joints, and the variation law of the reduction of transmission coefficients is contrary when the confining pressure is large.

Predicting rock bursts in mines

Science.gov (United States)

Spall, H.

1979-01-01

In terms of lives lost, rock bursts in underground mines can be as hazardous as earthquakes on the surface. So it is not surprising that fo the last 40 years the U.S Bureau of Mines has been using seismic methods for detecting areas in underground mines where there is a high differential stress which could lead to structural instability of the rock mass being excavated.

Construction experiences from underground works at Oskarshamn. Compilation report

International Nuclear Information System (INIS)

Carlsson, Anders; Christiansson, Rolf

2007-12-01

The main objective with this report is to compile experiences from the underground works carried out at Oskarshamn, primarily construction experiences from the tunnelling of the cooling water tunnels of the Oskarshamn nuclear power units 1,2 and 3, from the underground excavations of Clab 1 and 2 (Central Interim Storage Facility for Spent Nuclear Fuel), and Aespoe Hard Rock Laboratory. In addition, an account is given of the operational experience of Clab 1 and 2 and of the Aespoe HRL on primarily scaling and rock support solutions. This report, as being a compilation report, is in its substance based on earlier published material as presented in the list of references. Approximately 8,000 m of tunnels including three major rock caverns with a total volume of about 550,000 m 3 have been excavated. The excavation works of the various tunnels and rock caverns were carried out during the period of 1966-2000. In addition, minor excavation works were carried out at the Aespoe HRL in 2003. The depth location of the underground structures varies from near surface down to 450 m. As an overall conclusion it may be said that the rock mass conditions in the area are well suited for underground construction. This conclusion is supported by the experiences from the rock excavation works in the Simpevarp and Aespoe area. These works have shown that no major problems occurred during the excavation works; nor have any stability or other rock engineering problems of significance been identified after the commissioning of the Oskarshamn nuclear power units O1, O2 and O3, BFA, Clab 1 and 2, and Aespoe Hard Rock Laboratory. The underground structures of these facilities were built according to plan, and since than been operated as planned. Thus, the quality of the rock mass within the construction area is such that it lends itself to excavation of large rock caverns with a minimum of rock support

Construction experiences from underground works at Oskarshamn. Compilation report

Energy Technology Data Exchange (ETDEWEB)

Carlsson, Anders (Vattenfall Power Consultant AB, Stockholm (SE)); Christiansson, Rolf (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE))

2007-12-15

The main objective with this report is to compile experiences from the underground works carried out at Oskarshamn, primarily construction experiences from the tunnelling of the cooling water tunnels of the Oskarshamn nuclear power units 1,2 and 3, from the underground excavations of Clab 1 and 2 (Central Interim Storage Facility for Spent Nuclear Fuel), and Aespoe Hard Rock Laboratory. In addition, an account is given of the operational experience of Clab 1 and 2 and of the Aespoe HRL on primarily scaling and rock support solutions. This report, as being a compilation report, is in its substance based on earlier published material as presented in the list of references. Approximately 8,000 m of tunnels including three major rock caverns with a total volume of about 550,000 m3 have been excavated. The excavation works of the various tunnels and rock caverns were carried out during the period of 1966-2000. In addition, minor excavation works were carried out at the Aespoe HRL in 2003. The depth location of the underground structures varies from near surface down to 450 m. As an overall conclusion it may be said that the rock mass conditions in the area are well suited for underground construction. This conclusion is supported by the experiences from the rock excavation works in the Simpevarp and Aespoe area. These works have shown that no major problems occurred during the excavation works; nor have any stability or other rock engineering problems of significance been identified after the commissioning of the Oskarshamn nuclear power units O1, O2 and O3, BFA, Clab 1 and 2, and Aespoe Hard Rock Laboratory. The underground structures of these facilities were built according to plan, and since than been operated as planned. Thus, the quality of the rock mass within the construction area is such that it lends itself to excavation of large rock caverns with a minimum of rock support

Analysis of the stability of underground high-level nuclear waste repository in discontinuous rock mass using 3DEC

International Nuclear Information System (INIS)

Kwon, Sang Ki; Park, Jeong Hwa; Choi, Jong Won; Kang, Chul Hyung

2001-03-01

For the safe design of a high-level nuclear waste repository in deep location, it is necessary to confirm the stability of the underground excavations under the high overburden pressure and also to investigate the influence of discontinuities such as fault, fracture zone, and joints. In this study, computer simulations using 3DEC, which is a Distince Element (DEM) code, were carried out for determining important parameters on the stability of the disposal tunnel and deposition holes excavated in 500 m deep granite body. The development of plastic zone and stress and strain distributions were analyzed with various modelling conditions with variation on the parameters including joint numbers, tunnel size, joint properties, rock properties, and stress ratio. Furthermore, the influence of fracture zone, which is located around the underground excavations, on the stability of the excavation was investigated. In this study, the variation of stress and strain distribution due to the variation of fracture zone location, dip, and width was analyzed

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

A research on the excavation, support, and environment control of large scale underground space

Energy Technology Data Exchange (ETDEWEB)

Kang, Pil Chong; Kwon, Kwang Soo; Jeong, So Keul [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1995-12-01

With the growing necessity of the underground space due to the deficiency of above-ground space, the size and shape of underground structures tend to be complex and diverse. This complexity and variety force the development of new techniques for rock mass classification, excavation and supporting of underground space, monitoring and control of underground environment. All these techniques should be applied together to make the underground space comfortable. To achieve this, efforts have been made on 5 different areas; research on the underground space design and stability analysis, research on the techniques for excavation of rock by controlled blasting, research on the development of monitoring system to forecast the rock behaviour of underground space, research on the environment inspection system in closed space, and research on dynamic analysis of the airflow and environmental control in the large geos-spaces. The 5 main achievements are improvement of the existing structure analysis program(EXCRACK) to consider the deformation and failure characteristics of rock joints, development of new blasting design (SK-cut), prediction of ground vibration through the newly proposed wave propagation equation, development and In-Situ application of rock mass deformation monitoring system and data acquisition software, and trial manufacture of the environment inspection system in closed space. Should these techniques be applied to the development of underground space, prevention of industrial disaster, cut down of construction cost, domestication of monitoring system, improvement of tunnel stability, curtailment of royalty, upgrade of domestic technologies will be brought forth. (Abstract Truncated)

Instability risk analysis and risk assessment system establishment of underground storage caverns in bedded salt rock

Science.gov (United States)

Jing, Wenjun; Zhao, Yan

2018-02-01

Stability is an important part of geotechnical engineering research. The operating experiences of underground storage caverns in salt rock all around the world show that the stability of the caverns is the key problem of safe operation. Currently, the combination of theoretical analysis and numerical simulation are the mainly adopts method of reserve stability analysis. This paper introduces the concept of risk into the stability analysis of underground geotechnical structure, and studies the instability of underground storage cavern in salt rock from the perspective of risk analysis. Firstly, the definition and classification of cavern instability risk is proposed, and the damage mechanism is analyzed from the mechanical angle. Then the main stability evaluating indicators of cavern instability risk are proposed, and an evaluation method of cavern instability risk is put forward. Finally, the established cavern instability risk assessment system is applied to the analysis and prediction of cavern instability risk after 30 years of operation in a proposed storage cavern group in the Huai’an salt mine. This research can provide a useful theoretical base for the safe operation and management of underground storage caverns in salt rock.

Creep in jointed rock masses. State of knowledge

Energy Technology Data Exchange (ETDEWEB)

Glamheden, Rune (Golder Associates AB (Sweden)); Hoekmark, Harald (Clay Technology AB, Lund (Sweden))

2010-06-15

To describe creep behaviour in hard rock masses in a physically realistic way, elaborate models including various combinations of dash pots, spring elements and sliders would be needed. According to our knowledge, there are at present no numerical tools available that can handle such a creep model. In addition, there are no records over sufficient long time periods of tunnel convergence in crystalline rock that could be used to determine or calibrate values for the model parameters. A possible method to perform bounding estimates of creep movements around openings in a repository may be to use distinct element codes with standard built-in elasto-plastic models. By locally reducing the fracture shear strength near the underground openings a relaxation of fracture shear loads is reached. The accumulated displacements may then represent the maximum possible effects of creep that can take place in a jointed rock mass without reference to the actual time it takes to reach the displacements. Estimates based on results from analyses where all shear stresses are allowed to disappear completely will, however, be over-conservative. To be able to set up and analyse reasonably realistic numerical models with the proposed method, further assumptions regarding the creep movements and the creep region around the opening have to be made. The purpose of this report is to present support for such assumptions as found in the literature.

Creep in jointed rock masses. State of knowledge

International Nuclear Information System (INIS)

Glamheden, Rune; Hoekmark, Harald

2010-06-01

To describe creep behaviour in hard rock masses in a physically realistic way, elaborate models including various combinations of dash pots, spring elements and sliders would be needed. According to our knowledge, there are at present no numerical tools available that can handle such a creep model. In addition, there are no records over sufficient long time periods of tunnel convergence in crystalline rock that could be used to determine or calibrate values for the model parameters. A possible method to perform bounding estimates of creep movements around openings in a repository may be to use distinct element codes with standard built-in elasto-plastic models. By locally reducing the fracture shear strength near the underground openings a relaxation of fracture shear loads is reached. The accumulated displacements may then represent the maximum possible effects of creep that can take place in a jointed rock mass without reference to the actual time it takes to reach the displacements. Estimates based on results from analyses where all shear stresses are allowed to disappear completely will, however, be over-conservative. To be able to set up and analyse reasonably realistic numerical models with the proposed method, further assumptions regarding the creep movements and the creep region around the opening have to be made. The purpose of this report is to present support for such assumptions as found in the literature

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.

Rock engineering in Finland

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

Contains a large collection of short articles concerned with tunnels and underground caverns and their construction and use. The articles are grouped under the following headings: use of the subsurface space; water supply; waste water services; energy management (includes articles on power stations, district heating and oil storage and an article on coal storage); multipurpose tunnels; waste disposal; transport; shelters; sporting and recreational amenities located in rock caverns; storage facilities; industrial, laboratory, and service facilities; rock foundations; tourism and culture; utilization of rock masses; research on the disposal of nuclear waste; training and research in the field of rock engineering; site investigation techniques; design of structures in rock; construction; the environment and occupational safety; modern equipment technology; underground space in Helsinki.

The underground research laboratory room 209 excavation response test

International Nuclear Information System (INIS)

Simmons, G.R.

1992-02-01

The response of the rock mass to excavation is an important factor in the design and performance of underground excavations and installations. This is particularly true in the excavation of vaults for the disposal of nuclear fuel waste, where the conditions in the rock mass around the disposal areas may affect the performance of engineered sealing systems installed to isolate the waste. The factors influencing, and mechanisms controlling, rock mass response to excavation must be understood in order to accommodate excavation response effects in disposal vault design and construction

Underground nuclear explosion effects in granite rock fracturing

International Nuclear Information System (INIS)

Derlich, S.

1970-01-01

On the Saharan nuclear test site in Hoggar granite, mechanical properties of the altered zones were studied by in situ and laboratory measurements. In situ methods of study are drillings, television, geophysical and permeability measurements. Fracturing is one of the most important nuclear explosion effects. Several altered zones were identified. There are: crushed zone, fractured zone and stressed zone. Collapse of crushed and fractured zone formed the chimney. The extent of each zone can be expressed in terms of yield and of characteristic parameters. Such results are of main interest for industrial uses of underground nuclear explosives in hard rock. (author)

Underground nuclear explosion effects in granite rock fracturing

Energy Technology Data Exchange (ETDEWEB)

Derlich, S [Commissariat a l' Energie Atomique, Centre d' Etude de Bruyeres-le-Chatel (France)

1970-05-01

On the Saharan nuclear test site in Hoggar granite, mechanical properties of the altered zones were studied by in situ and laboratory measurements. In situ methods of study are drillings, television, geophysical and permeability measurements. Fracturing is one of the most important nuclear explosion effects. Several altered zones were identified. There are: crushed zone, fractured zone and stressed zone. Collapse of crushed and fractured zone formed the chimney. The extent of each zone can be expressed in terms of yield and of characteristic parameters. Such results are of main interest for industrial uses of underground nuclear explosives in hard rock. (author)

Seismic effects on underground openings

International Nuclear Information System (INIS)

Marine, I.W.; Pratt, H.R.; Wahi, K.K.; Science Applications, Inc., La Jolla, CA; Science Applications, Inc., Albuquerque, NM)

1982-01-01

Numerical modeling techniques were used to determine the conditions required for seismic waves generated by an earthquake to cause instability to an underground opening or create fracturing and joint movement that would lead to an increase in the permeability of the rock mass. Three different rock types (salt, granite, and shale) were considered as host media for the repository located at a depth of 600 m. Special material models were developed to account for the nonlinear material behavior of each rock type. The sensitivity analysis included variations in the in situ stress ratio, joint geometry, and pore pressures, and the presence or absence of large fractures. Three different sets of earthquake motions were used to excite the rock mass. The methodology applied was found to be suitable for studying the effects of earthquakes on underground openings. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass; however, a tremor with accelerations up to 0.95 g was amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In situ stress is a critical parameter in determining the subsurface effects of earthquakes but is nonexistent in evaluating the cause for surface damage. In shale with the properties assumed, even the moderate seismic load resulted in tunnel instability. These studies are all generic in nature and do not abrogate the need for site and design studies for specific facilities. 30 references, 14 figures, 8 tables

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.

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

Sampling and treatment of rock cores and groundwater under reducing environments of deep underground

International Nuclear Information System (INIS)

Ebashi, Katsuhiro; Yamaguchi, Tetsuji; Tanaka, Tadao

2005-01-01

A method of sampling and treatment of undisturbed rock cores and groundwater under maintained reducing environments of deep underground was developed and demonstrated in a Neogene's sandy mudstone layer at depth of GL-100 to -200 m. Undisturbed rock cores and groundwater were sampled and transferred into an Ar gas atmospheric glove box with minimized exposure to the atmosphere. The reducing conditions of the sampled groundwater and rock cores were examined in the Ar atmospheric glove box by measuring pH and Eh of the sampled groundwater and sampled groundwater contacting with disk type rock samples, respectively. (author)

Development of excavation technologies at the Canadian underground research laboratory

International Nuclear Information System (INIS)

Kuzyk, Gregory W.; Martino, Jason B.

2008-01-01

Several countries, Canada being among them, are developing concepts for disposal of used fuel from power generating nuclear reactors. As in underground mining operations, the disposal facilities will require excavation of many kilometres of shafts and tunnels through the host rock mass. The need to maintain the stability of excavations and safety of workers will be of paramount importance. Also, excavations required for many radioactive waste repositories will ultimately need to be backfilled and sealed to maintain stability and minimize any potential for migration of radionuclides, should they escape their disposal containers. The method used to excavate the tunnels and shafts, and the rock damage that occurs due to excavation, will greatly affect the performance characteristics of repository sealing systems. The underground rock mechanics and geotechnical engineering work performed at the Canadian Underground Research Laboratory (URL) has led to the development of excavation technologies that reduce rock damage in subsurface excavations. This paper discusses the excavation methods used to construct the URL and their application in planning for the construction of similar underground laboratories and repositories for radioactive wastes. (author)

Numerical modeling of the viscoplastic damage behaviour of rocks and application to underground storage facilities

International Nuclear Information System (INIS)

Hajdu, A.

2003-12-01

The long-term behavior of large, underground works of a civil engineering nature carried out in a rock mass is currently the subject of numerous studies. The object is to attain a better understanding of complex phenomena, such as the convergence of excavated cavities or the outbreak and development of damaged zones in the rock mass neighboring the works, in order to foresee them. This Ph.D. thesis is devoted to the analysis of viscoplastic strain in rocks and to the degradation of their mechanical properties with time, often referred to as deferred damage. A bibliographical record presents the current depth of understanding as regards underlying microstructural phenomena and summarizes the main theories upon which the modeling of these phenomena at the macroscopic scale is based. The formulations enabling a coupling between the viscous effects and the deferred damage are revisited and discussed in detail. One phenomenological model in particular, Lemaitre's viscoplastic constitutive damage law is retained for the numerical modeling. The calculations were performed with the help of a finite element code (CAST3M). Designs of nuclear waste disposal structures at great depth make up the subject of different case studies. The Lemaitre model, originally designed for metallic materials, is next the subject of a theoretical development of which the aim is to better adapt it to the description of the long-term mechanical behavior of rocks. The modifications focus on several points; notably that the hypotheses of anelastic strain at constant volume and of isotropy of damage are rejected. The main characteristics of time-dependent strain in rocks; in particular the phenomena of viscoplastic dilation and contraction as well as the anisotropy induced by damage to the rock matrix are reproduced by the proposed model. A parametric study is then undertaken, using the experimental results obtained on different types of rock, in order to demonstrate the model's capabilities

Rokibaar Underground = Rock bar Underground

Index Scriptorium Estoniae

2008-01-01

Rokibaari Underground (Küütri 7, Tartu) sisekujundus, mis pälvis Eesti Sisearhitektide Liidu 2007. a. eripreemia. Sisearhitekt: Margus Mänd (Tammat OÜ). Margus Männist, tema tähtsamad tööd. Plaan, 5 värv. vaadet, foto M. Männist

Information collection regarding geoscientific monitoring techniques during closure of underground facility in crystalline rock

International Nuclear Information System (INIS)

Hosoya, Shinichi; Yamashita, Tadashi; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onoe, Hironori; Ishibashi, Masayuki

2016-01-01

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock (granite) at Mizunami City in Gifu Prefecture, central Japan. On the occasion of the reform of the entire JAEA organization in 2014, JAEA identified the critical issues on the geoscientific research program: “Development of modelling technologies for mass transport”, “Development of drift backfilling technologies” and “Development of technologies for reducing groundwater inflow”, based on the latest results of the synthesizing R and D. The purposes of the “Development of drift backfilling technologies” are to develop closure methodology and technology, and long-term monitoring technology, and to evaluate resilience of geological environment. In order to achieve the purposes, previous information from the case example of underground facility constructed in crystalline rock in Europe has been collected in this study. In particular, the boundary conditions for the closure, geological characteristics, technical specifications, and method of monitoring have been focused. The information on the international project regarding drift closure test and development of monitoring technologies has also been collected. In addition, interviews were conducted to Finnish and Swedish specialists who have experiences involving planning, construction management, monitoring, and safety assessment for the closure to obtain the technical knowledge. Based on the collected information, concept and point of attention, which are regarding drift closure testing, and planning, execution management and monitoring on the closure of MIU, have been specified. (author)

Solid as a rock

International Nuclear Information System (INIS)

Pincus, H.J.

1984-01-01

Recent technologic developments have required a more comprehensive approach to the behavior of rock mass or rock substance plus discontinuities than was adequate previously. This work considers the inherent problems in such operations as the storage of hot or cold fluids in caverns and aquifers, underground storage of nuclear waste, underground recovery of heat from hydrocarbon fuels, tertiary recovery of oil by thermal methods, rapid excavation of large openings at shallow to great depths and in hostile environments, and retrofitting of large structures built on or in rock. The standardization of methods for determining rock properties is essential to all of the activities described, for use not only in design and construction but also in site selection and post-construction monitoring. Development of such standards is seen as a multidisciplinary effort

Two Sources of Nonisotropic Radiation From Underground Explosions in Granite

International Nuclear Information System (INIS)

Vorobiev, O. Yu.

2017-01-01

Significant tangential ground motion observed during underground explosions makes it difficult to distinguish them from natural earthquakes. Such motion can be generated by the source geometry and emplacement conditions, by the heterogeneous nature of the rock mass (mechanical properties may vary in space due to the presence of cracks, joints, faults, and various geologic layers) and also by the nonuniform in situ stress state. The last mechanism is increasingly important with depth when the difference in main principal stresses becomes significant. This paper is focused on the role of material strength of the rock mass in generation of nonradial motion during explosions in prestressed media. Numerical modeling of underground chemical explosions in granite at various depths has been conducted to compare two possible mechanisms of shear wave generation. The first, caused by rock mass anisotropy, is important at shallow depth. The second is related to elastic-plastic relaxation around the cavity created by the explosion. As a result, tangential motions for these two mechanisms have different signatures.

The role of post-failure brittleness of soft rocks in the assessment of stability of intact masses: FDEM technique applications to ideal problems

Science.gov (United States)

Lollino, Piernicola; Andriani, Gioacchino Francesco; Fazio, Nunzio Luciano; Perrotti, Michele

2016-04-01

Strain-softening under low confinement stress, i.e. the drop of strength that occurs in the post-failure stage, represents a key factor of the stress-strain behavior of rocks. However, this feature of the rock behavior is generally underestimated or even neglected in the assessment of boundary value problems of intact soft rock masses. This is typically the case when the stability of intact rock masses is treated by means of limit equilibrium or finite element analyses, for which rigid-plastic or elastic perfectly-plastic constitutive models, generally implementing peak strength conditions of the rock, are respectively used. In fact, the aforementioned numerical techniques are characterized by intrinsic limitations that do not allow to account for material brittleness, either for the method assumptions or due to numerical stability problems, as for the case of the finite element method, unless sophisticated regularization techniques are implemented. However, for those problems that concern the stability of intact soft rock masses at low stress levels, as for example the stability of shallow underground caves or that of rock slopes, the brittle stress-strain response of rock in the post-failure stage cannot be disregarded due to the risk of overestimation of the stability factor. This work is aimed at highlighting the role of post-peak brittleness of soft rocks in the analysis of specific ideal problems by means of the use of a hybrid finite-discrete element technique (FDEM) that allows for the simulation of the rock stress-strain brittle behavior in a proper way. In particular, the stability of two ideal cases, represented by a shallow underground rectangular cave and a vertical cliff, has been analyzed by implementing a post-peak brittle behavior of the rock and the comparison with a non-brittle response of the rock mass is also explored. To this purpose, the mechanical behavior of a soft calcarenite belonging to the Calcarenite di Gravina formation, extensively

Analysis of rock mass dynamic impact influence on the operation of a powered roof support control system

Science.gov (United States)

Szurgacz, Dawid; Brodny, Jaroław

2018-01-01

A powered roof support is a machine responsible for protection of an underground excavation against deformation generated by rock mass. In the case of dynamic impact of rock mass, the proper level of protection is hard to achieve. Therefore, the units of the roof support and its components are subject to detailed tests aimed at acquiring greater reliability, efficiency and efficacy. In the course of such test, however, it is not always possible to foresee values of load that may occur in actual conditions. The article presents a case of a dynamic load impacting the powered roof support during a high-energy tremor in an underground hard coal mine. The authors discuss the method for selecting powered roof support units proper for specific forecasted load conditions. The method takes into account the construction of the support and mining and geological conditions of an excavation. Moreover, the paper includes tests carried out on hydraulic legs and yield valves which were responsible for additional yielding of the support. Real loads impacting the support unit during tremors are analysed. The results indicated that the real registered values of the load were significantly greater than the forecasted values. The analysis results of roof support operation during dynamic impact generated by the rock mass (real life conditions) prompted the authors to develop a set of recommendations for manufacturers and users of powered roof supports. These include, inter alia, the need for innovative solutions for testing hydraulic section systems.

Influence of rock spalling on concrete lining in shaft sinking at the Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Tsusaka, Kimikazu; Inagaki, Daisuke; Nago, Makito; Koike, Masashi; Matsubara, Makoto; Sugawara, Kentaro

2013-01-01

A shaft is the shortest way to access the deep underground. In shaft sinking through large-scale faults or under low competence factor, spalling of shaft walls is likely to occur. Although earlier studies indicated that rock spalling is an undesirable phenomenon that threatens safety in excavation work and causes delay in construction schedule, there have been few studies which discussed damage to concrete lining induced by spalling. Japan Atomic Energy Agency has been constructing three shafts (one for ventilation and the others for access) to a depth of 500 m in the Horonobe Underground Research Laboratory. During the construction of the Ventilation Shaft (4.5 m diameter) below a depth of 250 m, rock spalling occurred at several depths and an open crack developed in the concrete lining installed just above the location of the rock spalling. In this study, the geometry of the shaft wall was measured using a three-dimensional laser scanner. Numerical analysis was also conducted to estimate changes in stress distribution and deformation induced by rock spalling in both the concrete lining and the surrounding rock. As a result, it was clarified that rock spalling induced a vertical tensile stress in the concrete lining. Especially, the tensile stress in a concrete lining was likely to exceed the tensile strength of the concrete lining when it developed more than 100 cm into the wall rock. (author)

Fuzzy mathematics method for theoretical analysis of ground movements due to underground excavation

Energy Technology Data Exchange (ETDEWEB)

Li Wenxiu (Changsa Research Institute of Mining and Metallurgy, Changsa (China))

1991-07-01

The analysis of the rock mass movements due to excavation operations is one of the many important problems of rock mass mechanics. It is difficult to calculate the ground movements due to underground excavation accurately because of the complexity of the problem. In this paper, the application is described of the fuzzy probability measures to the analysis of ground movements. Based on the definition of the fuzzy probability measure, the theories for both the two-dimensional and three-dimensional problems are developed and are applied to the analysis of ground movements due to underground excavation. 31 refs., 5 figs.

Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

Directory of Open Access Journals (Sweden)

Xuguang Chen

2014-01-01

Full Text Available Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.

Numerical simulation on zonal disintegration in deep surrounding rock mass.

Science.gov (United States)

Chen, Xuguang; Wang, Yuan; Mei, Yu; Zhang, Xin

2014-01-01

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.

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.

75 FR 57849 - Maintenance of Incombustible Content of Rock Dust in Underground Coal Mines

Science.gov (United States)

2010-09-23

... correlation between higher job risk and higher wages, suggesting that employees demand monetary compensation... DEPARTMENT OF LABOR Mine Safety and Health Administration 30 CFR Part 75 RIN 1219-AB76 Maintenance of Incombustible Content of Rock Dust in Underground Coal Mines AGENCY: Mine Safety and Health...

Underground reactor containments: An option for the future?

International Nuclear Information System (INIS)

Forsberg, C.W.; Kress, T.

1997-01-01

Changing world conditions and changing technologies suggest that serious consideration should be given to siting of nuclear power plants underground. Underground siting is not a new concept. Multiple research reactors, several weapons production reactors, and one power reactor have been built underground. What is new are the technologies and incentives that may now make underground siting a preferred option. The conditions and technologies, along with their implications, are discussed herein. Underground containments can be constructed in mined cavities or pits that are then backfilled with thick layers of rock and soil. Conventional above-ground containments resist assaults and accidents because of the strength of their construction materials and the effectiveness of their safety features that are engineered to reduce loads. However, underground containments can provide even more resistance to assaults and accidents because of the inertia of the mass of materials over the reactor. High-technology weapons or some internal accidents can cause existing strong-material containments to fail, but only very-high energy releases can move large inertial masses associated with underground containments. New methods of isolation may provide a higher confidence in isolation that is independent of operator action

Deformation properties of sedimentary rocks in the process of underground coal gasification

Directory of Open Access Journals (Sweden)

Mirosława Bukowska

2015-01-01

Full Text Available The article presents results of research into changes in deformation properties of rocks, under influence of temperature, during the process of underground coal gasification. Samples of carboniferous sedimentary rocks (claystones and sandstones, collected in different areas of Upper Silesian Coal Basin (GZW, were heated at the temperature of between 100 and 1000–1200 °C, and then subjected to uniaxial compression tests to obtain a full stress-strain curves of the samples and determine values of residual strain and Poisson's ratio. To compare the obtained values of deformation parameters of rocks, tested in dry-air state and after heating in a given range of temperature, normalised values of residual strain and Poisson's ratio were determined. Based on them, coefficient of influence of temperature on tested deformation parameters was determined. The obtained values of the coefficient can be applied in mining practice to forecast deformability of gangue during underground coal gasification, when in the direct surrounding of a georeactor there are claystones or sandstones. The obtained results were analysed based on classification of uniaxial compression strength of GZW gangue, which formed the basis for dividing claystones and sandstones into very low, low, medium and high uniaxial compression strength rocks. Based on the conducted tests it was concluded that the influence of uniaxial compression strength on the value of residual strain, unlike the influence of grain size of sandstones, is unambiguous within the range of changes in the parameter. Among claystones changes in the value of Poisson's ratio depending on their initial strength were observed. Sandstones of different grain size either increased or decreased the value of Poisson's ratio in comparison with the value determined at room temperature in dry-air conditions.

Critical assessment of seismic and geomechanics literature related to a high-level nuclear waste underground repository

Energy Technology Data Exchange (ETDEWEB)

Kana, D.D.; Vanzant, B.W.; Nair, P.K. [Southwest Research Inst., San Antonio, TX (USA). Center for Nuclear Waste Regulatory Analyses; Brady, B.H.G. [ITASCA Consulting Group, Inc., Minneapolis, MN (USA)

1991-06-01

A comprehensive literature assessment has been conducted to determine the nature and scope of technical information available to characterize the seismic performance of an underground repository and associated facilities. Significant deficiencies were identified in current practices for prediction of seismic response of underground excavations in jointed rock. Conventional analytical methods are based on a continuum representation of the host rock mass. Field observations and laboratory experiments indicate that, in jointed rock, the behavior of the joints controls the overall performance of underground excavations. Further, under repetitive seismic loading, shear displacement develops progressively at block boundaries. Field observations correlating seismicity and groundwater conditions have provided significant information on hydrological response to seismic events. However, lack of a comprehensive model of geohydrological response to seismicity has limited the transportability conclusions from field observations. Based on the literature study, matters requiring further research in relation to the Yucca Mountain repository are identified. The report focuses on understanding seismic processes in fractured tuff, and provides a basis for work on the geohydrologic response of a seismically disturbed rock mass. 220 refs., 43 figs., 11 tabs.

Critical assessment of seismic and geomechanics literature related to a high-level nuclear waste underground repository

International Nuclear Information System (INIS)

Kana, D.D.; Vanzant, B.W.; Nair, P.K.

1991-06-01

A comprehensive literature assessment has been conducted to determine the nature and scope of technical information available to characterize the seismic performance of an underground repository and associated facilities. Significant deficiencies were identified in current practices for prediction of seismic response of underground excavations in jointed rock. Conventional analytical methods are based on a continuum representation of the host rock mass. Field observations and laboratory experiments indicate that, in jointed rock, the behavior of the joints controls the overall performance of underground excavations. Further, under repetitive seismic loading, shear displacement develops progressively at block boundaries. Field observations correlating seismicity and groundwater conditions have provided significant information on hydrological response to seismic events. However, lack of a comprehensive model of geohydrological response to seismicity has limited the transportability conclusions from field observations. Based on the literature study, matters requiring further research in relation to the Yucca Mountain repository are identified. The report focuses on understanding seismic processes in fractured tuff, and provides a basis for work on the geohydrologic response of a seismically disturbed rock mass. 220 refs., 43 figs., 11 tabs

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)

Review of excavation methods and their implications for the near-field barrier of a deep underground repository

International Nuclear Information System (INIS)

Young, D.K.

1993-01-01

The report reviews excavation techniques for use in the construction of deep underground radioactive waste repositories, gives a summary of responses of the host rock to excavation and the means of measuring that response and discusses techniques for predicting that response. The review of excavation techniques included technical developments and current practice. To this end an extensive database was developed reviewing major excavations in rock types relevant to disposal and the techniques employed. Creation of an underground opening alters the properties of the rock mass around it. This study identifies stress, displacement, rock mass deformability and permeability as key parameters and reviews how they may be determined. Finally the report discusses the techniques available for predicting the behaviour of the near-field host rock. This concentrates on methods of numerical analysis since existing empirical or analytical methods are not considered suitable. (author)

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.

Influence of the Elastic Dilatation of Mining-Induced Unloading Rock Mass on the Development of Bed Separation

Directory of Open Access Journals (Sweden)

Weibing Zhu

2018-03-01

Full Text Available Understanding how mining-induced strata movement, fractures, bed separation, and ground subsidence evolve is an area of great importance for the underground coal mining industry, particularly for disaster control and sustainable mining. Based on the rules of mining-induced strata movement and stress evolution, accumulative dilatation of mining-induced unloading rock mass is first proposed in this paper. Triaxial unloading tests and theoretical calculation were used to investigate the influence of elastic dilatation of mining-induced unloading rock mass on the development of bed separation in the context of district No. 102 where a layer of super-thick igneous sill exists in the Haizi colliery. It is shown that the elastic dilatation coefficient of mining-induced unloading hard rocks and coal were 0.9~1.0‰ and 2.63‰ respectively under the axial load of 16 MPa, which increased to 1.30~1.59‰ and 4.88‰ when the axial load was 32 MPa. After successively excavating working faces No. 1022 and No. 1024, the elastic dilatation of unloading rock mass was 157.9 mm, which represented approximately 6.3% of the mining height, indicating the elastic dilatation of mining-induced unloading rock mass has a moderate influence on the development of bed separation. Drill hole detection results after grouting, showed that only 0.33 m of the total grouting filling thickness (1.67 m was located in the fracture zone and bending zone, which verified the result from previous drill hole detection that only small bed separation developed beneath the igneous sill. Therefore, it was concluded that the influences of elastic dilatation of mining-induced unloading rock mass and bulking of caved rock mass jointly contributed to the small bed separation space beneath the igneous sill. Since the accurate calculation of the unloading dilatation of rock mass is the fundamental basis for quantitative calculation of bed separation and surface subsidence, this paper is expected

Siting technology of underground nuclear power station

International Nuclear Information System (INIS)

Motojima, M.; Hibino, S.

1989-01-01

For the site of a nuclear power station, it may be possible to select a seaside mountain area, if the condition is suitable to excavate large rock caverns in which a reactor and other equipments are installed. As the case study on the siting technology for an underground nuclear power station, the following example was investigated. The site is a seaside steep mountain area, and almost all the equipments are installed in plural tunnel type caverns. The depth from the ground surface to the top of the reactor cavern is about 150 m, and the thickness of the rock pillar between the reactor cavern of 33 m W x 82 mH x 79 mD and the neighboring turbine cavern is 60 m. In this paper, the stability of rock caverns in this example, evaluated by numerical analysis, is described. The numerical analysis was carried out on the central cross section of the reactor cavern, taking the turbine cavern, geostress, the mechanical properties of rock mass and the process of excavation works in consideration. By the analysis, the underground caverns in this example were evaluated as stable, if the rock quality is equivalent to C H class or better according to the CRIEPI rock classification. (K.I.)

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.

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

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

Analysis of EDZ Development of Columnar Jointed Rock Mass in the Baihetan Diversion Tunnel

Science.gov (United States)

Hao, Xian-Jie; Feng, Xia-Ting; Yang, Cheng-Xiang; Jiang, Quan; Li, Shao-Jun

2016-04-01

Due to the time dependency of the crack propagation, columnar jointed rock masses exhibit marked time-dependent behaviour. In this study, in situ measurements, scanning electron microscope (SEM), back-analysis method and numerical simulations are presented to study the time-dependent development of the excavation damaged zone (EDZ) around underground diversion tunnels in a columnar jointed rock mass. Through in situ measurements of crack propagation and EDZ development, their extent is seen to have increased over time, despite the fact that the advancing face has passed. Similar to creep behaviour, the time-dependent EDZ development curve also consists of three stages: a deceleration stage, a stabilization stage, and an acceleration stage. A corresponding constitutive model of columnar jointed rock mass considering time-dependent behaviour is proposed. The time-dependent degradation coefficient of the roughness coefficient and residual friction angle in the Barton-Bandis strength criterion are taken into account. An intelligent back-analysis method is adopted to obtain the unknown time-dependent degradation coefficients for the proposed constitutive model. The numerical modelling results are in good agreement with the measured EDZ. Not only that, the failure pattern simulated by this time-dependent constitutive model is consistent with that observed in the scanning electron microscope (SEM) and in situ observation, indicating that this model could accurately simulate the failure pattern and time-dependent EDZ development of columnar joints. Moreover, the effects of the support system provided and the in situ stress on the time-dependent coefficients are studied. Finally, the long-term stability analysis of diversion tunnels excavated in columnar jointed rock masses is performed.

Fragment Size Distribution of Blasted Rock Mass

Science.gov (United States)

Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

2017-12-01

Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

Research of compression strength of fissured rock mass

Directory of Open Access Journals (Sweden)

А. Г. Протосеня

2017-03-01

Full Text Available The article examines a method of forecasting strength properties and their scale effect in fissured rock mass using computational modelling with final elements method in ABAQUS software. It shows advantages of this approach for solving tasks of determining mechanical properties of fissured rock mass, main stages of creating computational geomechanic model of rock mass and conducting a numerical experiment. The article presents connections between deformation during loading of numerical model, inclination angle of main fracture system from uniaxial and biaxial compression strength value, size of the sample of fissured rock mass and biaxial compression strength value under conditions of apatite-nepheline rock deposit at Plateau Rasvumchorr OAO «Apatit» in Kirovsky region of Murmanskaya oblast. We have conducted computational modelling of rock mass blocks testing in discontinuities based on real experiment using non-linear shear strength criterion of Barton – Bandis and compared results of computational experiments with data from field studies and laboratory tests. The calculation results have a high-quality match to laboratory results when testing fissured rock mass samples.

Effect of excavation method on rock mass displacement

International Nuclear Information System (INIS)

Sato, Toshinori; Kikuchi, Tadashi; Sugihara, Kozo

1998-01-01

Rock mass displacement measurements have been performed to understand rock mass behavior and its dependence on excavation method during drift excavation at the Tono mine. Rock mass displacements of 1.46 mm and 0.67 mm have been measured at one meter (0.33D: blasting, 0.42D: machine, D: width of drift) from the walls of drifts excavated by the drill and blasting method and machine, respectively. Numerical analysis of rock mass displacements with Finite Element Method has been performed assuming an excavation disturbed zone. Measured and analysed rock mass displacements are consistent with each other for the drift excavation by the drill and blasting method. The excavation disturbed zone was narrower for the drift excavated by machine than for the drift excavated by the drill and blasting method. (author)

Geological disposal of high-level radioactive waste and the role of rock engineering

International Nuclear Information System (INIS)

Sugihara, Kozo

2008-01-01

Japan Atomic Energy Agency (JAEA) and its predecessors have been conducting an extensive geoscientific research program since the 1970's in order to contribute to the formation of a firm scientific and technological basis for the geological disposal of high level radioactive waste in Japan. As a part of this program, in situ experiments have been performed at the Tono Mine in soft sedimentary rocks and at the Kamaishi Mine in hard crystalline rocks. An experiment on excavation disturbance has been one of these experiments and has revealed the extent and properties of the excavation disturbed zone (EDZ) and the applicability of available measurement methods. It is suggested that mechanical excavation and controlled excavation have reduced excavation damage of the rock mass around a drift, although some improvements in the currently available methods for measuring and simulating the EDZ are essential to understand excavation disturbance in more detail. JAEA is now promoting two underground research laboratory projects in Japan; the Mizunami Underground Research Laboratory (MIU) project for crystalline rocks and the Horonobe Underground Research Laboratory (Horonobe URL) project for sedimentary rocks. From a rock mechanical point of view, the major interest in these projects will be paid to failure phenomenon deep underground, rock stress estimation at larger scales and long-term physical stability of underground structure. These projects are open for international collaboration. (author)

Numerical simulation of phenomenon on zonal disintegration in deep underground mining in case of unsupported roadway

Science.gov (United States)

Han, Fengshan; Wu, Xinli; Li, Xia; Zhu, Dekang

2018-02-01

Zonal disintegration phenomenon was found in deep mining roadway surrounding rock. It seriously affects the safety of mining and underground engineering and it may lead to the occurrence of natural disasters. in deep mining roadway surrounding rock, tectonic stress in deep mining roadway rock mass, horizontal stress is much greater than the vertical stress, When the direction of maximum principal stress is parallel to the axis of the roadway in deep mining, this is the main reasons for Zonal disintegration phenomenon. Using ABAQUS software to numerical simulation of the three-dimensional model of roadway rupture formation process systematically, and the study shows that when The Direction of maximum main stress in deep underground mining is along the roadway axial direction, Zonal disintegration phenomenon in deep underground mining is successfully reproduced by our numerical simulation..numerical simulation shows that using ABAQUA simulation can reproduce Zonal disintegration phenomenon and the formation process of damage of surrounding rock can be reproduced. which have important engineering practical significance.

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.

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.

Assessment of rock mass decay in artificial slopes

NARCIS (Netherlands)

Huisman, M.

2006-01-01

This research investigates the decay of rock masses underlying slopes, and seeks to quantify the relations of such decay with time and geotechnical parameters of the slope and rock mass. Decay can greatly affect the geotechnical properties of rocks within engineering timescales, and may induce a

Geophysical aspects of underground fluid dynamics and mineral transformation process

Science.gov (United States)

Khramchenkov, Maxim; Khramchenkov, Eduard

2014-05-01

The description of processes of mass exchange between fluid and poly-minerals material in porous media from various kinds of rocks (primarily, sedimentary rocks) have been examined. It was shown that in some important cases there is a storage equation of non-linear diffusion equation type. In addition, process of filtration in un-swelling soils, swelling porous rocks and coupled process of consolidation and chemical interaction between fluid and particles material were considered. In the latter case equations of physical-chemical mechanics of conservation of mass for fluid and particles material were used. As it is well known, the mechanics of porous media is theoretical basis of such branches of science as rock mechanics, soil physics and so on. But at the same moment some complex processes in the geosystems lacks full theoretical description. The example of such processes is metamorphosis of rocks and correspondent variations of stress-strain state. In such processes chemical transformation of solid and fluid components, heat release and absorption, phase transitions, rock destruction occurs. Extensive usage of computational resources in limits of traditional models of the mechanics of porous media cannot guarantee full correctness of obtained models and results. The process of rocks consolidation which happens due to filtration of underground fluids is described from the position of rock mechanics. As an additional impact, let us consider the porous media consolidating under the weight of overlying rock with coupled complex geological processes, as a continuous porous medium of variable mass. Problems of obtaining of correct storage equations for coupled processes of consolidation and mass exchange between underground fluid and skeleton material are often met in catagenesi processes description. The example of such processes is metamorphosis of rocks and correspondent variations of stress-strain state. In such processes chemical transformation of solid and fluid

Earthquake damage to underground facilities

International Nuclear Information System (INIS)

Pratt, H.R.; Stephenson, D.E.; Zandt, G.; Bouchon, M.; Hustrulid, W.A.

1980-01-01

In order to assess the seismic risk for an underground facility, a data base was established and analyzed to evaluate the potential for seismic disturbance. Substantial damage to underground facilities is usually the result of displacements primarily along pre-existing faults and fractures, or at the surface entrance to these facilities. Evidence of this comes from both earthquakes and large explosions. Therefore, the displacement due to earthquakes as a function of depth is important in the evaluation of the hazard to underground facilities. To evaluate potential displacements due to seismic effects of block motions along pre-existing or induced fractures, the displacement fields surrounding two types of faults were investigated. Analytical models were used to determine relative displacements of shafts and near-surface displacement of large rock masses. Numerical methods were used to determine the displacement fields associated with pure strike-slip and vertical normal faults. Results are presented as displacements for various fault lengths as a function of depth and distance. This provides input to determine potential displacements in terms of depth and distance for underground facilities, important for assessing potential sites and design parameters

Seismic response of rock joints and jointed rock mass

International Nuclear Information System (INIS)

Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

1996-06-01

Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts and the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs

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

Geological data summary for a borehole drilled between 1991 September 16 and 1991 October 1 for the Transport Properties in Highly Fractured Rock Experiment at the Underground Research Laboratory

Energy Technology Data Exchange (ETDEWEB)

Woodcock, D. R.; Everitt, R. A.

1992-08-01

Borehole 101-013-HG4 was drilled between 1991 September 16 and October 1 from the 130 Level station, as part of the Transport Properties in Highly Fractured Rock Experiment, to explore the geological, hydrogeological and geochemical conditions of the rock mass in an area northwest of the Underground Research Laboratory (URL) shaft. The borehole was drilled to provide information at an intersection with Fracture Zone 2.0, 100 m to the west of boreholes collared from Room 211 of the 240 Level for future solute transport experiments within Fracture Zone 2.0, and to further our understanding of the rock mass in the area. Fracture Zones 2.5, 2.0, 1.9 and a subvertical joint zone in the footwall were all intersected in the borehole. Preliminary results from detailed core logging show that the lithostructural domains intersected in the borehole correlate with those previously identified in the URL shaft, and in nearby exploration boreholes drilled from the 130 Level. The domains are shallow-dipping toward the southeast and are parallel to the three main fracture zones intersected in the borehole.

Conducting Rock Mass Rating for tunnel construction on Mars

Science.gov (United States)

Beemer, Heidi D.; Worrells, D. Scott

2017-10-01

Mars analogue missions provide researchers, scientists, and engineers the opportunity to establish protocols prior to sending human explorers to another planet. This paper investigated the complexity of a team of simulation astronauts conducting a Rock Mass Rating task during Analogue Mars missions. This study was conducted at the Mars Desert Research Station in Hanksville, UT, during field season 2015/2016 and with crews 167,168, and 169. During the experiment, three-person teams completed a Rock Mass Rating task during a three hour Extra Vehicular Activity on day six of their two-week simulation mission. This geological test is used during design and construction of excavations in rock on Earth. On Mars, this test could be conducted by astronauts to determine suitable rock layers for tunnel construction which would provide explorers a permanent habitat and radiation shielding while living for long periods of time on the surface. The Rock Mass Rating system derives quantitative data for engineering designs that can easily be communicated between engineers and geologists. Conclusions from this research demonstrated that it is feasible for astronauts to conduct the Rock Mass Rating task in a Mars simulated environment. However, it was also concluded that Rock Mass Rating task orientation and training will be required to ensure that accurate results are obtained.

Rock Physical Interpretation of the Relationship between Dynamic and Static Young's Moduli of Sedimentary Rocks

Science.gov (United States)

Takahashi, T.

2017-12-01

The static Young's modulus (deformability) of a rock is indispensable for designing and constructing tunnels, dams and underground caverns in civil engineering. Static Young's modulus which is an elastic modulus at large strain level is usually obtained with the laboratory tests of rock cores sampled in boreholes drilled in a rock mass. A deformability model of the entire rock mass is then built by extrapolating the measurements based on a rock mass classification obtained in geological site characterization. However, model-building using data obtained from a limited number of boreholes in the rock mass, especially a complex rock mass, may cause problems in the accuracy and reliability of the model. On the other hand, dynamic Young's modulus which is the modulus at small strain level can be obtained from seismic velocity. If dynamic Young's modulus can be rationally converted to static one, a seismic velocity model by the seismic method can be effectively used to build a deformability model of the rock mass. In this study, we have, therefore, developed a rock physics model (Mavko et al., 2009) to estimate static Young's modulus from dynamic one for sedimentary rocks. The rock physics model has been generally applied to seismic properties at small strain level. In the proposed model, however, the sandy shale model, one of rock physics models, is extended for modeling the static Young's modulus at large strain level by incorporating the mixture of frictional and frictionless grain contacts into the Hertz-Mindlin model. The proposed model is verified through its application to the dynamic Young's moduli derived from well log velocities and static Young's moduli measured in the tri-axial compression tests of rock cores sampled in the same borehole as the logs were acquired. This application proves that the proposed rock physics model can be possibly used to estimate static Young's modulus (deformability) which is required in many types of civil engineering applications

Energy extracted from underground rock area by using a horizontal closed loop system in Mutah University/Jordan

International Nuclear Information System (INIS)

Al-Dabbas, Mohammed Awwad Ali; Al-Rousan, Ammar A.

2013-01-01

Highlights: ► The ground can be used as a storage tank to store hot or cooled water in Jordan. ► The stored energy in rocks was utilized to provide heating cooling, and hot water for homes. ► The underground geothermal horizontal loop in rocks was technically approved. ► It can extract up to six times the heat energy that used in electrical energy. ► Its low capital cost and zero environmental emissions. - Abstract: Earth Energy Systems (EESs) utilize the thermal energy that is stored in rocks and ground water under the earth’s surface to provide homes, commercial buildings, and industrial facilities with heating, cooling, and hot water. Solar energy is absorbed by the earth’s surface which stores up to 50% of the sun’s energy that radiates on it. Consequently, the earth and groundwater’s temperature is relatively constant compared to that of the surface air. The earth’s temperature is generally warmer than the surface temperature during the colder months of the year, while it is generally cooler than the surface temperature during the hot months of the year. In this study, energy was extracted from the underground rocks at Mutah University in Jordan by using the geothermal horizontal closed loop system. Two-meter holes were drilled into the earth’s surface; copper pipes were inserted for liquid to pass through them into the heat exchange system. Then, the liquid was circulated back into the ground. Several temperature differences were measured and reported in the cold and hot months. The experimental results showed that thermal energy stored in rocks can be used to provide homes with heating, cooling, and hot water with low capital cost and zero environmental emissions.

The principle of measuring unusual change of underground mass by optical astrometric instrument

Directory of Open Access Journals (Sweden)

Wang Jiancheng

2012-11-01

In this study, we estimate the deflection angle of the plumb line on a ground site, and give a relation between the angle, abnormal mass and site distance (depth and horizontal distance. Then we derive the abnormality of underground material density using the plumb lines measured at different sites, and study the earthquake gestation, development and occurrence. Using the deflection angles of plumb lines observed at two sites, we give a method to calculate the mass and the center of gravity of underground materials. We also estimate the abnormal masses of latent seismic zones with different energy, using thermodynamic relations, and introduce a new optical astrometric instrument we had developed.

Concept of underground nuclear power plant

International Nuclear Information System (INIS)

Onishi, Sotoaki

1976-01-01

The concept of constructing nuclear power plants on the sea or underground as the future sitting is based on moving the present power plants on the ground with actual results to the sea or underground without changing the design. The underground nuclear power plants have many similar points to underground hydro-electric power stations with many achievements in the construction viewpoint, though they have their proper difficult problems. Of course, it requires to excavate larger underground caves than the case of underground hydro-electric power plants. The maximum dimensions of the caves have been determined through experience in practice. Therefore the developments of design theory and construction technique are desirable in this field. In discussing underground construction, two evaluating methods are considered for the shielding effect of base rocks. The minimum vertical distance up to ground surface from the center of the cave differs depending upon the in-cave pressure, and the conditions of base rock, soil and underground water in case of the accident assumed in the design, and is approximately 60m, if the cave is assumed to be an indefinite cylindrical shape, by the safer side calculation in the above two evaluations. (Wakatsuki, Y.)

A method of modeling time-dependent rock damage surrounding underground excavations in multiphase groundwater flow

International Nuclear Information System (INIS)

Christian-Frear, T.; Freeze, G.

1997-01-01

Underground excavations produce damaged zones surrounding the excavations which have disturbed hydrologic and geomechanical properties. Prediction of fluid flow in these zones must consider both the mechanical and fluid flow processes. Presented here is a methodology which utilizes a mechanical model to predict damage and disturbed rock zone (DRZ) development around the excavation and then uses the predictions to develop time-dependent DRZ porosity relationships. These relationships are then used to adjust the porosity of the DRZ in the fluid flow model based upon the time and distance from the edge of the excavation. The application of this methodology is presented using a site-specific example from the Waste Isolation Pilot Plant, a US Department of Energy facility in bedded salts being evaluated for demonstration of the safe underground disposal of transuranic waste from US defense-related activities

Mineral and chemical composition of rock core and surface gas composition in Horonobe Underground Research Laboratory project. Phase 1

International Nuclear Information System (INIS)

Hiraga, Naoto; Ishii, Eiichi

2008-02-01

The following three kinds of analyses were conducted for the 1st phase of the Horonobe Underground Research Laboratory Project. Mineral composition analysis of core sample. Whole rock chemical composition analysis of core sample. Surface gas composition analysis. This document summarizes the results of these analyses. (author)

Sanford Underground Research Facility - The United State's Deep Underground Research Facility

Science.gov (United States)

Vardiman, D.

2012-12-01

The 2.5 km deep Sanford Underground Research Facility (SURF) is managed by the South Dakota Science and Technology Authority (SDSTA) at the former Homestake Mine site in Lead, South Dakota. The US Department of Energy currently supports the development of the facility using a phased approach for underground deployment of experiments as they obtain an advanced design stage. The geology of the Sanford Laboratory site has been studied during the 125 years of operations at the Homestake Mine and more recently as part of the preliminary geotechnical site investigations for the NSF's Deep Underground Science and Engineering Laboratory project. The overall geology at DUSEL is a well-defined stratigraphic sequence of schist and phyllites. The three major Proterozoic units encountered in the underground consist of interbedded schist, metasediments, and amphibolite schist which are crosscut by Tertiary rhyolite dikes. Preliminary geotechnical site investigations included drift mapping, borehole drilling, borehole televiewing, in-situ stress analysis, laboratory analysis of core, mapping and laser scanning of new excavations, modeling and analysis of all geotechnical information. The investigation was focused upon the determination if the proposed site rock mass could support the world's largest (66 meter diameter) deep underground excavation. While the DUSEL project has subsequently been significantly modified, these data are still available to provide a baseline of the ground conditions which may be judiciously extrapolated throughout the entire Proterozoic rock assemblage for future excavations. Recommendations for facility instrumentation and monitoring were included in the preliminary design of the DUSEL project design and include; single and multiple point extensometers, tape extensometers and convergence measurements (pins), load cells and pressure cells, smart cables, inclinometers/Tiltmeters, Piezometers, thermistors, seismographs and accelerometers, scanners (laser

Relative scale and the strength and deformability of rock masses

Science.gov (United States)

Schultz, Richard A.

1996-09-01

The strength and deformation of rocks depend strongly on the degree of fracturing, which can be assessed in the field and related systematically to these properties. Appropriate Mohr envelopes obtained from the Rock Mass Rating (RMR) classification system and the Hoek-Brown criterion for outcrops and other large-scale exposures of fractured rocks show that rock-mass cohesive strength, tensile strength, and unconfined compressive strength can be reduced by as much as a factor often relative to values for the unfractured material. The rock-mass deformation modulus is also reduced relative to Young's modulus. A "cook-book" example illustrates the use of RMR in field applications. The smaller values of rock-mass strength and deformability imply that there is a particular scale of observation whose identification is critical to applying laboratory measurements and associated failure criteria to geologic structures.

Proposal of rock mass behavior classification based on convergence measurement in shaft sinking through sedimentary soft rocks

International Nuclear Information System (INIS)

Tsusaka, Kimikazu

2010-01-01

Japan Atomic Energy Agency has been excavating deep shafts through sedimentary soft rocks in Horonobe, Hokkaido. From the viewpoint of the observational construction, site engineers need a practical guide to evaluate the field measurements conducted with shaft sinking. The author analyzed the relationship among initial deformation rate, observed deformation, the ratio of the modulus of elasticity of rock mass to the initial stress, and the magnitude of inelastic behavior of rock based on convergence measurements and investigation of rock mass properties on shaft walls. As a result, the rock mass behavior classification for shaft sinking which consists of three classes was proposed. (author)

Applicability of geomechanical classifications for estimation of strength properties in Brazilian rock masses.

Science.gov (United States)

Santos, Tatiana B; Lana, Milene S; Santos, Allan E M; Silveira, Larissa R C

2017-01-01

Many authors have been proposed several correlation equations between geomechanical classifications and strength parameters. However, these correlation equations have been based in rock masses with different characteristics when compared to Brazilian rock masses. This paper aims to study the applicability of the geomechanical classifications to obtain strength parameters of three Brazilian rock masses. Four classification systems have been used; the Rock Mass Rating (RMR), the Rock Mass Quality (Q), the Geological Strength Index (GSI) and the Rock Mass Index (RMi). A strong rock mass and two soft rock masses with different degrees of weathering located in the cities of Ouro Preto and Mariana, Brazil; were selected for the study. Correlation equations were used to estimate the strength properties of these rock masses. However, such correlations do not always provide compatible results with the rock mass behavior. For the calibration of the strength values obtained through the use of classification systems, ​​stability analyses of failures in these rock masses have been done. After calibration of these parameters, the applicability of the various correlation equations found in the literature have been discussed. According to the results presented in this paper, some of these equations are not suitable for the studied rock masses.

Safety substantiation for underground isolation of spent nuclear fuel or spent nuclear materials as a basis to develop reliable technological solutions

International Nuclear Information System (INIS)

Gupalo, T.A.; Beygul, V.P.; Gupalo, M.S.; Kudinov, K.G.

2000-01-01

Major issues of the technique for mining and ecological safety substantiation of multi-barrier systems for long-term underground isolation of spent nuclear materials and solidified wastes containing long-lived radionuclides have been presented. The experience with the use of this technique for assessment of ecological safety for the long-term storage of plutonium-containing intermediate level wastes in underground facilities existing in the crystalline rock mass has been considered. The probabilistic evaluations of events of the emergency sequences of abnormal situations are based on the results of 40-year in-situ investigations in the rock mass. Feasibility of optimization has been shown for technological design solutions on storage facilities by the ''risk-costs'' principle. (authors)

Numerical modeling of underground openings behavior with a viscoplastic approach

International Nuclear Information System (INIS)

Kleine, A.

2007-01-01

Nature is complex and must be approached in total modesty by engineers seeking to predict the behavior of underground openings. The engineering of industrial projects in underground situations, with high economic and social stakes (Alpine mountain crossings, nuclear waste repository), mean striving to gain better understanding of the behavioral mechanisms of the openings to be designed. This improvement necessarily involves better physical representativeness of macroscopic mechanisms and the provision of prediction tools suited to the expectations and needs of the engineers. The calculation tools developed in this work is in step with this concern for satisfying industrial needs and developing knowledge related to the rheology of geo-materials. These developments led to the proposing of a mechanical constitutive model, suited to lightly fissured rocks, comparable to continuous media, while integrating more particularly the effect of time. Thread of this study, the problematics ensued from the subject of the thesis is precisely about the rock mass delayed behavior in numerical modeling and its consequences on underground openings design. Based on physical concepts of reference, defined in several scales (macro/meso/micro), the developed constitutive model is translated in a mathematical formalism in order to be numerically implemented. Numerical applications presented as illustrations fall mainly within the framework of nuclear waste repository problems. They concern two very different configurations of underground openings: the AECL's underground canadian laboratory, excavated in the Lac du Bonnet granite, and the GMR gallery of Bure's laboratory (Meuse/Haute-Marne), dug in argillaceous rock. In this two cases, this constitutive model use highlights the gains to be obtained from allowing for delayed behavior regarding the accuracy of numerical tunnel behavior predictions in the short, medium and long terms. (author)

Rock mass classification system : transition from RMR to GSI.

Science.gov (United States)

2013-11-01

The AASHTO LRFD Bridge Design Specifications is expected to replace the rock mass rating : (RMR) system with the Geological Strength Index (GSI) system for classifying and estimating : engineering properties of rock masses. This transition is motivat...

A Careful Blasting Technique During Construction of underground Openings for Nuclear Waste Repository

International Nuclear Information System (INIS)

Ester, Z.; Vrkljan, D.

1998-01-01

Underground nuclear waste repositories are constructed in natural rock formations, with heterogenous compound and structure, and should be accommodated in design and construction according to rock conditions. The quality insurance of underground repository, during and after construction, is most demanding in view of contour and category of excavation. the technology of drilling and blasting, regarding the mechanical excavation, is accommodated in sense of response to cross section magnitude of underground openings, the rock conditions and category, the support performance and other design demands. The high level rock damage around underground openings, that is in opposition with reaching quality insurance. Conventional construction technology can be successful by implementation of controlled blasting technique avoiding extensive rock weakness. (author)

Estimation of hydrologic properties of an unsaturated, fractured rock mass

International Nuclear Information System (INIS)

Klavetter, E.A.; Peters, R.R.

1986-07-01

In this document, two distinctly different approaches are used to develop continuum models to evaluate water movement in a fractured rock mass. Both models provide methods for estimating rock-mass hydrologic properties. Comparisons made over a range of different tuff properties show good qualitative and quantitative agreement between estimates of rock-mass hydrologic properties made by the two models. This document presents a general discussion of: (1) the hydrology of Yucca Mountain, and the conceptual hydrological model currently being used for the Yucca Mountain site, (2) the development of two models that may be used to estimate the hydrologic properties of a fractured, porous rock mass, and (3) a comparison of the hydrologic properties estimated by these two models. Although the models were developed in response to hydrologic characterization requirements at Yucca Mountain, they can be applied to water movement in any fractured rock mass that satisfies the given assumptions

In Situ Observation of Hard Surrounding Rock Displacement at 2400-m-Deep Tunnels

Science.gov (United States)

Feng, Xia-Ting; Yao, Zhi-Bin; Li, Shao-Jun; Wu, Shi-Yong; Yang, Cheng-Xiang; Guo, Hao-Sen; Zhong, Shan

2018-03-01

This paper presents the results of in situ investigation of the internal displacement of hard surrounding rock masses within deep tunnels at China's Jinping Underground Laboratory Phase II. The displacement evolution of the surrounding rock during the entire excavation processes was monitored continuously using pre-installed continuous-recording multi-point extensometers. The evolution of excavation-damaged zones and fractures in rock masses were also observed using acoustic velocity testing and digital borehole cameras, respectively. The results show four kinds of displacement behaviours of the hard surrounding rock masses during the excavation process. The displacement in the inner region of the surrounding rock was found to be greater than that of the rock masses near the tunnel's side walls in some excavation stages. This leads to a multi-modal distribution characteristic of internal displacement for hard surrounding rock masses within deep tunnels. A further analysis of the evolution information on the damages and fractures inside the surrounding rock masses reveals the effects of excavation disturbances and local geological conditions. This recognition can be used as the reference for excavation and supporting design and stability evaluations of hard-rock tunnels under high-stress conditions.

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

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.

Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

OpenAIRE

Xuguang Chen; Yuan Wang; Yu Mei; Xin Zhang

2014-01-01

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration p...

Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica-Głogów Copper District

Science.gov (United States)

Skrzypkowski, Krzysztof; Korzeniowski, Waldemar; Zagórski, Krzysztof; Dudek, Piotr

2017-09-01

In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department "Polkowice-Sieroszowice" in the years 2010-2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the "Precymit" material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress-strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in

Status and prospects of a deep underground laboratory in China

International Nuclear Information System (INIS)

Kang, K J; Cheng, J P; Li, Y J; Yue, Q; Chen, Y H; Shen, M B; Wu, S Y

2010-01-01

An excellent candidate location for a deep underground laboratory with more than 2500 m of rock overburden has been identified at Sichuan Province in China. It can be accessed through a road tunnel of length 17.5 km, and is supported by services and amenities near the entrance provided by the local Ertan Hydropower Plant. The particle physics community in China is actively pursuing the construction of an underground laboratory at this location, under the leadership of Tsinghua University. Memorandum has been signed with Ertan Hydropower Plant which permits access to and construction of the underground laboratory - China JinPing Deep Underground Laboratory (CJPL). The basic features of this underground site, as well as the status and schedules of the construction of the first laboratory cavern are presented. The immediate goal is to have the first experiment operational in 2010, deploying an Ultra-Low-Energy Germanium detector for WIMP dark matter searches, with emphasis on the mass range of 1-10 GeV. The conceptual design of the experiment, as well as the future plans and prospects of the laboratory, will be surveyed.

OCENER, a one-dimensional computer code for the numerical simulation of the mechanical effects of peaceful underground nuclear explosions in rocks

International Nuclear Information System (INIS)

Gupta, S.C.; Sikka, S.K.; Chidambaram, R.

1979-01-01

An account is given of a one-dimensional spherical symmetric computer code for the numerical simulation of the effects of peaceful underground nuclear explosions in rocks (OCENER). In the code, the nature of the stress field and response of the medium to this field are modelled numerically by finite difference form of the laws of continuum mechanics and the constitutive relations of the rock medium in which the detonation occurs. It enables to approximate well the cavity growth and fracturing of the surrounding rock for contained explosions and the events upto the time the spherical symmetry is valid for cratering-type explosions. (auth.)

Effluents from a waste rock deposit of a former uranium mine in Saxony/Germany - Mass flow balance of water and dissolved solids

International Nuclear Information System (INIS)

Biehler, D.

2002-01-01

Soon after uranium mining had ceased in eastern Germany in 1990, work for remediation of several mining sites began. The Wismut GmbH, owner of the Mine of Dresden-Gittersee's waste rock dump, introduced the concept of reducing the impact to the environment via water and air paths by implementing a multi-layer soil cover. The deposit consists mainly of waste rock (clastic sediments of Doehlener Becken, deep metamorphic rocks) but also of low-grade ore (U-rich coal) and tailing materials. At the time when remediation started, the effluents completely infiltrated the underground. Because of previous surface exfiltration activities, they were already known to be very rich in dissolved solids, especially in sulphate and uranium. As demanded by the state authorities, the owner funded a vast hydrogeological study of the site. In testing the efficiency of surface sealing, the study indicated a mass flow balance of water and dissolved solids for the current situation, and predicted emissions into the water path which would occur after realisation of the proposed soil cover. The field investigation program consisted of: measurements of flow, of concentrations of dissolved solids (esp. U and Ra-226) and of contents of environmental isotopes in precipitation, surface runoff, seepage water and groundwater in the current condition of the dump; the study of waste rock material (geochemistry, mineralogy); waste rock material elution tests; underground investigation by drilling boreholes up to 270 m in depth. The resulting data allowed for: a hydrogeological conceptual model of the site; a consistent mass flow balance for the current condition of the dump; a prediction of concentrations in groundwater resulting after the realisation of a soil cover. The predictions show that the concentrations of dissolved solids in the contaminated groundwater would be significantly decreased. Furthermore it would be possible to reach the standards for drinking water with respect to uranium

Radiometric surveys in underground environment

Science.gov (United States)

Bochiolo, Massimo; Chiozzi, Paolo; Verdoya, Massimo; Pasquale, Vincenzo

2010-05-01

Due to their ability to travel through the air for several metres, gamma-rays emitted from natural radioactive elements can be successfully used in surveys carried out both with airborne and ground equipments. Besides the concentration of the radio-elements contained in rocks and soils and the intrinsic characteristics of the gamma-ray detector, the detected count rate depends on the solid angle around the spectrometer. On a flat outcrop, ground spectrometry detects the radiation ideally produced by a cylindrical mass of rock of about two metres in diameter and thickness of about half a meter. Under these geometrical conditions, the natural radioactivity can be easily evaluated. With operating conditions different from the standard ones, such as at the edge of an escarpment, the count rate halves because of the missing material, whereas in the vicinity of a rock wall the count rate will increase. In underground environment, the recorded count rate may even double and the in situ assessment of the concentration of radio-elements may be rather difficult, even if the ratios between the different radio-elements may not be affected. We tested the applicability of gamma-ray spectrometry for rapid assessment of the potential hazard levels related to radon and radiation dose rate in underground environment. A mine shaft, located in a zone of uranium enrichment in Liguria (Italy), has been investigated. A preliminary ground radiometric survey was carried out to define the extent of the ore deposit. Then, the radiometric investigation was focussed on the mine shaft. Due to rock mass above the shaft vault, the background gamma radiation can be considered of negligible influence on measurements. In underground surveys, besides deviations from a flat geometry, factors controlling radon exhalation, emanation and stagnation, such as fractures, water leakage and the presence of ventilation, should be carefully examined. We attempted to evaluate these control factors and collected

A research on the excavation and maintenance of underground energy storage

Energy Technology Data Exchange (ETDEWEB)

Shin, Hee-Soon; Chung, So-Keul; Ryu, Chang-Ha [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

1999-12-01

CAES which is called as a compressed air energy storage was firstly developed at Huntorf, Gen-nan in 1978. The capacity of that system was 290MW, and it can be treated as a first commercial power plant. CAES has a lot of merits, such as saving the unit price of power generation, averaging the peak demand, improvement of maintenance, enlarging the benefit of dynamic use. According to the literature survey, the unlined rock cavern should be proposed to be a reasonable storing style as a method of compressed air storage in Korea. In this study, the most important techniques were evaluated through the investigation of the foreign construction case studies, especially on the unlined rock caverns in hard rock mass. We decided the hill of the Korea Institute of Geology, Mining and Materials as CAES site. If we construct the underground spaces in this site, the demand for electricity nearby Taejon should be considered. So we could determine the capacity of the power plant as a 350MW. This capacity needs a underground space of 200,000, and we can conclude 4 parallel tunnels 550m deep from the surface through the numerical studies. Design parameters were achieved from 300m depth boring job and image processing job. Moreover the techniques for determination of joint characteristics from the images could be obtained. Blasting pattern was designed on the underground spaces, and automatic gas control system and thermomechanical characteristics on caverns were also studied. And finally the following research items could be proposed for future researches. (1) Establishment of criteria for selection of optimal tunnel type. (2) Evaluation of water tightening ability. (3) Investigation of Lining type. (4) Development of techniques for site investigation in deep underground project. (5) Evaluation of construction techniques for underground space and shaft. (6) Investigation of long-term maintenance for pressured tunnel. (author). 14 refs.

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

Study on an equivalent continuum model at the Mizunami Underground Research Laboratory

International Nuclear Information System (INIS)

Tanno, Takeo; Sato, Toshinori; Matsui, Hiroya; Sanada, Hiroyuki; Kumasaka, Hiroo; Tada, Hiroyuki

2012-01-01

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. geological disposal of HLW). This modelling study has a two-fold objective, to contribute to the evaluation of the mechanical stability of shaft and research drifts, and to plan the future studies. A crack tensor model, a method of an equivalent continuum model, has been studied at the MIU. In this study, the relationship between the estimated crack tensor parameters and the rock mass classification was revealed. (author)

Experimental investigation of fundamental processes in mining induced fracturing and rock instability.

CSIR Research Space (South Africa)

Napier, JAL

2002-03-01

Full Text Available The main themes of the project GAP601b have been experimental investigations of creep effects, further underground observations of time-dependent behaviour, investigation of scale effects and rock mass stability and studies of the interaction...

A study on the strength properties of the rock mass based on triaxial tests conducted at the Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Aoyagi, Kazuhei; Ishii, Eiichi; Fujita, Tomoo; Kondo, Keiji; Tsusaka, Kimikazu

2015-03-01

Japan Atomic Energy Agency (JAEA) has been conducting R and D activities at the off-site URL at Horonobe, Hokkaido, Japan in order to enhance reliability of technology related to deep geological disposal of HLW in sedimentary rocks. In this report, strength properties (cohesion and frictional angle) of rock masses in the Koetoi and Wakkanai formations are investigated on the basis of triaxial tests conducted in the Horonobe URL considering the relative depths to the formation. Strength properties investigated in this report are compared with the properties obtained in the designing phase. The cohesion in the Koetoi Formation increased with increasing depth. On the other hand, in the transition zone of the Wakkanai Formation, the cohesion increased significantly in the shallow Wakkanai formation (transition zone). Below the transition zone, the cohesion does not significantly depend on the depth. Thus the strength properties between two formations were found to be different. Comparing the cohesions and frictional angles determined from triaxial tests with the values determined in the designing phase, there was no agreement between these values in almost all the depth. Thus it is essential to determine cohesion and frictional angle considering the relative depths to the formation for detailed understanding of strength properties of rock mass. A CD-ROM is attached as an appendix. (J.P.N.)

Tensile rock mass strength estimated using InSAR

KAUST Repository

Jonsson, Sigurjon

2012-11-01

The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

Tensile rock mass strength estimated using InSAR

KAUST Repository

Jonsson, Sigurjon

2012-01-01

The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

Background intercomparison with escape-suppressed germanium detectors in underground mines

Energy Technology Data Exchange (ETDEWEB)

Szuecs, Tamas; Bemmerer, Daniel [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany)

2014-07-01

A key requirement for underground nuclear astrophysics experiments is the very low background level in germanium detectors underground. The reference for these purposes is the world's so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400 m of rock. The background at LUNA was studied in detail using an escape-suppressed Clover-type HPGe detector. Exactly the same detector was subsequently transported to the Felsenkeller underground laboratory in Dresden, shielded by 45 m of rock, and the background was shown to be only a factor of three higher than at LUNA when comparing the escape-suppressed spectra, with interesting consequences for underground nuclear astrophysics. As the next step of a systematic study of the effects of a combination of active and passive shielding on the cosmic ray induced background, this detector is now being brought to the ''Reiche Zeche'' mine in Freiberg/Sachsen, shielded by 150 m of rock. The data from the Freiberg measurement are shown and discussed.

Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica–Głogów Copper District

Directory of Open Access Journals (Sweden)

Skrzypkowski Krzysztof

2017-09-01

Full Text Available In the underground mines of the Legnica–Głogów Copper District (LGOM the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department “Polkowice–Sieroszowice” in the years 2010–2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation.

Normal dynamic deformation characteristics of non-consecutive jointed rock masses under impact loads

Science.gov (United States)

Zeng, Sheng; Jiang, Bowei; Sun, Bing

2017-08-01

In order to study deformation characteristics of non-consecutive single jointed rock masses under impact loads, we used the cement mortar materials to make simulative jointed rock mass samples, and tested the samples under impact loads by the drop hammer. Through analyzing the time-history signal of the force and the displacement, first we find that the dynamic compression displacement of the jointed rock mass is significantly larger than that of the intact jointless rock mass, the compression displacement is positively correlated with the joint length and the impact height. Secondly, the vertical compressive displacement of the jointed rock mass is mainly due to the closure of opening joints under small impact loads. Finally, the peak intensity of the intact rock mass is larger than that of the non-consecutive jointed rock mass and negatively correlated with the joint length under the same impact energy.

Creation and Plan of an Underground Geologic Radioactive Waste Isolation Facility at the Nizhnekansky Rock Massif in Russia

International Nuclear Information System (INIS)

Gupalo, T A; Kudinov, K G; Jardine, L J; Williams, J

2004-01-01

This joint geologic repository project in Russia was initiated in May 2002 between the United States (U.S.) International Science and Technology Center (ISTC) and the Federal State Unitary Enterprise ''All-Russian Research and Design Institute of Production Engineering'' (VNIPIPT). The project (ISTC Partner Project 2377) is funded by the U.S. Department of Energy Office of Civilian Radioactive Waste Management (DOE-RW) for a period of 2-1/2 years. ISTC project activities were integrated into other ongoing geologic repository site characterization activities near the Mining and Chemical Combine (MCC K-26) site. This allowed the more rapid development of a plan for an underground research laboratory, including underground design and layouts. It will not be possible to make a final choice between the extensively studied Verkhne-Itatski site or the Yeniseiski site for construction of the underground laboratory during the project time frame because additional data are needed. Several new sources of data will become available in the next few years to help select a final site. Studies will be conducted at the 1-km deep borehole at the Yeniseisky site where drilling started in 2004. And in 2007, after the scheduled shutdown of the last operating reactor at the MCC K-26 site, data will be collected from the rock massif as the gneiss rock cools, and the cool-down responses modeled. After the underground laboratory is constructed, the data collected and analyzed, this will provide the definitive evidence regarding the safety of the proposed geologic isolation facilities for radioactive wastes (RW). This data will be especially valuable because they will be collected at the same site where the wastes will be subsequently placed, rather than on hypothetical input data only. Including the operating costs for 10 to 15 years after construction, the cost estimate for the laboratory is $50M. With additional funding from non-ISTC sources, it will be possible to complete this

Underground design Laxemar, Layout D2

Energy Technology Data Exchange (ETDEWEB)

2009-11-15

relative to the maximum horizontal stress. The estimated amount of support is on average very low because of the very good quality rock mass anticipated. This conclusion is also supported by the underground experience at the Aespoe Hard Rock Laboratory. The layout of the repository area has the deposition tunnels aligned < 30 deg relative to the maximum horizontal stress. With this orientation spalling is not anticipated in the deposition tunnels or deposition holes. The excavations for the Repository Access (shafts and ramps) will encounter the greatest frequency of open water-bearing fractures located between 0 and 150 m depth. These access excavations may result in a groundwater drawdown that will need to be minimised. The rock mass at the repository horizon is expected to encounter water-bearing fractures approximately 1 every 10 m, and in some areas even more frequently. Groundwater inflows are expected to be significant at repository level requiring extensive grouting. Results from grouting analyses indicate that conventional grouting measures may not be sufficient to meet the inflow criterion. In some areas of the repository, e.g. hydraulic domain HRD-EW007, sealing may not be practical with cement-based grouts and other sealing technologies, such as silica sol technology, may be required. The design and layout presented in this report is based on information compiled at the end of the complete site investigation phase and contained in the report SDM Site TR-09-01. As with all site investigations, at the scale of the repository, there are uncertainties associated with the interpretation of geological information based on borehole investigations. These uncertainties were identified and the impact of these on the current design was evaluated using risk assessment methodologies. The conclusion from the risk assessment is that the available gross capacity of about 8,000 deposition positions is unlikely to be sufficient to host a repository with 6,000 deposited canisters

Rock mass evaluation for predicting tunnel constructability in the preliminary investigation stage. Phenomena causing difficult tunneling and rockburst prediction

International Nuclear Information System (INIS)

Shin, Koichi; Sawada, Masataka; Inohara, Yoshiki; Shidahara, Takumi; Hatano, Teruyoshi

2011-01-01

For the selection of the Detailed Investigation Areas for HLW disposal, predicting the tunnel constructability is one of the requirements together with assessing long-term safety. This report is the 1st of the three papers dealing with the evaluation of tunnel constructability. This paper deals with the geological factors relating to difficult tunneling such as squeezing, rockburst, and others. Also it deals with the prediction of rockburst. The 2nd paper will deal with the prediction of squeezing. The 3rd paper deals with the engineering characteristics of rock mass through rock mass classification. This paper about difficult tunneling has been based upon analysis of more than 500 tunneling reports about 280 tunnel constructions. The causes of difficult tunneling are related to (1) underground water, (2) mechanical properties of the rock, or (3) others such as gas. The geological factors for excessive water inflow are porous volcanic product of Quarternary, fault crush zone and hydrothermally altered zone of Green Tuff area, and degenerated mixed rock in accretionary complex. The geological factors for squeezing are solfataric clay at Quarternary volcanic zone, fault crush zone and hydrothermally altered zone of Green Tuff area, mudstone and fault crush zone of sedimentary rock of Neogene and later. Information useful for predicting rockburst has been gathered from previous reports. In the preliminary investigation stage, geological survey, geophysical survey and borehole survey from the surface are the source of information. Therefore rock type, P-wave velocity from seismic exploration and in-situ rock stress from hydrofracturing have been considered. Majority of rockburst events occurred at granitic rock, excluding coal mine where different kind of rockburst occurred at pillars. And P-wave velocity was around 5 km/s at the rock of rockburst events. Horizontal maximum and minimum stresses SH and Sh have been tested as a criterion for rockburst. It has been

Proceedings of the establishment conference of Professional Committee on Waste Underground Disposal of Chinese Society for Rock Mechanics and Engineering and the first academic seminar

International Nuclear Information System (INIS)

2006-07-01

Approved by the China Association for Science and Technology, Chinese Society for Rock Mechanics and Engineering newly established 'Professional Committee on Waste Underground Disposal'. The committee will organise the national and international academic exchange, and provide advice on discipline development, sustainable industrial development, environmental protection, etc.. This is the establishing conference of the professional committee, as well as the first academic seminar. The following topics on waste underground disposal are discussed: the theory, practice and exploration, project examples, new technologies and new methods. The contents include: waste disposal technology in the new century, the geological disposal of high level radioactive waste, LLW and ILW underground waste disposal, urban and industrial waste underground disposal, and etc.

Gravity-induced rock mass damage related to large en masse rockslides: Evidence from Vajont

Science.gov (United States)

Paronuzzi, Paolo; Bolla, Alberto

2015-04-01

The Vajont landslide is a well-known, reservoir-induced slope failure that occurred on 9 October 1963 and was characterized by an 'en masse' sliding motion that triggered various large waves, determining catastrophic consequences for the nearby territory and adjacent villages. During the Vajont dam construction, and especially after the disaster, some researchers identified widespread field evidence of heavy rock mass damage involving the presumed prehistoric rockslide and/or the 1963 failed mass. This paper describes evidence of heavy gravitational damage, including (i) folding, (ii) fracturing, (iii) faulting, and (iv) intact rock disintegration. The gravity-induced rock mass damage (GRMD) characterizes the remnants of the basal shear zone, still resting on the large detachment surface, and the 1963 failed rock mass. The comprehensive geological study of the 1963 Vajont landslide, based on the recently performed geomechanical survey (2006-present) and on the critical analysis of the past photographic documentation (1959-1964), allows us to recognize that most GRMD evidence is related to the prehistoric multistage Mt. Toc rockslide. The 1963 catastrophic en masse remobilization induced an increase to the prehistoric damage, reworking preexisting structures and creating additional gravity-driven features (folds, fractures, faults, and rock fragmentation). The gravity-induced damage was formed during the slope instability phases that preceded the collapse (static or quasi-static GRMD) and also as a consequence of the sliding motion and of the devastating impact between the failed blocks (dynamic GRMD). Gravitational damage originated various types of small drag folds such as flexures, concentric folds, chevron, and kink-box folds, all having a radius of 1-5 m. Large buckle folds (radius of 10-50 m) are related to the dynamic damage and were formed during the en masse motion as a consequence of deceleration and impact processes that involved the sliding mass. Prior

Underground engineering at the Basalt Waste Isolation Project

International Nuclear Information System (INIS)

1987-01-01

A special task group was organized by the US National Committee for Rock Mechanics and the Board on Radioactive Waste Management of the National Research Council to address issues relating to the geotechnical site characterization program for an underground facility to house high-level radioactive waste of the Basalt Waste Isolation Project (BWIP). Intended to provide an overview of the geotechnical program, the study was carried out by a task group consisting of ten members with expertise in the many disciplines required to successfully complete such a project. The task group recognized from the outset that the short time frame of this study would limit its ability to address all geotechnical issues in detail. Geotechnical issues were considered to range from specific technical aspects such as in-situ testing for rock mass permeability; rock hardness testing in the laboratory; or geologic characterizations and quantification of joints, to broader aspects of design philosophy, data collection, and treatment of uncertainty. The task group chose to focus on the broader aspects of underground design and construction, recognizing that the BWIP program utilizes a peer review group on a regular basis which reviews the specific technical questions related to geotechnical engineering. In this way, it was hoped that the review provided by the task group would complement those prepared by the BWIP peer review group

Prediction of tunnel boring machine performance using machine and rock mass data

International Nuclear Information System (INIS)

Dastgir, G.

2012-01-01

Performance of the tunnel boring machine and its prediction by different methods has been a hot issue since the first TBM came into being. For the sake of safe and sound transport, improvement of hydro-power, mining, civil and many other tunneling projects that cannot be driven efficiently and economically by conventional drill and blast, TBMs are quite frequently used. TBM parameters and rock mass properties, which heavily influence machine performance, should be estimated or known before choice of TBM-type and start of excavation. By applying linear regression analysis (SPSS19), fuzzy logic tools and a special Math-Lab code on actual field data collected from seven TBM driven tunnels (Hieflau expansion, Queen water tunnel, Vereina, Hemerwald, Maen, Pieve and Varzo tunnel), an attempt was made to provide prediction of rock mass class (RMC), rock fracture class (RFC), penetration rate (PR) and advance rate (AR). For detailed analysis of TBM performance, machine parameters (thrust, machine rpm, torque, power etc.), machine types and specification and rock mass properties (UCS, discontinuity in rock mass, RMC, RFC, RMR, etc.) were analyzed by 3-D surface plotting using statistical software R. Correlations between machine parameters and rock mass properties which effectively influence prediction models, are presented as well. In Hieflau expansion tunnel AR linearly decreases with increase of thrust due to high dependence of machine advance rate upon rock strength. For Hieflau expansion tunnel three types of data (TBM, rock mass and seismic data e.g. amplitude, pseudo velocity etc.) were coupled and simultaneously analyzed by plotting 3-D surfaces. No appreciable correlation between seismic data (Amplitude and Pseudo velocity) and rock mass properties and machine parameters could be found. Tool wear as a function of TBM operational parameters was analyzed which revealed that tool wear is minimum if applied thrust is moderate and that tool wear is high when thrust is

Hydrogeomechanics for rock engineering: coupling subsurface hydrogeomechanical assessement and hydrogeotechnical mapping on fracturated rock masses

OpenAIRE

Meirinhos, João Miguel de Freitas

2015-01-01

The present work aims to achieve and further develop a hydrogeomechanical approach in Caldas da Cavaca hydromineral system rock mass (Aguiar da Beira, NW Portugal), and contribute to a better understanding of the hydrogeological conceptual site model. A collection of several data, namely geology, hydrogeology, rock and soil geotechnics, borehole hydraulics and hydrogeomechanics, was retrieved from three rock slopes (Lagoa, Amores and Cancela). To accomplish a comprehensive analysis and rock e...

Experimental Characterization of Stress- and Strain-Dependent Stiffness in Grouted Rock Masses.

Science.gov (United States)

Kim, Ji-Won; Chong, Song-Hun; Cho, Gye-Chun

2018-03-29

Grouting of fractured rock mass prior to excavation results in grout-filled discontinuities that govern the deformation characteristics of a site. The influence of joint characteristics on the properties of grouted rocks is important in assessing the effects of grouting on jointed rock mass. However, grouting remains a predominantly empirical practice and the effects of grouting on rock joint behavior and material properties have yet to be accurately assessed. Granular materials, including jointed rocks, typically display nonlinear strain-dependent responses that can be characterized by the shear modulus degradation curve. In this study, the effects of grouting on the strain-dependent shear stiffness of jointed rock mass were investigated at the small-strain (below 10 -5 ) and mid-strain (10 -5 to 10 -3 ) ranges using the quasi-static resonant column test and rock mass dynamic test devices. The effects of curing time, axial stress, initial joint roughness, and grouted joint thickness were examined. The results show that (1) grouting of rock joints leads to decreased stress sensitivity and increased small-strain shear stiffness for all tested samples; (2) the grouted rock samples display similar modulus degradation characteristics as the applied grout material; (3) the initial joint roughness determines the stress-dependent behaviors and general stiffness range of the jointed and grouted rocks, but the strain-dependent behaviors are dependent on the properties of the grout material; (4) increased grouted joint thickness results in larger contribution of the grout properties in the overall grouted rock mass.

Research of the multibarrier system for an underground deposition of radioactive wastes

Directory of Open Access Journals (Sweden)

Marian Šofranko

2007-01-01

Full Text Available The paper deals in brief with research problems of multiple protection barrier systems for an underground storage of highly radioactive waste in connection with the problem of resolving a definite liquidation of this waste. This problem has a worlwide importance and is comprehensively investigated, evaluated and resolved in many well accepted research centers. Present the experts agree, that the most suitable way of the long-lived radioactive wastes liquidation is their storage into suitable underground geological formations. The core insulation of radioactive wastes from the biosphere for an extremly long time can be achieved by using a technical isolation barrier in combination with an appropriate rock mass.

Hydrogeological and geochemical monitoring system for deep disposal in rock mass

International Nuclear Information System (INIS)

Itoh, K.; Otsuka, Y.; Ohi, Y.

1996-01-01

For investigation and construction of deep underground disposal site, it is very important to monitor three dimensional hydrogeological and geochemical condition for long term in all stages of investigation, construction and management. In deep geological disposal site, permeability of rock mass should be extremely lower than conventional civil engineering field, and natural piezometric pressure should be much higher than conventional groundwater monitoring in civil engineering. So, pressure measuring device should have wide measuring range and high precision especially for interference hydraulic test in investigation stage. And, simultaneous pressure measurement in plural points would be required for cost minimization. Recently, some kinds of multi-point pressure monitoring system has been presented. However, most of all system requires borehole with large diameter, and for utilization in plural boreholes, centralized sensor control is very difficult. And, in groundwater sampling for geochemical investigation, it is important to keep original chemical condition through sampling and transportation from sampling depth to surface. For these purposes, the authors have developed multi well multi point piezometric pressure measuring device, and groundwater sampling system for 1,000m depth. (author)

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)

Inclusion of inhomogeneous deformation and strength characteristics in the problem on zonal disintegration of rocks

Science.gov (United States)

Chanyshev, AI; Belousova, OE

2018-03-01

The authors determine stress and deformation in a heterogeneous rock mass at the preset displacement and Cauchy stress vector at the boundary of an underground excavation. The influence of coordinates on Young’s modulus, shear modulus and ultimate strength is shown. It is found that regions of tension and compression alternate at the excavation boundary—i.e. zonal rock disintegration phenomenon is observed.

Characterization of deep-seated rock masses by means of borehole investigation

International Nuclear Information System (INIS)

1982-04-01

Swedish State Power Board. The main objective of the programme was to test a method of measuring in-situ rock stresses in the deep, water-filled boreholes and to correlate measured rock stresses with the hydraulic and geological properties of the rock mass. The investigations consist of the following activities: - Coredrillin of two main boreholes with a depth of 500 m and 250 m respectively. - Rock stress measurements at 11 and 9 main levels in the boreholes respectively. At each level at least 3 complete measurements were made. - Logging of the cores with respect to rock type, fractures and fracture characteristics. - Water injection tests in the boreholes. The rock mass investigated is composed of a gneiss granite of Svecocarelian age (1500 Ma), with inclusions of younger pegmatites and greenstones of variable ages. The fracture density is as a mean 2 fractures per meter with a marked decrease in frequency with increased depth. The fractures are generally coated with calcite and chlorite as the dominating coating minerals. For the rock stress measurements, the method of Leeman and Hayes was chosen. The result show that there is a very high stress level in the rock mass, recordings of about 70 MPa were taken below a horizontal fracture zone at 320 m depth. In this lower rock masses the high stresses were also illustrated by intense disking of the hollow core which made measurements impossible in large sections of the boreholes. Water injection tests were performed, mainly as double-packer tests alon the entire boreholes. For the evaluation, both stationary and transient calculation theories were used and the results show a good agreement. The hyddraulic conductivities of the rock mass vary from below 10 -10 m/s up to 10 -7 m/s. The conductivity decreases with depth, though there are zones even at great depth with high conductivity. (Author)

Improved RMR Rock Mass Classification Using Artificial Intelligence Algorithms

Science.gov (United States)

Gholami, Raoof; Rasouli, Vamegh; Alimoradi, Andisheh

2013-09-01

Rock mass classification systems such as rock mass rating (RMR) are very reliable means to provide information about the quality of rocks surrounding a structure as well as to propose suitable support systems for unstable regions. Many correlations have been proposed to relate measured quantities such as wave velocity to rock mass classification systems to limit the associated time and cost of conducting the sampling and mechanical tests conventionally used to calculate RMR values. However, these empirical correlations have been found to be unreliable, as they usually overestimate or underestimate the RMR value. The aim of this paper is to compare the results of RMR classification obtained from the use of empirical correlations versus machine-learning methodologies based on artificial intelligence algorithms. The proposed methods were verified based on two case studies located in northern Iran. Relevance vector regression (RVR) and support vector regression (SVR), as two robust machine-learning methodologies, were used to predict the RMR for tunnel host rocks. RMR values already obtained by sampling and site investigation at one tunnel were taken into account as the output of the artificial networks during training and testing phases. The results reveal that use of empirical correlations overestimates the predicted RMR values. RVR and SVR, however, showed more reliable results, and are therefore suggested for use in RMR classification for design purposes of rock structures.

Dynamic design method for deep hard rock tunnels and its application

Directory of Open Access Journals (Sweden)

Xia-Ting Feng

2016-08-01

Full Text Available Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in situ stress, such as rockburst, spalling, damage of deep surrounding rocks, and time-dependent damage, were observed during construction of these projects. To address these problems, the dynamic design method for deep hard rock tunnels is proposed based on the disintegration process of surrounding rocks using associated dynamic control theories and technologies. Seven steps are basically employed: (i determination of design objective, (ii characteristics of site, rock mass and project, and identification of constraint conditions, (iii selection or development of global design strategy, (iv determination of modeling method and software, (v preliminary design, (vi comprehensive integrated method and dynamic feedback analysis, and (vii final design. This dynamic method was applied to the construction of the headrace tunnels at Jinping II hydropower station. The key technical issues encountered during the construction of deep hard rock tunnels, such as in situ stress distribution along the tunnels, mechanical properties and constitutive model of deep hard rocks, determination of mechanical parameters of surrounding rocks, stability evaluation of surrounding rocks, and optimization design of rock support and lining, have been adequately addressed. The proposed method and its application can provide guidance for deep underground projects characterized with similar geological conditions.

Experimental Characterization of Stress- and Strain-Dependent Stiffness in Grouted Rock Masses

Directory of Open Access Journals (Sweden)

Ji-Won Kim

2018-03-01

Full Text Available Grouting of fractured rock mass prior to excavation results in grout-filled discontinuities that govern the deformation characteristics of a site. The influence of joint characteristics on the properties of grouted rocks is important in assessing the effects of grouting on jointed rock mass. However, grouting remains a predominantly empirical practice and the effects of grouting on rock joint behavior and material properties have yet to be accurately assessed. Granular materials, including jointed rocks, typically display nonlinear strain-dependent responses that can be characterized by the shear modulus degradation curve. In this study, the effects of grouting on the strain-dependent shear stiffness of jointed rock mass were investigated at the small-strain (below 10−5 and mid-strain (10−5 to 10−3 ranges using the quasi-static resonant column test and rock mass dynamic test devices. The effects of curing time, axial stress, initial joint roughness, and grouted joint thickness were examined. The results show that (1 grouting of rock joints leads to decreased stress sensitivity and increased small-strain shear stiffness for all tested samples; (2 the grouted rock samples display similar modulus degradation characteristics as the applied grout material; (3 the initial joint roughness determines the stress-dependent behaviors and general stiffness range of the jointed and grouted rocks, but the strain-dependent behaviors are dependent on the properties of the grout material; (4 increased grouted joint thickness results in larger contribution of the grout properties in the overall grouted rock mass.

Dynamic stability and failure modes of slopes in discontinuous rock mass

International Nuclear Information System (INIS)

Shimizu, Yasuhiro; Aydan, O.; Ichikawa, Yasuaki; Kawamoto, Toshikazu.

1988-01-01

The stability of rock slopes during earthquakes are of great concern in rock engineering works such as highway, dam, and nuclear power station constructions. As rock mass in nature is usually discontinuous, the stability of rock slopes will be geverned by the spatial distribution of discontinuities in relation with the geometry of slope and their mechanical properties rather than the rock element. The authors have carried out some model tests on discontinuous rock slopes using three different model tests techniques in order to investigate the dynamic behaviour and failure modes of the slopes in discontinuous rock mass. This paper describes the findings and observations made on model rock slopes with various discontinuity patterns and slope geometry. In addition some stability criterions are developed and the calculated results are compared with those of experiments. (author)

The arrangement of the seismic design method of the underground facility

International Nuclear Information System (INIS)

Tanai, Kenji; Horita, Masakuni; Dewa, Katsuyuki; Gouke, Mitsuo

2002-03-01

Earthquake resistance for the underground structure is higher than the ground structure. Therefore, the case of examining the earthquake resistance of underground structure was little. However, it carries out the research on the aseismic designing method of underground structure, since the tunnel was struck by Hyogo-ken Nanbu Earthquake, and it has obtained a much knowledge. However, an object of the most study was behavior at earthquake of the comparatively shallow underground structure in the alluvial plain board, and it not carry out the examination on behavior at earthquake of underground structure in the deep rock mass. In the meantime, underground disposal facility of the high level radioactive waste constructs in the deep underground, and it carries out the operation in these tunnels. In addition, it has made almost the general process of including from the construction start to the backfilling to be about 60 years (Japan Nuclear Fuel Cycle Development Institute, 1999). During these periods, it is necessary to also consider the earthquake resistance as underground structure from the viewpoint of the safety of facilities. Then, it extracted future problem as one of the improvement of the basis information for the decision of the safety standard and guideline of the country on earthquake-resistant design of the underground disposal facility, while it carried out investigation and arrangement of earthquake-resistant design cases, guidelines and analysis method on existing underground structure, etc. And, the research items for the earthquake resistance assessment of underground structure as case study of the underground research laboratory. (author)

Rock mass modification around a nuclear waste repository in welded tuff

International Nuclear Information System (INIS)

Mack, M.G.; Brandshaug, T.; Brady, B.H.

1989-08-01

This report presents the results of numerical analyses to estimate the extent of rock mass modification resulting from the presence of a High Level Waste (HLW) repository. Changes in rock mass considered are stresses and joint deformations resulting from disposal room excavation and thermal efffects induced by the heat generated by nuclear waste. rock properties and site conditions are taken from the Site Characterization Plan Conceptual Design Report for the potential repository site at Yucca Mountain, Nevada. Analyses were conducted using boundary element and distinct element methods. Room-scale models and repository-scale models were investigated for up to 500 years after waste emplacement. Results of room-scale analyses based on the thermoelastic boundary element model indicate that a zone of modified rock develops around the disposal rooms for both vertical and horizontal waste emplacement. This zone is estimated to extend a distance of roughly two room diameters from the room surface. Results from the repository-scale model, which are based on the thermoelastic boundary element model and the distinct element model, indicate a zone with modified rock mass properties starting approximately 100 m above and below the repository, with a thickness of approximately 200 m above and 150 m below the repository. Slip-prone subhorizontal features are shown to have a substantial effect on rock mass response. The estimates of rock mass modification reflect uncertainties and simplifying assumptions in the models. 32 refs., 57 figs., 1 tab

Determining the REV for Fracture Rock Mass Based on Seepage Theory

Directory of Open Access Journals (Sweden)

Lili Zhang

2017-01-01

Full Text Available Seepage problems of the fractured rock mass have always been a heated topic within hydrogeology and engineering geology. The equivalent porous medium model method is the main method in the study of the seepage of the fractured rock mass and its engineering application. The key to the method is to determine a representative elementary volume (REV. The FractureToKarst software, that is, discrete element software, is a main analysis tool in this paper and developed by a number of authors. According to the standard of rock classification established by ISRM, this paper aims to discuss the existence and the size of REV of fractured rock masses with medium tractility and provide a general method to determine the existence of REV. It can be gleaned from the study that the existence condition of fractured rock mass with medium tractility features average fracture spacing smaller than 0.6 m. If average fracture spacing is larger than 0.6 m, there is no existence of REV. The rationality of the model is verified by a case study. The present research provides a method for the simulation of seepage field in fissured rocks.

The effective stress concept in a jointed rock mass. A literature survey

International Nuclear Information System (INIS)

Olsson, Roger

1997-04-01

The effective stress concept was defined by Terzaghi in 1923 and was introduced 1936 in a conference at Harvard University. The concept has under a long time been used in soil mechanics to analyse deformations and strength in soils. The effective stress σ' is equal to the total stress σ minus the pore pressure u (σ'=σ-u). The concepts's validity in a jointed rock mass has been investigated by few authors. A literature review of the area has examined many areas to create an overview of the use of the concept. Many rock mechanics and rock engineering books recommend that the expression introduced by Terzaghi is suitable for practical purpose in rock. Nevertheless, it is not really clear if they mean rock or rock mass. Within other areas such as porous rocks, mechanical compressive tests on rock joints and determination of the permeability, a slightly changed expression is used, which reduces the acting pore pressure (σ'=σ-α·u). The α factor can vary between 0 and 1 and is defined differently for different areas. Under assumption that the pore system of the rock mass is sufficiently interconnected, the most relevant expression for a jointed rock mass, that for low effective stresses should the Terzagi's original expression with α=1 be used. But for high normal stresses should α=0.9 be used

Thermal characteristics of rocks for high-level waste repository

International Nuclear Information System (INIS)

Shimooka, Kenji; Ishizaki, Kanjiro; Okamoto, Masamichi; Kumata, Masahiro; Araki, Kunio; Amano, Hiroshi

1980-12-01

Heat released by the radioactive decay of high-level waste in an underground repository causes a long term thermal disturbance in the surrounding rock mass. Several rocks constituting geological formations in Japan were gathered and specific heat, thermal conductivity, thermal expansion coefficient and compressive strength were measured. Thermal analysis and chemical analysis were also carried out. It was found that volcanic rocks, i.e. Andesite and Basalt had the most favorable thermal characteristics up to around 1000 0 C and plutonic rock, i.e. Granite had also favorable characteristics under 573 0 C, transition temperature of quartz. Other igneous rocks, i.e. Rhyolite and Propylite had a problem of decomposition at around 500 0 C. Sedimentary rocks, i.e. Zeolite, Tuff, Sandstone and Diatomite were less favorable because of their decomposition, low thermal conductivity and large thermal expansion coefficient. (author)

A new energy-absorbing bolt for rock support in high stress rock masses

Energy Technology Data Exchange (ETDEWEB)

Charlie Chunlin Li [Norwegian University of Science and Technology (NTNU) (Norway)

2010-04-15

An energy-absorbing rock support device, called a D bolt, has been recently developed to counteract both burst-prone and squeezing rock conditions that occur during underground excavation. The bolt is a smooth steel bar with a number of anchors along its length. The anchors are firmly fixed within a borehole using either cement grout or resin, while the smooth sections of the bolt between the anchors may freely deform in response to rock dilation. Failure of one section does not affect the reinforcement performance of the other sections. The bolt is designed to fully use both the strength and the deformation capacity of the bolt material along the entire length. The bolt has large load-bearing and deformation capacities. Static pull tests and dynamic drop tests show that the bolt length elongates by 14-20% at a load level equal to the strength of the bolt material, thereby absorbing a large amount of energy. The impact average load of a 20 mm D bolt is 200-230 kN, with only a small portion of the load transferred to the bolt plate. The cumulative dynamic energy absorption of the bolt is measured to be 47 kJ/m. D bolts were tested in three deep mines. Filed measurements show that D bolts are loaded less than rebar bolts. This paper presents the layout and principle of the D bolt, and corresponding results from static, dynamic, and field tests.

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.

The influence of normal fault on initial state of stress in rock mass

Directory of Open Access Journals (Sweden)

Tajduś Antoni

2016-03-01

Full Text Available Determination of original state of stress in rock mass is a very difficult task for rock mechanics. Yet, original state of stress in rock mass has fundamental influence on secondary state of stress, which occurs in the vicinity of mining headings. This, in turn, is the cause of the occurrence of a number of mining hazards, i.e., seismic events, rock bursts, gas and rock outbursts, falls of roof. From experience, it is known that original state of stress depends a lot on tectonic disturbances, i.e., faults and folds. In the area of faults, a great number of seismic events occur, often of high energies. These seismic events, in many cases, are the cause of rock bursts and damage to the constructions located inside the rock mass and on the surface of the ground. To estimate the influence of fault existence on the disturbance of original state of stress in rock mass, numerical calculations were done by means of Finite Element Method. In the calculations, it was tried to determine the influence of different factors on state of stress, which occurs in the vicinity of a normal fault, i.e., the influence of normal fault inclination, deformability of rock mass, values of friction coefficient on the fault contact. Critical value of friction coefficient was also determined, when mutual dislocation of rock mass part separated by a fault is impossible. The obtained results enabled formulation of a number of conclusions, which are important in the context of seismic events and rock bursts in the area of faults.

The influence of normal fault on initial state of stress in rock mass

Science.gov (United States)

Tajduś, Antoni; Cała, Marek; Tajduś, Krzysztof

2016-03-01

Determination of original state of stress in rock mass is a very difficult task for rock mechanics. Yet, original state of stress in rock mass has fundamental influence on secondary state of stress, which occurs in the vicinity of mining headings. This, in turn, is the cause of the occurrence of a number of mining hazards, i.e., seismic events, rock bursts, gas and rock outbursts, falls of roof. From experience, it is known that original state of stress depends a lot on tectonic disturbances, i.e., faults and folds. In the area of faults, a great number of seismic events occur, often of high energies. These seismic events, in many cases, are the cause of rock bursts and damage to the constructions located inside the rock mass and on the surface of the ground. To estimate the influence of fault existence on the disturbance of original state of stress in rock mass, numerical calculations were done by means of Finite Element Method. In the calculations, it was tried to determine the influence of different factors on state of stress, which occurs in the vicinity of a normal fault, i.e., the influence of normal fault inclination, deformability of rock mass, values of friction coefficient on the fault contact. Critical value of friction coefficient was also determined, when mutual dislocation of rock mass part separated by a fault is impossible. The obtained results enabled formulation of a number of conclusions, which are important in the context of seismic events and rock bursts in the area of faults.

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

Integrated analysis of rock mass deformation within shaft protective pillar

Directory of Open Access Journals (Sweden)

Ewa Warchala

2016-01-01

Full Text Available The paper presents an analysis of the rock mass deformation resulting from mining in the vicinity of the shaft protection pillar. A methodology of deformation prediction is based on a deterministic method using Finite Element Method (FEM. The FEM solution is based on the knowledge of the geomechanical properties of the various geological formations, tectonic faults, types of mining systems, and the complexity of the behaviour of the rock mass. The analysis gave the stress and displacement fields in the rock mass. Results of the analysis will allow for design of an optimal mining system. The analysis is illustrated by an example of the shaft R-VIII Rudna Mine KGHM Polish Copper SA.

Sinkhole susceptibility in carbonate rocks of the Apulian karst (southern Italy)

Science.gov (United States)

Di Santo, Antonio; Fazio, Nunzio L.; Fiore, Antonio; Lollino, Piernicola; Luisi, Michele; Miccoli, Maria N.; Pagliarulo, Rosa; Parise, Mario; Perrotti, Michele; Pisano, Luca; Spalluto, Luigi; Vennari, Carmela; Vessia, Giovanna

2016-04-01

modelling the instability processes, and the development of charts for a preliminary evaluation of the stability of underground caves. Two distinct approaches were established to take into account the different petrographic, structural and geotechnical features of both the hard and soft carbonate rocks. The approach dealing with hard carbonate rocks (where natural karst caves develop) is based on speleological and geometrical surveys of the caves and on an integrated geological and geomechanical characterization of the carbonate rock mass, aimed at individuating the main critical aspects of the karst caves in terms of likely effects on the society. On the other hand, the approach to verify the stability of soft rocks where artificial cavities have been excavated is mostly dependent upon the peculiar petrographic and geomechanical characteristics of the calcarenite rock mass, typically massive and unaffected by tectonic discontinuities. As a consequence, the traditional analytical methods of rock mass classification fail in these materials, since the rock strength of soft calcarenites is mostly dependent upon sediment texture, porosity type and distribution and degree of cementation. The fluid circulation into the rock mass is also important because the removal of the rock matrix may induce a rapid deterioration of the mechanical behaviour of the rock mass. The approach to the calcarenite is mostly based on the characterization of petrographic and geotechnical parameters by means of direct sampling from the rock walls and in situ surveys (wells, trenches, etc.). Through implementation of the two approaches, our goal is to reconstruct accurate geometrical, geological and geotechnical models for both natural caves and artificial cavities. These models will be useful also to plan specific monitoring activities in order to understand the development of underground instability, and the related evolution through the rock mass, possibly threatening the urban areas and

Characteristic behavior of underground and semi-underground structure at earthquake

International Nuclear Information System (INIS)

Sawada, Yoshihiro; Komada, Hiroya

1985-01-01

An appropriate earthquake-resistant repository design is required to ensure the safety of the radioactive wastes (shallow or deep ground disposal of low- and high-level wastes, respectively). It is particularly important to understand the propagation characteristics of seismic waves and the behaviors of underground hollow structures at the time of an earthquake. This report deals with seismologic observations of rock beds and undergound structures. The maximum acceleration deep under the ground is found to be about 1/2 - 1/3 of that at the ground surface or along the rock bed in the horizontal direction and about 1/1 - 1/2 in the longitudinal direction. A large attenuation cannot be expected in shallow ground. The decrease in displacement amplitude is small compared to that in acceleration. The attenuation effect is larger for a small earthquake and at a short hypocentral distance. The attenuation factor reaches a maximum at a depth of several tens of meters. The seismic spectrum under the ground is flatter than that at the surface. The maximum acceleration along the side wall of a cavity is almost the same as that in the surrounding rock bed. An underground cavity shows complicated phase characteristics at the time of a small earthquake at a short hypocentral distance. (Nogami, K.)

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

Formulations and algorithms for problems on rock mass and support deformation during mining

Science.gov (United States)

Seryakov, VM

2018-03-01

The analysis of problem formulations to calculate stress-strain state of mine support and surrounding rocks mass in rock mechanics shows that such formulations incompletely describe the mechanical features of joint deformation in the rock mass–support system. The present paper proposes an algorithm to take into account the actual conditions of rock mass and support interaction and the algorithm implementation method to ensure efficient calculation of stresses in rocks and support.

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

THE EFFECT OF FISSURES IN DOLOMITE ROCK MASS ON BLASTING PROJECTS

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Branko Božić

1989-12-01

Full Text Available Rock fractures in the form of fissures are one of more important geological features of a tectonic system. They have an effect on mechanical behaviour of rook masses exposed to the actions of surface forces. For exploitation in dolomite quarries carried out by blasting of deep shot holes it is important to know the system of fissures within a rock mass for the rock brakes along already weakened planes (the paper is published in Croatian.

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)

Examination of earthquake Ground Motion in the deep underground environment of Japan

International Nuclear Information System (INIS)

Goto, J.; Tsuchi, H.; Mashimo, M.

2009-01-01

Among the possible impacts of earthquakes on the geological disposal system, ground motion is not included in the criteria for selecting a candidate repository site because, in general, ground motion deep underground is considered to be smaller than at the surface. Also, after backfilling/closure, the repository moves together with the surrounding rock. We have carried out a detailed examination of earthquake ground motion deep underground using extensive data from recent observation networks to support the above assumption. As a result, it has been reconfirmed that earthquake ground motion deep underground is relatively smaller than at the surface. Through detailed analysis of data, we have identified the following important parameters for evaluating earthquake ground motion deep underground: depth and velocity distribution of the rock formations of interest, the intensity of the short period component of earthquakes and incident angle of seismic waves to the rock formations. (authors)

Determination of near field excavation disturbance in crystalline rock

International Nuclear Information System (INIS)

Koopmans, R.; Hughes, R.W.

1986-01-01

The computerized dilatometer system has rapidly and economically provided deformation moduli of low and high modulus rock, determined the extent of excavation disturbance surrounding an underground opening and located open fracture within a rock mass. Results from both test sites indicate that the moduli obtained were influenced by the in situ tangential stress field. It has been shown that the near field excavation disturbance is kept to a minimum through the use of careful excavation techniques such as the tunnel boring machine. In turn, the in situ tangential stress levels and deformation moduli are maximized while the corresponding permeability is minimized

Introduction to numerical modeling of thermohydrologic flow in fractured rock masses

International Nuclear Information System (INIS)

Wang, J.S.Y.

1980-01-01

More attention is being given to the possibility of nuclear waste isolation in hard rock formations. The waste will generate heat which raises the temperature of the surrounding fractured rock masses and induces buoyancy flow and pressure change in the fluid. These effects introduce the potential hazard of radionuclides being carried to the biosphere, and affect the structure of a repository by stress changes in the rock formation. The thermohydrological and thermomechanical responses are determined by the fractures as well as the intact rock blocks. The capability of modeling fractured rock masses is essential to site characterization and repository evaluation. The fractures can be modeled either as a discrete system, taking into account the detailed fracture distributions, or as a continuum representing the spatial average of the fractures. A numerical model is characterized by the governing equations, the numerical methods, the computer codes, the validations, and the applications. These elements of the thermohydrological models are discussed. Along with the general review, some of the considerations in modeling fractures are also discussed. Some remarks on the research needs in modeling fractured rock mass conclude the paper

Evaluating the potential for large-scale fracturing at a disposal vault: an example using the underground research laboratory

Energy Technology Data Exchange (ETDEWEB)

Martin, C D; Chandler, N A; Brown, Anton

1994-09-01

The potential for large-scale fracturing (> 10 m{sup 2}) around a nuclear fuel waste disposal vault is investigated in this report. The disposal vault is assumed to be located at a depth of 500 m in the plutonic rocks of the Canadian Shield. The rock mass surrounding the disposal vault is considered to have similar mechanical properties and in situ stress conditions to that found at a depth of 420 m at the Underground Research Laboratory. Theoretical, experimental and field evidence shows that Mode I fractures propagate in a plane perpendicular to {sigma}{sub 3} and only if the tensile stress at the tip of the advancing crack is sufficient to overcome the tensile strength of the rock. Because the stress state at a depth of 500 m or more is compressive, and will very probably stay so during the 10,000 year life of the disposal vault, there does not appear to be any mechanism which could propagate large-scale Mode I fracturing in the rock mass surrounding the vault. In addition because {sigma}{sub 3} is near vertical any Mode I fracture propagation that might occur would be in a horizontal plane. The development of either Mode I or large-scale shear fractures would require a drastic change in the compressive in situ stress state at the depth of the disposal vault. The stresses developed as a result of both thermal and glacial loading do not appear sufficient to cause new fracturing. Glacial loading would reduce the shear stresses in the rock mass and hence improve the stability of the rock mass surrounding the vault. Thus, it is not feasible that large-scale fracturing would occur over the 10,000 year life of a disposal vault in the Canadian Shield, at depths of 500 m or greater, where the compressive stress state is similar to that found at the Underground Research Laboratory. 107 refs., 44 figs.

Evaluating the potential for large-scale fracturing at a disposal vault: an example using the underground research laboratory

International Nuclear Information System (INIS)

Martin, C.D.; Chandler, N.A.; Brown, Anton.

1994-09-01

The potential for large-scale fracturing (> 10 m 2 ) around a nuclear fuel waste disposal vault is investigated in this report. The disposal vault is assumed to be located at a depth of 500 m in the plutonic rocks of the Canadian Shield. The rock mass surrounding the disposal vault is considered to have similar mechanical properties and in situ stress conditions to that found at a depth of 420 m at the Underground Research Laboratory. Theoretical, experimental and field evidence shows that Mode I fractures propagate in a plane perpendicular to σ 3 and only if the tensile stress at the tip of the advancing crack is sufficient to overcome the tensile strength of the rock. Because the stress state at a depth of 500 m or more is compressive, and will very probably stay so during the 10,000 year life of the disposal vault, there does not appear to be any mechanism which could propagate large-scale Mode I fracturing in the rock mass surrounding the vault. In addition because σ 3 is near vertical any Mode I fracture propagation that might occur would be in a horizontal plane. The development of either Mode I or large-scale shear fractures would require a drastic change in the compressive in situ stress state at the depth of the disposal vault. The stresses developed as a result of both thermal and glacial loading do not appear sufficient to cause new fracturing. Glacial loading would reduce the shear stresses in the rock mass and hence improve the stability of the rock mass surrounding the vault. Thus, it is not feasible that large-scale fracturing would occur over the 10,000 year life of a disposal vault in the Canadian Shield, at depths of 500 m or greater, where the compressive stress state is similar to that found at the Underground Research Laboratory. 107 refs., 44 figs

Rock engineering applications, 1991

International Nuclear Information System (INIS)

Franklin, J.A.; Dusseault, M.B.

1991-01-01

This book demonstrates how to apply the theories and principles of rock engineering to actual engineering and construction tasks. It features insights on geology for mining and tunnelling applications. It is practical resource that focuses on the latest technological innovation and examines up-to-date procedures used by engineers for coping with complex rock conditions. The authors also discuss question related to underground space, from design approaches to underground housing and storage. And they cover the monitoring of storage caverns for liquid and gaseous products or toxic and radioactive wastes

Investigation of the development and the effect of an excavation damaged zone at KAERI underground research tunnel

Energy Technology Data Exchange (ETDEWEB)

Kwon, S.; Cho, W. J

2008-01-15

The understanding of the long term behavior of rock around an underground radioactive waste repository is essential for the safe design and operation of the repository and for assuring the safety and technical feasibility of geological disposal concept. The investigation of the influence of EDZ on rock mass behavior is important for the long term stability, economy, and safety points of view. In the case of underground repository, which requires high level safety criteria, the accurate prediction of the long and short term mechanical, hydraulic, and thermal behaviors is especially important. In this study, the size and characteristics of EDZ developed during the construction of the KAERI underground research tunnel, which was constructed by controlled blasting, were investigated using various methods. Goodman jack test for measuring deformation modulus, Georadar, rock core observation, MPBX, and stressmeter were carried out at KURT. The rock cores from the boreholes were tested in laboratory for estimating the EDZ size. Empirical and theoretical equations were also used for the prediction of EDZ. The results from laboratory and in situ tests were used in three-dimensional hydro-mechanical and thermo-mechanical analysis for the evaluation of the EDZ effect. The understanding of EDZ size and the property changes in EDZ from in situ and laboratory tests will be used for the planning, design, and analysis of in situ experiments in KURT. The results from the EDZ study will be helpful for the system design as well as safety analysis of a radioactive repository.

Modelling Geomechanical Heterogeneity of Rock Masses Using Direct and Indirect Geostatistical Conditional Simulation Methods

Science.gov (United States)

Eivazy, Hesameddin; Esmaieli, Kamran; Jean, Raynald

2017-12-01

An accurate characterization and modelling of rock mass geomechanical heterogeneity can lead to more efficient mine planning and design. Using deterministic approaches and random field methods for modelling rock mass heterogeneity is known to be limited in simulating the spatial variation and spatial pattern of the geomechanical properties. Although the applications of geostatistical techniques have demonstrated improvements in modelling the heterogeneity of geomechanical properties, geostatistical estimation methods such as Kriging result in estimates of geomechanical variables that are not fully representative of field observations. This paper reports on the development of 3D models for spatial variability of rock mass geomechanical properties using geostatistical conditional simulation method based on sequential Gaussian simulation. A methodology to simulate the heterogeneity of rock mass quality based on the rock mass rating is proposed and applied to a large open-pit mine in Canada. Using geomechanical core logging data collected from the mine site, a direct and an indirect approach were used to model the spatial variability of rock mass quality. The results of the two modelling approaches were validated against collected field data. The study aims to quantify the risks of pit slope failure and provides a measure of uncertainties in spatial variability of rock mass properties in different areas of the pit.

An experimental investigation of transient heat transfer in surrounding rock mass of high geothermal roadway

Directory of Open Access Journals (Sweden)

Zhang Yuan

2016-01-01

Full Text Available A self-designed experimental installation for transient heat transfer in the modelling surrounding rock mass of high geothermal roadways was elaborated in this paper. By utilizing the new installation, the temperature variation rules in surrounding rock mass of the high geothermal roadway during mechanical ventilation were studied. The results show that the roadway wall temperature decreases dramatically at the early stage of ventilation, and the temperature at every position of the surrounding rock mass is decreasing constantly with time passing by. From roadway wall to deep area, the temperature gradually increases until reaching original rock temperature. The relationship between dimensionless temperature and dimensionless radius demonstrates approximately exponential function. Meanwhile, the temperature disturbance range in the simulated surrounding rock mass extends gradually from the roadway wall to deep area in the surrounding rock mass. Besides, as the air velocity increases, heat loss in the surrounding rock mass rises and the ratio of temperature reduction becomes larger, the speed of disturbance range expansion also gets faster.

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

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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.

Example of fracture characterization in granitic rock

International Nuclear Information System (INIS)

Thorpe, R.K.

1981-03-01

A detailed study of geologic discontinuities for an underground heater test in highly fractured granitic rock is reported. Several prominent shear fractures were delineated within a 6 x 30 x 15 m rock mass by correlating surface mapping and borehole fracture logs. Oblique-reverse faulting is suspected on at least one of the surfaces, and its inferred borehole intercepts appear to be collinear in the direction of slickensiding observed in the field. Four distinct joint sets were identified, one of which coincides with the shear fractures. Another lies nearly horizontal, and two others are steeply inclined and orthogonal. Fracture lengths and spacings for the four joint sets are represented by lognormal probability distributions

Comparison of the effects in the rock mass of large-scale chemical and nuclear explosions. Final technical report, June 9, 1994--October 9, 1994

Energy Technology Data Exchange (ETDEWEB)

Spivak, A.A.

1995-04-01

It was found that in the first approximation the mechanical effect of underground nuclear explosion is analogous to the effect of chemical explosion. Really qualitative analysis shows that accompanying mechanical effects of nuclear and chemical explosions are the same: in the both cases explosion consequences are characterized by formation of the camouplet cavity (crater after explosion near free surface), destruction of the rock massif near explosion centre, creation of the stress wave, which forms seismoexplosive effect a long distance from explosion epicentre. Qualitative likeness of underground nuclear explosions and chemical explosions is the base of modelling the mechanical effects of the underground nuclear explosion. In this paper we`ll compare two explosions: nuclear (15-04-84) and chemical (27.06.95) with large power. These explosions were realized at the same geological conditions at Degelen test area, which is a part of the Semipalatinsk Test Site. In the case of the nuclear explosion, the charge was disposed in the face of the deep horizontal gallery. The charge of the chemical explosion was a semisphere from explosives at the rock massif surface. In the both case rock massif behavior after explosions was investigated at underground conditions (in the case of chemical explosion -- in the long underground excavation from explosion epicentre). Mechanical effects from the nuclear and chemical explosions were investigated with the same methods. The changes in geological medium after a large-scale explosive actions will be analyzed in detail too. Investigations of the influence of tectonic energy on the mechanical effects after underground nuclear, explosions represents the main interest. In this paper we`ll discuss this question on the data from underground nuclear explosion, realized 08.09.89 in the deep well at the Balapan test area, at the Semipalatinsk Test Site.

Earthquake damage to underground facilities and earthquake related displacement fields

International Nuclear Information System (INIS)

Pratt, H.R.; Stephenson, D.E.; Zandt, G.; Bouchon, M.; Hustrulid, W.A.

1982-01-01

The potential seismic risk for an underground facility is considered in the evaluation of its location and design. The possible damage resulting from either large-scale displacements or high accelerations should be considered in evaluating potential sites of underground facilities. Scattered through the available literature are statements to the effect that below a few hundred meters shaking and damage in mines is less than at the surface; however, data for decreased damage underground have not been completely reported or explained. In order to assess the seismic risk for an underground facility, a data base was established and analyzed to evaluate the potential for seismic disturbance. Substantial damage to underground facilities is usually the result of displacements primarily along pre-existing faults and fractures, or at the surface entrance to these facilities. Evidence of this comes from both earthquakes as a function of depth is important in the evaluation of the hazard to underground facilities. To evaluate potential displacements due to seismic effects of block motions along pre-existing or induced fractures, the displacement fields surrounding two types of faults were investigated. Analytical models were used to determine relative displacements of shafts and near-surface displacement of large rock masses. Numerical methods were used to determine the displacement fields associated with pure strike-slip and vertical normal faults. Results are presented as displacements for various fault lengths as a function of depth and distance. This provides input to determine potential displacements in terms of depth and distance for underground facilities, important for assessing potential sites and design parameters

Forensic Excavation of Rock Masses: A Technique to Investigate Discontinuity Persistence

Science.gov (United States)

Shang, J.; Hencher, S. R.; West, L. J.; Handley, K.

2017-11-01

True persistence of rock discontinuities (areas with insignificant tensile strength) is an important factor controlling the engineering behaviour of fractured rock masses, but is extremely difficult to quantify using current geological survey methodologies, even where there is good rock exposure. Trace length as measured in the field or using remote measurement devices is actually only broadly indicative of persistence for rock engineering practice and numerical modelling. Visible traces of discontinuities are treated as if they were open fractures within rock mass classifications, despite many such traces being non-persistent and actually retaining considerable strength. The common assumption of 100% persistence, based on trace length, is generally extremely conservative in terms of strength and stiffness, but not always so and may lead to a wrong prediction of failure mechanism or of excavatability. Assuming full persistence would give hopelessly incorrect predictions of hydraulic conductivity. A new technique termed forensic excavation of rock masses is introduced, as a procedure for directly investigating discontinuity persistence. This technique involves non-explosive excavation of rock masses by injecting an expansive chemical splitter along incipient discontinuities. On expansion, the splitter causes the incipient traces to open as true joints. Experiments are described in which near-planar rock discontinuities, through siltstone and sandstone, were opened up by injecting the splitter into holes drilled along the lines of visible traces of the discontinuities in the laboratory and in the field. Once exposed the surfaces were examined to investigate the pre-existing persistence characteristics of the incipient discontinuities. One conclusion from this study is that visible trace length of a discontinuity can be a poor indicator of true persistence (defined for a fracture area with negligible tensile strength). An observation from this series of experiments

Thermally induced rock stress increment and rock reinforcement response

International Nuclear Information System (INIS)

Hakala, M.; Stroem, J.; Nujiten, G.; Uotinen, L.; Siren, T.; Suikkanen, J.

2014-07-01

This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the brittle

Thermally induced rock stress increment and rock reinforcement response

Energy Technology Data Exchange (ETDEWEB)

Hakala, M. [KMS Hakala Oy, Nokia (Finland); Stroem, J.; Nujiten, G.; Uotinen, L. [Rockplan, Helsinki (Finland); Siren, T.; Suikkanen, J.

2014-07-15

This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the

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

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

Crack propagation of brittle rock under high geostress

Science.gov (United States)

Liu, Ning; Chu, Weijiang; Chen, Pingzhi

2018-03-01

Based on fracture mechanics and numerical methods, the characteristics and failure criterions of wall rock cracks including initiation, propagation, and coalescence are analyzed systematically under different conditions. In order to consider the interaction among cracks, adopt the sliding model of multi-cracks to simulate the splitting failure of rock in axial compress. The reinforcement of bolts and shotcrete supporting to rock mass can control the cracks propagation well. Adopt both theory analysis and simulation method to study the mechanism of controlling the propagation. The best fixed angle of bolts is calculated. Then use ansys to simulate the crack arrest function of bolt to crack. Analyze the influence of different factors on stress intensity factor. The method offer more scientific and rational criterion to evaluate the splitting failure of underground engineering under high geostress.

Geological-Technical and Geo-engineering Aspects of Dimensional Stone Underground Quarrying

Science.gov (United States)

Fornaro, Mauro; Lovera, Enrico

Underground exploitation of dimensional stones is not a novelty, being long since practised, as proved by a number of historical documents and by a certain number of ancient quarrying voids throughout the world. Anyway, so far, open cast quarrying has been the most adopted practice for the excavation of dimensional stones. One primary reason that led to this situation is of course connected to the lower production costs of an open cast exploitation compared to an underground one. This cheapness has been supported by geological and technical motives: on the one hand, the relative availability of surface deposits and, on the other, the development of technologies, which often can be used only outdoor. But, nowadays, general costs of quarrying activities should be re-evaluated because new, and often proper, restrictions have been strongly rising during recent years. As a consequence of both environmental and technical restrictions, pressure will more and more arise to reduce open cast quarrying and to promote underground exploitations. The trend is already well marked for weak rocks - for instance in the extractive basin of Carrara, where about one hundred quarries are active, 30 per cent is working underground, but also in Spain, Portugal and Greece the number of underground marble quarries is increasing - but not yet for hard rock quarrying, where only few quarries are working underground all around the world. One reason has to be found in cutting technologies traditionally used. In weak rocks, diamond wire saw and chain cutter are usable, with few adaptations, in underground spaces, while drilling and blasting, the traditional exploitation method for hard stone, is not easily usable in a confined space, where often only one free face is available. Many technicians and researchers agree that two technologies will probably open the door to underground quarrying in hard rocks: diamond wire and water jet. The first one is already available; the second should still be

The Impact of the Rock Mass Deformation on Geometric Changes of a Historical Chimney in the Salt Mine of Bochnia

Science.gov (United States)

Szafarczyk, Anna; Gawałkiewicz, Rafał

2018-03-01

There are many ways of the geometry measurement of slim objects, with the application of geodetic and photogrammetric methods. A modern solution in the diagnostics of slim objects is the application of laser scanning, with the use of a scanner of a scanning total station. The point cloud, obtained from the surface of the scanned object gives the possibility of generating not only information on structural surface deformations, but also facilitates obtaining the data on the geometry of the axis of the building, as a basic indicator of the characteristics of its deformation. The cause of the change in the geometry of slim objects is the impact of many external and internal factors. These objects are located in the areas of working or closed underground mines. They can be impacted by the ground and they can face the results of the convergence of cavities. A specific structure of the salt rock mass causes subsequent convergence of the post-exploitation cavities, which has the influence on the behaviour of the terrain surface and the related objects. The authors analysed the impact of the changes in the rock mass and the surface on the changes of the industrial chimney in the Bochnia Salt Mine.

Laboratory testing of a long expansion rock bolt support for energy-absorbing applications

Directory of Open Access Journals (Sweden)

Skrzypkowski Krzysztof

2018-01-01

Full Text Available The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.

Laboratory testing of a long expansion rock bolt support for energy-absorbing applications

Science.gov (United States)

Skrzypkowski, Krzysztof

2018-01-01

The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.

Borehole heater test at KAERI Underground Research Tunnel

International Nuclear Information System (INIS)

Kwon, S. K.; Cho, W. J.; Jeon, S. W.

2009-09-01

thermo-mechanical test in Korea. In the future, the results from the test will be utilized for different projects such as spent fuel storage, geothermal energy, sequestration of carbon-dioxide, and underground petroleum storage, which require the clear understanding on the thermo-mechanical behavior of rock mass

A Comparative Study of Ground and Underground Vibrations Induced by Bench Blasting

Directory of Open Access Journals (Sweden)

Xiuzhi Shi

2016-01-01

Full Text Available Ground vibrations originating from bench blasting may cause damage to slopes, structures, and underground workings in close proximity to an operating open-pit mine. It is important to monitor and predict ground vibration levels induced by blasting and to take measures to reduce their hazardous effects. The aims of this paper are to determine the weaker protection objects by comparatively studying bench blasting induced vibrations obtained at surface and in an underground tunnel in an open-pit mine and thus to seek vibration control methods to protect engineering objects at the site. Vibrations arising from measurement devices at surface and in an underground tunnel at the Zijinshan Open-Pit Mine were obtained. Comparative analysis of the peak particle velocities shows that, in the greatest majority of cases, surface values are higher than underground values for the same vibration distance. The transmission laws of surface and underground vibrations were established depending on the type of rock mass, the explosive charge, and the distance. Compared with the Chinese Safety Regulations for Blasting (GB6722-2014, the bench blasting induced vibrations would not currently cause damage to the underground tunnel. According to the maximum allowable peak particle velocities for different objects, the permitted maximum charges per delay are obtained to reduce damage to these objects at different distances.

Comparison of laboratory, in situ, and rock mass measurements of the hydraulic conductivity of metamorphic rock at the Savannah River Plant near Aiken, South Carolina

International Nuclear Information System (INIS)

Marine, I.W.

1980-01-01

In situ testing of exploratory wells in metamorphic rock indicates that two types of fracturing occur in the rock mass. Rock containing small openings that permit only extremely slow movement of water is termed virtually impermeable rock. Rock containing openings of sufficient size to permit transmission of water at a significantly faster rate is termed hydraulically transmissive rock. Laboratory methods are unsuitable for measuring hydraulic conductivity in hydraulically transmissive rock; however, for the virtually impermeable rock, values comparable to the in situ tests are obtained. The hydraulic conductivity of the rock mass over a large region is calculated by using the hydraulic gradient, porosity, and regional velocity. This velocity is determined by dividing the inferred travel distance by the age of water which is determined by the helium content of the water. This rock mass hydraulic conductivity value is between the values measured for the two types of fractures, but is closer to the measured value for the virtually impermeable rock. This relationship is attributed to the control of the regional flow rate by the virtually impermeable rock where the discrete fractures do not form a continuous open connection through the entire rock mass. Thus, laboratory methods of measuring permeability in metamorphic rock are of value if they are properly applied

Shape and Reinforcement Optimization of Underground Tunnels

Science.gov (United States)

Ghabraie, Kazem; Xie, Yi Min; Huang, Xiaodong; Ren, Gang

Design of support system and selecting an optimum shape for the opening are two important steps in designing excavations in rock masses. Currently selecting the shape and support design are mainly based on designer's judgment and experience. Both of these problems can be viewed as material distribution problems where one needs to find the optimum distribution of a material in a domain. Topology optimization techniques have proved to be useful in solving these kinds of problems in structural design. Recently the application of topology optimization techniques in reinforcement design around underground excavations has been studied by some researchers. In this paper a three-phase material model will be introduced changing between normal rock, reinforced rock, and void. Using such a material model both problems of shape and reinforcement design can be solved together. A well-known topology optimization technique used in structural design is bi-directional evolutionary structural optimization (BESO). In this paper the BESO technique has been extended to simultaneously optimize the shape of the opening and the distribution of reinforcements. Validity and capability of the proposed approach have been investigated through some examples.

An exploration of unsaturated zone during in-situ heating test in sedimentary soft rocks

International Nuclear Information System (INIS)

Kubota, Kenji; Suzuki, Koichi; Ikenoya, Takafumi; Takakura, Nozomu; Tani, Kazuo

2011-01-01

In-situ heating test has been conducted to evaluate the influence of high temperature in an underground facility at a depth of 50 m. Resistivity monitoring is thought to be effective to map the extent of the high temperature and unsaturated zone. So we have conducted resistivity tomography during the heating test. As a result, the resistivity of the rock mass around the heating well was decreased and this area was gradually expanded from the heated area during the heating. This suggests that high temperature zone is detected by resistivity tomography. The results also suggested that resistivity was increased by unsaturation of rock mass around the heating well. (author)

The Practical Application of Aqueous Geochemistry in Mapping Groundwater Flow Systems in Fractured Rock Masses

Science.gov (United States)

Bursey, G.; Seok, E.; Gale, J. E.

2017-12-01

Flow to underground mines and open pits takes place through an interconnected network of regular joints/fractures and intermediate to large scale structural features such as faults and fracture zones. Large scale features can serve either as high permeability pathways or as barriers to flow, depending on the internal characteristics of the structure. Predicting long term water quality in barrier-well systems and long-term mine water inflows over a mine life, as a mine expands, requires the use of a 3D numerical flow and transport code. The code is used to integrate the physical geometry of the fractured-rock mass with porosity, permeability, hydraulic heads, storativity and recharge data and construct a model of the flow system. Once that model has been calibrated using hydraulic head and permeability/inflow data, aqueous geochemical and isotopic data provide useful tools for validating flow-system properties, when one is able to recognize and account for the non-ideal or imperfect aspects of the sampling methods used in different mining environments. If groundwater samples are collected from discrete depths within open boreholes, water in those boreholes have the opportunity to move up or down in response to the forces that drive groundwater flow, whether they be hydraulic gradients, gas pressures, or density differences associated with variations in salinity. The use of Br/Cl ratios, for example, can be used to determine if there is active flow into, or out of, the boreholes through open discontinuities in the rock mass (i.e., short-circuiting). Natural groundwater quality can also be affected to varying degrees by mixing with drilling fluids. The combined use of inorganic chemistry and stable isotopes can be used effectively to identify dilution signals and map the dilution patterns through a range of fresh, brackish and saline water types. The stable isotopes of oxygen and hydrogen are nearly ideal natural tracers of water, but situations occur when deep

[The Research Advancement and Conception of the Deep-underground Medicine].

Science.gov (United States)

Xie, He-Ping; Liu, Ji-Feng; Gao, Ming-Zhong; Wan, Xue-Hong; Liu, Shi-Xi; Zou, Jian; Wu, Jiang; Ma, Teng-Fei; Liu, Yi-Lin; Bu, Hong; Li, Wei-Min

2018-03-01

The 21th century is the century of exploring and utilizing the underground space. In the future, more and more people will spend more and more time living or/and working in the underground space. However,we know little about the effect on the health of human caused by the underground environment. Herein,we systematically put forward the strategic conception of the deep-underground medicine,in order to reveal relative effects and mechanism of the potential factors in the deep underground space on human's physiological and psychological healthy,and to work out the corresponding countermeasures. The original deep-underground medicine includes the following items. ①To model different depth of underground environment according to various parameters (such as temperature,radiation,air pressure, rock,microorganism), and to explore their quantitative character and effects on human health and mechanism. ② To study the psychological change, maintenance of homeostasis and biothythm of organism in the deep underground space. ③ To learn the association between psychological healthy of human and the depth, structure, physical environment and working time of underground space. ④ To investigate the effect of different terrane and lithology on healthy of human and to deliberate their contribution on organism growth. ⑤ To research the character and their mechanism of growth,metabolism,exchange of energy,response of growth, aging and adaptation of cells living in deep underground space. ⑥ To explore the physiological feature,growth of microbiome and it's interaction with host in the deep underground space. ⑦ To develop deep-underground simulation space, the biologically medical technology and equipments. As a research basis,a deep-underground medical lab under a rock thickness of about 1 470 m has been built,which aims to operate the research of the effect on living organism caused by different depth of underground environment. Copyright© by Editorial Board of Journal

Application of tomographics methods for determination of rock failure in situ

Directory of Open Access Journals (Sweden)

Pandula Blažej

1996-03-01

Full Text Available Rock Failure determination closely connects with optimalization of rock disintegration as well excavation of underground openings. The aim of this optimalization is than to reach desired fragmentation during the blasting as well as choose the most suitable excavation technology. Study of rock failure can be very useful to reach this goal. In practice it can be done on the basis of personal technological experiences of blasting operator obtained in long term experiences in situ conditions. Because in many cases that experiences can not be utilised, it is necessary to learn against more precise rock failure evaluation. It can also down the costs of disintegration as well as excavation. The paper deals with results of common geophysical methods and methods of seismic tomography achieved at the hidden rock failure determination in the rock masses of the Ruzin dam during projecting the outlet equipment.

Geo-Engineering Evaluation of Rock Masses for Crushed Rock and Cut Stones in Khartoum State, Sudan

Science.gov (United States)

Kheirelseed, E. E.; Ming, T. H.; Abdalla, S. B.

The purpose of this study is to find artificial coarse aggregates and cut stones around Khartoum. To meat the objectives of the study, data from both field and laboratory are collected. The field data includes geological investigations based on different methods and samples collection, whereas the laboratory tests consists of specific gravity, water absorption, impact value, crushing value, Los Angeles abrasion, soundness tests. The field and laboratory results were weighed and compiled together to reveal the engineering performance of the different rock masses in term of cut stone and crushed aggregates. The results show that most of the examined rock masses are suitable for crushing, building and dressed stones. For decorative slabs only foliated granite and syenite masses can be used.

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)

Logistics background study: underground mining

Energy Technology Data Exchange (ETDEWEB)

Hanslovan, J. J.; Visovsky, R. G.

1982-02-01

Logistical functions that are normally associated with US underground coal mining are investigated and analyzed. These functions imply all activities and services that support the producing sections of the mine. The report provides a better understanding of how these functions impact coal production in terms of time, cost, and safety. Major underground logistics activities are analyzed and include: transportation and personnel, supplies and equipment; transportation of coal and rock; electrical distribution and communications systems; water handling; hydraulics; and ventilation systems. Recommended areas for future research are identified and prioritized.

30 CFR 57.3461 - Rock bursts.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons to...

International mining forum 2004, new technologies in underground mining, safety in mines proceedings

Energy Technology Data Exchange (ETDEWEB)

Jerzy Kicki; Eugeniusz Sobczyk (eds.)

2004-01-15

The book comprises technical papers that were presented at the International Mining Forum 2004. This event aims to bring together scientists and engineers in mining, rock mechanics, and computer engineering, with a view to explore and discuss international developments in the field. Topics discussed in this book are: trends in the mining industry; new solutions and tendencies in underground mines; rock engineering problems in underground mines; utilization and exploitation of methane; prevention measures for the control of rock bursts in Polish mines; and current problems in Ukrainian coal mines.

Fuzzy cluster quantitative computations of component mass transfer in rocks or minerals

International Nuclear Information System (INIS)

Liu Dezheng

2000-01-01

The author advances a new component mass transfer quantitative computation method on the basis of closure nature of mass percentage of components in rocks or minerals. Using fuzzy dynamic cluster analysis, and calculating restore closure difference, and determining type of difference, and assisted by relevant diagnostic parameters, the method gradually screens out the true constant component. Then, true mass percentage and mass transfer quantity of components of metabolic rocks or minerals are calculated by applying the true constant component fixed coefficient. This method is called true constant component fixed method (TCF method)

The Impact of Temperatures on the Stability of Rocks Surrounding a Single Fracture

Science.gov (United States)

Zhang, Yan; Li, Ning; Dai, Jun

2018-05-01

Research on the influence of temperature and the accompanying stress on the stability of the rocks surrounding an underground tunnel has become ever more important. This paper constructs a geometric model of a single-fracture tunnel by combining a high-temperature underground tunnel as the object of study with an example that uses a high-temperature tunnel segment in the water diversion tunnel of a hydropower station in Xinjiang. Based on the relevant theoretical analysis, with the consideration of different working conditions, a numerical experimental analysis was conducted to determine the two-dimensional transient temperature field distribution of the tunnel rock mass by using a numerical analysis software. The experimental data was consistent with the measured data. The calculated results show the following: a. when the temperature difference is greater, the stress concentration is higher near the fracture of the surrounding rock; b. the degree of the stress concentration in the crack tip region is not positively correlated to the distance, and there is a sensitive region where the stress varies.

Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

Directory of Open Access Journals (Sweden)

Nanying Shentu

2014-05-01

Full Text Available Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA. Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications.

Mechanical response of jointed granite during shaft sinking at the Canadian Underground Research Laboratory

International Nuclear Information System (INIS)

Chan, T.; Lang, P.A.; Thompson, P.M.

1985-01-01

As part of the geoscience research within the Canadian Nuclear Fuel Waste Management Program, Atomic Energy of Canada Limited (AECL) is constructing an underground research laboratory (URL) in a previously undisturbed portion of a granitic intrusive, the Lac du Bonnet batholith, approximately 100 km northeast of Winnipeg, Manitoba. The overall geotechnical objectives of the URL are to assess and improve our ability to interpret and predict the geological, geophysical, geochemical, geomechanical and hydrogeological conditions of large bodies of plutonic rock, as well as to assess the accuracy of mathematical models used to predict the near-field mechanical and hydrogeological responses of the rock mass to excavation and thermal loading. Construction will be completed in July, 1986. Large-scale testing will commence soon afterwards and will last until the facility is decommissioned in the year 2000. A rectangular access shaft, 255 m deep x 2.8 m x 4.8 m, was sunk during the period May 1984 to March 1985. Rock displacements and stress changes were monitored as the excavation face (bottom) of the shaft advanced. The major objectives of this monitoring were (a) to evaluate and improve the ability of numerical models in predicting the mechanical response of the rock mass, (b) to back-calculate the rock-mass deformation modulus as a function of depth, (c) to assess the influence of natural fractures on the mechanical response of the granitic rock mass, and (d) to evaluate the quality of the geomechanical instrumentation, to determine instrumentation needs for future field experiments. Analysis of the data from this monitoring will aid the design and modelling of further experiments in the URL. In this paper, the rock displacements measured by an array of extensometers at 15 m below ground surface are presented and compared with predictions by a three-dimensional elastic continuum finite-element model

Numerical simulation of the time-dependent deformation behaviour of clay-stone rock mass at the Tournemire site with 2D and 3D models

International Nuclear Information System (INIS)

Rutenberg, M.; Lux, K. H.

2011-01-01

Clay-stone rock masses are a reasonable alternative to e.g. salt rock masses as a host rock for underground radioactive waste repositories because of their very low permeability as well as their radionuclide retention capacity. Though clay-stone has been explored for many years, there is still a need for further research on its hydro-mechanical behaviour. Convergence measurements over a 4-year period in the tunnel system of the argillaceous Tournemire site in France yielded the presence of a time-dependent deformation behaviour in indurated clay. Moreover, a mine-by test was carried out with extensometer measurements capturing the rock mass deformation during the excavation process of a new gallery in 2003.This work focuses on the validation of a constitutive model by means of a three-dimensional (3D) simulation of the mine-by test. The utilised constitutive model Hou/Lux-T is based on the viscous constitutive model Lubby2 with which time-dependent deformation behaviour of salt rock can appropriately be simulated. It has been adapted to clay-stone by considering anisotropy effects, and in addition it features a strain-dependent fracture and failure criterion. The results of the mine-by-test simulation show that the calculated stresses and deformations in the rock mass seem to behave reasonably under this constitutive model with respect to time-dependency. A comparison of the 3D results to the results of a simplified two-dimensional (2D) simulation confirms the adequacy of using a 2D model with the constitutive model Hou/Lux-T for the setting at hand, described in the text (material parameters, time scale), in order to assess load-bearing capacity and deformability of the gallery near field away from heading face and tunnel crossing. Finally, a comparison of the 3D simulation results to the extensometer measurement results yields the principal ability of the used constitutive model to describe time-dependent evolutions of stresses and deformations during a three

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.

Empirical Assessment of the Mean Block Volume of Rock Masses Intersected by Four Joint Sets

Science.gov (United States)

Morelli, Gian Luca

2016-05-01

The estimation of a representative value for the rock block volume ( V b) is of huge interest in rock engineering in regards to rock mass characterization purposes. However, while mathematical relationships to precisely estimate this parameter from the spacing of joints can be found in literature for rock masses intersected by three dominant joint sets, corresponding relationships do not actually exist when more than three sets occur. In these cases, a consistent assessment of V b can only be achieved by directly measuring the dimensions of several representative natural rock blocks in the field or by means of more sophisticated 3D numerical modeling approaches. However, Palmström's empirical relationship based on the volumetric joint count J v and on a block shape factor β is commonly used in the practice, although strictly valid only for rock masses intersected by three joint sets. Starting from these considerations, the present paper is primarily intended to investigate the reliability of a set of empirical relationships linking the block volume with the indexes most commonly used to characterize the degree of jointing in a rock mass (i.e. the J v and the mean value of the joint set spacings) specifically applicable to rock masses intersected by four sets of persistent discontinuities. Based on the analysis of artificial 3D block assemblies generated using the software AutoCAD, the most accurate best-fit regression has been found between the mean block volume (V_{{{{b}}_{{m}} }}) of tested rock mass samples and the geometric mean value of the spacings of the joint sets delimiting blocks; thus, indicating this mean value as a promising parameter for the preliminary characterization of the block size. Tests on field outcrops have demonstrated that the proposed empirical methodology has the potential of predicting the mean block volume of multiple-set jointed rock masses with an acceptable accuracy for common uses in most practical rock engineering applications.

Research on application of mobile diesel equipment in underground mines (IV)

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-01

This research commenced in 1994 for the purpose of providing safety and environmental measures of underground mines where the mobile diesel equipment are operating. In this last research year, researches on filtering of diesel particulate matter, design of underground layout and disaster prevention have been carried out. 1) A study to reduce DPM(Diesel Particulate Matter) emission: It was known that water scrubber is only one practical way to reduce DPM emission as of now. There are several kinds of the sophisticated DPM filters, but it is not practical yet to be used in underground equipment due to the many adverse effects of the devices such as tremendous increase of SOx, NOx and back pressure etc. 2) Design of underground layout and their maintenance: Layout of underground structure has to be designed based on rock mechanical analysis and the concept of active support has to be adopted considering the large openings are requested to accommodate heavy duty diesel equipment in underground. Rock bolt and shotcrete will be the most applicable method to support such a large dimensional tunnels. 3) A study for disaster prevention in the case of the underground fire: There are two categories of possible disaster or hazard in workings where diesel equipment are operating. One is the disasters by exhaust pollutants and the other is the underground fire. (author). 35 refs., 27 tabs., 56 figs.

Underground transmission tomography

International Nuclear Information System (INIS)

Geibka, C.

1990-01-01

Several underground tomographic transmission surveys have been carried out. Targets were cavities, ore veins and fault zones. Examples from measurements in a german heavy/fluor spar mine a lead/zinc mine and a rock laboratory of the Swiss National Cooperative for the Storage of Radioactive waste are presented. Measurements were carried out between boreholes and road ways. The recording equipment was the intrinsically safe SEAMEX85 system built and sold by WBK. Receivers were mounted in a chain of 6 two-component probes. Sources were an inhole hammer a sledge hammer a sparker and explosives from a single detonator to 180 g depending on the distance and absorption of the rock material. Cavities showed very distinct velocity reductions between 30 and 50%. Different vein material showed velocity reduction as well as velocity increase relative to the surrounding rock

Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

Directory of Open Access Journals (Sweden)

Marte Gutierrez

2015-12-01

Full Text Available Fracture systems have strong influence on the overall mechanical behavior of fractured rock masses due to their relatively lower stiffness and shear strength than those of the rock matrix. Understanding the effects of fracture geometrical distribution, such as length, spacing, persistence and orientation, is important for quantifying the mechanical behavior of fractured rock masses. The relation between fracture geometry and the mechanical characteristics of the fractured rock mass is complicated due to the fact that the fracture geometry and mechanical behaviors of fractured rock mass are strongly dependent on the length scale. In this paper, a comprehensive study was conducted to determine the effects of fracture distribution on the equivalent continuum elastic compliance of fractured rock masses over a wide range of fracture lengths. To account for the stochastic nature of fracture distributions, three different simulation techniques involving Oda's elastic compliance tensor, Monte Carlo simulation (MCS, and suitable probability density functions (PDFs were employed to represent the elastic compliance of fractured rock masses. To yield geologically realistic results, parameters for defining fracture distributions were obtained from different geological fields. The influence of the key fracture parameters and their relations to the overall elastic behavior of the fractured rock mass were studied and discussed. A detailed study was also carried out to investigate the validity of the use of a representative element volume (REV in the equivalent continuum representation of fractured rock masses. A criterion was also proposed to determine the appropriate REV given the fracture distribution of the rock mass.

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

Rock Fracture Toughness Study Under Mixed Mode I/III Loading

Science.gov (United States)

Aliha, M. R. M.; Bahmani, A.

2017-07-01

Fracture growth in underground rock structures occurs under complex stress states, which typically include the in- and out-of-plane sliding deformation of jointed rock masses before catastrophic failure. However, the lack of a comprehensive theoretical and experimental fracture toughness study for rocks under contributions of out-of plane deformations (i.e. mode III) is one of the shortcomings of this field. Therefore, in this research the mixed mode I/III fracture toughness of a typical rock material is investigated experimentally by means of a novel cracked disc specimen subjected to bend loading. It was shown that the specimen can provide full combinations of modes I and III and consequently a complete set of mixed mode I/III fracture toughness data were determined for the tested marble rock. By moving from pure mode I towards pure mode III, fracture load was increased; however, the corresponding fracture toughness value became smaller. The obtained experimental fracture toughness results were finally predicted using theoretical and empirical fracture models.

AECL's underground research laboratory: technical achievements and lessons learned

International Nuclear Information System (INIS)

Ohta, M.M.; Chandler, N.A.

1997-03-01

During the development of the research program for the Canadian Nuclear Fuel Waste Management Program in the 1970's, the need for an underground facility was recognized. AECL constructed an Underground Research Laboratory (URL) for large-scale testing and in situ engineering and performance-assessment-related experiments on key aspects of deep geological disposal in a representative geological environment. Ale URL is a unique geotechnical research and development facility because it was constructed in a previously undisturbed portion of a granitic pluton that was well characterized before construction began, and because most of the shaft and experimental areas are below the water table. The specific areas of research, development and demonstration include surface and underground characterization; groundwater and solute transport; in situ rock stress conditions; temperature and time-dependent deformation and failure characteristics of rock; excavation techniques to minimize damage to surrounding rock and to ensure safe working conditions; and the performance of seals and backfills. This report traces the evolution of the URL and summarizes the technical achievements and lessons learned during its siting, design and construction, and operating phases over the last 18 years. (author)

Effect of blasting on the strength of a rock mass

Energy Technology Data Exchange (ETDEWEB)

Muller, L

1964-01-01

Although the fact that blasting concussions tend to loosen a rock mass has always been known, the enormous reduction in strength associated with such loosening is not generally recognized. Recent investigations of the effect of blasting on a rock mass have shown that even slight loosening may markedly reduce the strength. This factor introduces a new slant on modern blasting methods, some of which will have to be considered more critically. The sensitivity of the mass to impacts depends on stress concentrations at the end of joints (Kerbspannungen) and on tensile stresses developed in the immediate vicinity of a joint, even in regions where the field stresses are not tensile. Thus, the sensitivity depends on the shape and orientation of the joints and particularly on the degree of separation of the individual joint families. The orientation of the joint families to the strains produced by blasting is just as important as the reduction in overall strength arising from the drop in friction due to the effects of the ''knocking out'' process (Foppl) on the joint body complex. Concussions may critically increase the degree of separation of the joint network thus reducing the tensile and shear strengths of the rock mass. (19 refs.)

Effect of blasting on the strength of a rock mass

Energy Technology Data Exchange (ETDEWEB)

Muller, L.

1964-01-01

Although the fact that blasting concussions tend to loosen a rock mass has always been known, the enormous reduction in strength associated with such loosening is not generally recognized. Recent investigations of the effect of blasting on a rock mass have shown that even slight loosening may markedly reduce the strength. This factor introduces a new slant on modern blasting methods, some of which will have to be considered more critically. The sensitivity of the mass to impacts depends on stress concentrations at the end of joints (Kerbspannungen) and on tensile stresses developed in the immediate vicinity of a joint, even in regions where the field stresses are not tensile. Thus, the sensitivity depends on the shape and orientation of the joints and particularly on the degree of separation of the individual joint families. The orientation of the joint families to the strains produced by blasting is just as important as the reduction in overall strength arising from the drop in friction due to the effects of the ''knocking out'' process (Foppl) on the joint body complex. Concussions may critically increase the degree of separation of the joint network thus reducing the tensile and shear strengths of the rock mass. (19 refs.)

Rock stress measurements in the Grimsel Underground Rock Laboratory and their geological interpretation

International Nuclear Information System (INIS)

Braeuer, V.; Heusermann, S.; Pahl, A.

1989-01-01

Rock stress is being studied as part of the Swiss-German cooperation between the National Cooperative for the Storage of Radioactive Waste (NAGRA), the Research Centre for Environmental Sciences (GSF), and the Federal Institute for Geosciences and Natural Resources (BGR) in the Grimsel Rock Laboratory in Switzerland. Several methods and various equipment for measuring rock stress have been developed and tested in an approximately 200-m borehole drilled from a gallery at a depth of 450 m. The measurements were made continually during overcoring; the data were recorded and processed in a computer located downhole or outside the borehole. The results of the overcoring tests and of frac tests indicate a principle horizontal stress of 25-40 MPa, directed mainly NW-SE. Detailed geological mapping shows relationships between stress and rock structure. A zone of nearly unfractured rock exhibits an increase in stress and a change in stress direction. (orig.)

In Situ Observation of Rock Spalling in the Deep Tunnels of the China Jinping Underground Laboratory (2400 m Depth)

Science.gov (United States)

Feng, Xia-Ting; Xu, Hong; Qiu, Shi-Li; Li, Shao-Jun; Yang, Cheng-Xiang; Guo, Hao-Sen; Cheng, Yuan; Gao, Yao-Hui

2018-04-01

To study rock spalling in deep tunnels at China Jinping Underground Laboratory Phase II (CJPL-II), photogrammetry method and digital borehole camera were used to quantify key features of rock spalling including orientation, thickness of slabs and the depth of spalling. The failure mechanism was analysed through scanning electron microscope and numerical simulation based on FLAC3D. Observation results clearly showed the process of rock spalling failure: a typical spalling pattern around D-shaped tunnels after top-heading and bottom bench were discovered. The orientation and thickness of the slabs were obtained. The slabs were parallel to the excavated surfaces of the tunnel and were related to the shape of the tunnel surface and orientation of the principal stress. The slabs were alternately thick and thin, and they gradually increased in thickness from the sidewall inwards. The form and mechanism of spalling at different locations in the tunnels, as influenced by stress state and excavation, were analysed. The result of this study was helpful to those rethinking the engineering design, including the excavation and support of tunnels, or caverns, at high risk of spalling.

Simulation of hydraulic disturbances caused by the underground rock characterisation facility in Olkiluoto, Finland

International Nuclear Information System (INIS)

Loefman, J.; Ferenc, M.

2004-01-01

Spent fuel from the Finnish nuclear power plants will be disposed of in a repository to be excavated in crystalline bedrock at a depth of 400-700 metres in Olkiluoto. The extensive site investigations carried out since the early 1980's will next focus on the construction of an underground rock characterisation facility (ONKALO) in 2004-2010. The open tunnel system will constitute a major hydraulic disturbance for the site's groundwater conditions for hundreds of years. Especially, inflow of groundwater into the tunnels results in a drawdown of groundwater table and upcoming of deep saline groundwater, which the present study aimed to assess by means of a 3D finite element simulation. The modelled bedrock volume, which horizontally covered the whole Olkiluoto island, was conceptually divided into hydraulic units, planar fracture zones and sparsely fractured rock between the zones, which were both separately treated as porous media. The geometry of the fracture zones was based on the geological bedrock model. Simulations showed that without engineering measures (e.g. grouting) taken to limit inflow of groundwater into the open tunnels, the hydraulic disturbances could be drastic. The tunnels draw groundwater from all directions in the bedrock. A major part of inflow comes from the well-conductive subhorizontal fracture zones intersected by the access tunnel and the shaft. The simulations show that the resulting drawdown of groundwater table may be from tens to hundreds of metres and the depressed area may extend over the area of the island. The results also indicate that the salinity of groundwater is gradually rising around and below the tunnel system, and locally concentration (TDS) may rise rather high in the vicinity of the tunnels. However, the disturbances can significantly be reduced by the grouting of rock. (orig.)

Underground leaching - A method for the economic extraction of uranium from low-grade ores; Podzemnoe vyshchelachivanie - sposob ehkonomicheskogo izvlecheniya urana iz bednykh rud

Energy Technology Data Exchange (ETDEWEB)

Zefirov, A P [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj EHnergii SSSR, Moskva, Union of Soviet Socialist Republics (Russian Federation)

1967-06-15

The method of underground leaching of uranium ores has a number of advantages over extraction followed by processing of the ores in factories. It has been studied in two types of deposit, occurring in rock masses and sandy shales. Research techniques were worked out accordingly for the leaching of uranium from large-grained ore (-200 mm) and from layers in natural stratification. Special models were constructed permitting the simulation of underground leaching conditions. The results obtained were checked in field conditions on experimental plots and experimental underground blocks. The investigations demonstrated the practicability of the process of underground leaching of uranium from certain ores and made it possible to work out flow-sheets and routines for an industrial process, information about which is given in the paper. (author)

An Illustration of Determining Quantitatively the Rock Mass Quality Parameters of the Hoek-Brown Failure Criterion

Science.gov (United States)

Wu, Li; Adoko, Amoussou Coffi; Li, Bo

2018-04-01

In tunneling, determining quantitatively the rock mass strength parameters of the Hoek-Brown (HB) failure criterion is useful since it can improve the reliability of the design of tunnel support systems. In this study, a quantitative method is proposed to determine the rock mass quality parameters of the HB failure criterion, namely the Geological Strength Index (GSI) and the disturbance factor ( D) based on the structure of drilling core and weathering condition of rock mass combined with acoustic wave test to calculate the strength of rock mass. The Rock Mass Structure Index and the Rock Mass Weathering Index are used to quantify the GSI while the longitudinal wave velocity ( V p) is employed to derive the value of D. The DK383+338 tunnel face of Yaojia tunnel of Shanghai-Kunming passenger dedicated line served as illustration of how the methodology is implemented. The values of the GSI and D are obtained using the HB criterion and then using the proposed method. The measured in situ stress is used to evaluate their accuracy. To this end, the major and minor principal stresses are calculated based on the GSI and D given by HB criterion and the proposed method. The results indicated that both methods were close to the field observation which suggests that the proposed method can be used for determining quantitatively the rock quality parameters, as well. However, these results remain valid only for rock mass quality and rock type similar to those of the DK383+338 tunnel face of Yaojia tunnel.

Evaluation of Rock Bolt Support for Polish Hard Rock Mines

Science.gov (United States)

Skrzypkowski, Krzysztof

2018-03-01

The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead "Olkusz - Pomorzany" mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt "Olkusz - 20A" is able to overcome the load.The second purpose of the study was to obtain load - displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

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.

Three-Dimensional Numerical Analysis of Compound Lining in Complex Underground Surge-Shaft Structure

Directory of Open Access Journals (Sweden)

Juntao Chen

2015-01-01

Full Text Available The mechanical behavior of lining structure of deep-embedded cylinder surge shaft with multifork tunnel is analyzed using three-dimensional nonlinear FEM. With the elastic-plastic constitutive relations of rock mass imported and the implicit bolt element and distributed concrete cracking model adopted, a computing method of complex surge shaft is presented for the simulation of underground excavations and concrete lining cracks. In order to reflect the interaction and initial gap between rock mass and concrete lining, a three-dimensional nonlinear interface element is adopted, which can take into account both the normal and tangential characteristics. By an actual engineering computation, the distortion characteristics and stress distribution rules of the dimensional multifork surge-shaft lining structure under different behavior are revealed. The results verify the rationality and feasibility of this computation model and method and provide a new idea and reference for the complex surge-shaft design and construction.

Photoelastic stress investigation in underground large hole in permafrost soil (statics, thermoelasticity, dynamics, photoelastic strain-gauges)

Science.gov (United States)

Savostjanov, V. N.; Dvalishvili, V. V.; Sakharov, V. N.; Isajkin, A. S.; Frishter, L.; Starchevsky, A. V.

1991-12-01

The development of many-year-frost rock (MYFR) region hydrotechnic construction, the MYFR being quite a reliable construction based provided it is situated outside the seasonal temperature fluctuation layer, requires the rock stress-deformed state evaluating criteria working out with maximal possible account of static, dynamic, blast-hole drilling, and temperature effect on their properties. In estimating the hydroelectrical power station (HPS) underground building stress-deformed state the present work refers to experimental data and calculations, received by solving a linear task with further account of the building profile changing effect in the process of construction and the concrete and rock mechanic properties heterogeneity. The proposed order is justified, provided the rock mass defrosting depth value is small as compared to the rock separate block dimensions and it corresponds to the building construction period. The results are given for the Kolymskaya Hydroelectrical Power Station building cross-section, considered under flat deformation conditions.

Geomechanics in hard rock mining-Lessons from two case histories

International Nuclear Information System (INIS)

Heuze, F.E.

1982-01-01

This paper summarizes the geomechanics programs conducted in two hard rock underground mining operations in the Western United States, between 1966 and 1981. The two projects were directed towards understanding the behavior of the rock masses, at the scale of the caverns. To this end, the emphasis was put on large scale field measurements, complemented by limited laboratory testing. The results of these observations were used to build realistic finite element models of the underground chambers. In the marble mine, at Crestmore, California, the models were applied to the structural optimization of the room-and-pillar pattern. In the granite mining, at Climax, Nevada Test Site, the models explained some unusual stress changes observed during excavation. Based on the large number of geomechanical techniques employed, specific conclusions and recommendations are offered regarding the quality, applicability, and usefulness of the various methods. The two case histories clearly indicate that numerical models are extremely useful for a detailed understanding of the structural behavior of mine openings. To be realistic, these models must be based first and foremost on large scale field observations. The lessons learned on these two projects also are directly applicable to the design and analysis of nuclear waste repositories in hard rocks such as basalt, granite, and welded tuff

Underground mining of aggregates. Main report

OpenAIRE

Brown, Teresa J.; Coggan, John S.; Evans, David J.; Foster, Patrick J.; Hewitt, Jeremy; Kruyswijk, Jacob B.; Smith, Nigel; Steadman, Ellie J.

2010-01-01

This report examines the economic feasibility of underground mining for crushed rock aggregates in the UK, but particularly in the London, South East and East of England regions (the South East area of England). These regions import substantial volumes of crushed rock, primarily from the East Midlands and South West regions, requiring relatively long transport distances to market for this bulk commodity. A key part of the research was to determine whether or not aggregate could be produced an...

Numerical modeling of the geomechanical response of a rock mass to a radioactive waste repository

International Nuclear Information System (INIS)

Hardy, M.P.; St John, C.M.; Hocking, G.

1979-06-01

Geotechnical numerical models capable of predicting the thermomechanical response and groundwater movements around an underground radioactive waste repository are vital to the success of the nuclear waste disposal program. In the absence of directly related engineering experience, the design, risk assessment, and licensing procedures of a repository will be reliant on predictions made using such models. This paper reviews models being used to assist in repository design and summarizes the results of a recent parametric study of underground disposal in basaltic rocks. On the basis of preliminary site data, it is concluded that the allowable areal density of heat-generating waste will be controlled by the stability of placement rooms and the boreholes in which waste canisters are placed. Regional effects including thermally induced upward groundwater flow, appear to present less severe problems

Overview of geotechnical methods to characterize rock masses

International Nuclear Information System (INIS)

Heuze, F.E.

1981-12-01

The methods that are used to characterize discontinuous rock masses from a geotechnical point of view are summarized. Emphasis is put on providing key references on each subject. The topics of exploration, in-situ stresses, mechanical properties, thermal properties, and hydraulic properties are addressed

Novel, low-vibration excavation techniques for underground radioactive waste storage

International Nuclear Information System (INIS)

Kogelmann, W.J.

1994-01-01

In order to meet the construction specifications of the challenging Yucca Mountain nuclear waste repository, novel, low-vibration tunneling and shaft sinking techniques must be applied. Conventional roadheaders, even with reduced cutting speed, cannot be employed due to the high strength and widely varying physical properties of the rock formations. The Multi Tool Miner (MTM) concept utilizes both an impact hammer, for efficient hard rock mining, and a cutter head, tooled with drag-bits (picks), to profile tunnel walls down to the sound, undisturbed rock, in order to meet the 10,000-year stability requirement for underground structures. As the operational requirements and rock conditions at the Yucca Mountain site are not suitable for wide, transverse open-quotes ripperclose quotes cutting drums, a small diameter, in-line, open-quotes milling augerclose quotes cutter head was developed. The synergetic combination of high-production hammer excavation and precise milling will facilitate the construction of stable, long-life underground structures within the budget limitations mandated by Congress

Underground disposal of radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

NONE

1979-08-15

Disposal of low- and intermediate-level radioactive wastes by shallow land burial, emplacement in suitable abandoned mines, or by deep well injection and hydraulic fracturing has been practised in various countries for many years. In recent years considerable efforts have been devoted in most countries that have nuclear power programmes to developing and evaluating appropriate disposal systems for high-level and transuranium-bearing waste, and to studying the potential for establishing repositories in geological formations underlaying their territories. The symposium, organized jointly by the IAEA and OECD's Nuclear Energy Agency in cooperation with the Geological Survey of Finland, provided an authoritative account of the status of underground disposal programmes throughout the world in 1979. It was evidence of the experience that has been gained and the comprehensive investigations that have been performed to study various options for the underground disposal of radioactive waste since the last IAEA/NEA symposium on this topic (Disposal of Radioactive Waste into the Ground) was held in 1967 in Vienna. The 10 sessions covered the following topics: National programme and general studies, Disposal of solid waste at shallow depth and in rock caverns, underground disposal of liquid waste by deep well injection and hydraulic fracturing, Disposal in salt formations, Disposal in crystalline rocks and argillaceous sediments, Thermal aspects of disposal in deep geological formations, Radionuclide migration studies, Safety assessment and regulatory aspects.

Development of digital photogrammetry for measurements of displacements in underground excavation

International Nuclear Information System (INIS)

Ohnishi, Yuzo; Ohtsu, Hiroyasu; Nishiyama, Satoshi; Ono, Tetsu; Matsui, Hiroya

2002-03-01

Because deformations are important indicators of the degree of stability during construction of rock structures, monitoring of deformation is a key element of construction of tunnels and structures for the underground research laboratory. Especially in the construction and maintenance of underground excavation, monitoring of deformations is needed for obtaining useful information to control its stability. We have been developing the application of digital photogrammetry to monitoring techniques in rock structures. Photogrammetric process has undergone a remarkable evolution with its transformation into digital photogrammetry. Photogrammetry has the advantage of measuring deformation of an object by some photos with easy measurements and excellent cost performance. In this paper, we present that the digital photogrammetry can monitor the displacements of the underground excavation accurately along with a capability of real-time measurement. (author)

Rock stress measurements in ONKALO underground characterisation facility at Olkiluoto at depth of 120 m

International Nuclear Information System (INIS)

Fecker, E.

2007-04-01

In November and December 2006 overcoring stress measurements have been conducted in the boreholes ONK-PP74, ONK-PP75 and ONK-PP77 in a niche of the access tunnel of the ONKALO underground characterisation facility at the Olkiluoto site. Measurements have been done using the CSIRO 3D stress measuring cell. This cell is one of the mostly used cells in the whole world for estimation of the state of stress in rock when doing the borehole measurements. The boreholes are at a depth of about 120 m under the ground surface. The rock where the measurements have been conducted is a foliated migmatitic gneiss (subtypes veined and diatexitic gneiss). Parallel to the overcoring measurements a glue test has been conducted in the laboratory to check the quality of the bonding of the stress cells to the rock. The result showed that the glue makes a good contact between the rock and the stress cell, but air bubbles, which have normally been observed within the glue and at the edges, proved this time to be disadvantageous. Normally such air bubbles have dimensions of about one millimetre, but sometimes certain bubbles may become notably bigger. In the ONKALO overcored probes sawn apart such air bubbles were found both in wet and dry probe conditions. In the test series eight stress measurements have been provided, three of them failed for technical reasons. At one of these three tests the glue has extruded too early, at the other two tests the overcoring was not conducted deep enough. At the remaining five tests in spite of the glue test results a calculation of the stress tensor could be made. Four of these five measurements can be seen as relatively successful. The results of these measurements show a major principal stress of 14.8 MPa in average, trending northwest - southeast, and with a dipping of 11 degrees in average. (orig.)

Experiments, conceptual design, preliminary cost estimates and schedules for an underground research facility

International Nuclear Information System (INIS)

Korbin, G.; Wollenberg, H.; Wilson, C.; Strisower, B.; Chan, T.; Wedge, D.

1981-09-01

Plans for an underground research facility are presented, incorporating techniques to assess the hydrological and thermomechanical response of a rock mass to the introduction and long-term isolation of radioactive waste, and to assess the effects of excavation on the hydrologic integrity of a repository and its subsequent backfill, plugging, and sealing. The project is designed to utilize existing mine or civil works for access to experimental areas and is estimated to last 8 years at a total cost for contruction and operation of $39.0 million (1981 dollars). Performing the same experiments in an existing underground research facility would reduce the duration to 7-1/2 years and cost $27.7 million as a lower-bound estimate. These preliminary plans and estimates should be revised after specific sites are identified which would accommodate the facility

Rock mass characterization for Copenhagen Metro using face logs

DEFF Research Database (Denmark)

Hansen, Sanne Louise; Galsgaard, Jens; Foged, Niels Nielsen

2015-01-01

An extension of the existing Metro in central Copenhagen is currently under construction. We present a comparison of the different field logging techniques available from a large number of borehole logs and face logs carried out during the construction in cooperation with the constructor and client......, describing rock mass characteristics using detailed face logging with geological description and recording of induration and fracturing, giving a field RQD value during excavation, combined with televiewer logs, when available, has shown to be a valuable tool for rock mass characterization compared......’s representatives, which illustrate and approve the applied methods. The new ‘Cityringen’ Metro will consist of two 16 km single track tunnels, with 17 stations and 3 construction and ventilation shafts. The geological ground conditions are dominated by glacial and postglacial deposits overlying Paleocene Greensand...

Engineering effects of underground nuclear explosions

International Nuclear Information System (INIS)

Boardman, Charles R.

1970-01-01

Useful effects of contained underground nuclear explosions are discussed in light of today's most promising potential applications. Relevant data obtained through exploration of explosion environments of nine U.S. tests in competent rock are summarized and presented as a practical basis for estimating magnitudes of effects. Effects discussed include chimney configuration, permeability, and volume as well as rubble particle size distributions and extents of permeability change in the chimney wall rock. Explosion mediums include shale, granite, dolomite, and salt. (author)

Engineering effects of underground nuclear explosions

Energy Technology Data Exchange (ETDEWEB)

Boardman, Charles R [CER Geonuclear Corporation, Las Vegas, NV (United States)

1970-05-01

Useful effects of contained underground nuclear explosions are discussed in light of today's most promising potential applications. Relevant data obtained through exploration of explosion environments of nine U.S. tests in competent rock are summarized and presented as a practical basis for estimating magnitudes of effects. Effects discussed include chimney configuration, permeability, and volume as well as rubble particle size distributions and extents of permeability change in the chimney wall rock. Explosion mediums include shale, granite, dolomite, and salt. (author)

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.

A review of international underground laboratory developments

International Nuclear Information System (INIS)

Cheng Jianping; Yue Qian; Wu Shiyong; Shen Manbin

2011-01-01

Underground laboratories are essential for various important physics areas such as the search for dark matter, double beta decay, neutrino oscillation, and proton decay. At the same time, they are also a very important location for studying rock mechanics, earth structure evolution,and ecology. It is essential for a nation's basic research capability to construct and develop underground laboratories. In the past, China had no high-quality underground laboratory,in particular no deep underground laboratory,so her scientists could not work independently in major fields such as the search for dark matter,but had to collaborate with foreign scientists and share the space of foreign underground laboratories. In 2009, Tsinghua university collaborated with the Ertan Hydropower Development Company to construct an extremely deep underground laboratory, the first in China and currently the deepest in the world, in the Jinping traffic tunnel which was built to develop hydropower from the Yalong River in Sichuan province. This laboratory is named the China Jinping Underground Laboratory (CJPL) and formally opened on December 12, 2010. It is now a major independent platform in China and can host various leading basic research projects. We present a brief review of the development of various international underground laboratories,and especially describe CJPL in detail. (authors)

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

Current status and recommended future studies of underground supercriticality of fissile material

International Nuclear Information System (INIS)

Bowman, C.D.

1996-06-01

More than a year has passed since we released our original report pointing out the possibility of natural or induced rearrangement of fissile material underground into a critical mass, the possibility of positive feedback in underground configurations, the confinement of the rock to produce significant yield, and the possibility of venting or explosion. The nuclear weapons and repository storage groups at both Los Alamos and Livermore have been critical of our work while others have defended our calculations on wet and dry criticality. The conditions we identified for positive and negative feedback are no longer contested. The role of confinement of the rock in enhancing the yield from the explosion is still unsettled, and that is addressed later in this paper. The likelihood of confinement, venting, or explosive dispersion also remains unsettled and that is addressed here as well. Some critics of our work have tried to show that the probability of reconfiguration by natural processes is very small. They argue further that emplacement can be done in such a way as to make the probability even smaller. Of course these additional efforts will raise the cost of waste emplacement and the question arises as to how much is enough. The answer to this question seems to not be an easy one

Modeling of coupled thermodynamic and geomechanical performance of underground compressed air energy storage in lined rock caverns

Energy Technology Data Exchange (ETDEWEB)

Rutqvist, Jonny; Kim, Hyung-Mok; Ryu, Dong-Woo; Synn, Joong-Ho; Song, Won-Kyong

2012-06-01

We applied coupled nonisothermal, multiphase fluid flow and geomechanical numerical modeling to study the coupled thermodynamic and geomechanical performance of underground compressed air energy storage (CAES) in concrete-lined rock caverns. The paper focuses on CAES in lined caverns at relatively shallow depth (e.g., 100 m depth) in which a typical CAES operational pressure of 5 to 8 MPa is significantly higher than both ambient fluid pressure and in situ stress. We simulated a storage operation that included cyclic compression and decompression of air in the cavern, and investigated how pressure, temperature and stress evolve over several months of operation. We analyzed two different lining options, both with a 50 cm thick low permeability concrete lining, but in one case with an internal synthetic seal such as steel or rubber. For our simulated CAES system, the thermodynamic analysis showed that 96.7% of the energy injected during compression could be recovered during subsequent decompression, while 3.3% of the energy was lost by heat conduction to the surrounding media. Our geomechanical analysis showed that tensile effective stresses as high as 8 MPa could develop in the lining as a result of the air pressure exerted on the inner surface of the lining, whereas thermal stresses were relatively smaller and compressive. With the option of an internal synthetic seal, the maximum effective tensile stress was reduced from 8 to 5 MPa, but was still in substantial tension. We performed one simulation in which the tensile tangential stresses resulted in radial cracks and air leakage though the lining. This air leakage, however, was minor (about 0.16% of the air mass loss from one daily compression) in terms of CAES operational efficiency, and did not significantly impact the overall energy balance of the system. However, despite being minor in terms of energy balance, the air leakage resulted in a distinct pressure increase in the surrounding rock that could be

Seepage into an Underground Opening Constructed in Unsaturated Fractured Rock Under Evaporative Conditions, RPR 29013(C)

International Nuclear Information System (INIS)

Trautz, R. C.; Wang, Joseph S. Y.

2001-01-01

Liquid-release tests, performed in boreholes above an underground opening constructed in unsaturated fractured rock, are used in this study to evaluate seepage into a waste emplacement drift. Evidence for the existence of a capillary barrier at the ceiling of the drift is presented, based on field observations (including spreading of the wetting front across the ceiling and water movement up fractures exposed in the ceiling before seepage begins). The capillary barrier mechanism has the potential to divert water around the opening, resulting in no seepage when the percolation flux is at or below the seepage threshold flux. Liquid-release tests are used to demonstrate that a seepage threshold exists and to measure the magnitude of the seepage threshold flux for three test zones that seeped. The seepage data are interpreted using analytical techniques to estimate the test-specific strength of the rock capillary forces (α -1 ) that prevent water from seeping into the drift. Evaporation increases the seepage threshold flux making it more difficult for water to seep into the drift and producing artificially inflated α -1 values. With adjustments for evaporation, the minimum test-specific threshold is 1,600 mm/yr with a corresponding α -1 of 0.027 m

Felsenkeller shallow-underground accelerator laboratory for nuclear astrophysics

Science.gov (United States)

Bemmerer, D.; Cowan, T. E.; Gohl, S.; Ilgner, C.; Junghans, A. R.; Reinhardt, T. P.; Rimarzig, B.; Reinicke, S.; Röder, M.; Schmidt, K.; Schwengner, R.; Stöckel, K.; Szücs, T.; Takács, M.; Wagner, A.; Wagner, L.; Zuber, K.

2015-05-01

Favored by the low background in underground laboratories, low-background accelerator-based experiments are an important tool to study nuclear reactions involving stable charged particles. This technique has been used for many years with great success at the 0.4 MV LUNA accelerator in the Gran Sasso laboratory in Italy, proteced from cosmic rays by 1400 m of rock. However, the nuclear reactions of helium and carbon burning and the neutron source reactions for the astrophysical s-process require higher beam energies than those available at LUNA. Also the study of solar fusion reactions necessitates new data at higher energies. As a result, in the present NuPECC long range plan for nuclear physics in Europe, the installation of one or more higher-energy underground accelerators is strongly recommended. An intercomparison exercise has been carried out using the same HPGe detector in a typical nuclear astrophysics setup at several sites, including the Dresden Felsenkeller underground laboratory. It was found that its rock overburden of 45m rock, together with an active veto against the remaining muon flux, reduces the background to a level that is similar to the deep underground scenario. Based on this finding, a used 5 MV pelletron tandem with 250 μA upcharge current and external sputter ion source has been obtained and transported to Dresden. Work on an additional radio-frequency ion source on the high voltage terminal is underway. The project is now fully funded. The installation of the accelerator in the Felsenkeller is expected for the near future. The status of the project and the planned access possibilities for external users will be reported.

Prediction of underground argon content for dark matter experiments

International Nuclear Information System (INIS)

Mei, D.-M.; Spaans, J.; Keller, C.; Yin, Z.-B.; Koppang, M.; Hime, A.; Gehman, V. M.

2010-01-01

In this paper, we demonstrate the use of physical models to evaluate the production of 39 Ar and 40 Ar underground. Considering both cosmogenic 39 Ar production and radiogenic 40 Ar production in situ and from external sources, we can derive the ratio of 39 Ar to 40 Ar in underground sources. We show for the first time that the 39 Ar production underground is dominated by stopping negative muon capture on 39 K and (α,n) induced subsequent 39 K(n,p) 39 Ar reactions. The production of 39 Ar is shown as a function of depth. We demonstrate that argon depleted in 39 Ar can be obtained only if the depth of the underground resources is greater than 500 m.w.e. below the surface. Stopping negative muon capture on 39 K dominates over radiogenic production at depths of less than 2000 m.w.e., and that production by muon-induced neutrons is subdominant at any depth. The depletion factor depends strongly on both radioactivity level and potassium content in the rock. We measure the radioactivity concentration and potassium concentration in the rock for a potential site of an underground argon source in South Dakota. Depending on the probability of 39 Ar and 40 Ar produced underground being dissolved in the water, the upper limit of the concentration of 39 Ar in the underground water at this site is estimated to be in a range of a factor of 1.6 to 155 less than the 39 Ar concentration in the atmosphere. The calculation tools presented in this paper are also critical to the dating method with 39 Ar.

Design of underground layout and their maintenance

Energy Technology Data Exchange (ETDEWEB)

Kim, Bok Youn; Kang, Chang Hee; Jo, Young Do; Lim, Sang Taek [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1997-12-01

Layout of underground structure has to be designed based on rock mechanical analysis and the concept of active support has to be adopted considering the large openings are requested to accommodate heavy duty diesel equipment in underground. Rock bolt and shotcrete will be the most applicable method to support such a large dimensional tunnels. 1) Direction: The main haulage way of the mines where diesel equipment are operating is ramp way system. For optimizing safety measures, and minimizing maintenance cost of the tunnels, it is strongly recommended that all the tunnels including ramp way, rooms and sublevels should be designed in parallel to the direction of principal stress and perpendicular to the direction of major discontinuity. 2) Inclination: Basically, the inclination of the ramp way depends on the specification of the equipment, but 10-15% is usual. The steep inclination needs less initial investment but there will be an adverse effects such as higher operating and maintenance costs. 3) Profile (Cross section): The maximum dimension of the equipment operating in local mines appeared 12.8m long, 3.705m wide and 3.68m high. Considering the dimension, the requested profile simply can be calculated to 4m x 4m, but it should be decided according to the regulated minimum clearances from the walls and roof. The minimum inner curvature radius of the tunnels should be more than 5.2m, and in this case, the tunnel width of the curved zone should be more than 5.5m. 4) Sight distance and braking distance: For the safe operation of the equipment, the sight distance must be longer than braking distance, so that the driver can hold up the equipment safely after finding the obstacles in front of him. The maximum braking distance without heating of brake shoe is 60m. 5) Support and maintenance: Due to the large dimensional tunnels where diesel equipment are operating, the conventional supporting system is not applicable. Therefore, the active support concept should be

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

Field observations and failure analysis of an excavation damaged zone in the Horonobe Underground Research Laboratory

International Nuclear Information System (INIS)

Aoyagi, Kazuhei; Ishii, Eiichi; Ishida, Tsuyoshi

2017-01-01

In the construction of a deep underground facility, the hydromechanical properties of the rock mass around an underground opening are changed significantly due to stress redistribution. This zone is called an excavation damaged zone (EDZ). In high-level radioactive waste disposal, EDZs can provide a shortcut for the escape of radionuclides to the surface environment. Therefore, it is important to develop a method for predicting the detailed characteristics of EDZs. For prediction of the EDZ in the Horonobe Underground Research Laboratory of Japan, we conducted borehole televiewer surveys, rock core analyses, and repeated hydraulic conductivity measurements. We observed that niche excavation resulted in the formation of extension fractures within 0.2 to 1.0 m into the niche wall, i.e., the extent of the EDZ is within 0.2 to 1.0 m into the niche wall. These results are largely consistent with the results of a finite element analysis implemented with the failure criteria considering failure mode. The hydraulic conductivity in the EDZ was increased by 3 to 5 orders of magnitude compared with the outer zone. The hydraulic conductivity in and around the EDZ has not changed significantly in the two years following excavation of the niche. These results show that short-term unloading due to excavation of the niche created a highly permeable EDZ. (author)

Underground siting of nuclear power plants

International Nuclear Information System (INIS)

Pinto, S.; Telleschi, P.

1978-10-01

Two of the main underground siting alternatives, the rock cavity plant and the pit siting, have been investigated in detail and two layouts, developed for specific sites, have been proposed. The influence of this type of siting on normal operating conditions and during abnormal occurences have been investigated. (Auth.)

Solid-Gas Coupling Model for Coal-Rock Mass Deformation and Pressure Relief Gas Flow in Protection Layer Mining

OpenAIRE

Zhu, Zhuohui; Feng, Tao; Yuan, Zhigang; Xie, Donghai; Chen, Wei

2018-01-01

The solid-gas coupling model for mining coal-rock mass deformation and pressure relief gas flow in protection layer mining is the key to determine deformation of coal-rock mass and migration law of pressure relief gas of protection layer mining in outburst coal seams. Based on the physical coupling process between coal-rock mass deformation and pressure-relief gas migration, the coupling variable of mining coal-rock mass, a part of governing equations of gas seepage field and deformation fiel...

Image resolution influence on determination of resin injection rock mass

Science.gov (United States)

Wang, Weixing; Hakami, Eva

2006-01-01

In the context of nuclear waste repositories, an important approach to understanding brittle rock mass behavior to integrate new and powerful observational and numerical methods with multi-functional 3-D imaging and visualization techniques. Since 1994, Swedish Nuclear Fuel and Waste Management Company (SKB) have identified the need for a better understanding of radionuclide transport and retention processes in fractured rock. As a cooperation project between Sweden and China, we sampled a number of rock specimens for analyze rock fracture network by optical image technique. The samples are resin injected, in which way; opened fractures can be seen clearly by means of UV (Ultraviolet) light illumination. In the study period, we used different optical focuses to obtain the images from the same samples; we found that Image resolution influences on porosity determination of resin injected rock mass. This paper presents and discusses the six issues based on our research results: (1) Fracture porosity increases as camera focus distance decreases; (2) Porosity increases as illumination increases in resin injected fracture images; (3) To roughly estimate the porosity, the low resolution image can be used; (4) To collect more details of fracture information, the high resolution image is needed; (5) The resolution of image should be determined based on the aim of fracture analysis; (6) To acquire high resolution image, constructing a special illumination (standard) box maybe helpful to avoid light reflection and diffusion.

A Review of Rock Bolt Monitoring Using Smart Sensors

Directory of Open Access Journals (Sweden)

Gangbing Song

2017-04-01

Full Text Available Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.

A Review of Rock Bolt Monitoring Using Smart Sensors.

Science.gov (United States)

Song, Gangbing; Li, Weijie; Wang, Bo; Ho, Siu Chun Michael

2017-04-05

Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.

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)

Radionuclides in an underground environment

International Nuclear Information System (INIS)

Thompson, J.L.

1996-01-01

In the 100 years since Becquerel recognized radioactivity, mankind has been very successful in producing large amounts of radioactive materials. We have been less successful in reaching a consensus on how to dispose of the billions of curies of fission products and transuranics resulting from nuclear weapons testing, electrical power generation, medical research, and a variety of other human endeavors. Many countries, including the United States, favor underground burial as a means of disposing of radioactive wastes. There are, however, serious questions about how such buried wastes may behave in the underground environment and particularly how they might eventually contaminate water, air and soil resources on which we are dependent. This paper describes research done in the United States in the state of Nevada on the behavior of radioactive materials placed underground. During the last thirty years, a series of ''experiments'' conducted for other purposes (testing of nuclear weapons) have resulted in a wide variety of fission products and actinides being injected in rock strata both above and below the water table. Variables which seem to control the movement of these radionuclides include the physical form (occlusion versus surface deposition), the chemical oxidation state, sorption by mineral phases of the host rock, and the hydrologic properties of the medium. The information gained from these studies should be relevant to planning for remediation of nuclear facilities elsewhere in the world and for long-term storage of nuclear wastes

Hydrogeological Characteristics of Fractured Rocks around the In-DEBS Test Borehole at the Underground Research Facility (KURT)

Science.gov (United States)

Ko, Nak-Youl; Kim, Geon Young; Kim, Kyung-Su

2016-04-01

In the concept of the deep geological disposal of radioactive wastes, canisters including high-level wastes are surrounded by engineered barrier, mainly composed of bentonite, and emplaced in disposal holes drilled in deep intact rocks. The heat from the high-level radioactive wastes and groundwater inflow can influence on the robustness of the canister and engineered barrier, and will be possible to fail the canister. Therefore, thermal-hydrological-mechanical (T-H-M) modeling for the condition of the disposal holes is necessary to secure the safety of the deep geological disposal. In order to understand the T-H-M coupling phenomena at the subsurface field condition, "In-DEBS (In-Situ Demonstration of Engineered Barrier System)" has been designed and implemented in the underground research facility, KURT (KAERI Underground Research Tunnel) in Korea. For selecting a suitable position of In-DEBS test and obtaining hydrological data to be used in T-H-M modeling as well as groundwater flow simulation around the test site, the fractured rock aquifer including the research modules of KURT was investigated through the in-situ tests at six boreholes. From the measured data and results of hydraulic tests, the range of hydraulic conductivity of each interval in the boreholes is about 10-7-10-8 m/s and that of influx is about 10-4-10-1 L/min for NX boreholes, which is expected to be equal to about 0.1-40 L/min for the In-DEBS test borehole (diameter of 860 mm). The test position was determined by the data and availability of some equipment for installing In-DEBS in the test borehole. The mapping for the wall of test borehole and the measurements of groundwater influx at the leaking locations was carried out. These hydrological data in the test site will be used as input of the T-H-M modeling for simulating In-DEBS test.

Analysis and design of SSC underground structures

International Nuclear Information System (INIS)

Clark, G.T.

1993-01-01

This paper describes the analysis and design of underground structures for the Superconducting Super Collider (SSC) Project. A brief overview of the SSC Project and the types of underground structures are presented. Engineering properties and non-linear behavior of the geologic materials are reviewed. The three-dimensional sequential finite element rock-structure interaction analysis techniques developed by the author are presented and discussed. Several examples of how the method works, specific advantages, and constraints are presented. Finally, the structural designs that resulted from the sequential interaction analysis are presented

Outline and results of study on excavation response of rock mass around shaft in shaft excavation effects project

International Nuclear Information System (INIS)

Sugihara, Kozo; Matsui, Hiroya; Sato, Toshinori

1993-01-01

A shaft, with a diameter of 6 m and a depth of 150 m, has been newly excavated in sedimentary rock and excavation response of rock mass around the shaft has been measured and analyzed. Excavation response has been evaluated based on the results of measurement of rock mass movement, such as displacement and strain, and change of rock property, such as deformability and permeability. This study indicates that rock property has been changed with in about 1 m from the shaft wall, and rock mass movement and property change has been influenced by rock facies, fracture and re-distributed stress. The relation between property change and these factors is remained to be evaluated in future study. (author)

Dynamic Response of Underground Circular Lining Tunnels Subjected to Incident P Waves

Directory of Open Access Journals (Sweden)

Hua Xu

2014-01-01

Full Text Available Dynamic stress concentration in tunnels and underground structures during earthquakes often leads to serious structural damage. A series solution of wave equation for dynamic response of underground circular lining tunnels subjected to incident plane P waves is presented by Fourier-Bessel series expansion method in this paper. The deformation and stress fields of the whole medium of surrounding rock and tunnel were obtained by solving the equations of seismic wave propagation in an elastic half space. Based on the assumption of a large circular arc, a series of solutions for dynamic stress were deduced by using a wave function expansion approach for a circular lining tunnel in an elastic half space rock medium subjected to incident plane P waves. Then, the dynamic response of the circular lining tunnel was obtained by solving a series of algebraic equations after imposing its boundary conditions for displacement and stress of the circular lining tunnel. The effects of different factors on circular lining rock tunnels, including incident frequency, incident angle, buried depth, rock conditions, and lining stiffness, were derived and several application examples are presented. The results may provide a good reference for studies on the dynamic response and aseismic design of tunnels and underground structures.

Survey of existing underground openings for in-situ experimental facilities

International Nuclear Information System (INIS)

Wollenberg, H.; Graf, A.; Strisower, B.; Korbin, G.

1981-07-01

In an earlier project, a literature search identified 60 underground openings in crystalline rock capable of providing access for an in-situ experimental facility to develop geochemical and hydrological techniques for evaluating sites for radioactive waste isolation. As part of the current project, discussions with state geologists, owners, and operators narrowed the original group to 14. Three additional sites in volcanic rock and one site in granite were also identified. Site visits and application of technical criteria, including the geologic and hydrologic settings and depth, extent of the rock unit, condition, and accessibility of underground workings, determined four primary candidate sites: the Helms Pumped Storage Project in grandiodorite of the Sierra Nevada, California; the Tungsten Queen Mine in Precambrian granodiorite of the North Carolina Piedmont; the Mount Hope Mine in Precambrian granite and gneiss of northern New Jersey; and the Minnamax Project in the Duluth gabbro complex of northern Minnesota

Modelling of underground geomechanical characteristics for electrophysical conversion of oil shale

International Nuclear Information System (INIS)

Bukharkin, A A; Koryashov, I A; Martemyanov, S M; Ivanov, A A

2015-01-01

Oil shale energy extraction is an urgent issue for modern science and technique. With the help of electrical discharge phenomena it is possible to create a new efficient technology for underground conversion of oil shale to shale gas and oil. This method is based on Joule heat in the rock volume. During the laboratory experiments the problem has arisen, when the significant part of a shale fragment is being heated, but the further heating is impossible due to specimen cracking. It leads to disruption in current flow and heat exchange. Evidently, in the underground conditions these failure processes will not proceed. Cement, clay and glass fiber/epoxy resin armature have been used for modelling of geomechanical underground conditions. Experiments have shown that the use of a reinforcing jacket makes it possible to convert a full rock fragment. Also, a thermal field extends radially from the centre of a tree-type structure, and it has an elliptic cross section shape. It is explained by the oil shale anisotropy connected with a rock laminar structure. Therefore, heat propagation is faster along the layers than across ones. (paper)

Rock fracture dynamics research at AECL's Underground Research Laboratory: applications to geological disposal of radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Young, R.P. [Univ. of Toronto, Toronto, ON (Canada); Haycox, J.R. [Applied Seismology Consultants Limited, Shrewsbury, Shropshire (United Kingdom); Martino, J. [Atomic Energy of Canada Limited, Pinawa, MB (Canada)

2011-07-01

Studies of rock fracture dynamics at AECL's Underground Research Laboratory (URL) have helped to provide a fundamental understanding of how crystalline rock responds to stresses induced from excavation, pressurization and temperature changes. The data acquired continue to provide insights into how a facility for the future geological disposal of radioactive waste could be engineered. Research into microseismic (MS), acoustic emission (AE), and ultrasonic velocity measurements has been performed on the full-scale sealed, pressurized, and heated horizontal elliptical tunnel at the Tunnel Sealing Experiment (TSX). The continuous monitoring of the experiment for 8 years provides a unique dataset for the understanding of the medium-term performance of an engineered disposal facility. This paper summarizes the results, interpretations and key findings of the experiment paying particular focus to the heating and cooling/depressurization of the chamber. Initial drilling of the tunnel and bulkheads causes microfracturing around the tunnel, mapped by MS and AEs, and is used as a benchmark for fracturing representing the excavated damaged zone (EDZ). There is no further extension to the volume during pressurization or heating of the tunnel suggesting an increase in crack density and coalescence of cracks rather than extension into unfractured rock. The dominant structure within the seismic cloud has been investigated using a statistical approach applying the three-point method. MS events in the roof exhibit a dominant pattern of sub-horizontal and shallow-dipping well defined planar features, but during cooling and depressurization a 45 degree dip normal to the tunnel axis is observed, which may be caused by movement in the rock-concrete interface due to differential cooling of the bulkhead and host rock. Cooling and depressurization of the TSX have not led to a significant increase in the number of MS or AE events. Ultrasonic results suggest the rock gets even stiffer

The Spatial Assessment of the Current Seismic Hazard State for Hard Rock Underground Mines

Science.gov (United States)

Wesseloo, Johan

2018-06-01

Mining-induced seismic hazard assessment is an important component in the management of safety and financial risk in mines. As the seismic hazard is a response to the mining activity, it is non-stationary and variable both in space and time. This paper presents an approach for implementing a probabilistic seismic hazard assessment to assess the current hazard state of a mine. Each of the components of the probabilistic seismic hazard assessment is considered within the context of hard rock underground mines. The focus of this paper is the assessment of the in-mine hazard distribution and does not consider the hazard to nearby public or structures. A rating system and methodologies to present hazard maps, for the purpose of communicating to different stakeholders in the mine, i.e. mine managers, technical personnel and the work force, are developed. The approach allows one to update the assessment with relative ease and within short time periods as new data become available, enabling the monitoring of the spatial and temporal change in the seismic hazard.

Continuum model for water movement in an unsaturated fractured rock mass

International Nuclear Information System (INIS)

Peters, R.R.; Klavetter, E.A.

1988-01-01

The movement of fluids in a fractured, porous medium has been the subject of considerable study. This paper presents a continuum model that may be used to evaluate the isothermal movement of water in an unsaturated, fractured, porous medium under slowly changing conditions. This continuum model was developed for use in evaluating the unsaturated zone at the Yucca Mountain site as a potential repository for high-level nuclear waste. Thus its development has been influenced by the conditions thought to be present at Yucca Mountain. A macroscopic approach and a microscopic approach are used to develop a continuum model to evaluate water movement in a fractured rock mass. Both approaches assume that the pressure head in the fractures and the matrix are identical in a plane perpendicular to flow. Both approaches lead to a single-flow equation for a fractured rock mass. The two approaches are used to calculate unsaturated hydrologic properties, i.e., relative permeability and saturation as a function of pressure head, for several types of tuff underlying Yucca Mountain, using the best available hydrologic data for the matrix and the fractures. Rock mass properties calculated by both approaches are similar

Groundwater flow modeling in construction phase of the Mizunami Underground Research Laboratory project

International Nuclear Information System (INIS)

Onoe, Hironori; Saegusa, Hiromitsu; Takeuchi, Ryuji

2016-01-01

This paper comprehensively describes the result of groundwater flow modeling using data of hydraulic responses due to construction of Mizunami Underground Research Laboratory (MIU) in Mizunami, Gifu, in order to update hydrogeological model based on stepwise approach for crystalline fractured rock in Japan. The results showed that large scale hydraulic compartment structures which has significant influence on change of groundwater flow characteristics are distributed around MIU. Furthermore, it is concluded that hydrogeological monitoring data and groundwater flow modeling during construction of deep underground facilities are effective for hydrogeological characterization of heterogeneous fractured rock. (author)

Microseismicity of an Unstable Rock Mass: From Field Monitoring to Laboratory Testing

Science.gov (United States)

Colombero, C.; Comina, C.; Vinciguerra, S.; Benson, P. M.

2018-02-01

The field-scale microseismic (MS) activity of an unstable rock mass is known to be an important tool to assess damage and cracking processes eventually leading to macroscopic failures. However, MS-event rates alone may not be enough for a complete understanding of the trigger mechanisms of mechanical instabilities. Acoustic Emission (AE) techniques at the laboratory scale can be used to provide complementary information. In this study, we report a MS/AE comparison to assess the stability of a granitic rock mass in the northwestern Italian Alps (Madonna del Sasso). An attempt to bridge the gap between the two different scales of observation, and the different site and laboratory conditions, is undertaken to gain insights on the rock mass behavior as a function of external governing factors. Time- and frequency-domain parameters of the MS/AE waveforms are compared and discussed with this aim. At the field scale, special attention is devoted to the correlation of the MS-event rate with meteorological parameters (air temperature and rainfalls). At the laboratory scale, AE rates, waveforms, and spectral content, recorded under controlled temperature and fluid conditions, are analyzed in order to better constrain the physical mechanisms responsible for the observed field patterns. The factors potentially governing the mechanical instability at the site were retrieved from the integration of the results. Abrupt thermal variations were identified as the main cause of the site microsesimicity, without highlighting irreversible acceleration in the MS-event rate potentially anticipating the rock mass collapse.

Modelling of rock mass response to glaciation in the Dounreay area, Scotland

International Nuclear Information System (INIS)

Errington, M.

1992-01-01

This report presents the results of a modelling study undertaken to investigate the potential response of a faulted rock mass to glacial loading. The modelled rock mass was a 10X10X10 km region around Dounreay. This site was selected as one of the two locations under consideration by UK Nirex Ltd for a deep repository for the disposal of low and intermediate radioactive waste. The model selected for the study was 3DEC, a distinct element code which has been used in similar modelling studies in Sweden. A set of seven regional fractures and five rock types were identified in the region to be modelled. Properties for these discontinuities and media were derived from published information where possible or from data for similar regimes. A number of parameters were selected for sensitivity studies. The results of the study form a useful basis for assessing the extent of fracture movement which might be expected in the region modelled. Site-specific results cannot be extended to other areas but the results of the sensitivity study indicate those parameters which have a significant effect on the modelled behaviour of the rock mass and which would thus require site-specific determination. (Author)

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

Characteristics of micro transfer paths and diffusion phenomena in the matrix of deep crystalline rock

International Nuclear Information System (INIS)

Ishibashi, Masayuki; Sasao, Eiji; Hama, Katsuhiro

2016-01-01

Matrix diffusion is one of the important phenomena for evaluating the safety of the geological disposal of high level waste because it has an effect of retarding mass transport in crystalline rocks. Previous studies indicated that the altered granitic rocks have high retardation functions due to the micropore formation associated with hydrothermal alteration; however, there has not been enough knowledge on the matrix diffusion in weakly unaltered rocks (macroscopically unaltered rocks). Since the macroscopically altered granitic rocks in Japan are likely to be affected by deuteric alteration due to hydrothermal flu resulting from crystallization of granitic magma, it is important to understand the effect of deuteric alteration on the matrix diffusion. Therefore, detailed observations were carried out to clarify the effects of deuteric alteration focused on the macroscopically unaltered granite sampled from 300 m and 500 m below ground levels at the Mizunami Underground Research Laboratory, central Japan. The results provide that the micropores are selectively formed in plagioclases due to deuteric alteration and they have the potential of acting as matrix diffusion paths. This is indicating the possibility that deuteric alteration can retard the mass transport in crystalline rocks in Japan. That plays a significant role in enforcing the barrier function of crystalline rocks. (author)

In situ measurement of the thermal conductivity in propylite rock mass

International Nuclear Information System (INIS)

Shimooka, Kenji; Araki, Kunio; Suda, Shintaro.

1982-11-01

The safety evaluation for the geological disposal of the high level waste becomes an urgent problem to establish the backend of nuclear fuel cycle. The stability of the original host rock and the flow of groundwater will be perturbed by the thermal disturbances from the waste. So the heater experiment at a depth of 90 m below the surface was carried out to study the conduction of decay heat. For measuring the thermal conductivity of propylite rock mass, a cylindrical heater and 13 thermocouples were inserted in 6 boreholes. The power output of the heater was kept at 880 W constant during the experimental periods of 61 days. From the observed temperature rise around the heater, the thermal conductivity 2.1 W/m 0 C was calculated by steady-state calculation. The value of the rock mass was found to be slightly bigger compared with 1.5 - 1.6 W/m 0 C of core samples. (author)

Geotechnical core and rock mass characterization for the UK radioactive waste repository design

International Nuclear Information System (INIS)

Rawlings, C.G.; Barton, N.; Loset, F.; Vik, G.; Bhasin, R.K.; Smallwood, A.; Davies, N.

1996-01-01

The NGI method of characterizing joints (using JRC, JCS and φ r ) and characterizing rock masses (using the Q-system) have been and are currently being used extensively in geotechnical consultancy projects. One such project recently completed for UK Nirex Ltd included the logging of 8 km of 100-mm-diameter drill core from boreholes up to 2km in depth. Preliminary rock reinforcement designs were derived from the Q-system statistics, which were logged in parallel with JRC, JCS and φ r . The data from the NGI method of characterizing joints and the Q-system for characterizing rock masses have also been used as the basis for UDEC-BB numerical modelling of the proposed cavern excavations for the disposal of solid, low- and intermediate-level radioactive wastes. The purpose of this numerical modelling was to investigate the stability of rock caverns and in particular the rock reinforcement requirements (giving predicted bolt loads and rock deformations), the extent of the disturbed zone (joint shearing and hydraulic aperture) with respect to cavern orientation, the effect of various pillar widths, and the effect of the cavern excavation sequence. (Author)

SEEPAGE INTO DRIFTS IN UNSATRUATED FRACTURED ROCK AT YUCCA MOUNTAIN

International Nuclear Information System (INIS)

JENS BIRHOLZER; GUOMIN LI; CHIN-FU TSANG; YVONNE TSANG

1998-01-01

An important issue for the long-term performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of the future seepage rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, as it is located in thick, partially saturated, fractured tuff formations. The long-term situation in the drifts several thousand years after waste emplacement will be characterized by a relative humidity level close to or equal to 100%. as the drifts will be sealed and unventilated, and the waste packages will have cooled. The underground tunnels will then act as capillary barriers for the unsaturated flow, ideally diverting water around them, if the capillary forces are stronger than gravity and viscous forces. Seepage into the drifts will only be possible if the hydraulic pressure in the rock close to the drift walls increases to positive values; i.e., the flow field becomes locally saturated. In the present work, we have developed and applied a methodology to study the potential rate of seepage into underground cavities embedded in a variably saturated, heterogeneous fractured rock formation. The fractured rock mass is represented as a stochastic continuum where the fracture permeabilities vary by several orders of magnitude. Three different realizations of random fracture permeability fields are generated, with the random permeability structure based on extensive fracture mapping, borehole video analysis, and in-situ air permeability testing. A 3-D numerical model is used to simulate the heterogeneous steady-state flow field around the drift, with the drift geometry explicitly represented within the numerical discretization grid. A variety of flow scenarios are considered assuming present-day and future climate conditions at Yucca Mountain. The numerical study is complemented by theoretical evaluations of the drift seepage problem, using stochastic perturbation theory to develop a better

Long-term terrain protection over the underground log dumps. Dlouhodoba ochrana terenu nad podzemnimi slozisti

Energy Technology Data Exchange (ETDEWEB)

Vacek, J [Ustav geotechniky CSAV, Praha (Czechoslovakia)

1992-02-01

Results of experimental research of surface danger of the terrain over underground log dumps are given. Time influence and rock structure influence on surface deformation were analyzed for the purpose of solving rock stability. The example of solving underground cavities influence on surface by using equivalent modelling method is described. This way enables us to take geotechnic route, influence of driving advance and the method backfilling into consideration. The method is convenient for evaluation of landslide effects and for safeguarding measures. 9 figs.

Surrounding rock stress analysis of underground high level waste repository

International Nuclear Information System (INIS)

Liu Wengang; Wang Ju; Wang Guangdi

2006-01-01

During decay of nuclear waste, enormous energy was released, which results in temperature change of surrounding rock of depository. Thermal stress was produced because thermal expansion of rock was controlled. Internal structure of surrounding rock was damaged and strength of rock was weakened. So, variation of stress was a dynamic process with the variation of temperature. BeiShan region of Gansu province was determined to be the depository field in the future, it is essential to make research on granite in this region. In the process of experiment, basic physical parameters of granite were analyzed preliminary with MTS. Long range temperature and stress filed was simulated considering the damage effect of surrounding rock, and rules of temperature and stress was achieved. (authors)

Rock mass deformation properties of closely jointed basalt

International Nuclear Information System (INIS)

Kim, K.; Cramer, M.L.

1982-12-01

The deformational behavior of the Columbia River basalt is being investigated as part of a comprehensive site characterization program intended to determine the feasibility of constructing a nuclear waste repository in basalt at Hanford, Washington. Direct field measurements were conducted in a 2-m cube of basalt to obtain truly representative rock mass deformation properties. Load was applied to the test block in three orthogonal directions through the use of flat jacks in two perpendicular planes and a cable anchor system in the third. This configuration allowed the block to be placed in a simulated triaxial stress state at stress levels up to 12.5 MPa. The deformation at the center of the test block was monitored through the use of an optical measurement system developed for this project. The results indicate that the vertically oriented columnar joints have a significant influence on the deformation behavior of the basalt. The modulus in the direction parallel to the column axis was approx. 30 GPa, while the modulus value perpendicular to the columns was approx. 20 GPa. Laboratory measurements of intact specimens taken from this area yielded a value of 80 GPa with no indication of anisotropy. Hysteresis was observed in all loading cycles, but was distinctly more pronounced perpendicular to the column axis, indicative of significant joint displacement in this direction. The results of this test represent the first true rock mass modulus data obtained in closely jointed rock on a large scale. These measurement methods have eliminated many of the ambiguities associated with borehole jacking and surface measurement techniques

Case study of siting technology for underground nuclear power plant

International Nuclear Information System (INIS)

Hibino, Satoshi; Komada, Hiroya; Honsho, Shizumitsu; Fujiwara, Yoshikazu; Motojima, Mutsumi; Nakagawa, Kameichiro; Nosaki, Takashi

1991-01-01

Underground siting method is one of new feasible siting methods for nuclear power plants. This report presents the results on case studies on underground siting. Two sites of a steeply inclined and plateau like configurations were selected. 'Tunnel type cavern; all underground siting' method was applied for the steeply inclined configuration, and 'shaft type semi-cavern; partial underground siting' method was applied for the plateau like configuration. The following designs were carried out for these two sites as case studies; (1) conceptual designs, (2) geological surveys and rock mechanics tests, (3) stability analysis during cavern excavations, (4) seismic stability analysis of caverns during earthquake, (5) reinforcement designs for caverns, (6) drainage designs. The case studies showed that these two cases were fully feasible, and comparison between two cases revealed that the 'shaft type semi-cavern; partial underground siting' method was more suitable for Japanese islands. As a first step of underground siting, therefore, the authors recommend to construct a nuclear power plant by this method. (author)

Underground openings production line 2012. Design, production and initial state of the underground openings

International Nuclear Information System (INIS)

2013-08-01

The Underground Openings Line Production Line report describes the design requirements, the design principles, the methods of construction and the target properties for the underground rooms required for the final repository. It is one of five Production Line reports, namely the: Underground Openings Line report, Canister report, Buffer report, Backfill report, Closure report. Together, these reports cover the lifespan of the underground phases of the final repository from the start of construction of the underground rooms to their closure. Posiva has developed reference methods for constructing the underground rooms. Tunnels will be constructed using the drill and blast technique, shafts will be constructed using raise boring and the deposition holes will be constructed by reverse down reaming. Underground openings will be made safe by reinforcement by using rock bolts, net or shotcrete, depending on which type of opening is being considered, and groundwater inflows will be limited by grouting. Posiva's requirements management system (VAHA) sets out the specifications for the enactment of the disposal concept at Olkiluoto under five Levels - 1 to 5, from the most generic to the most specific. In this report, the focus is on Level 4 and 5 requirements, which provide practical guidance for the construction of the underground openings. The design requirements are presented in Level 4 and the design specification in Level 5 In addition to the long-term safety-related requirements included in VAHA, there are additional requirements regarding the operation of underground openings, e.g. space requirements due to the equipment used and its maintenance, operational and fire safety. The current reference design for the disposal facility is presented based on the design requirements and design specifications. During the lifespan of the repository the reference design will be revised and updated according to the design principles as new information is available. Reference

Geostatistical methods for rock mass quality prediction using borehole and geophysical survey data

Science.gov (United States)

Chen, J.; Rubin, Y.; Sege, J. E.; Li, X.; Hehua, Z.

2015-12-01

For long, deep tunnels, the number of geotechnical borehole investigations during the preconstruction stage is generally limited. Yet tunnels are often constructed in geological structures with complex geometries, and in which the rock mass is fragmented from past structural deformations. Tunnel Geology Prediction (TGP) is a geophysical technique widely used during tunnel construction in China to ensure safety during construction and to prevent geological disasters. In this paper, geostatistical techniques were applied in order to integrate seismic velocity from TGP and borehole information into spatial predictions of RMR (Rock Mass Rating) in unexcavated areas. This approach is intended to apply conditional probability methods to transform seismic velocities to directly observed RMR values. The initial spatial distribution of RMR, inferred from the boreholes, was updated by including geophysical survey data in a co-kriging approach. The method applied to a real tunnel project shows significant improvements in rock mass quality predictions after including geophysical survey data, leading to better decision-making for construction safety design.

In-situ experiments for the determination of rock properties and behaviour at the Meuse/Haute Marne Centre

Directory of Open Access Journals (Sweden)

Conil N.

2010-06-01

Full Text Available Andra is in charge of studying the feasibility of a disposal facility for longlived high-level nuclear waste (LL-HLW in a deep geological environment. With this aim, dedicated experiments have been carried out for several years at the Meuse/Haute Marne Underground Research Laboratory excavated in a 500 m deep argillaceous rock formation. These experiments include determining the feasibility of the excavation of disposal cells for LL-HLW, consisting of 40 meter long, 70 cm in diameter, horizontal cased micro tunnels. The hydro mechanical impact of the excavation of such openings on the rock mass behaviour is continuously monitored as well as their mean term mechanical behaviour. Since LL-HLW produce heat, the impact of temperature on the surrounding rock mass and on the micro tunnel steel casing will also be studied. Specific instrumentation has been developed to study this impact. The first step of the microtunnel excavation tests, carried out in 2009, has led to improving the excavation method and the drilling machine. These improvements will be tested in the next step of the excavation tests planned for 2010. The THM experiment dedicated to studying the behaviour of the rock mass under thermal solicitation started early 2010. The behaviour of a steel casing in contact with the rock mass and under thermal solicitation will be studied in an experiment scheduled to start in September 2010.

The underground laboratory. A unique scientific tool to design a reversible storage

International Nuclear Information System (INIS)

2010-07-01

The National Radioactive Waste Management Agency (Andra), was established by the December 1991 Waste Act as a public body in charge of the long-term management of all radioactive waste, under the supervision of the Ministry of Ecology, Energy, Sustainable Development and the Sea (formerly the Ministry of Industry and the Ministry of Environment), and the Ministry of Research. The Andra is carrying out studies on deep reversible waste storage for high-level and long living intermediate-level radioactive wastes thanks to the underground laboratory of its Meuse/Haute-Marne center. This brochure presents the geologic surveys which have led to the selection of the Callovo-Oxfordian argillite formation for the sitting of the underground lab and the underground architecture of the lab. The rock mechanic, heat transfer and rock-fluid interaction experiments carried out in the lab in collaboration with several scientific partners are briefly summarised

Investigative study of the underground excavations for a nuclear waste repository in tuff: Nevada Nuclear Waste Storage Investigations Project

International Nuclear Information System (INIS)

St John, C.M.

1987-07-01

Numerical studies were conducted on the behavior of a tuff rock mass within which emplacement drifts for a nuclear waste repository are excavated. The first study evaluated the effects of rockbolting and excavation-induced damage on the behavior of the rock mass round typical drifts. The second study provided a simple means of assessing the significance of drift shape, drift size, and in-situ state of stress on the deformation and stress in the vicinity of drifts for vertical and horizontal emplacement of waste. Neither study considered the effect of heating of the rock mass after emplacement of the waste so the conclusions pertain only to the conditions immediately after excavation of the underground openings. The results of analyses of the rockbolted excavations indicated that rockbolts do not have a significant influence on the states of deformation or stress within the rock mass, and that the rockbolts are subjected to acceptable levels of stress even if installed as close to the face of the excavation as possible. Accordingly, rockbolts were not considered in the study of drift shape, drift size, and the in-situ state of stress. That study indicated that stable openings of the dimensions investigated can be constructed within a tuff rock mass with the properties assumed. Of the parameters investigated, the in-situ state of stress appeared to be most important. Potentially adverse conditions were predicted if the in-situ horizontal stress is very low, but current indications are that it lies within a range which is consistent with good conditions and a stable roof. 28 refs., 49 figs., 11 tabs

Preliminary state-of-the-art survey: mining techniques for salt and other rock types

Energy Technology Data Exchange (ETDEWEB)

1976-12-01

This is a systematic review of the state-of-the-art of underground mining and excavation technology in the U.S. as applied to salt, limestone, shale, and granite. Chapter 2 covers the basic characteristics of these rock types, the most frequently used underground mining methods, shaft and slope entry construction, equipment, and safety and productivity data. Chapters 3 and 4 summarize underground salt and limestone mining in the U.S. Chapter 5 shows that large amounts of thick shale exist in the U.S., but little is mined. Chapter 6 discusses underground excavations into granite-type rocks. Suggestions are given in the last chapter for further study. (DLC)

Inter-disciplinary Interactions in Underground Laboratories

Science.gov (United States)

Wang, J. S.; Bettini, A.

2010-12-01

Many of underground facilities, ranging from simple cavities to fully equipped laboratories, have been established worldwide (1) to evaluate the impacts of emplacing nuclear wastes in underground research laboratories (URLs) and (2) to measure rare physics events in deep underground laboratories (DULs). In this presentation, we compare similarities and differences between URLs and DULs in focus of site characterization, in quantification of quietness, and in improvement of signal to noise ratios. The nuclear waste URLs are located primarily in geological medium with potentials for slow flow/transport and long isolation. The URL medium include plastic salt, hard rock, soft clay, volcanic tuff, basalt and shale, at over ~500 m where waste repositories are envisioned to be excavated. The majority of URLs are dedicated facilities excavated after extensive site characterization. The focuses are on fracture distributions, heterogeneity, scaling, coupled processes, and other fundamental issues of earth sciences. For the physics DULs, the depth/overburden thickness is the main parameter that determines the damping of cosmic rays, and that, consequently, should be larger than, typically, 800m. Radioactivity from rocks, neutron flux, and radon gas, depending on local rock and ventilation conditions (largely independent of depth), are also characterized at different sites to quantify the background level for physics experiments. DULs have been constructed by excavating dedicated experimental halls and service cavities near to a road tunnel (horizontal access) or in a mine (vertical access). Cavities at shallower depths are suitable for experiments on neutrinos from artificial source, power reactors or accelerators. Rocks stability (depth dependent), safe access, and utility supply are among factors of main concerns for DULs. While the focuses and missions of URLs and DULs are very different, common experience and lessons learned may be useful for ongoing development of new

On thermal properties of hard rocks as a host environment of an underground thermal energy storage

Science.gov (United States)

Novakova, L.; Hladky, R.; Broz, M.; Novak, P.; Lachman, V.; Sosna, K.; Zaruba, J.; Metelkova, Z.; Najser, J.

2013-12-01

With increasing focus on environmentally friendly technologies waste heat recycling became an important issue. Under certain circumstances subsurface environment could be utilized to accommodate relatively large quantity of heat. Industrial waste heat produced during warm months can be stored in an underground thermal energy storage (UTES) and used when needed. It is however a complex task to set up a sustainable UTES for industrial scale. Number of parameters has to be studied and evaluated by means of thermohydromechanical and chemical coupling (THMC) before any UTES construction. Thermal characteristics of various rocks and its stability under thermal loading are amongst the most essential. In the Czech Republic study two complementary projects THMC processes during an UTES operation. The RESEN project (www.resen.cz) employs laboratory tests and experiments to characterise thermal properties of hard rocks in the Bohemian Massif. Aim of the project is to point out the most suitable rock environment in the Bohemian Massif for moderate to ultra-high temperature UTES construction (Sanyal, 2005). The VITA project (www.geology.cz/mokrsko) studies THM coupling in non-electrical temperature UTES using long term in-situ experiment. In both projects thermal properties of rocks were studied. Thermal conductivity and capacity were measured on rock samples. In addition an influence of increasing temperature and moisture content was considered. Ten hard rocks were investigated. The set included two sandstones, two ignibrites, a melaphyr, a syenite, two granites, a gneiss and a serpentinite. For each rock there were measured thermal conductivity and capacity of at least 54 dried samples. Subsequently, the samples were heated up to 380°C in 8 hours and left to cool down. Thermal characteristics were measured during the heating period and after the sample reached room temperature. Heating and cooling cycle was repeated 7 to 10 times to evaluate possible UTES-like degradation of

Controlled drill ampersand blast excavation at AECL's Underground Research Laboratory

International Nuclear Information System (INIS)

Kuzyk, G.W.; Onagi, D.P.; Thompson, P.M.

1996-01-01

A controlled drill and blast method has been developed and used to excavate the Underground Research Laboratory, a geotechnical facility constructed by Atomic Energy of Canada Limited (AECL) in crystalline rock. It has been demonstrated that the method can effectively reduce the excavation disturbed zone (EDZ) and is suitable for the construction of a used fuel disposal vault in the plutonic rock of the Canadian Shield

Blasting technologies in the underground uranium mining operations of AG/SDAG Wismut. Pt. 2

International Nuclear Information System (INIS)

Roschlau, H.

1994-01-01

This is a series of articles on selected problems: The step cut technique developed by Wismut; rock burst alarm systems; stress relief blasting to prevent rock burst; endogenous underground fires caused by self-ignition of rock strata; cooling of hot boreholes; block subsidence in slicing and caving; roadway drivage in sublevel steping with self-consolidating fill. (orig./HP) [de

Development of a smart rock bolt for underground monitoring operations

CSIR Research Space (South Africa)

Moema, JS

2003-07-01

Full Text Available of magnetic methods in measuring the stress or microstructural transformation in an individual bolt in both laboratory and underground environment. The corrosion performance of the smart bolt alloy was evaluated in synthetic mine water and compared...

Stress–strain state of adjacent rock mass under slice mining of steeply dipping ore bodies

Science.gov (United States)

Baryshnikov, VD; Gakhova, LN

2018-03-01

Under analysis is the stress state of rock mass surrounding stopes in the initial cutting layer displaced in plan relative to the above-lying extracted layer in the overcut rock mass. The authors determine the boundaries of the post-limiting deformation zones during stoping advance using the Mohr–Coulomb criterion. The sequence of stoping to ensure better support conditions is proposed.

Horonobe Underground Research Laboratory project. Plans of investigations during shaft and drift excavation (Construction of underground facilities: Phase II)

International Nuclear Information System (INIS)

2005-06-01

Horonobe Underground Research Laboratory Project is planned for over 20 years to establish the scientific and technical basis for the underground disposal of high-level radioactive wastes in Japan. The investigations are conducted by JNC in three phases, from the surface (Phase I), during the construction of the underground facilities (Phase II), and using the facilities (Phase III). This report concerns the investigation plans for Phase II. During excavation of shafts and drifts, detailed geological and borehole investigation will be conducted and the geological model constructed in Phase I is evaluated and revised by newly acquired data of geophysical and geological environment. Detailed in-situ experiments, as well as the effects of shaft excavation, are also done to study long-term changes, rock properties, groundwater flow and chemistry to ensure the reliability of repository technology and establish safety assessment methodology. (S. Ohno)

A study on excavation of rock mass by lasers. Researching the possibility of utilizing low-power lasers

Energy Technology Data Exchange (ETDEWEB)

Ito, Fumio [Taisei Corporation, Technology Research Center, Yokohama, Kanagawa (Japan)

2000-03-01

The object of this research is to develop the techniques of rock-mass excavation by laser irradiation. This rock-mass excavation technique by lasers has a characteristic of extremely little effect to the surroundings of an excavation site no matter how the target rock mass is with regard to geological aspects and given physical property. Moreover, it could be utilized in excavation of waste dump facilities, which need to be re-buried, and applied to excavation of long piles and tunnels, which are drilled through different kinds of strata, and to improvement of rock mass and ground. Lasers have a characteristic of concentrating the energy into a limited point and not only discontinue or cut a large area with a small output like sharp scissors but also block up the cracks deep inside the rock mass by fusing vitrification for its improvement. It leads to restrain the loss of energy, minimization of the effected environment, effective utilization of resources and energy, environmental restoration, and improvement of the working environment. In the field of nuclear fuel, which includes excavating dump pits, dismantling a furnace, and taking appropriate steps of mine remains, excavating, cutting, and fusing could be required to do within a limited space of rock mass or concrete. Up to the present, those things have been done mainly by large machines, but it is too scarce in possibility for them to improve their large size, heavy weight, difficulty in unmanned operation, limited shapes of cutting, and stabilization of waste. In this research the concrete system images have been examined, doing the fundamental researches about higher-power lasers, smaller sizing, transmitting by fibers to find our the breakthrough to realization of laser excavation, This year, as the summary of examining the laser excavation techniques, utilizing a low-power laser, which is thought to be highly effective in rock-mass improvement, will be examined, considering application of the technique

Sinkhole development induced by underground quarrying, and the related hazard

Science.gov (United States)

Parise, M.; Delle Rose, M.

2009-04-01

Sinkholes are extremely widespread in Apulia, a very flat and carbonate region, that acted as the foreland during the phases of building up of the Southern Apenninic Chain in Miocene time. This is due to the presence of soluble rocks throughout the region, that highly predispose the area to this very subtle natural hazard. In addition to the natural setting, which favours their development, sinkholes may also be induced by anthropogenic activities. In the latter sense, underground quarrying represents one of the most dangerous activities in karst areas. Apulia has a long history of quarrying. Since the roman time, the local rocks, from the Cretaceous micritic limestones to the Quaternary calcarenites, have been intensely quarried and used as building and ornamental materials. In several settings of the region, the rocks with the best petrographic characteristics are located at depths ranging from a few to some tens of meters. This caused the opening of many underground quarries, and the development of a complex network of subterranean galleries. Underground quarrying had a great impulse at the turn between the XIX and the XX century, when a large number of quarries was opened. Later on, after the Second World War, most of the quarries were progressively abandoned, even because of the first signs of instability, both underground and at the ground surface. With time, the memory of the presence and development of the underground quarries was progressively lost, with severe repercussions on the safety of the land above the excavated areas. Lack of knowledge of the subterranean pattern of galleries, combined with the expansion of the built-up areas at the surface, resulted in increasing significantly the vulnerability of exposed elements at risk. Events such as the 29 March, 2007, at Gallipoli only by chance did not result in any casualties, when a 15-mt wide and 5-mt deep sinkhole opened in a few hours at a road crossing, above the site of an old underground quarry

Multi-geophysical approaches to detect karst channels underground - A case study in Mengzi of Yunnan Province, China

Science.gov (United States)

Gan, Fuping; Han, Kai; Lan, Funing; Chen, Yuling; Zhang, Wei

2017-01-01

Mengzi locates in the south 20 km away from the outlet of Nandong subsurface river, and has been suffering from water deficiency in recent years. It is necessary to find out the water resources underground according to the geological characteristics such as the positions and buried depths of the underground river to improve the civil and industrial environments. Due to the adverse factors such as topographic relief, bare rocks in karst terrains, the geophysical approaches, such as Controlled Source Audio Magnetotellurics and Seismic Refraction Tomography, were used to roughly identify faults and fracture zones by the geophysical features of low resistivity and low velocity, and then used the mise-a-la-masse method to judge which faults and fracture zones should be the potential channels of the subsurface river. Five anomalies were recognized along the profile of 2.4 km long and showed that the northeast river system has several branches. Drilling data have proved that the first borehole indicated a water bearing channel by a characteristics of rock core of river sands and gravels deposition, the second one encountered water-filled fracture zone with abundant water, and the third one exposed mud-filled fracture zone without sustainable water. The results from this case study show that the combination of Controlled Source Audio Magnetotellurics, Seismic Refraction Tomography and mise-a-la-Masse is one of the effective methods to detect water-filled channels or fracture zones in karst terrains.

Data acquisition of mass transport parameters

International Nuclear Information System (INIS)

Iwasaki, Riyo; Hama, Katsuhiro; Morikawa, Keita; Hosoya, Shinichi

2017-02-01

Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) has been carrying out the Mizunami Underground Research Laboratory (MIU) Project, which is a scientific study understanding the deep geological environment as a basis of research and development for geological disposal of high level radioactive wastes. The aim of the MIU project is to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock, and to develop a range of engineering techniques for deep underground application. This project has three overlapping phases: Surface-based investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). Currently, the project is being carried out under the Phase III. Mass transport study is mainly performed as part of Phase III project. In Phase III, the goal of mass transport study is to obtain a better understanding of mass transport phenomena in the geological environment as well as to develop technologies for measurement of the mass transport parameters, model construction, numerical analysis and validation of those technologies. This study was planned to understand the influence of the geological characteristics of fracture on the mass transport parameters. This report presents the results of diffusion experiment, observation of polished thin section, sorption experiment and porophysicality measurement. (author)

Proceedings of the 6th underground operators conference

International Nuclear Information System (INIS)

Golosinski, T.S.

1995-01-01

This conference presents recent development in underground mining operations. A large number of papers reported on underground mining practice in the Eastern Goldfields area of Western Australia and in the traditional mining centres of Mount Isa and Broken Hill. These are supplemented by papers reporting on other underground mining developments all throughout Australia and in several overseas countries known for advanced mining expertise. Apart from papers dealing with metalliferous mining, a number of papers related to coal mining present recent developments related to the topic. The papers are grouped into sessions relating to ground control, rock mechanics, management and human resources, mining methods, mining equipment, control and communications, mine backfill, mining operations, drilling and blasting and coal mining. Relevant papers have been individually indexed/abstracted. Tabs., figs., refs

Numerical simulation of stress wave propagation from underground nuclear explosions

Energy Technology Data Exchange (ETDEWEB)

Cherry, J T; Petersen, F L [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1970-05-01

This paper presents a numerical model of stress wave propagation (SOC) which uses material properties data from a preshot testing program to predict the stress-induced effects on the rock mass involved in a Plowshare application. SOC calculates stress and particle velocity history, cavity radius, extent of brittle failure, and the rock's efficiency for transmitting stress. The calculations are based on an equation of state for the rock, which is developed from preshot field and laboratory measurements of the rock properties. The field measurements, made by hole logging, determine in situ values of the rock's density, water content, and propagation velocity for elastic waves. These logs also are useful in judging the layering of the rock and in choosing which core samples to test in the laboratory. The laboratory analysis of rock cores includes determination of hydrostatic compressibility to 40 kb, triaxial strength data, tensile strength, Hugoniot elastic limit, and, for the rock near the point of detonation, high-pressure Hugoniot data. Equation-of-state data are presented for rock from three sites subjected to high explosive or underground nuclear shots, including the Hardhat and Gasbuggy sites. SOC calculations of the effects of these two shots on the surrounding rock are compared with the observed effects. In both cases SOC predicts the size of the cavity quite closely. Results of the Gasbuggy calculations indicate that useful predictions of cavity size and chimney height can be made when an adequate preshot testing program is run to determine the rock's equation of state. Seismic coupling is very sensitive to the low-pressure part of the equation of state, and its successful prediction depends on agreement between the logging data and the static compressibility data. In general, it appears that enough progress has been made in calculating stress wave propagation to begin looking at derived numbers, such as number of cracks per zone, for some insight into the

Numerical simulation of stress wave propagation from underground nuclear explosions

International Nuclear Information System (INIS)

Cherry, J.T.; Petersen, F.L.

1970-01-01

This paper presents a numerical model of stress wave propagation (SOC) which uses material properties data from a preshot testing program to predict the stress-induced effects on the rock mass involved in a Plowshare application. SOC calculates stress and particle velocity history, cavity radius, extent of brittle failure, and the rock's efficiency for transmitting stress. The calculations are based on an equation of state for the rock, which is developed from preshot field and laboratory measurements of the rock properties. The field measurements, made by hole logging, determine in situ values of the rock's density, water content, and propagation velocity for elastic waves. These logs also are useful in judging the layering of the rock and in choosing which core samples to test in the laboratory. The laboratory analysis of rock cores includes determination of hydrostatic compressibility to 40 kb, triaxial strength data, tensile strength, Hugoniot elastic limit, and, for the rock near the point of detonation, high-pressure Hugoniot data. Equation-of-state data are presented for rock from three sites subjected to high explosive or underground nuclear shots, including the Hardhat and Gasbuggy sites. SOC calculations of the effects of these two shots on the surrounding rock are compared with the observed effects. In both cases SOC predicts the size of the cavity quite closely. Results of the Gasbuggy calculations indicate that useful predictions of cavity size and chimney height can be made when an adequate preshot testing program is run to determine the rock's equation of state. Seismic coupling is very sensitive to the low-pressure part of the equation of state, and its successful prediction depends on agreement between the logging data and the static compressibility data. In general, it appears that enough progress has been made in calculating stress wave propagation to begin looking at derived numbers, such as number of cracks per zone, for some insight into the

Character and levels of radioactive contamination of underground waters at Semipalatinsk test site

Energy Technology Data Exchange (ETDEWEB)

Subbotin, S.; Lukashenko, S.; Turchenko, Y. [Institute of radiation safety and ecology (Kazakhstan)

2014-07-01

According to the data of RK government commission, 470 explosions have been set off at the Semipalatinsk Test Site (STS), inclusive of 26 surface, 90 in the air and 354 underground nuclear explosions (UNE), 103 of those have been conducted in tunnels and 251 - in boreholes. Underground nuclear explosions have been conducted at STS in horizontal mines, called - 'tunnels' ('Degelen' test site) and vertical mines called 'boreholes' ('Balapan' and 'Sary-Uzen' test sites). Gopher cavities of boreholes and tunnels are in different geotechnical conditions, that eventually specify migration of radioactive products with underground waters. Central cavities of UNE in holes are located significantly below the level of distribution of underground water. High temperature remains for a long time due to presence of overlying rock mass. High temperatures contribute to formation of thermal convection. When reaching the cavity, the water heat up, dissolve chemical elements and radionuclides and return with them to the water bearing formation. In the major part of 'Balapan' site for underground water of regional basin is characterized by low concentrations of radionuclides. High concentrations of {sup 137}Cs in underground water have been found only in immediate vicinity to 'warfare' boreholes. Formation of radiation situation in the 'Balapan' test site area is also affected by local area of underground water discharge. It is located in the valley of Shagan creek, where the concentration of {sup 3}H reaches 700 kBq/l. Enter of underground water contaminated with tritium into surface water well continue. In this case it is expected that tritium concentration in discharge zone can significantly change, because this migration process depends on hydro geological factors and the amount of atmospheric precipitation. Central cavities of nuclear explosions, made in tunnels, are above the level of underground

Steady-state flow in a rock mass intersected by permeable fracture zones

International Nuclear Information System (INIS)

Lindbom, B.

1986-12-01

Level 1 of HYDROCOIN consists of seven well-defined test problems. This paper is concerned with Case 2, which is formulated as a generic groundwater flow situation often found in crystalline rock with highly permeable fracture zones in a less permeable rock mass. The case is two-dimensional and modelled with 8-noded, isoparametric, rectangular elements. According to the case definition, calculations of hydraulic head and particle tracking are performed. The computations are carried out with varying degree of discretisation in order to analyse possible impact on the result with respect to nodal density. Further calculations have been performed mainly devoted to mass balance deviations and how these are affected by permeability contrasts, varying degree of spatial discretisation and distortion of finite elements. The distribution of hydraulic head in the domain is less sensitive to differences in nodal density than the trajectories. The hydraulic heads show similar behaviour for three meshes with varying degrees of discretisation. The particle tracking seems to be more sensitive to the level of discretisation. The results obtained with a coarse and medium mesh indicate completely different solutions for one of the pathlines. The coarse mesh is too sparsely discretised for the specified problem. The local mass balance is evaluated for seven runs. The mass balance deviation seems to be considerably more sensitive to the level of discretisation than to both permeability contrasts and deformation of elements. The permeability contrasts between the rock mass and fracture zones vary from a factor of 1000 to 1 (homogeneous properties) with increments of a factor of 10. These calculations in fact give better mass balance with increasing permeability contrasts, contrary to what could be expected. (orig./HP)

Numerical simulation of the time-dependent deformation behaviour of clay-stone rock mass at the Tournemire site with 2D and 3D models

International Nuclear Information System (INIS)

Rutenberg, M.; Lux, K.H.

2010-01-01

deformations, and/or; - effects from various hydraulic or hydro-mechanical influences on the saturated rock mass after excavation, such as: - changes of pore pressure (inducing consolidation) and water content (desaturation and re-saturation, due to evaporation/condensation/sorption processes), - shrinking/swelling processes due to (de-)hydration of the clay-stone. Previous investigations yielded the principal applicability of a viscous constitutive model on clay-stone and the principal transferability of this kind of physical model from salt rock to clay-stone whilst taking into account additional characteristics typical for clay-stone, such as the anisotropy of the primary stress state, the transverse isotropy of the stress-strain relationship regarding the orientation of inherent bedding planes, the presence of a latent but mechanically effective discontinuity fabric, or effects from hydraulic processes (e.g. desaturation, see above). Current research work incorporating own laboratory investigations and deformation measurement data acquired in underground openings at the Tournemire site has led to some success in developing a viscous physical model allowing for the aforementioned characteristics for a two-dimensional numerical simulation of this very well documented case study. This model was employed in a next step for a three-dimensional numerical simulation of a drift excavation in the framework of an actually conducted mine-by test. In this test, rock mass deformations in various places at different distances from the drift were recorded by extensometer measurements during the excavation process. An obtained simulation result with the measurement data published by Rejeb et al. (2007) for the extensometer closest to the drift is shown. The order of magnitude of the calculated values is within the order of magnitude of the recorded data, and although a discrepancy in magnitude is still remaining, a trend correspondence between the simulated and the measured deformations

Rock properties data base

Energy Technology Data Exchange (ETDEWEB)

Jackson, R.; Gorski, B.; Gyenge, M.

1991-03-01

As mining companies proceed deeper and into areas whose stability is threatened by high and complex stress fields, the science of rock mechanics becomes invaluable in designing underground mine strata control programs. CANMET's Mining Research Laboratories division has compiled a summary of pre- and post-failure mechanical properties of rock types which were tested to provide design data. The 'Rock Properties Data Base' presents the results of these tests, and includes many rock types typical of Canadian mine environments. The data base also contains 'm' and 's' values determined using Hoek and Brown's failure criteria for both pre- and post-failure conditions. 7 refs., 3 tabs., 9 figs., 1 append.

Preliminary assessment of potential underground stability (wedge and spalling) at Forsmark, Simpevarp and Laxemar sites

Energy Technology Data Exchange (ETDEWEB)

Martin, Derek [Univ. of Alberta, Edmonton (Canada). Geotechnical Engineering

2005-12-15

In SKB's Underground Design Premises the objective in the early design phase is to estimate if there is sufficient space for the repository at a site. One of the conditions that could limit the space available is stability of the underground openings, i.e., deposition tunnels and deposition boreholes. The purpose of this report is to provide a preliminary assessment of the potential for wedge instability and spalling that may be encountered at the Forsmark, Simpevarp and Laxemar sites based on information from the site investigations program up to July 30, 2004. The rock mass spalling strength was defined using the in-situ results from SKB's Aespoe Pillar Stability Experiment and AECL's Mine-by Experiment. These experiments suggest that the rock mass spalling strength for crystalline rocks can be estimated as 0.57 of the mean laboratory uniaxial compressive strength. A probability-based methodology utilizing this in-situ rock mass spalling strength has been developed for assessing the risk for spalling in a repository at the Forsmark, Simpevarp and Laxemar sites. The in-situ stresses and the uniaxial compressive strength data from these sites were used as the bases for the analyses. Preliminary findings from all sites suggest that, generally, the risk for spalling increases as the depth of the repository increases, simply because the stress magnitudes increase with depth. The depth at which the risk for spalling is significant, depends on the individual sites which are discussed below. The greatest uncertainty in the spalling analyses for Forsmark is related to the uncertainty in the horizontal stress magnitudes and associated stress gradients with depth. The confidence in these analyses can only be increased by increasing the confidence in the stress and geology model for the site. From the analyses completed it appears that spalling in the deposition tunnels can be controlled by orienting the tunnels approximately parallel to the maximum horizontal

Studies on engineering technologies in the Mizunami Underground Research Laboratory. FY 2007 (Contract research)

International Nuclear Information System (INIS)

Noda, Masaru; Suyama, Yasuhiro; Nobuto, Jun; Ijiri, Yuji; Mikake, Shinichiro; Matsui, Hiroya

2009-07-01

The Mizunami Underground Research Laboratory (MIU) of the Japan Atomic Energy Agency is a major site for geoscientific research to advance the scientific and technological basis for geological disposal of high-level radioactive waste in crystalline rock. Studies on relevant engineering technologies in the MIU consist of a) research on design and construction technology for very deep underground applications, and b) research on engineering technology as a basis of geological disposal. In the Second Phase of the MIU project (the construction phase), engineering studies have focused on research into design and construction technologies for deep underground. The main subjects in the study of very deep underground structures consist of the following: 'Demonstration of the design methodology', 'Demonstration of existing and supplementary excavation methods', 'Demonstration of countermeasures during excavation' and 'Demonstration of safe construction'. In the FY 2007 studies, identification and evaluation of the subjects for study of engineering technologies in the construction phase were carried out to optimize future research work. Specific studies included: validation of the existing design methodology based on data obtained during construction; validation of existing and supplementary rock excavation methods for very deep shafts; estimation of rock stability under high differential water pressures, methodology on long-term maintenance of underground excavations and risk management systems for construction of underground structures have been performed. Based on these studies, future research focused on the four subject areas, which are 'Demonstration of the design methodology', 'Demonstration of existing and supplementary excavation methods', 'Demonstration of countermeasures during excavation' and 'Demonstration of safe construction', has been identified. The design methodology in the first phase of the MIU Project (surface-based investigation phase) was verified to

Layout Optimization for the Repository within a discontinuous and saturated granitic rock mass

International Nuclear Information System (INIS)

Kim, Jhin Wung; Choi, Jong Won; Bae, Dae Seok

2005-12-01

The objective of the present study is a layout optimization of a single and double layer repositories within a repository site with special joint set arrangements. Single and double layer repository models, subjected to the variation of repository depth, cavern spacing, pitch, and layer spacing, are analyzed for the thermal, hydraulic, and mechanical interaction behavior during the period of 2000 years from waste emplacement. Material properties used for the granitic rock mass, rock joints, PWR spent fuel, disposal canister, compacted bentonite, backfill material, and groundwater are the data collected domestically, and foreign data are used for some of the data not available domestically. The repository model includes a saturated granitic rock mass with joints, PWR spent fuel in a disposal canister surrounded by compacted bentonite inside a deposition hole, and backfill material in the rest of the space within a repository cavern

A Model of Equilibrium Conditions of Roof Rock Mass Giving Consideration to the Yielding Capacity of Powered Supports

Science.gov (United States)

Jaszczuk, Marek; Pawlikowski, Arkadiusz

2017-12-01

The work presents the model of interactions between the powered roof support units and the rock mass, while giving consideration to the yielding capacity of the supports - a value used for the analysis of equilibrium conditions of roof rock mass strata in geological and mining conditions of a given longwall. In the model, the roof rock mass is kept in equilibrium by: support units, the seam, goafs, and caving rocks (Fig. 1). In the assumed model of external load on the powered roof support units it is a new development - in relation to the model applied in selection of supports based on the allowable deflection of roof theory - that the load bearing capacity is dependent on the increment of the inclination of the roof rock mass and on the properties of the working medium, while giving consideration to the air pockets in the hydraulic systems, the load of the caving rocks on the caving shield, introducing the RA support value of the roof rock mass by the coal seam as a closed-form expression and while giving consideration to the additional support provided by the rocks of the goaf as a horizontal component R01H of the goaf reaction. To determine the roof maintenance conditions it is necessary to know the characteristics linking the yielding capacity of the support units with the heading convergence, which may be measured as the inclination angle of the roof rock mass. In worldwide mining, Ground Reaction Curves are used, which allow to determine the required yielding capacity of support units based on the relation between the load exerted on the unit and the convergence of the heading ensuring the equilibrium of the roof rock mass. (Figs. 4 and 8). The equilibrium of the roof rock mass in given conditions is determined at the displacement of the rock mass by the α angle, which impacts the following values: yielding capacity of units FN, vertical component of goaf reaction R01V and the horizontal component of goaf reaction R01H. In the model of load on the support

Test procedures for salt rock

International Nuclear Information System (INIS)

Dusseault, M.B.

1985-01-01

Potash mining, salt mining, design of solution caverns in salt rocks, disposal of waste in salt repositories, and the use of granular halite backfill in underground salt rock mines are all mining activities which are practised or contemplated for the near future. Whatever the purpose, the need for high quality design parameters is evident. The authors have been testing salt rocks in the laboratory in a number of configurations for some time. Great care has been given to the quality of sample preparation and test methodology. This paper describes the methods, presents the elements of equipment design, and shows some typical results

Relationship between the rock mass deformation and places of occurrence of seismological events

Energy Technology Data Exchange (ETDEWEB)

Janusz Makowka; Jozef Kabiesz; Lin-ming Ddou [Central Mining Institute, Katowice (Poland)

2009-09-15

Static effort of rock mass very rarely causes of rock burst in Polish coal mines. Rock bursts with source in the seismic tremor within the roof rock layers are prevailing. A seismic tremor is an effect of rupture or sliding in roof layers above the exploited panel in coal seam, sometime in a distance from actual exploitation. Sliding, as a rule occurs in fault zone and tremors in it are expected, but monolithic layer rupture is very hard to predict. In a past few years a practice of analyzing state of deformation in high energy seismic tremors zones has been employed. It let gathering experience thanks to witch determination of dangerous shape of reformatted roof is possible. In the paper some typical forms of roof rocks deformations leading to seismic tremor occurrence will be presented. In general these are various types of multidirectional rock layers bending. Real examples of seismic events and rock bursts in the Czech Republic will be shown. 5 refs., 6 figs.

Buffer mass test - Rock drilling and civil engineering

International Nuclear Information System (INIS)

Pusch, R.

1982-09-01

The buffer mass test (BMT) is being run in the former 'ventilation drift' in which a number of rock investigations were previously conducted. A number of vertical pilot holes were drilled from the tunnel floor to get information of the water inflow in possible heater hole position. The final decision of the location of the heater holes was then made, the main principle being that much water should be available in each hole with the possible exception of one of the holes. Thereafter, the diameter 0.76 m heater holes were drilled to a depth of 3-3.3 m. Additional holes were then drilled for rock anchoring of the lids of the four outer heater holes, for the rock mechanical investigation, as well as for a number of water pressure gauges. The inner, about 12 m long part of the tunnel, was separated from the outer by bulwark. The purpose of this construction was to confine a backfill, the requirements of the bulwark being to withstand the swelling pressure as well as the water pressure. Outside the bulwark an approximately 1.5-1.7 m thick concrete slab was cast on the tunnel floor, extending about 24.7 m from the bulwark. Boxing-outs with the same height as the slab and with the horizontal dimensions 1.8 x 1.8 m, were made and rock-anchored concrete lids were cast on top of them after backfilling. The slab which thus represents 'rock', also forms a basal support of the bulwark. The lids permits access to the backfill as well as to the underlying, highly compacted bentonite for rapid direct determination of the water distributin at the intended successive test stops. The construction of the slab and lids will be described in this report. (Author)

Handling and final disposal of nuclear waste. Hard Rock Laboratory

International Nuclear Information System (INIS)

1989-09-01

The purpose of the Hard Rock Laboratory is to provide an opportunity for research and development in a realistic and undisturbed underground rock environment down to the depth planned for the future repository. The R and D work in the underground laboratory has the following main goals: To test the quality and appropriateness of different methods for characterizing the bedrock with respect to conditions of importance for a final repository. To refine and demonstrate methods for how to adapt a repository to the local properties of the rock in connection with planning and construction. And, finally, to collect material and data of importance for the safety of the future repository and for confidence in the quality of the safety assessments 13 figs, 3 tabs

30 CFR 817.73 - Disposal of excess spoil: Durable rock fills.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Disposal of excess spoil: Durable rock fills...-UNDERGROUND MINING ACTIVITIES § 817.73 Disposal of excess spoil: Durable rock fills. The regulatory authority may approve the alternative method of disposal of excess durable rock spoil by gravity placement in...

Compact rock material gas permeability properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

2014-09-15

Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens’ permeability evolution is related to the relative particle movements and microcrack closure.

Depth optimization for the Korean HLW repository System within a discontinuous and saturated granitic rock mass

International Nuclear Information System (INIS)

Kim, Jhin Wung; Bae, Dae Seok; Choi, Jong Won

2005-12-01

The present study is to evaluate the material properties of the compacted bentonite, backfill material, canister cast iron insert, and the rock mass for the Korean HLW repository system. These material properties are either measured, or taken from other countries, through the evaluation of the thermal, hydraulic, and mechanical interaction behavior of a repository. After the evaluation of the material properties, the most appropriate and economical depth as well as the layout of a single layer repository is to be recommended. Material properties used for the granitic rock mass, rock joints, PWR spent fuel, disposal canister, compacted bentonite, backfill material, and ground water are the data collected domestically, and foreign data are used for some of the data not available domestically. The repository model includes a saturated granitic rock mass with joints, PWR spent fuel in a disposal canister surrounded by compacted bentonite inside a deposition hole, and backfill material in the rest of the space within a repository cavern

Investigation of the stability of blocks around underground openings by using the boundary element method

Directory of Open Access Journals (Sweden)

Murat Ünal

2002-03-01

Full Text Available In this study, a two-dimensional software was developed by using the boundary element method, in order to model and solve the rock mechanics problems encountered in surface and underground excavations. Stability of rock wedges formed at the roof of underground excavations were investigated in detail by using this software. The behaviour of the symmetric wedge on different joint stiffnesses was studied using a modified boundary element software. Then the results obtained were discussed and compared with the analytical solution, considering the surface tractions, shear stresses (developed along the discontinuity, wedge displacements and strains (along the wedge height.

Mizunami Underground Research Laboratory project. Rock mechanical investigations measurement of the rock strain and displacement during shaft excavation at GL.-200m level of research galley

International Nuclear Information System (INIS)

Hirano, Toru; Seno, Yasuhiro; Hikima, Ryoichi; Matsui, Hiroya

2011-09-01

In order to establish the scientific and technical basis for geological disposal of high-level radioactive waste, Japan Atomic Energy Agency (JAEA) is proceeding with the geoscientific research in the research galleries excavated at the Mizunami Underground Research Laboratory (MIU). One of the scientific and technical objectives of this project is to understand the change of geological environment due to excavation of research galleries. The investigation described herein is the measurement of the rock strain / displacement while pre-excavation grouting or excavating of the shaft around the GL.-200m level of research gallery. A brief summary is presented as follows. 1) Apparent strain with pre-excavation grouting: Injection pressure during pre-excavation grouting could explain the observed strain. Maximum principal strain 'E1' (extension) was oriented to NS direction. The measured fracture system at the site includes a fracture set perpendicular to E1. We infer that these fracture expanded due to grout injection pressure. 2) Apparent strain during excavation of the shaft: Rock behavior of stress release was observed when the bottom of shaft passed by and lining of shaft was constructed. The observed strain was very small and almost same scale as the expected strain for elastic material. But the observed strain of radial direction was compression whereas the expected strain was extension. Therefore it was estimated that rock behavior was affected by cracks. 3) Applicability of the FBG sensors for in situ displacement measurement near the shaft: FBG sensors were stable and reliable in comparison to strain meters or inclinometers. There was no electrical equipment trouble nor large drift in measurements. FBG results can lead to understand bending mode of borehole. But we cannot specify the displacement direction from these data in some cases. (author)

Pore pressure measurement plan of near field rock used on three dimensional groundwater flow analysis in demonstration test of cavern type disposal facility

International Nuclear Information System (INIS)

Onuma, Kazuhiro; Terada, Kenji; Matsumura, Katsuhide; Koyama, Toshihiro; Yajima, Kazuaki

2008-01-01

Demonstration test of underground cavern type disposal facilities is planed though carrying out construction of full scale engineering barrier system which simulated in the underground space in full scale and under actual environment. This test consists of three part, these are construction test, performance test and measurement test. Behavior of near field rock mass is measured about hydrological behavior under and after construction to evaluate effect at test facility. To make plan of pore pressure measurement, three dimensional groundwater flow analysis has been carried out. Based on comparison of analysis before and after test, detail plan has been studied. (author)

Stability of underground openings in the Yucca Mountain repository

International Nuclear Information System (INIS)

Blejwas, T.E.

1989-01-01

The licensing of a repository for high level radioactive waste will require assurances that underground openings do not experience frequent major instabilities, which are defined here as sudden movements of blocks of rock that limit the functions of the openings. Although the design of nuclear power plant structure is controlled by strict adherence to building or professional- engineering codes, this approach is not practical for the structural design of underground facilities because the design must accommodate a varied and partially defined geologic setting. However, regulations require the reduction of the potential for deleterious rock movement and the design of openings to maintain the option to retrieve waste. The present plans for meeting these requirements for a repository at Yucca Mountain, Nevada, include a program of state-of-the- art analyses and modified forms of existing empirically based design methods. An extensive experimental program is required to provide confidence in the results of the design- analysis process

Stability of underground openings in the Yucca Mountain repository

International Nuclear Information System (INIS)

Blejwas, T.E.

1989-01-01

The licensing of a repository for high-level radioactive waste will require assurances that underground openings do not experience frequent major instabilities, which are defined here as sudden movements of blocks of rock that limit the functions of the openings. Although the design of nuclear power plant structures is controlled by strict adherence to building or professional-engineering codes, this approach is not practical for the structural design of underground facilities because the design must accommodate a varied and partially defined geologic setting. However, regulations require the reduction of the potential for deleterious rock movement and the design of openings to maintain the option to retrieve waste. The present plans for meeting these requirements for a repository at Yucca Mountain, Nevada, include a program of state-of-the-art analyses and modified forms of existing empirically based design methods. An extensive experimental program is required to provide confidence in the results of the design-analysis process. 7 refs., 1 fig

Exploration of cystalline rocks for nuclear waste repositories: Some strategies for area characterization

International Nuclear Information System (INIS)

Trask, N.J.; Roseboom, E.H.; Watts, R.D.; Bedinger, M.S.

1991-01-01

A general strategy for the exploration of crystalline rock massed in the eastern United States for the identification of potential sites for high-level radioactive waste repositories has been generated by consideration of the Department of Energy (DOE) Siting Guidelines, available information on these crystalline rocks, and the capabilities and limitations of various exploration methods. The DOE has recently screened over 200 crystalline rock massed in 17 states by means of literature surveys and has recommended 12 rock masses for more intensive investigation including field investigations. The suggested strategy applies to the next stage of screen where the objective is to identify those potential sites that merit detailed site characterization including an exploratory shaft and underground study. This document discusses strategies for reconnaissance and field investigations, including the early phases of drilling, to provide geoscience information on the areas under construction. A complete Area Characterization Plan, to be developed by DOE with involvement of the states within which the areas to be studied are located, will outline all of the investigations to be carried out in the area phase including their cost and scheduling. Here, we provide input for the Area Characterization Plan by discussing what we believe to be the most important issues that need to be addressed in this phase and suggesting methods for their resolution. This report is not intended as a complete outline of area phase geoscience investigations, however. 79 refs., 4 figs

Participation of civil engineers in designing facilities in rock salt

International Nuclear Information System (INIS)

Duddeck, H.; Westhaus, T.

1990-01-01

For the design of underground facilities in rock salt layers or domes, as caverns for repositories, the civil engineering approach may be useful. The underground openings are analysed by determining the displacements and the stresses for actual states and hypothetical situations. The paper reports on the state of art in the development of suited time dependent material laws for rock salt, on time integration methods for the analysis, and on a possible procedure for a consistent safety analysis. The examples given include caverns filled by oil, analysis of a mine with vertical excavation chambers, and dams closing mine galleries. (orig.) [de

Underground rock storage concepts for natural gas and LPG in Finland

International Nuclear Information System (INIS)

Saerkkae, P.

1990-01-01

Natural gas storage concepts are developed in Finland for both deep, unlined rock storages and cryogenic lined, near-surface storages. For butane and propane, Neste Oy has two unlined rock storages in Porvoo. Up to now, experiences are good on storage of LPG in rock temperature and higher than hydrostatic pressure. (author). 3 refs, 8 figs

Characterisation and geostatistical analysis of clay rocks in underground facilities using hyper-spectral images

International Nuclear Information System (INIS)

Becker, J.K.; Marschall, P.; Brunner, P.; Cholet, C.; Renard, P.; Buckley, S.; Kurz, T.

2012-01-01

Document available in extended abstract form only. Flow and transport processes in geological formations are controlled by the porosity and permeability which in turn are mainly controlled by the fabric and the mineralogical composition of the rock. For the assessment of transport processes in water-saturated Clay-stone formations, the relevant scales are ranging essentially from kilometers to nanometers. The spatial variability of the mineralogical composition is a key indicator for the separation of transport scales and for the derivation of the effective transport properties at a given scale. Various laboratory and in-situ techniques are available for characterizing the mineralogical composition of a rock on different scales. The imaging spectroscopy presented in this paper is a new site investigation method suitable for mapping the mineralogical composition of geological formations in 2D on a large range of scales. A combination of imaging spectrometry with other site characterization methods allows the inference of the spatial variability of the mineralogical composition in 3D over a wide range of scales with the help of advanced geostatistical methods. The method of image spectrometry utilizes the fact that the reflection of electromagnetic radiation from a surface is a function of the wavelength, the chemical-mineralogical surface properties, and physical parameters such as the grain size and surface roughness. In remote sensing applications using the sun as the light source, the reflectance is measured within the visible and infrared range, according to the atmospheric transmissibility. Many rock-forming minerals exhibit diagnostic absorption features within this range, which are caused by electronic and vibrational processes within the crystal lattice. The exact wavelength of an absorption feature is controlled by the type of ion, as well as the position of the ion within the lattice. Spectral signatures of minerals are described by a number of authors

3D Cosmic Ray Muon Tomography from an Underground Tunnel

Science.gov (United States)

Guardincerri, Elena; Rowe, Charlotte; Schultz-Fellenz, Emily; Roy, Mousumi; George, Nicolas; Morris, Christopher; Bacon, Jeffrey; Durham, Matthew; Morley, Deborah; Plaud-Ramos, Kenie; Poulson, Daniel; Baker, Diane; Bonneville, Alain; Kouzes, Richard

2017-05-01

We present an underground cosmic ray muon tomographic experiment imaging 3D density of overburden, part of a joint study with differential gravity. Muon data were acquired at four locations within a tunnel beneath Los Alamos, New Mexico, and used in a 3D tomographic inversion to recover the spatial variation in the overlying rock-air interface, and compared with a priori knowledge of the topography. Densities obtained exhibit good agreement with preliminary results of the gravity modeling, which will be presented elsewhere, and are compatible with values reported in the literature. The modeled rock-air interface matches that obtained from LIDAR within 4 m, our resolution, over much of the model volume. This experiment demonstrates the power of cosmic ray muons to image shallow geological targets using underground detectors, whose development as borehole devices will be an important new direction of passive geophysical imaging.

Underground infrastructure damage for a Chicago scenario

Energy Technology Data Exchange (ETDEWEB)

Dey, Thomas N [Los Alamos National Laboratory; Bos, Rabdall J [Los Alamos National Laboratory

2011-01-25

Estimating effects due to an urban IND (improvised nuclear device) on underground structures and underground utilities is a challenging task. Nuclear effects tests performed at the Nevada Test Site (NTS) during the era of nuclear weapons testing provides much information on how underground military structures respond. Transferring this knowledge to answer questions about the urban civilian environment is needed to help plan responses to IND scenarios. Explosions just above the ground surface can only couple a small fraction of the blast energy into an underground shock. The various forms of nuclear radiation have limited penetration into the ground. While the shock transmitted into the ground carries only a small fraction of the blast energy, peak stresses are generally higher and peak ground displacement is lower than in the air blast. While underground military structures are often designed to resist stresses substantially higher than due to the overlying rocks and soils (overburden), civilian structures such as subways and tunnels would generally only need to resist overburden conditions with a suitable safety factor. Just as we expect the buildings themselves to channel and shield air blast above ground, basements and other underground openings as well as changes of geology will channel and shield the underground shock wave. While a weaker shock is expected in an urban environment, small displacements on very close-by faults, and more likely, soils being displaced past building foundations where utility lines enter could readily damaged or disable these services. Immediately near an explosion, the blast can 'liquefy' a saturated soil creating a quicksand-like condition for a period of time. We extrapolate the nuclear effects experience to a Chicago-based scenario. We consider the TARP (Tunnel and Reservoir Project) and subway system and the underground lifeline (electric, gas, water, etc) system and provide guidance for planning this scenario.

Technical support for GEIS: radioactive waste isolation in geologic formations. Volume 7. Baseline rock properties-basalt

International Nuclear Information System (INIS)

1978-04-01

This volume, Y/OWI/TM-36/7 Baseline Rock Properties--Basalt, is one of a 23-volume series, ''Technical Support for GEIS: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-36'' which supplements a ''Contribution to Draft Generic Environmental Impact Statement on Commercial Waste Management: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-44.'' The series provides a more complete technical basis for the preconceptual designs, resource requirements, and environmental source terms associated with isolating commercial LWR wastes in underground repositories in salt, granite, shale and basalt. Wastes are considered from three fuel cycles: uranium and plutonium recycling, no recycling of spent fuel and uranium-only recycling. This report contains an evaluation of the results of a literature survey to define the rock mass properties of a generic basalt, which could be considered as a geological medium for storing radioactive waste. The general formation and structure of basaltic rocks is described. This is followed by specific descriptions and rock property data for the Dresser Basalt, the Amchitka Island Basalt, the Nevada Test Site Basalt and the Columbia River Group Basalt. Engineering judgment has been used to derive the rock mass properties of a typical basalt from the relevant intact rock property data and the geological information pertaining to structural defects, such as joints and faults

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.)

Swedish Hard Rock Laboratory first evaluation of preinvestigations 1986-87 and target area characterization

International Nuclear Information System (INIS)

Gustafson, G.; Stanfors, R.; Wikberg, P.

1988-06-01

SKB plans to site an underground research laboratory in the Simpevarp area. A regional survey started in 1986 and an extensive programme for geology, geohydrology and hydrochemistry was carried through. This report gives an evaluation of all available data gathered from the start of the project up to the drilling of core boreholes in some target areas in the autumn of 1987. A descriptive geological-tectonic model on a regional scale is presented that is intended to constitute a basis for the hydrogeological modelling work. Preliminary rock mass descriptions are also presented on a more detailed scale for some minor parts of the area. It is recommended that the island Aespoe is the principal target area for the continued work on the Swedish Hard Rock Laboratory. (orig.)

Infilling Littleton Street Mine, Wallsall, with colliery spoil rock paste

Energy Technology Data Exchange (ETDEWEB)

Jarvis, S.T.; Braithwaite, P.A. [Ove Arup and Partners, Birmingham (United Kingdom)

1993-12-31

Describes the filling of an abandoned underground mine with low strength (12-20 kPa) paste made of coal mining waste. With a volume of 550,000 m{sup 3}, it was the largest mine to be filled with rock paste to date. The abandoned mine, flooded with underground water, consists of room and pillar workings at shallow depth of 35 to 60 m. Height of the underground mine cavity varies between 4 and 8 m. The process of infilling and tests and systems for monitoring infilling completeness and strength are described. Benefits of rock paste over other forms of infilling are discussed. Land reclamation work at the source sites is also described. Mineral waste source sites and specifications of the materials are given. After work completion, about 18 ha of derelict urban land were released for redevelopment. 6 refs.

Underground coal mining technology - the future

Energy Technology Data Exchange (ETDEWEB)

Lama, R P [Kembla Coal and Coke Pty Limited, Wollongong, NSW (Australia)

1989-01-01

Discusses development of underground coal mining in Australia in the last four decades. The following aspects are reviewed: technology for underground mining (longwall mining, unidirectional cutting, bidirectional cutting, operation of more than one shearer on a working face, optimum dimensions of longwall blocks), longwall productivity (productivity increase will depend on increasing the availability factor of equipment, reducing failures due to human errors, organizational models, improving on-site decision making, improving monitoring, maintenance, planning and scheduling, concept of 'Transparent Mine'), roadway development systems (types of heading machines, standard systems for mine drivage and roof bolting and their productivity), size of coal mines, man and material transport systems (20,000-30,000 t/d from a single longwall face, mine shafts with a diameter 9-10 m), mine layout design (layout of longwall blocks, main intakes and returns situated in rock layers), mine environmental systems (ventilation systems, gas control), management, training and interpersonal relationships. Future coal mines will be developed with an integral capacity of 8-10 Mt/a from a single longwall operation with main development arteries placed in rocks. Development of gate roadways will require novel solutions with continuous cutting, loading and bolting. Information technology, with the concept of 'transparent mine', will form the backbone of decision making.

Development of a Comprehensive Plan for Scientific Research, Exploration, and Design: Creation of an Underground Radioactive Waste Isolation Facility at the Nizhnekansky Rock Massif

International Nuclear Information System (INIS)

Jardine, L J

2005-01-01

ISTC Partner Project No.2377, ''Development of a General Research and Survey Plan to Create an Underground RW Isolation Facility in Nizhnekansky Massif'', funded a group of key Russian experts in geologic disposal, primarily at Federal State Unitary Enterprise All-Russian Design and Research Institute of Engineering Production (VNIPIPT) and Mining Chemical Combine Krasnoyarsk-26 (MCC K-26) (Reference 1). The activities under the ISTC Partner Project were targeted to the creation of an underground research laboratory which was to justify the acceptability of the geologic conditions for ultimate isolation of high-level waste in Russia. In parallel to this project work was also under way with Minatom's financial support to characterize alternative sections of the Nizhnekansky granitoid rock massif near the MCC K-26 site to justify the possibility of creating an underground facility for long-term or ultimate isolation of radioactive waste (RW) and spent nuclear fuel (SNF). (Reference 2) The result was a synergistic, integrated set of activities several years that advanced the geologic repository site characterization and development of a proposed underground research laboratory better than could have been expected with only the limited funds from ISTC Partner Project No.2377 funded by the U.S. DOE-RW. There were four objectives of this ISTC Partner Project 2377 geologic disposal work: (1) Generalize and analyze all research work done previously at the Nizhnekansky granitoid massif by various organizations; (2) Prepare and issue a declaration of intent (DOI) for proceeding with an underground research laboratory in a granite massif near the MCC K-26 site. (The DOI is similar to a Record of Decision in U.S. terminology). (3) Proceeding from the data obtained as a result of scientific research and exploration and design activities, prepare a justification of investment (JOI) for an underground research laboratory in as much detail as the available site characterization

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)

A basic study on underground storage of LNG

Energy Technology Data Exchange (ETDEWEB)

Kim, Min-Kyu; Lee, Kyung-Han; Kang, Sun-Duck [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

1999-12-01

In 1997, import of LNG was 11,378 thousand of about 2.3 billion US dollars. The demand of LNG(Liquefied Natural Gas) in Korea has been increased since 1987 with the rate of 20% annually. It is also estimated that this trend will be continued until 2010. Long-term estimation says that demand will increase with 9.1% and total demand of 2010 will be 23 million ton that is four times larger than that of 1994. Bases of unloading and store of LNG is necessary to complete the network of LNG distribution system to cover all of the country from import to final supply terminal at home. The construction plan of LNG bases with 49 tanks was published and is going on now at three bases, Pyungtaek, Incheon and Tongyoung. The total cost for this construction will be over 5,400 billion Won. All the LNG tanks are planned to build on the surface. The construction of LNG tanks on the surfaces is conventional but it damage the surface green area and is very vulnerable on safety, especially in Korea Peninsula with potentially unstable of military confrontation. And Korea is so small and limited in available land that it is not easy to find proper places for construction of more LNG tanks on surface. Underground LNG stores in rock will be a good alternative for tanks on surface in the view points of environmental and safety. It is also reported that it can be cheaper than that of on surfaces. It is well known that bed rocks in Korea is good to build underground structure like LNG stores. This report is basic research to seek for the possibility of LNG store construction in underground rocks. The important two questions on it is that whether it is possible technically and economically or not. The technical focus in this report is the stability of underground cavern for storage of LNG, energy conservation in operation, tightness against leakage of stored gas to surface and safety. Some statistic on LNG in Korea is given for this study with its future. (author). 25 refs., 36 tabs., 88 figs.

Rock mass characterization for storage of nuclear waste in granite

International Nuclear Information System (INIS)

Witherspoon, P.A.; Nelson, P.; Doe, T.; Thorpe, R.; Paulsson, B.; Gale, J.; Forster, C.

1979-02-01

The rock mass characterization in granite adjacent to an iron mine at Stripa, Sweden is being carried out by four different methods. The mechanical characterization includes monitoring the responses to thermal loading of jointed rock in situ, and mechanical tests on cores from 25 mm to 1 m in diameter. Geological characterization includes detailed surface mapping, subsurface mapping, and core mapping. Geophysical characterization uses a variety of borehole techniques, with emphasis on sonic methods. The hydrologic characterization is done through injection tests, pump tests, water pressure measurements, and controlled inflow tests to tunnels. Since the data are not yet complete, only tentative conclusions can be drawn regarding the best combinations of techniques for rock-mass characterization. Mapping studies are useful in defining continuity and fracture-system geometry. They do not give aperture, a factor significant in terms of both water flow and the displacements due to heating. Of the geophysical techniques, sonic methods appear most effective in fracture definition; other methods, gamma and neutron particularly, give data on radionuclide and water content and need further analysis with geologic and hydrologic data to determine their significance. Hydrologic work yields primarily aperture data, which with fracture geometry can be used to calculate directional permeabilities. Pressure measurements may provide one means of assessing fracture continuity. Finally, laboratory tests on large cores suggest considerable refinement in testing techniques may be needed before stress-aperture data can be extrapolated from laboratory to field

Shale Failure Mechanics and Intervention Measures in Underground Coal Mines: Results From 50 Years of Ground Control Safety Research

Science.gov (United States)

2015-01-01

Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak shale. This paper will present a historical narrative on the research the National Institute for Occupational Safety and Health has conducted in relation to rock mechanics and shale. This paper begins by first discussing how shale is classified in relation to coal mining. Characterizing and planning for weak roof sequences is an important step in developing an engineering solution to prevent roof failures. Next, the failure mechanics associated with the weak characteristics of shale will be discussed. Understanding these failure mechanics also aids in applying the correct engineering solutions. The various solutions that have been implemented in the underground coal mining industry to control the different modes of failure will be summarized. Finally, a discussion on current and future research relating to rock mechanics and shale is presented. The overall goal of the paper is to share the collective ground control experience of controlling roof structures dominated by shale rock in underground coal mining. PMID:26549926

A rock characterisation facility consultative document

International Nuclear Information System (INIS)

1992-10-01

This U.K. Nirex Ltd., consultative document describes a proposed underground rock characterisation facility, east of Sellafield, for conducting geophysical surveys as a basis for refining long-term safety analysis of an underground repository for intermediate-level and low-level radioactive wastes. Planning application will be submitted in 1993. The construction of shafts and galleries is described and the site's geologic, topographical, climatic and archaeological features discussed. The effects to the local environment and on local populations and other socio-economic factors are discussed. (UK)

Between-hole acoustic surveying and monitoring of a granitic rock mass

International Nuclear Information System (INIS)

Paulsson, B.N.P.; King, M.S.

1980-02-01

The purpose of this technical note is to present preliminary results of an acoustic monitoring study performed as part of a comprehensive rock mechanic and geophysics research program (Ref.20) associated with large-scale heater tests in an abandoned iron-ore mine in central Sweden. The investigation was performed in a fractured granitic rock mass at a sub-surface depth of 340 m, in a drift adjacent to the original iron-ore mine workings. Acoustic monitoring took place between four empty, dry, vertical boreholes of 10 m depth spaced in the vicinity of a vertical heater borehole in the floor of a drift

Research on Construction Optimization of Three-Connected-Arch Hydraulic Underground Cavities Considering Creep Property

Directory of Open Access Journals (Sweden)

Bao-yun Zhao

2014-01-01

Full Text Available In order to prevent the creep of surrounding rock in long-term construction, with consideration of different construction methods and other factors during the construction of large-scale underground cavity, three different construction schemes are designed for specific projects and a nonlinear viscoelastic-plastic creep model which can describe rock accelerated creeping is introduced and applied to construction optimization calculation of the large-scale three-connected-arch hydraulic underground cavity through secondary development of FLAC3D. The results show that the adoption of middle cavity construction method, the second construction method, enables the maximum vault displacement of 16.04 mm. This method results in less stress redistribution and plastic zone expansion to the cavity’s surrounding rock than the other two schemes, which is the safest construction scheme. The conclusion can provide essential reference and guidance to similar engineering for construction optimization.

The destabilizing influence of heat flow on the geological environment during underground nuclear explosions

International Nuclear Information System (INIS)

Politikov, M.I.; Kamberov, I.M.; Krivchenko, V.F.; Lukashenko, S.N.; Solodukhin, V.P.

2001-01-01

The study has determined the fact that the processes of gas-radioactive ectoplasm intrusion from nuclear cavities in the geological environment bring the significant contribution in bosom destabilizing besides the mechanical rock destruction as affected by underground nuclear explosions. Not only heat field forming that reduces the rock resistance and increases its porosity is related to it, but also the forming, on the way, of man-caused contamination aureoles of the geological environment, including the underground water bearing horizon. Unfortunately, this problem is hardly studied, mainly for the lack of reliable apparatus and methods. Judging by the results of information search, the best way to solve the problem is not yet known. (author)

Cataclastic effects in rock salt laboratory and in situ measurements

International Nuclear Information System (INIS)

Gramberg, J.; Roest, J.P.A.

1984-01-01

The aim of the research is the determination of eventual cataclastic effects in environmental rock salt of a heated part of a vertical deep test bore hole, a model for HLW disposal. Known cataclastic systems from hard rock mining and rock salt mines will form the starting point for the explanation of convergence of underground cavity walls. In rock salt, however, different elements seem to prevail: crystal plasticity and micro-cataclasis. The environmental measurements at the deep bore hole have to be carried out from a distance. To this end the acoustic micro-seismic method will be a suitable one. The appropriate equipment for micro-seismic cross hole measurement is designed, constructed and tested in the laboratory as well as underground. Acoustic velocity data form a crucial point. A micro-seismic acoustic P-wave model, adapted to the process of structural changes, is developed. P-wave velocity measurements in rock salt cubes in the laboratory are described. An underground cross hole measurement in the wall of a gallery with semi-circular section is treated and analysed. A conclusion was that, in this case, no macro-cataclasis (systematic large fractures) will be involved in the process of gallery convergence, but that the mechanism proved to be a combination of crystal plasticity and micro-cataclasis. The same mechanism might be expected to be present in the environmental rock salt of the HLW-disposal deep bore hole. As a result this environmental rock salt might be expected to be impermeable. A plan for the application of the developed equipment during the heating test on the ECN-deep-bore-hole is shown. A theory on ''disking'' or ''rim cracks'' is presented in an annex

Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

Directory of Open Access Journals (Sweden)

Amin Keshavarz

2016-04-01

Full Text Available In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided for analysis. Given the footing and rock parameters, the code can calculate the stress characteristics network and obtain the stress distribution under the footing. The seismic effects have been applied as the horizontal and vertical pseudo-static coefficients. The results of this paper are very close to those of the other studies. The seismic bearing capacity of weightless rock masses can be obtained using the proposed equations and graphs without calculating the whole stress characteristics network.

Planning of the in-situ creep test in sedimentary soft rocks under high temperature

International Nuclear Information System (INIS)

Takakura, Nozomu; Yoshikawa, Kazuo; Okada, Tetsuji; Sawada, Masataka; Tani, Kazuo; Takeda, Kayo

2007-01-01

Research has been conducted on underground facilities for energy storage and waste disposal in sedimentary soft rocks. One of the research topics is that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, it is necessary to develop a method for evaluating the long-term stability of caverns in sedimentary soft rocks as influenced by changes in the external environment. This report presents the plan of field creep test for the purpose to establish the evaluation method of long-term stability of caverns in soft rocks. A series of field creep test is performed to study the influence of high temperature in an underground facility at a depth of 50 meters. (author)

Study of the mineralogical transformations of granite by underground nuclear explosions

International Nuclear Information System (INIS)

Faure, Jean

1970-01-01

The object of the following communication is to prove new data about the petrographic effects of the underground nuclear explosions. It is founded on the results of trench tests in granite rock. The samples are collected by drilling and the temperature of the rock was measured in the hole. Four types of melted rocks can be sorted, grey-green glass and pumices, beige to red-brown pumices, dark lavas, dark veinlets and crushed granite. The distribution of these rocks is studied. Optical microscopy, X-rays and chemical analysis, study by electron probe, are made. The results complete previously published data. They are interesting as far as the use of nuclear explosions for industrial applications is concerned. (author)

Study of the mineralogical transformations of granite by underground nuclear explosions

Energy Technology Data Exchange (ETDEWEB)

Faure, Jean [Commissariat a I' Energie Atomique, Centre d' Etudes de Bruyeres-le-Chatel (France)

1970-05-15

The object of the following communication is to prove new data about the petrographic effects of the underground nuclear explosions. It is founded on the results of trench tests in granite rock. The samples are collected by drilling and the temperature of the rock was measured in the hole. Four types of melted rocks can be sorted, grey-green glass and pumices, beige to red-brown pumices, dark lavas, dark veinlets and crushed granite. The distribution of these rocks is studied. Optical microscopy, X-rays and chemical analysis, study by electron probe, are made. The results complete previously published data. They are interesting as far as the use of nuclear explosions for industrial applications is concerned. (author)

Blasting Impact by the Construction of an Underground Research Tunnel in KAERI

International Nuclear Information System (INIS)

Kwon, S.; Cho, W. J.

2005-12-01

The underground research tunnel, which is under construction in KAERI for the validation of HLW disposal system, is excavated by drill and blasting method using high-explosives. In order not to disturb the operation at the research facilities such as HANARO reactor, it is critical to develop a blasting design , which will not influence on the facilities, even though several tens of explosives are detonated almost simultaneously. To develop a reasonable blasting design, a test blasting at the site should be performed. A preliminary analysis for predicting the expected vibration and noise by the blasting for the construction of the underground research tunnel was performed using a typical empirical equation. From the study, a blasting design could be developed not to influence on the major research facilities in KAERI. For the validation of the blasting design, a test blasting was carried out at the site and the parameters of vibration equation could be determined using the measured data during the test blasting. Using the equation, it was possible to predict the vibration at different locations at KAERI and to conclude that the blasting design would meet the design criteria at the major facilities in KAERI. The study would verify the applicability of blasting method for the construction of a research tunnel in a rock mass and that would help the design and construction of large scale underground research laboratory, which might be carried out in the future. It is also meaningful to accumulate technical experience for enhancing the reliability and effectiveness of the design and construction of the HLW disposal repository, which will be constructed in deep underground by drill and blasting technique

The origin of groundwater salinity in granitic rocks: identification and characterisation of chloride sources

International Nuclear Information System (INIS)

Savoye, Sebastien

1998-01-01

This research thesis aims at clearly identifying the possible origins of chlorine in solution in underground waters in a granitic environment, and is thus a first step in the prediction of concentration of dissolved compounds in waters in crystalline environment, with respect to the geological context. In a first part, the author proposes a synthetic and critical overview of knowledge and previous studies: definition of the term 'salinity', presentation of geochemical tracers, presentation of available data on potential chlorine sources in granitic rocks. The author then describes the experimental protocols and studied sites, reports results of the characterisation of different chlorine tanks performed on samples from each studied site. Based on mass assessment calculations and on the use of tracers, the author finally discusses the contribution of each of the chlorine tanks to the salinity of underground waters [fr

Calculation of stresses in a rock mass and lining in stagewise face drivage

Science.gov (United States)

Seryakov, VM; Zhamalova, BR

2018-03-01

Using the method of calculating mechanical state of a rock mass for the conditions of stagewise drivage of a production face in large cross-section excavations, the specific features of stress redistribution in lining of excavations are found. The zones of tensile stresses in the lining are detected. The authors discuss the influence of the initial stress state of rocks on the tension stress zones induced in the lining in course of the heading advance

Bypassing and tightening of an underground water retention system in permeable karst: case study of the hydropower plant (HPP) Bribin, Indonesia

Science.gov (United States)

Kudella, Peter; Loges, Iryna; Mutschler, Thomas; Eiche, Elisabeth; Ruppert, Julia; Neumann, Thomas

2016-09-01

In the framework of the Integrated Water Resources Management (IWRM) joint research project in the karst area of Gunung Kidul, Province of Yogyakarta Special Region on the Java Island, Indonesia, an underground hydropower driven water extraction facility in the cave "Bribin" was developed using pump-as-turbine-driven systems for freshwater supply of the rural area. As numerous other caves in the Gunung Kidul area, Bribin is part of a ramified system of all-season water-bearing subterraneous rivers and natural caves in karstic limestone. The elliptic cross section of the cave was completely closed with a concrete barrage, thus creating a year-round underground retention volume with an operational storage level of approx. 15 m. This contribution highlights the geotechnical and geohydraulic challenges handled within the sub-project "Short-time and long-time behaviour of karst rock surrounding pressure-bearing underground water-retaining structures". One key to the feasibility of an artificial water retention scheme in a natural cave is to ensure the mechanical stability of the cave roof and sidewalls. The necessary geotechnical investigations are described. Another key to the effectiveness of such a water retention concept is the control and minimization of "lost" seepage water bypassing the barrage structure through the karst rock mass. Measures to monitor and to explain the seepage phenomena are presented as well as grouting efforts to minimize them. The limitations of improving the overall tightness will be discussed. Interpretation includes the use of analytical and numerical methods.

Tunnel Design by Rock Mass Classifications

Science.gov (United States)

1990-01-01

Engineering," revised second edition, Institution of Mining and Metallurgy, London, 1977, pp 113-115 and 150-192. 42. Selmer - Olsen , R., and Broch, E...to wall when a)/03 > 10, re- stability) ................ 10-5 0.66-0.33 0.5-2.0 duce oc and ot to L. Mild rock burst (massive 0.6 cc and 0.6 on rock ...5-2.5 0.33-0.16 5-10 where: 0 c = uncon-fined compression M. Heavy rock burst (massive strength, at = rock

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)

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

Microseism Induced by Transient Release of In Situ Stress During Deep Rock Mass Excavation by Blasting

Science.gov (United States)

Yang, Jianhua; Lu, Wenbo; Chen, Ming; Yan, Peng; Zhou, Chuangbing

2013-07-01

During deep rock mass excavation with the method of drill and blast, accompanying the secession of rock fragments and the formation of a new free surface, in situ stress on this boundary is suddenly released within several milliseconds, which is termed the transient release of in situ stress. In this process, enormous strain energy around the excavation face is instantly released in the form of kinetic energy and it inevitably induces microseismic events in surrounding rock masses. Thus, blasting excavation-induced microseismic vibrations in high-stress rock masses are attributed to the combined action of explosion and the transient release of in situ stress. The intensity of stress release-induced microseisms, which depends mainly on the magnitude of the in situ stress and the dimension of the excavation face, is comparable to that of explosion-induced vibrations. With the methods of time-energy density analysis, amplitude spectrum analysis, and finite impulse response (FIR) digital filter, microseismic vibrations induced by the transient release of in situ stress were identified and separated from recorded microseismic signals during a blast of deep rock masses in the Pubugou Hydropower Station. The results show that the low-frequency component in the microseismic records results mainly from the transient release of in situ stress, while the high-frequency component originates primarily from explosion. In addition, a numerical simulation was conducted to demonstrate the occurrence of microseismic events by the transient release of in situ stress, and the results seem to have confirmed fairly well the separated vibrations from microseismic records.

Going Underground in Singapore

CERN Multimedia

John Osborne (GS/SEM)

2010-01-01

Singapore has plans to build a massive Underground Science City (USC) housing R&D laboratories and IT data centres. A delegation involved in the planning to build the subterranean complex visited CERN on 18 October 2010 to learn from civil engineers and safety experts about how CERN plans and constructs its underground facilities.   The delegation from Singapore. The various bodies and corporations working on the USC project are currently studying the feasibility of constructing up to 40 caverns (60 m below ground) similar in size to an LHC experiment hall, in a similar type of rock. Civil engineering and geotechnical experts are calculating the maximum size of the cavern complex that can be safely built. The complex could one day accommodate between 3000 and 5000 workers on a daily basis, so typical issues of size and number of access shafts need to be carefully studied. At first glance, you might not think the LHC has much in common with the USC project; as Rolf Heuer pointed out: &ldq...

Impact of bearing plates dimensions on interaction of mine workings support and rock mass

Directory of Open Access Journals (Sweden)

Marek Rotkegel

2015-01-01

Full Text Available The aim of the research presented in this article is to assess the impact of bearing plates dimensions on the interaction of steel arch support and rock mass. The analysis of the bearing plates was based on laboratory tests and numerical calculations using the FLAC3D program (a finite difference method and the strain-hardening/softening model based on prescribed variations of Mohr–Coulomb properties. The article presents the results of laboratory tests on selected bearing plates and the results of numerical analysis of the interaction between the bearing plates and rock mass with coal, clay stone and sandstone properties.

The Application of Spectral Analysis of Surface Wave (SASW) Method as a New Rock Mass Classification Technique in Engineering Geology

International Nuclear Information System (INIS)

Abdul Rahim Samsuddin; Abdul Ghani Rafek; Umar Hamzah; Suharsono; Khairul Anuar Mohd Nayan

2008-01-01

Spectral analysis of surface waves (SASW) is a seismic method that uses the dispersive characteristics of Rayleigh waves propagating through layered material to evaluate S-wave velocity profile. The SASW is an in situ non intrusive method for geotechnical site characterization which is cost effective as compared to the conventional drilling method. In this study, a total of 20 stations from 13 sites were selected. A software (WINSASW 2.0) was used for the inversion process to produce S-wave velocity versus depth profiles. These profiles were then separately analyzed in relation to several engineering rock mass geological parameters such as stiffness, rock quality designation (RQD), anisotropy and the excavability properties. The analysis of the SASW data was based on the assumption that the rock mass is an isotropic homogeneous material with various intensity of discontinuity which influenced the velocity of surface wave propagation within the rock mass. Measurement of dynamic soil properties was carried out employing the shear wave velocities and the N values of the Standard Penetration Test (N SPT ) from borehole data. A new linear equation V s = 4.44 N SPT + 213.84 which relates S-wave and N SPT was deduced. An empirical equation is also proposed to calculate Rock Quality Designation (RQD) values based on S-wave velocity derived from SASW and that of ultrasonic tests. The result of this equation was found to be less than 10% in comparison to the RQD obtained from actual borehole data. An isotropic analysis of the rock mass was carried out using S-wave velocities derived from SASW measurements in four directions. The plots of S-wave - ultrasonic velocity ratio versus ultrasonic velocity were used to evaluate the excavability properties of rock mass. Five classes of rock mass excavability curves were finally proposed in relation to easy digging, easy ripping, hard ripping, hydraulic breaking and blasting. (author)

The underground retrievable storage (URS) high-level waste management concept

International Nuclear Information System (INIS)

Ramspott, L.D.

1991-01-01

This papers presents the concept of long-term underground retrievable storage (URS) of spent reactor fuel in unsaturated rock. Emplacement would be incremental and the system is planned to be experimental and flexible. The rationale for retrievability is examined, and a technical basis for 300-year retrievability is presented. Maximum isolation is the rationale for underground as opposed to surface storage. Although the potential repository site at Yucca Mountain Nevada would be suitable for a URS, alternate sites are discussed. The technical issues involved in licensing a URS for 300 years are simpler than licensing a 10,000 year repository. 16 refs

Seismic Response Analysis of Concrete Lining Structure in Large Underground Powerhouse