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Sample records for pile foundations

  1. Grouting for Pile Foundation Improvement

    NARCIS (Netherlands)

    Van der Stoel, A.E.C.

    2001-01-01

    The aim of this research was to examine the use of grouting methods for pile foundation improvement, a generic term that is used here to define both foundation renovation (increasing the bearing capacity of a pile foundation that has insufficient bearing capacity) and foundation protection (safeguar

  2. Mono pile foundation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lyngesen, S.; Brendstrup, C.

    1997-02-01

    The use of mono piles as foundations for maritime structures has been developed during the last decades. The installation requirements within the offshore sector have resulted in equipment enabling driving of piles up to 3-4 m to large penetration depths. The availability of this equipment has made the use of large mono piles feasible as foundations for structures like wind turbines. The mono pile foundations consists of three parts; the bare pile, a conical transition and a boat landing. All parts are prefitted at the yard in order to minimise the installation work that has to be carried out offshore. The study of a mono pile foundations for a 1.5 MW wind turbine has been conducted for two locations, Horns Rev and Roedsand. Three different water depths: 5, 8 and 11 m have been investigated in the study. The on-site welding between pile and conical transition is performed by an automatic welding machine. Final testing and eventually repair of the weld are conducted at least 16 hours after welding. This is followed by final installation of J-tube, tie-in to subsea cables and installation of the impressed current system for corrosive protection of the mono pile. The total cost for procurement and installation of the mono pile using the welded connection is estimated. The price does not include procurement and installation of access platform and boat landing. These costs are estimated to 250.000 DKK. Depending on water depth the cost of the pile ranges from 2,2 to 2,7 million DKK. Procurement and fabrication of the pile are approx. 75% of the total costs. The remaining 25% are due to installation. The total costs are very sensitive to the unit price of pile steel. During the project it became obvious that ice load has a very large influence on the dimensions of the mono pile. (EG)

  3. A simplified analysis method for piled raft and pile group foundations with batter piles

    Science.gov (United States)

    Kitiyodom, Pastsakorn; Matsumoto, Tatsunori

    2002-11-01

    A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to vertical, lateral, and moment loads, using a hybrid model in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. Both the vertical and lateral resistances of the piles as well as the raft base are incorporated into the model. Pile-soil-pile, pile-soil-raft and raft-soil-raft interactions are taken into account based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with several existing methods for single piles, pile groups and piled rafts. Workable design charts are given for the estimation of the lateral displacement and the load distribution of piled rafts from the stiffnesses of the raft alone and the pile group alone. Additionally, parametric studies were carried out concerning batter pile foundations. It was found that the use of batter piles can efficiently improve the deformation characteristics of pile foundations subjected to lateral loads.

  4. Experimental study on pile-end post-grouting piles for super large bridge pile foundations

    Institute of Scientific and Technical Information of China (English)

    Weiming GONG; Guoliang DAI; Haowen ZHANG

    2009-01-01

    The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper. There are totally 21 test piles. The maximum pile diameter varies from 2.5 m to 3 m, and the maximum length is 125m; the bearing capacity of the post-grouting piles is over ten thousands tons. Based on the test results, the bearing capacity,displacement, and beating characteristics before and after grouting were analyzed. The results show that the beating capacity of the piles is increased in different degrees after grouting although the technical parameters, including the patterns of grouting pipes, pressure, dosages of cement, duration of grouting lasting time, are different. However,the obtained values are very discrete. In addition, the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles. The research results have been applied in the design of bridge foundation.

  5. Experiments of Multi-element Composite Foundation with Steel Pipe Pile and Gravel Pile

    Institute of Scientific and Technical Information of China (English)

    WANG Xian-zhi; ZHENG Jun-jie

    2008-01-01

    A set of self-developed apparatus for foundation physical model were utilized to conduct model tests of the multi-element composite foundation with a steel pipe pile and several gravel piles. Some load-bearing characteristics of the multi-element composite foundation, including the curves of foundation settlement, stresses of piles, pile-soil stress ratio, and load-sharing ratio of piles and soil, were obtained to study its working performances in silty sand soil. The experimental results revealed that the multi-element composite foundation with steel pipe pile and gravel pile contributed more than the gravel pile composite foundation in improving the bearing capacity of the silty fine sand.

  6. Pile Spacing Optimization of Short Piled Raft Foundation System for Obtaining Minimum Settlement on Peat

    Science.gov (United States)

    Suro, S. M.; Bakar, I.; Sulaeman, A.

    2016-07-01

    Short Piled Raft is a modified piled raft foundation system, which represents combination between raft foundation and pile foundation, but the length of pile is relatively shorter. The basic concept of the Short Piled Raft foundation system considers the passive soil pressure creating a stiff condition of slab-pile system. This means that the thin concrete slab floats on the supporting soil, while the piles serve as stiffeners concrete slab and also to reduce settlement of the foundation. Slab to pile ratio of such system has been mentioned by several researchers, however the optimum pile spacing of stability performance for obtaining minimum settlement on peat haven't been clearly discussed. In this study, finite element method to simulate the stability performance related to settlement of Short Piled Raft foundation system was used. Short Piled Raft foundation system with concrete slab of 7.0 m x 7.0 m square was assumed to be built on peat with the thickness of 3.5 m. The material properties of pile and raft were constant. The outer diameter of galvanized steel pipe as pile was 0.30 m; raft thickness was considered to be constant of 0.15 m and the length of pile was 3.0 m, while the pile spacing varied from 0.50 to 3.00 m. Point load varied from 0 to 100 kN with increment of 20 kN was also considered as a static load, acted on the centre of the concrete slab. Optimization was done by comparing each numerical result of simulations, thus conclusion can easily be drawn. The optimum pile spacing was 1.00 m which produced minimum settlement of 30.11 mm under the load of 100 kN.

  7. Design Optimization of Piles for Offshore Wind Turbine Jacket Foundations

    DEFF Research Database (Denmark)

    Sandal, Kasper; Zania, Varvara

    Numerical methods can optimize the pile design. The aim of this study is to automatically design optimal piles for offshore wind turbine jacket foundations (Figure 1). Pile mass is minimized with constraints on axial and lateral capacity. Results indicate that accurate knowledge about soil...

  8. Design Optimization of Piles for Offshore Wind Turbine Jacket Foundations

    OpenAIRE

    Sandal, Kasper; Zania, Varvara

    2016-01-01

    Numerical methods can optimize the pile design. The aim of this study is to automatically design optimal piles for offshore wind turbine jacket foundations (Figure 1). Pile mass is minimized with constraints on axial and lateral capacity. Results indicate that accurate knowledge about soil characteristics can translate into significant cost reductions.

  9. Use of geothermal piles combined with pile foundations

    Directory of Open Access Journals (Sweden)

    Ivan Kuzytskyi

    2016-07-01

    Full Text Available The possibility of use of geothermal piles in conditions of cold climate is considered. Full-scale experiment is conducted for using this technology in Kiev. Obtained results testify about a possibility for using the system in conditions of Ukraine, but this technology requires more detailed study and simulation of multiannual cycle of use of geothermal piles 

  10. Bearing capacity and mechanical behavior of CFG pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    陈秋南; 赵明华; 周国华; 张主华

    2008-01-01

    CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.

  11. Optimum design methodologies for pile foundations in London

    Directory of Open Access Journals (Sweden)

    Christos Letsios

    2014-12-01

    Full Text Available Given the importance of pile foundations in geotechnical engineering for supporting high-significance structures such as bridges, high-rise buildings, power plant stations, offshore platforms and museums, it becomes a necessity to find the best pile foundation design in terms of performance and economy. The number of piles required might exceed several hundreds or even thousands while the pile foundation cost might exceed 20% of the construction cost of the superstructure. In this work the problem of finding optimized designs of pile foundations is examined and is performed in accordance to two design code recommendations, namely Eurocode 7 and DIN 4014. The proposed structural optimization procedure is implemented in two real-world cases both located in London, UK in order to assess the efficiency of the proposed design formulation.

  12. Settlement calculation for long-short composite piled raft foundation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; ZHANG Ling; YANG Ming-hui

    2006-01-01

    The mechanism of long-short composite piled raft foundation was discussed. Assuming the relationship between shear stress and shear strain of the surrounding soil was elasto-plastic, shear displacement method was employed to establish the different explicit relational equations between the load and the displacement at the top of pile in either elastic or elasto-plastic period. Then Mylonakis & Gazetas model was introduced to simulate the interaction between two piles or between piles and soil. Considering the effect of cushion, the flexible coefficients of interaction were provided. With the addition of a relevant program, the settlement calculation for long-short composite piled raft foundation was developed which could be used to account for the interaction of piles,soil and cushion. Finally, the calculation method was used to analyze an engineering example. The calculated value of settlement is 10.2 mm, which is close to the observed value 8.8 mm.

  13. Optimization of pile design for offshore wind turbine jacket foundations

    DEFF Research Database (Denmark)

    Sandal, Kasper; Zania, Varvara

    The aim of this study is to use numerical methods of structural design optimization to design piles for offshore wind turbine jacket foundations. Pile mass is minimized with constraints on axial and lateral capacity. Results indicate that accurate knowledge about soil characteristics can translate...

  14. Optimization of pile design for offshore wind turbine jacket foundations

    OpenAIRE

    Sandal, Kasper; Zania, Varvara

    2016-01-01

    The aim of this study is to use numerical methods of structural design optimization to design piles for offshore wind turbine jacket foundations. Pile mass is minimized with constraints on axial and lateral capacity. Results indicate that accurate knowledge about soil characteristics can translate into significant cost reductions.

  15. Centrifuge model test on dynamic behavior of group-pile foundation With inclined piles and its numerical simulation

    Institute of Scientific and Technical Information of China (English)

    Feng ZHANG; Katsunori OKAWA; Makoto KIMURA

    2008-01-01

    In this paper, dynamic behavior of a grouppile foundation with inclined piles in loose sand has been investigated with centrifuge model tests. The test results are also simulated with elastoplastic dynamic finite ele-ment method, in which, not only sectional force of piles, stress of ground, but also deformation of piles are calcu-lated using a three-dimensional elastoplastic dynamic finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure, a pile foundation and surround-ing ground are considered together so that interaction between pile foundation and soils can be properly simu-lated because the nonlinearities of both the pile and the ground are described with suitable constitutive models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests.

  16. THE NEW STRUCTURE OF A PLATE-PILE FOUNDATION

    Directory of Open Access Journals (Sweden)

    SAMORODOV О. V.

    2016-01-01

    Full Text Available Raising of problem. In the construction of high-rise buildings with significant loads on foundations and bedding at the base of not rocky soils tend to use the most common pile foundation to reduce the deformation and correspond to regulations [1] on the maximum permissible deformation. Monitoring of the stress-strain state (SSS pile foundations constructed buildings shows the existing reserves of bearing capacity on the one hand - soil bases of the second group of limit states, on the other - the foundation of the first group of limit states by regulating the SSS foundation during construction and exploitation. Therefore, are increasingly using more progressive structure of foundations consisting of piles and of plate, as well as methods for their construction [2 - 10], however, in their design there are a number of disadvantages associated with the ambiguity of the application of methods for the calculation of such structures, which allows to do only partial conclusions and recommendations. Purpose. Is proposing the new structure of a plate-pile foundation, which overcomes the drawbacks of the existing design solutions and methods of consruction their, as well as is proposing an engineering method of a determination of basic parameters. Conclusion. Is proposes the new structure of a plate-pile foundation and the method of a determination of basic parameters his in the design of a soil base to the maximum permissible deformation Su buildings. Efficiency of application this type plate-pile foundation obtained by rational distribution resistance between a plate and piles, when under load from the building to the first work fully incorporated plate that allows maximum deformed for plate, and then the piles - due to of the hinge connection with the plate. Thus, depending on the maximum permissible deformation for buildings resistance of plate part of a full load of more than 50%, that significantly reduces the consumption of concrete.

  17. Lateral response of pile foundations in liquefiable soils

    Directory of Open Access Journals (Sweden)

    Asskar Janalizadeh

    2015-10-01

    Full Text Available Liquefaction has been a main cause of damage to civil engineering structures in seismically active areas. The effects of damage of liquefaction on deep foundations are very destructive. Seismic behavior of pile foundations is widely discussed by many researchers for safer and more economic design purposes. This paper presents a pseudo-static method for analysis of piles in liquefiable soil under seismic loads. A free-field site response analysis using three-dimensional (3D numerical modeling was performed to determine kinematic loads from lateral ground displacements and inertial loads from vibration of the superstructure. The effects of various parameters, such as soil layering, kinematic and inertial forces, boundary condition of pile head and ground slope, on pile response were studied. By comparing the numerical results with the centrifuge test results, it can be concluded that the use of the p-y curves with various degradation factors in liquefiable sand gives reasonable results.

  18. FIELD INVESTIGATIONS OF PILED-RAFT FOUNDATIONS WITH SHORT-LENGTH CONIC PILES IN BUILDING AREAS OF MINSK

    Directory of Open Access Journals (Sweden)

    V. A. Sernov

    2015-01-01

    Full Text Available In recent time piled foundations are extensively applied due to an increase of storeys in buildings constructed in Minsk and load increment on the soil. Preference is given to this approach even in the case when relatively firm soil occurs in the top part of the foundation bed. In this case maximum usage of the foundation bed bearing capacity and reduction of foundation cost are considered as top-priority tasks for designers. One of the ways to increase the bearing capacity of piled foundations is the necessity to take into account resistance of foundation bed soil located under raft bottom. The raft as well as a shallow foundation is capable to transfer a significant part of building load into the soil. Such approach makes it possible to reduce a number of piles in the foundation or shorten their length. Then it results in shortening of the construction period and significant reduction in zero cycle. However up to the present moment reliable calculation methods that permit to take into account soil resistance in the raft base. An analysis of previous investigations on the matter executed by various researchers and a number of field investigations have been carried out with the purpose to develop the proposed methods.The paper presents results of field investigations on foundations consisting of short stamped tapered piles which are joined together with the help of the raft fragment. Strength and deformation characteristics of the bases are increasing while making such foundations in the fill-up soil. In this case the filled-up ground layer becomes a bearing layer both for piles and rafts as well. Improvement of high-plastic clay-bearing soil properties is ensured by ramming dry concrete mix under pile foot. The paper describes an experience on application of the piled-raft foundation in complicated engineering and geological conditions while constructing the Orthodox Church in Minsk.

  19. Non-probabilistic fuzzy reliability analysis of pile foundation stability by interval theory

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Randomness and fuzziness are among the attributes of the influential factors for stability assessment of pile foundation.According to these two characteristics, the triangular fuzzy number analysis approach was introduced to determine the probability-distributed function of mechanical parameters. Then the functional function of reliability analysis was constructed based on the study of bearing mechanism of pile foundation, and the way to calculate interval values of the functional function was developed by using improved interval-truncation approach and operation rules of interval numbers. Afterwards, the non-probabilistic fuzzy reliability analysis method was applied to assessing the pile foundation, from which a method was presented for nonprobabilistic fuzzy reliability analysis of pile foundation stability by interval theory. Finally, the probability distribution curve of nonprobabilistic fuzzy reliability indexes of practical pile foundation was concluded. Its failure possibility is 0.91%, which shows that the pile foundation is stable and reliable.

  20. Calculation method of composite foundation sedimentation of grouting pile with cover plate under embankment load

    Institute of Scientific and Technical Information of China (English)

    顾长存; 洪昌地; 马文彬; 李雪平

    2008-01-01

    Grouting pile is a new soft soil foundation treatment method with characteristics such as no vibration, no noise, no soil compaction, light construction machines and quick construction velocity and so on. At present, study on reinforcement mechanism and design calculation method of composite foundation of grouting pile is initially started without design specifications, so it is usually required to draw on design specifications of stump pile when designing composite foundation of grouting pile while grouting pile has its characteristics and difference although reinforcement mechanisms and construction processes of two types of piles are similar. Sedimentation formula of composite foundation of grouting pile with cover plate is educed and a suitable deformation mode is proposed by aiming to deformation characteristics of composite foundation of grouting pile with cover plate under embankment load on basis of relevant sedimentation theories of composite foundation by combination of characteristics of composite foundation of grouting pile. The sedimentation calculation formula of grouting pile with cover plate under embankment load is educed according to balance relation of force and displacement coordination conditions by elastic theory and sedimentation calculation model established is validated by sedimentation monitoring documents of one expressway in China.

  1. WAVE CURRENT FORCES ON THE PILE GROUP OF BASE FOUNDATION FOR THE EAST SEA BRIDGE, CHINA

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of the two structures of the bridge foundation designed for the East Sea Bridge, the wave current forces on four types of oblique piles, the pile group and the single piles at different positions in the pile group considering the effect of the super structures were experimentally investigated. The relationship between the wave current forces and the associated wave parameters, and the comparison of the wave current forces on the pile groups and the single piles were systematically analyzed. The group effectiveness and the reduction coefficient for the wave current forces on the group were examined for engineering design.

  2. Force analysis of pile foundation in rock slope based on upper-bound theorem of limit

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; LIU Jian-hua; LIU Dai-quan; WANG You

    2008-01-01

    Based on the characteristic that the potential sliding surfaces of rock slope are commonly in the shape of either line or fold line, analysis thought of conventional pile foundation in the flat ground under complex load condition was applied and the upper-bound theorem of limit analysis was used to compute thrust of rock layers with all possible distribution shapes. The interaction of slope and pile was considered design load in terms of slope thrust, and the finite difference method was derived to calculate inner-force and displacement of bridge pile foundation in rock slope under complex load condition. The result of example shows that the distribution model of slope thrust has certain impact on displacement and inner-force of bridge pile foundation. The maximum displacement growth rate reaches 54% and the maximum moment and shear growth rates reach only 15% and 20%, respectively, but the trends of inner-force and displacement of bridge pile foundation are basically the same as those of the conventional pile foundation in the flat ground. When the piles bear the same level lateral thrust, the distribution shapes of slope thrust have different influence on inner-force of pile foundation, especially the rectangle distribution, and the triangle thrust has the smallest displacement and inner-force of pile foundation.

  3. A performance case study of energy pile foundation at Rosborg Gymnasium (Denmark)

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Jensen, Rasmus Lund; Poulsen, Søren Erbs

    2016-01-01

    The Rosborg Gymnasium building in Vejle (Denmark) is partially founded on 200 foundation pile heat exchangers (energy piles). The thermo-active foundation has supplemented the heating and free cooling needs of the building since 2011 (4,000 m2 living area). Operational data from the ground source...

  4. Comprehensive Detection and Analysis of Defects in Foundation Pile of Bridge

    Institute of Scientific and Technical Information of China (English)

    WANG Qi-ren; HE Ji-shan; YANG Tian-chun

    2003-01-01

    In the process of piling ,there are many various defects in foundation pile of bridge such as mud-bearing,sediment-bearing, isolation, honeycomb, broken piles, and so on, showing physical and mechanical features of low-density and low-intensity. In fact, by using the comprehensive detection of acoustic transmission method, the reflected wave method as well as drill coring sample method, and the rational utilization of engineering geological condition in field, the characteristics, size and location of common defects of foundation pile of bridge can be accurately detected and judged and the integrity of piles and the quality of concrete can be impersonally estimated.comprehensive detecting and analyzing methods on this kind of piles are introduced briefly. The physical characters of defects and basic features of detecting curves and their corresponding relation are emphasized, and causes are analyzed in in detail in this paper.

  5. Conditions of Proper Interaction of Low-Pressure Injection Piles (LIP) with Structure and Soil, Carrying Capacity of Pile Anchorage in Foundation

    Science.gov (United States)

    Pachla, Henryk

    2016-12-01

    The formation of a pile in the existing foundation and soil creates a new foundation construction which has a structure of foundation-pile-soil. This construction must be able to transfer loads from the foundation to the pile and from the pile to the soil. The pile structure has to transfer an imposed load. From the point of view of continuum mechanics determination of the capacity of such a system is preceded by the analysis of contact problem of three contact surfaces. Each of these surfaces is determined by different pairs of materials. The pair which creates a pile anchorage is a material from which the foundation is built (structure of stone and grout, brick and grout, concrete or reinforced concrete and grout. The pile structure is formed by grout and steel rebar. The pile formed in soil is created by a pair of grout and soil. What is important is that on contact surfaces the materials adhering to one another are subjected to different deformation types that are controlled by mechanical properties and geometry of these surfaces. In the paper, additional conditions that should be fulfilled for the foundation-pile-soil system to make load transfer from foundation to soil possible and safe are presented. The results of research done by the author on foundation-pile contact surface are discussed. The tests were targeted at verifying the bearing capacity of anchorage and deformation of piles made of grout and other materials from which foundations are built. The specimens were tested in tension and compression. The experiments were conducted on the amount specimens which is regarded as small sample to enable the statistical analysis of the results.

  6. Long-term settlement prediction of high-speed railway bridge pile foundation

    Institute of Scientific and Technical Information of China (English)

    杨奇; 冷伍明; 张升; 聂如松; 魏丽敏; 赵春彦; 刘维正

    2014-01-01

    The process and characteristics of loading on high-speed railway bridge pile foundation were firstly obtained by means of field research and analysis, and the corresponding loading function was presented. One-dimensional consolidation equation of elastic multilayered soils was then established with single drainage or double drainages under multilevel loading. Moreover, the formulas for calculating effective stress and settlement were derived from the Laplace numerical inversion transform. The three-dimensional composite analysis method of bridge pile group was improved, where the actual load conditions of pile foundation could be simulated, and the consolidation characteristics of soil layers beneath pile were also taken into account. Eventually, a corresponding program named LTPGS was developed to improve the calculation efficiency. The comparison between long-term settlement obtained from the proposed method and the in-situ measurements of pile foundation was illustrated, and a close agreement is obtained. The error between computed and measured results is less than 1 mm, and it gradually reduces with time. It is shown that the proposed method can effectively simulate the long-term settlement of pile foundation and program LTPGS can provide a reliable estimation.

  7. Construction technology on pile foundation of No. 6 main pier in Dashengguan Yangtze Bridge

    Institute of Scientific and Technical Information of China (English)

    Hongbin YU; Zeping LIAN

    2009-01-01

    Based on pile foundation construction of No. 6 main pier, deep mudstone geological foundation and deep-water construction in Nanjing-Dashengguan Yangtze Bridge, the method of super-large-diameter bored pile in deep water is studied. The spread drill, application of PHP mud, and choice of machine are solved by adopting two machines of KTY4000 and KPG300A. Besides, the airlift reversing circulation is selected in slag discharge. The results show that this method can ensure successfully the construction of pier foundation to satisfy the demands of codes.

  8. Analytical Analysis and Field Test Investigation of Consolidation for CCSG Pile Composite Foundation in Soft Clay

    Directory of Open Access Journals (Sweden)

    Jin Yu

    2013-01-01

    Full Text Available Low-grade concrete-cored sand-gravel (CCSG pile composite foundation is a new kind of composite foundation for thick and soft clay ground treatment. An analytical solution was derived for calculating the consolidation process of this composite foundation by considering coefficients of horizontal permeability in smear zone, the radial flow within the sand-gravel shell, and the impervious property of concrete-cored pile. The results show that Terzaghi’s one-dimensional consolidation solution and the consolidation analytical solution of ordinary composite foundation were special cases of this solution. Curves of the average consolidation degree of the composite foundation under various nondimensional parameters were observed using the program based on the theoretical formula. Meanwhile, a series of in situ measurements including the settlement of pile and soil, the pore water pressure, and the total stress under embankment load were obtained on the CCSG pile composite foundation on a section of Zhenjiang-Liyang highway. The analyzed results show that the new style composite foundation patent technology has many advantages such as small differential postconstruction settlement (differential is not good, small is, reliable quality, high bearing capacity, and stability. And the consolidation of composite foundation is largely affected by the nondimensional parameters. The analytical solution is finally verified with the actual measurement data.

  9. Settlement of composite foundation with discrete material pile considering modulus change

    Institute of Scientific and Technical Information of China (English)

    曹文贵; 刘海涛; 李翔; 张永杰

    2008-01-01

    Based on deeply discussing the deformation mechanism of composite foundation with discrete material pile, firstly, the settlement of composite foundation in rigid foundation conditions was assumed to consist of two parts, an expanding part and an un-expanding part. Then, in view of the differences of deformation properties between the expanding part and the un-expanding part, the relationships between the pile modulus and the applied load in these two parts were respectively developed. Thirdly, by introducing the above relationships into settlement analysis, a new method to calculate displacement of composite foundation with discrete material pile was proposed by using the multi-stage loading theory and the layer-wise summation approach. This method is effective not only for accounting for the effect of variations of pores on deformation modulus of the pile body in different depths, but also for describing the characteristics of different deformation mechanisms of the pile body with varying depth. Finally, the proposed method was used to a practical composite foundation problem, whose theoretical results were presented and compared to those of other methods. The rationality and feasibility of this method are identified through comparative analysis.

  10. Reliability of Foundation Pile Based on Settlement and a Parameter Sensitivity Analysis

    OpenAIRE

    Shujun Zhang; Luo Zhong; Zhijun Xu

    2016-01-01

    Based on the uncertainty analysis to calculation model of settlement, the formula of reliability index of foundation pile is derived. Based on this formula, the influence of coefficient of variation of the calculated settlement at pile head, coefficient of variation of the permissible limit of the settlement, coefficient of variation of the measured settlement, safety coefficient, and the mean value of calculation model coefficient on reliability is analyzed. The results indicate that (1) hig...

  11. Study of vibrating foundations considering soil-pile-structure interaction for practical applications

    Institute of Scientific and Technical Information of China (English)

    Hart Yingcai

    2008-01-01

    An investigation of soil-pile-structure interaction is carried out, based on a large reciprocating compressor installed on an elevated concrete foundation (table top structure). A practical method is described for the dynamic analysis, and compared with a 3D finite element (FE) model. Two commercial software packages are used for dynamic analysis considering the soil-pile-structure interaction (SPSI). Stiffness and damping of the pile foundation are generated fi-om a computer program, and then input into the FE model. To examine the SPSI thoroughly, three cases for the soil, piles and superstructure are considered and compared. In the first case, the interaction is fully taken into account, that is, both the superstructure and soil-pile system are flexible. In the second case, the superstructure is flexible but fixed to a rigid base, with no deformation in the base (no SSI). In the third case, the dynamic soil-pile interaction is taken into account, but the table top structure is assumed to be rigid. From the comparison beteen the results of these three cases some conclusions are made, which could be helpful for engineering practice.

  12. System of submarine linking between the legs of a platform and the relating foundation piles

    Energy Technology Data Exchange (ETDEWEB)

    Aggradi, G.P.F.; Di Mugello, B.; Ferrante, C.M.

    1987-09-22

    This patent describes a system for submarine linking between anchoring cylinders affixed to a platform leg and a related foundation pile. The anchoring cylinders are composed of two coaxial cylinders, one of which is an outer cylinder having a substantial thickness of high yield strength steel, the other of which is an inner cylinder having a thickness of low yield strength steel. The thickness is less than the thickness of the outer cylinder, wherein the outer cylinder and the inner cylinder are butt-welded to each other at their ends so as to define an annular chamber between the cylinders. The chamber being radially inwardly expansible by the application of pressure. The related foundation pile is composed of high yield strength steel in a zone where the submarine linking is to be accomplished. The zone of the pile including an outer surface with alternating slots and toothing and an inner thickened surface.

  13. A performance case study of energy pile foundation at Rosborg Gymnasium (Denmark)

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Jensen, Rasmus Lund; Poulsen, Søren Erbs

    2016-01-01

    The Rosborg Gymnasium building in Vejle (Denmark) is partially founded on 200 foundation pile heat exchangers (energy piles). The thermo-active foundation has supplemented the heating and free cooling needs of the building since 2011 (4,000 m2 living area). Operational data from the ground source...... ground heat extraction/injection activity , this paper provides a performance study of the energy pile-based ground source heat pump installation utilising operational data. The study demonstrates that the measured seasonal performance factors so far are lower than expected: 2.7 in heating mode and 4.......2 in cooling mode. Nevertheless, there is room for improvement if novel energy management strategies are applied. This highlights the relevance of considering the daily heating/cooling requirements of the building during the design phase of the heating and cooling system. Moreover, this study demonstrates...

  14. A performance case study of energy pile foundation at Rosborg Gymnasium (Denmark)

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Jensen, Rasmus Lund; Poulsen, Søren Erbs

    2016-01-01

    ground heat extraction/injection activity , this paper provides a performance study of the energy pile-based ground source heat pump installation utilising operational data. The study demonstrates that the measured seasonal performance factors so far are lower than expected: 2.7 in heating mode and 4......The Rosborg Gymnasium building in Vejle (Denmark) is partially founded on 200 foundation pile heat exchangers (energy piles). The thermo-active foundation has supplemented the heating and free cooling needs of the building since 2011 (4,000 m2 living area). Operational data from the ground source.......2 in cooling mode. Nevertheless, there is room for improvement if novel energy management strategies are applied. This highlights the relevance of considering the daily heating/cooling requirements of the building during the design phase of the heating and cooling system. Moreover, this study demonstrates...

  15. 桥梁桩基施工技术探析%Analysis of the Bridge Pile Foundation Construction Technology

    Institute of Scientific and Technical Information of China (English)

    金永亮

    2014-01-01

    The foundation of bridge construction is the pile foundation construction. In the process of pile foundation con-struction, the col apse hole, broken pile and other quality prob-lems are easily occur. This article through the introduction of bridge pile foundation construction technology to summarize the main technical points of pile foundation construction of ea-ch link.%桥梁施工的基础是桩基施工,在桩基的施工过程中,容易出现塌孔、断桩等质量问题。本文通过对桥梁桩基施工工艺的介绍,总结了桩基施工各个环节的技术要点。

  16. CONDUCTING AND ANALYZING THE RESULTS OF THE EXPERIMENTAL BOX TEST OF RETAINING WALL MODELS WITHOUT PILES AND ON THE PILE FOUNDATION

    Directory of Open Access Journals (Sweden)

    M. A. Lisnevskyi

    2015-08-01

    Full Text Available Purpose. Taking into consideration that the bearing capacity of the foundation may be insufficient, in the study it is assumed that pile foundation can be used to reduce the impact of the construction of new retaining structures on roads and railways near the existing buildings or in areas of dense urban development and ensure the stability of the foundation. To reduce the volume of excavation it is necessary to choose the economic structure of the retaining wall. To do this, one should explore stress-strain state (SSS of the retaining walls, to develop methods to improve their strength and stability, as well as to choose the most appropriate method of their analysis. Methodology. In the design of retaining walls foundation mat and piles are considered as independent elements. Since the combined effect of the retaining wall, piles and foundation mat as well as the effect of soil or rock foundation on the structure are considered not fully, so there are some limitations in the existing design techniques. To achieve the purpose the box tests of retaining walls models without piles and with piles for studying their interaction with the surrounding soil massif were conducted. Findings. Laboratory simulation of complex systems «surrounding soil – retaining wall – pile» was carried out and on the basis of the box test results were analyzed strains and its main parameters of the stress-strain state. Analysis of the results showed that the structure of a retaining wall with piles is steady and stable. Originality. So far, in Ukraine has not been carried out similar experimental box tests with models of retaining walls in such combinations. In the article has been presented unique photos and test results, as well as their analysis. Practical value. Using the methodology of experimental tests of the retaining wall models with piles and without them gives a wider opportunity to study stress-strain state of such structures.

  17. Comparison between Dynamic Responses of Hollow and Solid Piles for Offshore Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Bayat, Mehdi; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2013-01-01

    The offshore wind energy industry is turning out ever larger numbers of offshore wind turbines every year. One way to achieve a cost-effective design is to have a better understanding of the dynamic response of offshore structures. That is why it is getting more and more important to understand...... the dynamic behavior of soil and interaction between soil and piles. To avert damage to offshore foundation, it becomes necessary to identify and quantify the soil-structure interaction and the related damping effects on the system. In this study, a single pile is investigated by means of boundary integral...

  18. Helical piles: an innovative foundation design option for offshore wind turbines.

    Science.gov (United States)

    Byrne, B W; Houlsby, G T

    2015-02-28

    Offshore wind turbines play a key part in the renewable energy strategy in the UK and Europe as well as in other parts of the world (for example, China). The majority of current developments, certainly in UK waters, have taken place in relatively shallow water and close to shore. This limits the scale of the engineering to relatively simple structures, such as those using monopile foundations, and these have been the most common design to date, in UK waters. However, as larger turbines are designed, or they are placed in deeper water, it will be necessary to use multi-footing structures such as tripods or jackets. For these designs, the tension on the upwind footing becomes the critical design condition. Driven pile foundations could be used, as could suction-installed foundations. However, in this paper, we present another concept-the use of helical pile foundations. These foundations are routinely applied onshore where large tension capacities are required. However, for use offshore, a significant upscaling of the technology will be needed, particularly of the equipment required for installation of the piles. A clear understanding of the relevant geotechnical engineering will be needed if this upscaling is to be successful.

  19. Dynamic Soil-Pile Interaction for large diameter monopile foundations

    DEFF Research Database (Denmark)

    Zania, Varvara

    2013-01-01

    fatigue may be problematic. In the third case except from the cost increase, the wind induced fatigue is an additional issue to be dealt with. The second concept is the one prevailing in current design practice and it actually sets the natural frequency of vibration of the OWT inside the narrow margin......Monopile foundations have been used in a large extent to support offshore wind turbines (OWT), being considered as a reliable and cost effective design solution. The accurate estimation of their dynamic response characteristics is essential, since the design of support structures for OWTs has been......’ rule and are usually reported in double terms of the stiffness of the OWT and the foundation, i.e. soft –soft, soft – stiff, and stiff – stiff design approaches. In the first case the eigenfrequency of the system is reduced to excessively low values, where the cost reduction is considerable but wave...

  20. INTERACTION OF A LONG PILE OF FINITE STIFFNESS WITH SURROUNDING SOIL AND FOUNDATION CAP

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan Zaven Grigor’evich

    2015-09-01

    Full Text Available The article presents the formulation and analytical solution to a quantification of stress strain state of a two-layer soil cylinder enclosing a long pile, interacting with the cap. The solution of the problem is considered for two cases: with and without account for the settlement of the heel and the underlying soil. In the first case, the article is offering equations for determining the stresses of pile’s body and the surrounding soil according to their hardness and the ratio of radiuses of the pile and the surrounding soil cylinder, as well as formulating for determining equivalent deformation modulus of the system “cap-pile-surrounding soil” (the system. Assessing the carrying capacity of the soil under pile’s heel is of great necessity. In the second case, the article is solving a second-order differential equation. We gave the formulas for determining the stresses of the pile at its top and heel, as well as the variation of stresses along the pile’s body. The article is also formulating for determining the settlement of the foundation cap and equivalent deformation modulus of the system. It is shown that, pushing the pile into underlying layer results in the reducing of equivalent modulus of the system.

  1. Numerical simulation on the seismic absorption effect of the cushion in rigid-pile composite foundation

    Science.gov (United States)

    Han, Xiaolei; Li, Yaokun; Ji, Jing; Ying, Junhao; Li, Weichen; Dai, Baicheng

    2016-06-01

    In order to quantitatively study the seismic absorption effect of the cushion on a superstructure, a numerical simulation and parametric study are carried out on the overall FEA model of a rigid-pile composite foundation in ABAQUS. A simulation of a shaking table test on a rigid mass block is first completed with ABAQUS and EERA, and the effectiveness of the Drucker-Prager constitutive model and the finite-infinite element coupling method is proved. Dynamic time-history analysis of the overall model under frequent and rare earthquakes is carried out using seismic waves from the El Centro, Kobe, and Bonds earthquakes. The different responses of rigid-pile composite foundations and pile-raft foundations are discussed. Furthermore, the influence of thickness and modulus of cushion, and ground acceleration on the seismic absorption effect of the cushion are analyzed. The results show that: 1) the seismic absorption effect of a cushion is good under rare earthquakes, with an absorption ratio of about 0.85; and 2) the seismic absorption effect is strongly affected by cushion thickness and ground acceleration.

  2. Experimental and Numerical Study on Modal Dynamic Response of Water-Surrounded Slender Bridge Pier with Pile Foundation

    National Research Council Canada - National Science Library

    Yulin Deng; Qingkang Guo; Lueqin Xu

    2017-01-01

      This paper presents an experimental program performed to study the effect of fluid-structure interaction on the modal dynamic response of water-surrounded slender bridge pier with pile foundation...

  3. Co-Evolution Optimization of Anchored Row Piles for Deep Foundation Pit

    Institute of Scientific and Technical Information of China (English)

    周东; 吴恒; 李陶声; 韦日钰; 陈秋莲

    2001-01-01

    The thinking of co-evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been already developed successfully. For the co-evolution algorithm providing an evolutionary mechanism to simulate ever-changing problem space, it is an optimization algorithm that has high performance, especially applying to the optimization of complicated system of retaining and protecting for deep foundation pit. It is shown by many engineering practices that the co-evolution algorithm has obvious optimization effect, so it can be an important method of optimization of retaining and protecting for deep foundation pit. Here the authors discuss the co-evolution model, object function, all kinds of constraint conditions and their disposal methods, and several key techniques of system realization.

  4. Generation of stress-strain state in combined strip pile foundation beds through pressing of soil

    Directory of Open Access Journals (Sweden)

    Stepanov Maxim

    2017-01-01

    Full Text Available When erecting high-rise buildings, weak underlying soils cause a number of problems in design and construction. In order to ensure the required non-exceedance of the ultimate limit settlements, the combined strip pile foundation has been developed allowing the soil bed to be pre-stressed. This is achieved by injection of pressurized mortar (pressing. The paper analyzes the effect of soil pre-stressing followed by pressing of foundation with the cement mortar, as applied to existing structures using the Plaxis 3D software package in conditions of volume deformation and the Hardening Soil Model. Variable order of foundation pressing allows the required parameters of soil bed to be achieved in plan and depth, thus improving interaction with the foundation and superstructure.

  5. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  6. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    Directory of Open Access Journals (Sweden)

    Ruiqing Lang

    2014-01-01

    Full Text Available Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  7. The Deformation of Overburden Soil and Interaction with Pile Foundations of Bridges Induced by Normal Faulting

    Science.gov (United States)

    Wu, Liang-Chun; Li, Chien-Hung; Chan, Pei-Chen; Lin, Ming-Lang

    2017-04-01

    overburden soil and embedded pile foundations subjected to normal faulting. In order to validate this numerical model, it is compared to sandbox experiments. Since the 3-D numerical analysis corresponds to the sandbox expeiments, the response of pile foundations and ground deformation induced by normal faulting are discussed. To understand the 3-D behavior of ground deformation and pile foundations, the observation such as the triangular shear zone, the width of primary deformation zone and the inclination, displacements, of the pile foundations are discussed in experiments and simulations. Furthermore, to understand the safty of bridges crossing faulting zone. The different superstructures of bridges, simple beam and continuous beam will be discussed subsequently in simulations.

  8. 桩伴侣与基桩抗震的概念设计%Pile Partner and the Conceptual Earthquake-resistant Design of Foundation Pile

    Institute of Scientific and Technical Information of China (English)

    薛江炜; 葛忻声; 蔡景珞; 杨勇

    2013-01-01

    It is uncertain that the lateral components such as basement wall and cap side wall bearing horizontal load,so the conventional pile foundation with low cap might endure lateral force that is larger,and even cause its damage.The applying of pile partner to improve traditional foundation pile structure form is put for ward,especially when there is few frictional force between pile cap and soil,or the soil modulus is small.The partner can be component for anti-earthquake concept design under rare earthquake action,pile partner may be sacrificed firstly to keep pile perform well.The improper design of composite foundation will destroy or weaken the isolation effect of pillow,and can be solved by reserving buffer space between pile and partner.%地下室外墙、承台侧壁等侧向构件承担水平荷载具有很大的不确定性,常规采用的低承台桩基有可能承受较大的甚至导致破坏的水平力,建议用桩伴侣改善传统基桩的构造形式,特别是对于承台与桩间土摩擦力小或者桩身范围地基土模量低的两类状况.在罕遇地震时,作为抗震概念设计的耗能构件,首先牺牲伴侣,避免或延迟桩头的破坏;复合地基如果设计不当会破坏或削弱褥垫层隔震的效果,可在伴侣与桩之间预留缓冲空间.

  9. Consolidation analysis of composite foundation with partially penetrated cement fly-ash gravel (CFG) piles under changing permeable boundary conditions

    Institute of Scientific and Technical Information of China (English)

    邹新军; 赵增明; 徐洞斌

    2015-01-01

    Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel (CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage (permeable CFG pile bodies) and the later stage (impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors (including the replacement ratem, the treatment depthh1, the permeability coefficientKs1,Kv2and compression modulusEs1,Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.

  10. On Pile Foundation Construction Technology and Its Application%论桩基础施工技术和应用

    Institute of Scientific and Technical Information of China (English)

    肖蓓

    2014-01-01

    地基基础工程施工前,根据打(沉)桩方法的不同,钢筋混凝土预制桩基础施工有锤击沉桩法、静力压桩法及振动法等,以锤击沉桩法和静力压桩法应用最为普遍。钢筋混凝土灌注桩是一种直接在现场桩位上就地成孔,然后在孔内浇筑混凝土或安放钢筋笼再浇筑混凝土而成的桩。按其成孔方法不同,可分为钻孔灌注桩、沉管灌注桩、人工挖空和挖空扩底灌注桩。%Before foundation construction, depending on the piling method, the basic construction of precast reinforced concrete piles have hammer pile sinking method, static pressure piling method and the vibration method, in which hammer pile sinking method and static pressure piling method are most commonly used. Reinforced concrete pile is a pile directly in the field on the spot into the hole, and then pouring concrete reinforcement cage placed in the holes or pouring concrete from the pile again. According to different holing methods, it can be divided into cast-in-situ bored pile, tube-sinking cast-in-situ pile, artificial hollowed out and hollowed reamed pile.

  11. Dynamic-stiffness matrix of embedded and pile foundations by indirect boundary-element method

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, J.P.; Darbre, G.R. (Electrowatt Engineering Services Ltd., Zurich (Switzerland))

    1984-08-01

    The boundary-integral equation method is well suited for the calculation of the dynamic-stiffness matrix of foundations embedded in a layered visco-elastic halfspace (or a transmitting boundary of arbitrary shape), which represents an unbounded domain. It also allows pile groups to be analyzed, taking pile-soil-pile interaction into account. The discretization of this boundary-element method is restricted to the structure-soil interface. All trial functions satisfy exactly the field equations and the radiation condition at infinity. In the indirect boundary-element method distributed source loads of initially unknown intensities act on a source line located in the excavated part of the soil and are determined such that the prescribed boundary conditions on the structure-soil interface are satisfied in an average sense. In the two-dimensional case the variables are expanded in a Fourier integral in the wave number domain, while in three dimensions, Fourier series in the circumferential direction and Bessel functions of the wave number domain, while in three dimensions, Fourier series in the circumferential direction and Bessel functions of the wave number in the radial direction are selected. Accurate results arise with a small number of parameters of the loads acting on a source line which should coincide with the structure-soil interface. In a parametric study the dynamic-stiffness matrices of rectangular foundations of various aspect ratios embedded in a halfplane and in a layer built-in at its base are calculated. For the halfplane, the spring coefficients for the translational directions hardly depend on the embedment, while the corresponding damping coefficients increase for larger embedments, this tendency being more pronounced in the horizontal direction.

  12. Seismic Analysis of Deep Water Pile Foundation Based on Three-Dimensional Potential-Based Fluid Elements

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2013-01-01

    Full Text Available This paper investigates the use of three-dimensional (3D ϕ-u potential-based fluid elements for seismic analyses of deep water pile foundation. The mathematical derivations of the potential-based formulations are presented for reference. The potential-based modeling technique is studied and validated through experimental data and analytical solutions. Earthquake time history analyses for a 9-pile foundation in dry and different water environments are conducted, respectively. The seismic responses are discussed to investigate the complex effect of earthquake-induced fluid-structure interaction. Through the analyses, the potential-based fluid and interface elements are shown to perform adequately for the seismic analyses of pile foundation-water systems, and some interesting conclusions and recommendations are drawn.

  13. Centrifuge investigation of the axial cyclic behaviour of a single pile used for the foundation of a jacket type offshore wind turbine

    OpenAIRE

    BLANC, Matthieu; Thorel, Luc; ISORNA, Rocio; Dano, Christophe; Kotronis, Panagiotis; PHILIPPE, Maxime

    2015-01-01

    International audience; The jacket type offshore wind turbine transfers efficiently the horizontal load applied on the wind turbine to an axial load on the four piles of its foundation. The axial behaviour of one single pile of the foundation is investigated in a geotechnical centrifuge. The model pile, tested under a 100 g centrifuge acceleration, is designed to represent a cast-in-place pile with a 1.8 m diameter and a 40 m embedded length. The pile, installed in dense Fontainebleau sand, i...

  14. Numerical investigation of piled raft foundation in mitigating embankment vibrations induced by high-speed trains

    Institute of Scientific and Technical Information of China (English)

    付强; 刘汉龙; 丁选明; 郑长杰

    2015-01-01

    A three-dimensional dynamic finite element model of track-ballast-embankment and piled raft foundation system is established. Dynamic response of a railway embankment to a high-speed train is simulated for two cases: soft ground improved by piled raft foundation, and untreated soft ground. The obtained results are compared both in time domain and frequency domain to evaluate the effectiveness of the ground improvement in mitigating the embankment vibrations induced by high-speed trains. The results show that ground improving methods can significantly reduce the embankment vibrations at all considered train speeds(36-432 km/h). The ground response to a moving load is dictated largely by the relationship between load speed and characteristic value of wave velocities of the ground medium. At low speeds, the ground response from a moving load is essentially quasi-static. That is, the displacements fields are essential the static fields under the load simply moving with it. For the soft ground, the displacement on the ballast surface is large at all observed train speeds. For the model case where the ground is improved by piled raft foundation, the peak displacement is reduced at all considered train speeds compared with the case without ground improvement. Based on the effect of energy-dissipating of ballast-embankment-ground system with damping, the train-induced vibration waves moving in ballast and embankment are trapped and dissipated, and thus the vibration amplitudes of dynamic displacement outside the embankment are significantly reduced. But for the vibration amplitude of dynamic velocity, the vibration waves in embankment are absorbed or reflected back, and the velocity amplitudes at the ballast and embankment surface are enhanced. For the change of the vibration character of embankment and ballast, the bearing capacity and dynamic character are improved. Therefore, both of the static and dynamic displacements are reduced by ground improvement; the dynamic

  15. Numerical investigation of piled raft foundation in mitigating embankment vibrations induced by high-speed trains

    Institute of Scientific and Technical Information of China (English)

    付强; 刘汉龙; 丁选明; 郑长杰

    2015-01-01

    A three-dimensional dynamic finite element model of track-ballast-embankment and piled raft foundation system is established. Dynamic response of a railway embankment to a high-speed train is simulated for two cases: soft ground improved by piled raft foundation, and untreated soft ground. The obtained results are compared both in time domain and frequency domain to evaluate the effectiveness of the ground improvement in mitigating the embankment vibrations induced by high-speed trains. The results show that ground improving methods can significantly reduce the embankment vibrations at all considered train speeds (36− 432 km/h). The ground response to a moving load is dictated largely by the relationship between load speed and characteristic value of wave velocities of the ground medium. At low speeds, the ground response from a moving load is essentially quasi-static. That is, the displacements fields are essential the static fields under the load simply moving with it. For the soft ground, the displacement on the ballast surface is large at all observed train speeds. For the model case where the ground is improved by piled raft foundation, the peak displacement is reduced at all considered train speeds compared with the case without ground improvement. Based on the effect of energy-dissipating of ballast-embankment-ground system with damping, the train-induced vibration waves moving in ballast and embankment are trapped and dissipated, and thus the vibration amplitudes of dynamic displacement outside the embankment are significantly reduced. But for the vibration amplitude of dynamic velocity, the vibration waves in embankment are absorbed or reflected back, and the velocity amplitudes at the ballast and embankment surface are enhanced. For the change of the vibration character of embankment and ballast, the bearing capacity and dynamic character are improved. Therefore, both of the static and dynamic displacements are reduced by ground improvement; the dynamic

  16. State-of-the-art review of some artificial intelligence applications in pile foundations

    Institute of Scientific and Technical Information of China (English)

    Mohamed A. Shahin

    2016-01-01

    Geotechnical engineering deals with materials (e.g. soil and rock) that, by their very nature, exhibit varied and uncertain behavior due to the imprecise physical processes associated with the formation of these materials. Modeling the behavior of such materials in geotechnical engineering applications is complex and sometimes beyond the ability of most traditional forms of physically-based engineering methods. Artificial intelligence (AI) is becoming more popular and particularly amenable to modeling the complex behavior of most geotechnical engineering applications because it has demonstrated superior predictive ability compared to traditional methods. This paper provides state-of-the-art review of some selected AI techniques and their applications in pile foundations, and presents the salient features associated with the modeling development of these AI techniques. The paper also discusses the strength and limitations of the selected AI techniques compared to other available modeling approaches.

  17. Explore the Pile Foundation Construction and Supporting of the Soft Soil Foundation in the Foundation Pit Excavation%基坑开挖中软土地基的支护与桩基施工研究

    Institute of Scientific and Technical Information of China (English)

    龙永卫

    2014-01-01

    在软土地基的开挖过程中,桩体支护结构及桩基的应用非常广泛。本文主要结合两个实例,对分别对深基坑灌注桩支护工程及基坑开挖和桩基施工进行了探讨,以掌握施工程序、要点及方式等。%In the process of soft soil foundation excavation, the pile and pile foundation retaining structure have a very wi-de range of applications. This article combines with two inst-ances to discuss the deep foundation pit support engineering as wel as the foundation pit excavation and pile foundation cons-truction, in order to grasp the construction procedures, essenti-als and ways, etc.

  18. SHAKING TABLE TEST AND EFFECTIVE STRESS ANALYSIS ON SEISMIC PERFORMANCE WITH SEISMIC ISOLATION RUBBER TO THE INTERMEDIATE PART OF PILE FOUNDATION IN LIQUEFACTION

    Science.gov (United States)

    Uno, Kunihiko; Otsuka, Hisanori; Mitou, Masaaki

    The pile foundation is heavily damaged at the boundary division of the ground types, liquefied ground and non-liquefied ground, during an earthquake and there is a possibility of the collapse of the piles. In this study, we conduct a shaking table test and effective stress analysis of the influence of soil liquefaction and the seismic inertial force exerted on the pile foundation. When the intermediate part of the pile, there is at the boundary division, is subjected to section force, this part increases in size as compared to the pile head in certain instances. Further, we develop a seismic resistance method for a pile foundation in liquefaction using seismic isolation rubber and it is shown the middle part seismic isolation system is very effective.

  19. Analysis and design for inelastic structural response of extended pile shaft foundations in laterally spreading ground during earthquakes

    Science.gov (United States)

    Khosravifar, Arash

    Experiences from past earthquakes have shown that lateral spreading associated with liquefaction of cohesionless soils can be a cause of severe damage to bridge foundations. Large diameter extended pile shafts can be an effective bridge foundation choice for areas subjected to lateral spreading because they offer greater stiffness and strength relative to the magnitude of lateral spreading loads that can develop against them. A limited degree of plastic hinging below the ground surface may be allowable in design of extended pile shafts. Issues for design for extended pile shafts include: (a) how to estimate the demands due to superstructure inertia and lateral spreading in liquefied soils, and (b) how to combine these two loads in estimating the local and global inelastic demands on the structure. Studies of the response of pile foundations and pile-supported structures in liquefiable soils using physical models, numerical models, and case studies have provided the basis for a number of design recommendations. The guidance is, however, quite varied regarding how lateral spreading and superstructure inertial loads should be combined in design. To answer the above questions a series of Nonlinear Dynamic Finite Element Analyses (NDA) have been performed to investigate inelastic response of extended pile shafts subjected to liquefaction-induced lateral spreading, covering a range of soil, pile, and ground motion conditions. The results of NDA were first used to show that combined effects of lateral spreading and superstructure inertia produce larger demands than are produced by either loading case alone, such that the combined demand cannot be enveloped by analyzing the two load cases separately. The results were then used to evaluate current equivalent static analysis (ESA) method (Caltrans, 2008), with the relatively poor agreement illustrating the limitations of methods that do not combine the two loads. The results of NDA parametric study were then used to develop

  20. Multifield coupling model and its applications for pile foundation in permafrost

    Institute of Scientific and Technical Information of China (English)

    WU; Yaping; ZHU; Yuanlin; GUO; Chunxiang; SU; Qiang; MA; We

    2005-01-01

    Importing the interface element which links the frozen soil base with concrete piles and considering the couplings of stress field, temperature field and moisture field, this paper establishes the nonlinear visco-elastic plastic finite element model of pile-soil. For a practical bridge structure the stress field and displacement field of single pile in freezing process are calculated.This paper emphatically studies the process of the tangential frost heave stress field, freezing stress field and displacement field varying with time, and ulteriorly studies time variation process of single pile carrying capacity in freezing process.

  1. Application of CFG Pile in Foundation Treatment%CFG桩在地基处理中的应用

    Institute of Scientific and Technical Information of China (English)

    高小强

    2014-01-01

    CFG (Cement Fly-ash Gravel) is composed of gr-avel, stone dust, sand, fly ash mixing cement with water. The application of CFG pile can effectively increase foundation bearing capacity and reduce the set lement, so as to ensure the economic construction. This article carried on the analysis to the application of CFG pile in foundation treatment.%CFG(Cement Fly-ash Gravel)由碎石、石屑、砂、粉煤灰掺水泥加水拌和而成。采用CFG桩能够有效地增加地基的承载力、降低沉降量,从而保证施工的经济性。文章对CFG桩在地基处理中的应用进行了分析。

  2. Seismic Material Properties of Reinforced Concrete and Steel Casing Composite Concrete in Elevated Pile-Group Foundation

    Directory of Open Access Journals (Sweden)

    Zhou Mi

    2015-09-01

    Full Text Available The paper focuses on the material mechanics properties of reinforced concrete and steel casing composite concrete under pseudo-static loads and their application in structure. Although elevated pile-group foundation is widely used in bridge, port and ocean engineering, the seismic performance of this type of foundation still need further study. Four scale-specimens of the elevated pile-group foundation were manufactured by these two kinds of concrete and seismic performance characteristic of each specimen were compared. Meanwhile, the special soil box was designed and built to consider soil-pile-superstructure interaction. According to the test result, the peak strength of strengthening specimens is about 1.77 times of the others and the ultimate displacement is 1.66 times of the RC specimens. Additionally, the dissipated hysteric energy capability of strengthening specimens is more than 2.15 times of the others as the equivalent viscous damping ratio is reduced by 50%. The pinching effect of first two specimens is more obvious than latter two specimens and the hysteretic loops of reinforced specimens are more plumpness. The pseudo-static tests also provided the data to quantitatively assessment the positive effect of steel casing composite concrete in aseismatic design of bridge.

  3. Numeric simulation analysis of load-settlement relation of pile in layer foundation

    Institute of Scientific and Technical Information of China (English)

    WANG You-qing

    2006-01-01

    Considering the level distribution of soil layers, the soils surrounding pile are simulated with level finite layer elements. Supposing that the vertical deformation of the soil elements surrounding pile varies in the form of exponent function with radial distance, and considering the nonlinear constitutive relation of stress and strain, the stiffness matrix is established. The mechanics behavior of the pile-soil interface is simulated with a nonlinear interface element. This method can truly express the behavior of the pile-soil system. The load-settlement relation Q-S curves of two big diameter prototype piles on bearing test are analyzed, and satisfying results are obtained. This method is reasonable in theory and feasible in engineering.

  4. 双速度法检测基桩完整性试验研究%Experimental Study on Integrity Inspection of Foundation Pile by Double Speed Test

    Institute of Scientific and Technical Information of China (English)

    唐勇

    2012-01-01

    The low strain test method of foundation pile is applied to check the integrity of bridge foundation pile, driven pile and anti-sliding pile extensively, but the check is difficult to be carried out in case of restrained pile top. Then the double speed test could be used, which could be also applied in case of the foundation pile of existing building, the foundation pile being connected to upper structure, and the pile length unknown. Through single and double speed tests for 16 model piles with and without cap, 766 groups of data are obtained for analysis. As a result, it is proved that the method could be absolutely applied in engineering foundation pile inspection and has realistic meaning about the related integrity check.%基桩低应变测试法被广泛应用于测试桥梁基桩、打入桩和抗滑桩等的完整性。但是,桩顶非自由的情况测试就非常困难。此时可采用双速度法检测,此方法也适于测试已有建筑物下的基桩及基桩与上部结构相连且桩长未知的情况。通过16根有承台和无承台模型桩的单速度和双速度测试,取得766组数据进行分析,得出此方法完全可以应用于工程基桩检测中,对基桩完整性检测具有现实意义。

  5. Performance of pile foundation for the civil infrastructure of high speed rail in severe ground subsidence area

    Science.gov (United States)

    Yang, H. W.

    2015-11-01

    In this study, the performance of pile foundation is assessed for the 30 km long viaduct bridge structure seating in the ground subsidence area in the central part of Taiwan. The focus of this paper is placed on the settlement behaviour of a continuous 3-span R. C. viaduct bridge supported on piles adjacent to highway embankment. Monitoring data accumulated over the last 12 years indicate that the observed pace of the settlement of the viaduct structure in other sections matches that of the ground. However, the bridge piers adjacent to the embankment have been suffering an additional approximately 1 cm settlement every year since the completion of the embankment construction. It was believed that the piers may suffer from enormous negative skin friction owing to the surcharge from the embankment and groundwater depression. This paper first summarizes the settlement analysis results to quantify the settlement of pile due to regional ground subsidence and the combined effects from ground water fluctuation and embankment surcharge loading. Accordingly, a loading path on P'-q stress space is formulated to illustrate the loading variation subject to the combined loading effects that can explain why the combined effect becoming significant on settlement control for civil infrastructure in ground subsidence area.

  6. Dimensioning of pile systems for the foundation of offshore wind power plants; Bemessung von Pfaehlen fuer die Gruendung von Offshore-Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Achmus, Martin [Hannover Univ. (Germany). Inst. fuer Geotechnik

    2012-11-01

    In the near future, an enormous number of wind power plants are built in offshore wind turbine arrays in the North Sea and Baltic Sea. In the dimensioning of foundation structures aspects have to be taken into account which are irrelevant in the dimensioning of conventional onshore structures and offshore structures. Under this aspect, the author of the contribution under consideration reports on a dimensioning of pile systems of pile founded structures. An overview of current issues and solutions is given.

  7. Research on Mechanism and Dynamic Characteristics of Composite Foundation with Multi-type Piles%多桩型复合地基作用机理与动力特性研究

    Institute of Scientific and Technical Information of China (English)

    张艳美; 潘振华; 张鸿儒; 王震; 黄春霞

    2015-01-01

    To meet the requirements of bearing capacity and anti-liquefaction of liquefiable founda-tions,the reinforcement of liquefiable soil using CFG piles combined with gravel piles is used in engineering.In this study,a composite foundation with multi-type piles composed of gravel piles and CFG piles was analyzed.In composite foundations with multi-type piles,gravel piles are sup-plemented piles that are mainly used to accelerate the foundation drainage consolidation.CFG piles are the main piles that undertake greater seismic load and reduce the dynamic pore pressure and post-earthquake settlement of the foundation.A composite foundation with multi-type piles com-posed of gravel and CFG piles can improve the bearing capacity and liquefaction resistance of a liquefiable foundation.A three dimensional numerical model was established and the dynamic characteristics of a composite foundation with multi-type piles was studied through numerical simulation;the influence of design parameters such as the ratio of pile type,pile diameter,pile length,CFG pile body stiffness,and gravel pile body permeability on dynamic characteristics of a composite foundation with multi-type piles was analyzed.The results show that the dynamic de-formation of a composite foundation,including gravel pile composite foundation,CFG pile com-posite foundation,and composite foundation with multi-type piles is obviously smaller than that of a natural foundation during earthquakes,and the dynamic deformation decreases with increase in the number of CFG piles.When the ratio of gravel piles and CFG piles is 4:5,the dynamic de-formation curve of a composite foundation with multi-type piles is close to that of the CFG pile composite foundation and the influence of the increase in the amount of CFG piles on the reduc-tion in the dynamic deformation of the composite foundation is no longer obvious.When the ratio of gravel piles and CFG piles is 4:5,the dynamic pore water pressure of the composite foundation

  8. Analyzes the Application of Pile Foundation Construction in the Construction Engineering%桩基施工在建筑工程应用分析

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    The pile foundation construction is the base form, which is the most commonly used in construction engineering. This article describes the type of pile, piling pile types as wel as different foundation construction technology, analyzes the application characteristics of pile construction technology un-der different conditions so as to provide reference for the sel-ection of pile foundation construction building in the practical application of construction engineering.%  桩基工程是建筑工程最常用的基础形式。本文通过对桩基种类、打桩类型以及不同桩基施工技术的介绍,分析了不同条件下桩基施工技术的应用特点,为建筑工程实际应用中桩基施工的选取提供了参考依据。

  9. 桩基承载能力的有限元分析%Finite Element Analysis of Bearing Capacity of Pile Foundation

    Institute of Scientific and Technical Information of China (English)

    彭银辉; 吕世斌; 耿立伟

    2012-01-01

    针对工程实例,利用ABAQUS有限元软件建立单桩承载力的有限元计算模型,研究桩基承载特性,并与桩基静载试验所得实测数据比较。结果表明,模拟计算结果与工程实际基本吻合,说明采用的计算方法和模型是合理可行的。同时研究了在不同桩土界面摩擦系数条件下桩的沉降和轴向力变化情况,为不同工程地质条件的桩基设计提供参考。%On account of practical case,finite element calculation model of single pile bearing capacity is established with ABAQUS to study the bearing characteristics of pile foundation and compare with actual measurement data of static loading test of pile foundation.The result shows that simulated calculation result is basically consistent with actual engineering,which indicates that the adopted calculation method and model are reasonable and feasible.Meanwhile,the change of settlement and axial force of pile under different frictional coefficient of pile soil is studied,providing references for pile foundation design in different engineering geological conditions.

  10. 软土地层桥梁群桩基础沉降模型%Settlement model of bridge pile group foundation in soft soil stratum

    Institute of Scientific and Technical Information of China (English)

    汪优; 王星华; 刘建华; 蔡君君

    2012-01-01

    Based on the settlement characteristics of bridge pile foundation on soft soil stratum, the similarity rule of pile group model in this geological situation was derived. The indoor model of pile group foundation with pile cap was self-designed and analyzed. The test results show that the additional stress attenuates with the increase of depth and its distribution form approximates as triangular form within the scope of the pile body. At the same time, the vertical stress of pile-side soil increases as the settlement of pile top increases correspondingly. Moreover, the vertical stress of pile-side soil has not shown obvious converge even though the settlement of pile top is greater near the ultimate load. When the pile group foundation is under applied loads, representing different construction stages, the pile-side soil of upper pile body generates larger excess pore water pressure dissipating with time gradually, which indicates that the soil consolidation process needs some time to be finished. Furthermore, the relationship between load-settlement of pile group shows apparent non-linear characteristics, and its P-S curve can be divided into three /stages of linear phase, yielding stage and the overall destruction phase. In addition, the displacement rebound of pile group is small during unloading because the pile group generates large plastic deformation after the external load is applied. Therefore, the settlement of pile group foundation is one of the control conditions in the pile foundation design.%根据软土地层桥梁群桩基础的沉降特性,推导该地质环境下群桩模型试验相似法则,自行设计带承台群桩基础的室内模型并开展试验研究.试验结果表明:在桩身范围内,附加应力随深度衰减,在分布形式上,附加应力分布形式可近似为三角形;同时,桩侧土体的竖向应力随着桩顶沉降的增加而相应的增加,在接近极限荷载产生较大沉降时也没有表现出明显收敛的现

  11. Stress Ratio-Strain Relation of Pile and Soil in Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    LIU Fei; GAO Quan-chen; JING Lai-wang; ZHAO Yan-lin

    2004-01-01

    A series of triaxial compression tests were arried out by means of composite-reinforced soil samples to simulate the interaction between soil and pile. The samples are made of gravel or lime-soil with different length at the center. The experiment indicates that the strength of the composite samples can not be obtained by superimposure of reinforcing pile and soil simply according to their replacement proportion. It also indicates the law for stress ratio of reinforcing column to soil. The stress ratio of reinforcing column to soil increases and reaches peak rapidly while load and strain is small. Then the ratio decreases. This law is in accordance with the measuring resuits in construction site.

  12. Analysis and treatment of common problems in design and construction of concrete pile foundation%混凝土桩基设计与施工常见问题分析与处理

    Institute of Scientific and Technical Information of China (English)

    潘志芳

    2016-01-01

    From the Pile foundation selection and construction craft,the PaPer introduces the common Problems in the reinforced concrete Pile foundation design,exPlores the selection PrinciPle for the Pile hammer in the Pile foundation construction,and illustrates the reasons and treat-ment measures for the Pile foundation cracks,so as to accumulate exPerience for the design and construction of the Pile foundation.%从桩基选型与施工工艺两方面,介绍了钢筋混凝土桩基设计中常见的问题,探讨了桩基施工中桩锤的选择原则,并阐述了桩基裂缝的产生原因及处理措施,为桩基的设计与施工积累了经验。

  13. Pile Foundation Construction Technology of Modern Construction Engineering%浅析现代建筑工程桩基工程施工技术

    Institute of Scientific and Technical Information of China (English)

    仵安东

    2014-01-01

    The quality of a construction has great relationship with the construction technology of pile foundation enginee- ring. To improve the pile foundation engineering technology and to ensure its quality can improve the level and quality of the overal construction. This paper gives a brief introduction on the pile foundation engineering construction technology of modern construction projects.%一项建筑施工质量的好坏,很大联系就在于桩基工程的施工技术。要对桩基工程的技术进行提高、保证其质量过关,可以提高整体建筑的水平和质量。本文就现代建筑工程桩基工程施工技术方面进行了简要的介绍。

  14. Application of Excel in Estimating the Vertical Bearing Capacity of Pile Foundation%Excel在桩基竖向承载力估算中的应用

    Institute of Scientific and Technical Information of China (English)

    尤苏南

    2013-01-01

    Use Excel's strong functions of data looking for, data calculation and data processing, carry out the estimation of vertical bearing capacity of single-pile comply with the common formula, large diameter pile formula, socket-pile formula, anti-pull up pile formula, later inject mortar formula etc. only need to set up its function, formula and simple macro order, enter the stratum data and the parameter of pile foundation calculation. Specially fit for the pile foundation scheme selection for the large and complicated project with different location, different device, different pile type, different pile diameter and different pile end bearing layer, largely enhance the work efficiency.%  利用Excel强大的数据查找、计算、处理功能,只需进行Excel的函数、公式、简单宏命令设置,输入地层数据和桩基计算参数,就能按桩基的通用公式、大直径桩公式、嵌岩桩公式、抗拔桩公式、后注浆公式等,进行单桩竖向承载力估算。尤其适用于大型或复杂工程中不同工点、不同装置、不同桩型、不同桩径、不同桩端持力层等多种条件下的桩基方案比选,可以大大提高工作效率。

  15. 刚性桩复合地基模型拟动力试验研究%Pseudo-dynamic test study on rigid-pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    鲍鹏; 刘德辉

    2013-01-01

    为了研究刚性桩复合地基的抗震性能,依据相似理论,建立几何相似比为1∶10的3×3刚性桩复合地基群桩模型,采用拟动力的试验方法,研制一套试验系统.通过在桩身粘贴电阻应变片、垫层中埋设应变片、砂箱外壁连接位移传感器等方法分别测出桩身应变、垫层变形值、砂箱位移,并对上述数值进行分析研究,得出刚性桩复合地基在地震作用下的响应规律,为刚性桩复合地基在抗震设防地区的应用提供理论指导.%In order to study the seismic performance of rigid-pile composite foundation,a 3 × 3 rigid-pile composite foundation pile group model with geometric similarity ratio of 1:10 was established based on the similarity theory.A test system was developed by using pseudo-dynamic test methods.The pile strain,cushion deformation and sandbox displacement were measured by pasting resistance strain gauges in the pile,burying strain gauges in the cushion and connecting displacement sensors between the outer walls of the sandbox respectively.The above data was analyzed and the response of rigid-pile composite foundation under seismic action was obtained,which can be theoretical guidance for the application of the rigid-pile composite foundation in seismic fortification areas.

  16. Analysis of concrete foundation piles using structure-integrated fibre-optic sensors; Strukturanalyse von Betonpfaehlen durch eingebettete faseroptische Sensoren

    Energy Technology Data Exchange (ETDEWEB)

    Schallert, Matthias [Gesellschaft fuer Schwingungsuntersuchungen und Dynamische Pruefmethoden (GSP) mbH, Mannheim (Germany); Hofmann, Detlef; Habel, Wolfgang R. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany)

    2008-07-01

    Reinforced concrete piles are often used for structures on non-sufficiently bearing soil areas. Assessment of bearing capacity and bearing behaviour of large concrete piles remains a difficult task under specific soil conditions and pile geometries. Usually static and dynamic pile tests are carried out for quality assurance. From dynamic measurements taken only from the pile head, the bearing behaviour and structural integrity can be derived using the one-dimensional theory of wave propagation. More precise information about the pile features can be achieved by highly resolving fibre-optic sensors based on Fabry-Perot technology, distributed over several locations along the pile length. Small scale piles and real driven piles have been tested. This paper describes the sensor, the sensor installation, and experimental results of tests in laboratory as well as test results for recording the wave propagation in the small scale piles. (orig.)

  17. 超高层建筑桩筏基础的桩顶反力计算研究%Study of computation of load on pile top of piled raft foundation for superhigh buildings

    Institute of Scientific and Technical Information of China (English)

    巢斯; 赵锡宏; 张保良; 姜文辉; 孔娟; 肖俊华; 袁聚云

    2011-01-01

    Based on the settlement data of the piled raft foundation in 88-storey, 4 m thick raft of Jinmao Building and 1O1-storey,4.5m thick raft of Shanghai World Financial Center (SWFC), it is demonstrated that piled raft foundation is a real elastic body.Meanwhile, the eccentric compression formula and method on interaction between superstructure and foundation (mixed method) are used to compute the load on pile top of piled raft foundation for two superhigh buildings just mentioned and 121-stroey, 6 m thick raft of Shanghai Tower which is under construction and compare each other in detail.The computed results have shown that the mixed method used is feasible and reasonable.It is hoped that the article 3.1.3 in China Technical Codefor Building Pile Foundations (JGJ 94 - 2008) can change the traditional conception to use the eccentric compression formula for computing the load on pile top of piled raft foundation.%根据上海高88层、筏板厚度为4 m的金茂大厦和高101层、筏板厚度为4.5 m的上海环球金融中心桩筏基础的实测沉降资料,论证超高层建筑的桩筏基础为弹性体.对以上两幢超高层建筑和正在建造中的高121层、筏板厚度为6 m的上海中心大厦的桩筏基础,采用偏心受压公式和高层建筑与地基基础共同作用理论方法(混合法)进行详细对比计算,论证按弹性体计算桩顶反力的合理性,阐明(JGJ94-2008)的3.1.8条的正确性和合理性.期望能够改变过去按偏心受压公式计算桩顶反力的传统观念,提高设计水平.

  18. In situ mortality experiments with juvenile sea bass (Dicentrarchus labrax in relation to impulsive sound levels caused by pile driving of windmill foundations.

    Directory of Open Access Journals (Sweden)

    Elisabeth Debusschere

    Full Text Available Impact assessments of offshore wind farm installations and operations on the marine fauna are performed in many countries. Yet, only limited quantitative data on the physiological impact of impulsive sounds on (juvenile fishes during pile driving of offshore wind farm foundations are available. Our current knowledge on fish injury and mortality due to pile driving is mainly based on laboratory experiments, in which high-intensity pile driving sounds are generated inside acoustic chambers. To validate these lab results, an in situ field experiment was carried out on board of a pile driving vessel. Juvenile European sea bass (Dicentrarchus labrax of 68 and 115 days post hatching were exposed to pile-driving sounds as close as 45 m from the actual pile driving activity. Fish were exposed to strikes with a sound exposure level between 181 and 188 dB re 1 µPa².s. The number of strikes ranged from 1739 to 3067, resulting in a cumulative sound exposure level between 215 and 222 dB re 1 µPa².s. Control treatments consisted of fish not exposed to pile driving sounds. No differences in immediate mortality were found between exposed and control fish groups. Also no differences were noted in the delayed mortality up to 14 days after exposure between both groups. Our in situ experiments largely confirm the mortality results of the lab experiments found in other studies.

  19. 越南某船厂车间基础桩型的选择%Selection on Pile Type for Workshop Foundation in a Shipyard in Vietnam

    Institute of Scientific and Technical Information of China (English)

    成俊霖

    2012-01-01

    根据EPC工程拟建车间的场地地质、水文、气象等资料,对分段装焊车间基础对比分析了几种桩型,经过试桩和技术经济对比分析,最终选用了PHC管桩用于基础,达到经济合理,安全实用的目的。%According to the geological, hydrological and meteorological materials of the field in a workshop to be established in EPC project, several pile types are compared and analyzed against the foundation of block assembly and welding workshop. Through trial piling and comparison in technology and economy, PHC pipe pile is adopted to the foundation for the purpose of economical rationality, safety and practicability.

  20. Installation of a mono pile as a foundation structure of a tidal turbine; Installation eines Monopfahls als Gruendungsstruktur fuer eine Gezeitenturbine

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Stefan [BAUER Spezialtiefbau GmbH, Schrobenhausen (Germany). Bautechnik; Bauer, Thomas [BAUER AG, Schrobenhausen (Germany)

    2012-11-01

    Tidal turbines enable a power generation from the flow energy of the sea. Usually heavy weight structures are used for the foundation of tidal turbines. However, these heavy weight structures are not fixed to the bottom of the sea. A mono pile being embedded in the bottom of the sea is an alternative which is a significant benefit for operators of tidal turbine operator.

  1. A simplified algorithm for the design of piled raft foundations applied for the case study of a building erected within Żoliborz-Szczęśliwice glacial tunnel valley

    Directory of Open Access Journals (Sweden)

    Kacprzak Grzegorz

    2015-06-01

    Full Text Available A common engineering solution for excessive settlement with raft foundation (s is the use of piles in order to reduce the vertical displacements, in this method, the whole structural load is transferred to the piles. This is an overly cautious approach, and there remains a need to find an optimal design method for a building’s foundations. Such a solution may be the piled raft foundation, which allows a reduction of the number of piles due to the integration of the raft in the bearing capacity of the foundation. The aim of the article is to estimate the contribution of foundation elements such as the raft and the piles in the bearing capacity of a residential building located in Warsaw, where the geological conditions are characterized by organic soil layers, principally of gyttja.

  2. Analysis and treatment of quality problem of boulder in foundation pile project%基桩遇孤石质量问题的分析与处理

    Institute of Scientific and Technical Information of China (English)

    杨文武

    2015-01-01

    基于地基与基础等强置换、地基压力扩散原理及复合地基理论,以孤石加固法、结构加固法、复合地基与基础加固法及等强补桩法比较,分析了某建筑主体结构已施工基桩遇孤石的承载力、沉降量不能全部满足要求的处理方案,探讨复合地基加固法和等强补桩法的应用。提高土层压缩模量是复合地基加固的重要途径,合理、有效地确定地基处理范围是复合地基加固的重要环节。%Based on the equal strength displacement theory of foundation and foundation, ground pressure diffusion principle and the theory of composite foundation, comparisons of boulder reinforcement method, the structure reinforcement method, composite foundation and pile foundation reinforcement method and equal strength reinforcement method were made.The treatment plan for bearing capacity and settle-ment under requirements due to boulder encountered in a foundation pile which main structure has been built was analyzed.Application of composite foundation reinforcement method and equal strength pile reinforcement method were discussed.Improvement of the soil compres-sion modulus is the important way of compound foundation reinforcement, reasonable and effective determination of the scope of the founda-tion treatment is an important part of the composite foundation reinforcement.

  3. Some Consideration on Elastic Pile Foundation Analysis by Poulos%对Poulos弹性桩基分析的考察(英文)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The elastic pile foundation analysis by Poulos is well developed and has been adopted by some countries in their design guideline. In the vertical load analysis,the author has discovered that the approach by Poulos is sensitive to the number of segments used for analysis and can lead to some unreasonable results for pile in finite depth of soil. In the lateral load analysis,the group interaction factor which is claimed to be a linear relation of the departure angleby Poulos is found to be a linear relation of by the author.

  4. 液化地基中群桩基础地震响应分析%Seismic response analysis of pile groups in liquefiable foundations

    Institute of Scientific and Technical Information of China (English)

    刘星; 王睿; 张建民

    2015-01-01

    可液化地基中桩基础地震响应分析一直是岩土工程抗震研究的热点和难点。针对这一问题,采用砂土液化大变形统一本构模型来描述可液化地基土体的应力应变关系,建立了一个3×5的群桩三维计算模型,采用三维弹塑性有限元动力时程分析,将地基、群桩基础和上部结构作为一个系统研究群桩基础的地震动响应规律,重点关注桩与土的运动相互作用以及水平方向的弯矩在地震荷载作用下的分配情况。结果表明可液化地基中桩基础的弯矩受桩与土运动相互作用影响显著;不同桩的弯矩最大值不同,角桩最大,边桩次之,中心桩最小;弯矩最大值出现的位置不相同,角桩和边桩弯矩最大值出现在上部非液化层与液化层界面处,中心桩弯矩最大值出现在桩头处。%The seismic analysis of pile foundations in liquefiable ground is an important subject in geotechnical earthquake engineering. A computational model of a 3×5 pile group is established in OpenSees FEM program, and considering soil foundations, the pile group and the upper structure as a system, a unified plastic constitutive model for large post-liquefaction deformation of sand is employed. Special attention is given to the kinematic interaction between piles and soil and distribution of the moment in pile groups. The results show that the soil-pile kinematic interaction has a significant influence on the moment of piles in liquefiable ground. The moment distribution in pile groups indicates that the maximum moment of the corner piles is the largest, and that of the central piles is the smallest. The positions of the maximum moment of different piles are different. The maximum moments in the corner piles and the edge piles are at the interface between the upper layer and the liquefied layer, but the maximum moment in the central piles is at the pile top.

  5. 桥梁高桩承台基础抗震性能研究%Study of earthquake-resistant performance of high pile cap foundation of bridge

    Institute of Scientific and Technical Information of China (English)

    韩振峰; 叶爱君

    2016-01-01

    文章通过3个钢筋混凝土群桩试件在低周反复荷载作用下的受力性能试验研究 ,讨论了群桩基础破坏形态及滞回特征 ,解释了其破坏机理 ,分析了土体参数、密实度及桩身自由段长度等对其延性的影响.结果表明 ,极限状态时 ,群桩结构受力模式会由地基梁模型转变为悬臂柱模型 ;减小自由长度和提高土体含水率都会增加其抗震性能.在OpenSees有限元框架中建立了群桩基础有限元模型 ,使用弹塑性纤维梁柱单元模拟桩体 ,采用非线性p-y单元模拟桩土相互作用 ;对模型进行了单调 Pushover分析 ,并且对分析结果与试验结果进行了比较 ,结果表明该模型能很好地模拟试验数据.%Firstly ,based on an experimental research on three reinforced concrete pile foundation specimens tested under low cyclic loads ,the destroy pattern and hysteretic characteristic of pile group foundation were discussed ,the destroy mechanism was explained ,and the effect of soil parameters ,compactness ,and free length of the pile on the foundation ductility was analyzed .The results show that the mechanical pattern of the foundation may change from the foundation beam model to the cantilever column model at the ultimate state ,and reducing free length of the pile and raising the moisture content of the soil can improve the earth-quake-resistant performance of the foundation .Secondly ,a finite element model of this foundation was built in the OpenSees framework .In the model ,the fiber element was used to simulate the pile shaft ,and the non-linear p-y element was used to simulate the soil-pile interaction .Thirdly ,the monotonic Pushover analysis was performed on the model ,and the results were compared with the test results .The results show good co-herence with the experimental data .

  6. Experimental research on combined pile composite foundation with vibro-replacement stone columns and CFG piles%振冲碎石桩与CFG桩组合桩型复合地基试验研究

    Institute of Scientific and Technical Information of China (English)

    李继才; 丛建; 曹军; 余博闻

    2017-01-01

    The vibro-replacement stone columns are mainly used to treat the shallow-layer soil and generate one kind of composite foundation in order to reinforce the bearing capacity of the foundation,decrease the settlement and eliminate the sand liquefaction.The CFG pile is settled at the centroid of four gravel columns and the tip of the CFG pile is deep in the hard layer,which plays an important role in controlling the bearing capacity and the displacement of the composite foundation.This paper researches the composite foundation consisting of the vibro-replacement stone columns and the CFG piles before and after the treatment by the static sounding test,the dynamic sounding test and the static load test.The results indicate that the vibro-replacement stone column in the combinedpile composite foundation largely increases the bearing capacity of the single CFG pile and the soil layer,and the smaller the distance between piles,the greater the strengthening effects will be.%振冲碎石桩主要加固浅层地基,与桩间土构成复合地基,使地基承载力提高、变形减少,并可消除砂土层的液化;CFG桩布置在4根碎石桩的形心,桩端置于相对硬层,对复合地基的承载力和变形起控制作用.对某工程试验区振冲碎石桩与CFG桩组合桩型复合地基加固前后静力触探、动力触探和静载荷试验等进行研究,结果表明组合桩型复合地基中的碎石桩较大程度地提高了CFG桩的单桩承载力和地基承载力,桩距越小,加固效果越好.

  7. Influence of mechnical behavior of pile-soil interface on dynamic characteristics of pile foundation%桩土界面力学行为对桩基动力特性的影响

    Institute of Scientific and Technical Information of China (English)

    尚正祥; 胡伟; 席娜丽

    2012-01-01

    结合构建的饱和土结构性动力本构模型以及通用有限元程序,以城市高架桥梁建设中常采用的单柱墩基础为原型,建立了摩擦桩-土-结构体系、端承桩-土-结构体系的有限元-无限元计算模型.分完全粘结、滑移无开裂、开裂无滑移、开裂滑移四种情况考察了桩土界面力学行为对两种系统动力反应特性的影响,得出如下结论:无论是端承桩还是摩擦桩,界面力学行为对桩截面的剪应力和桩身水平位移分布形态影响均不大.四种情况中,完全粘结时,摩擦桩在近地表处桩截面剪应力值最大,开裂滑移时最小,而端承桩则刚好相反.水平位移分布均可分为线性增大和加速非线性增大两个阶段,以近地表处为分界点,且均以开裂滑移时最大,完全粘结时最小.界面力学行为极大地改变了端承桩桩身加速度时程的分布形态,但对摩擦桩则几乎没有改变;对于不同界面力学行为,两种桩型在近地表处均出现加速度峰值,完全粘结时值最大,开裂滑移时最小.相比摩擦桩而言,界面力学行为对端承桩的影响要大的多,研究分析时应引起足够的重视.%Conbining dynamic constitutive model of saturated soil with general finite element program, the finite -infinite element models of end bearing and friction pile foundations were established. Four situations of interface between pile and soil including absolutely jointed, slippage, crack, both slippage and crack were considered to study the interface' s effect on pile foundation's dynamic characteristics. The results are as follows; no matter end bearing pile or friction ones, the interface' s mechanical behavior has a little influence on the distributions of pile section ' s shear stress and pile' s horizontal displacement. In these four situations, frictional pile section' s shear stress arrives at the maximum when interface is absolutely jointed, and arrives at the minimum ones when

  8. Research on the Horizontal Displacement Coefficient of Soil Surrounding Pile in Layered Foundations by Considering the Soil Mass’s Longitudinal Continuity

    Directory of Open Access Journals (Sweden)

    Yao Wen-Juan

    2013-01-01

    Full Text Available When utilizing the p-y curve to simulate the nonlinear characteristics of soil surrounding pile in layered foundations, due to having not taken into account the soil mass’s longitudinal continuity, the calculation deviation of horizontal displacement increases with the growth of a load. This paper adopted the layered elasticity system theory to consider the soil mass’s longitudinal continuity, as well as utilizing the research method for layered isotropic bodies, assuming that the horizontal resistance is evenly distributed around the perimeter of the pile's cross-section. Then an appropriate transfer matrix method of horizontal displacement coefficient for the soil surrounding pile in layered foundations was established. According to the calculation principle of finite element equivalent load, the horizontal displacement coefficient matrix was deduced as well as providing a corrected formula for the horizontal displacement of soil surrounding pile through the p-y curve method when the external load was increased. Following the established model, a program was created which was used for calculating and analyzing the horizontal displacement coefficient matrix of three-layered soil in order to verify this method’s validity and rationale. Where there is a relatively large discrepancy in the soil layers’ properties, this paper’s method is able to reflect the influence on the layered soil’s actual distributional difference as well as the nearby soil layers’ interaction.

  9. 软土路基中多型桩复合地基的应用研究%Study on the Application of Multi-type-pile Composite Foundation in the Soft Soil Subgrade

    Institute of Scientific and Technical Information of China (English)

    吁燃; 王曙光

    2016-01-01

    为了充分发挥碎石桩与素混凝土桩的优点,将碎石桩与素混凝土桩组合成多型桩复合地基。通过理论计算,分析碎石桩与素混凝土桩组成的多型桩复合地基受力原理。以某高速公路深层软土路基的处理为例,采用多型桩复合地基对该软土路基进行处理,取得了良好的经济效益。%The multi-type-pile composite foundation of gravel pile and plain concrete pile is composed to exert the advantages of crushed stone pile and concrete pile.The load-bearing principle of multi-type-pile composite foundation composed of gravel pile and plain concrete pile is analyzed.Taking an engineering of deep soft soil treatment in the highway for example,the multi-type-pile composite foundation is used,and it achieves good economic performances.

  10. 桩基建筑物运行中稳定性的治理措施%Management of Stability of Pile-Foundation Buildings in Service

    Institute of Scientific and Technical Information of China (English)

    Vladimir P. Vlasov

    2004-01-01

    The vast majority of buildings in Russia have been constructed on pile foundations incorporating a ventilated air space between the structure and ground surface (passive construction method, or Principle I in the Russian Building Code 2.02.04-88). Warming of the frozen soil during the life of the structure is one of the primary factors leading to structural damage. This paper presents a new technique for preventing failure in engineering structures.

  11. Design and Application of Composite Foundation of Long and Short Piles%长短桩复合地基的设计与应用

    Institute of Scientific and Technical Information of China (English)

    李国春

    2012-01-01

    依托杭州某高速公路工程实践,介绍了长短桩复合地基的作用机理、设计及在实际工程中的应用。%Based on project case of an expressway in Hangzhou, mechanism of action, design and application in practical project of composite foundation of long and short piles are introduced.

  12. Analysis on the Soft Soil Foundation Pit Slope Excavation of Foundation Piles%软土基坑放坡开挖对坑内工程桩的影响分析

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      在软土基坑中,放坡开挖将引发坑内工程桩产生偏位和附加弯矩。为尽可能减小基坑放坡开挖对坑内工程桩所产生的不利影响,应对基坑开挖深度进行严格控制,且相比增大坡脚至建筑物底板距离,采用缓坡率可更为有效减小对工程桩产生危害。%In soft soil foundation excavation, slope excavation wil cause the bias and additional moment of engineering piles. To reduce the adverse effect as far as possible of the founda-tion pit slope excavation of foundation piles, should strictly co-ntrol the depth of foundation pit excavation, and compared wi-th increasing distance from bot om to toe of buildings, the ram-p rate can be more effective to reduce the harm to the engine-ering pile.

  13. Design and construction of scour protection for deep-water group pile foundation structures of two pylons in the Sutong Bridge project

    Institute of Scientific and Technical Information of China (English)

    He Ping; Guan Yijun; Zhang Xiongwen; Zhang Qun; Zhou Jianhua

    2009-01-01

    Sutong Bridge, as a world-record cable-stayed bridge with its main span exceeding 1 000 m constructed in Yangtze River estuary region in China, is located at a site with complicated hydrologic conditions and poor geotechnical conditions and therefore, scour protection will be a decisive factor for ensuring smooth and successful construction of this bridge. This paper, starting from structural description of deep-water group pile foundation, analyzes impact to the bridge safety introduced by scour and its protection and further presents different solutions of scour protection for foundation structures of this bridge.

  14. On common accidents in pile foundation construction of roads and bridges and treatment%公路桥梁桩基施工中的常见事故及处理方法

    Institute of Scientific and Technical Information of China (English)

    王飞虎

    2014-01-01

    Combining with work experience,the paper introduces common construction methods for bridge pile foundation,indicates the factors which affect the construction quality of pile foundation construction of roads and bridges,and points out the solutions to the hole collapse,and concrete grouting in the pile foundation construction,so as to ensure the construction quality of bridge pile foundation projects.%结合实际工作经验,介绍了桥梁桩基常用的施工方法,论述了影响公路桥梁桩基施工质量的因素,并提出了对于桥梁桩基施工中塌孔、混凝土灌注问题的解决措施,以确保桥梁桩基工程的施工质量。

  15. Risk analysis of the delayed ettringite formation in pile caps foundation in the metropolitan region of Recife - PE - Brasil

    Directory of Open Access Journals (Sweden)

    I. F. Torres

    Full Text Available ABSTRACT Currently, there is an awareness that is critical to assess the durability characteristics of concrete with as much attention as the mechanical properties. The durability of concrete structures can often be affected by chemical attacks, jeopardizing its performance and security. When concrete is subjected to high temperature at early ages, many physical and chemical changes in hardened concrete may occur. It iswidely accepted that concrete subjected to these conditions of temperature and exposed to moisture is prone to cracking due to Delayed Ettringite Formation (DEF. This work aims at providing a DEF risk analysis on foundation pile caps at the Metropolitan Region of Recife - PE. Temperature rise measurement was performed in situ at 5 different caps through datalogger and thermocouples equipments. Furthermore, the Duggan test was performed in order to assess the level of expansion of 3 cements studied: X (CP II E 40, Y (CP II F 32 and Z (CP V ARI RS. Simultaneously, the chemical compositions of these cements and their respective clinkers were quantified by analysis of X-ray fluorescence (XRF. The cement X (CP II E 40 showed the chemical characteristics favoring with more intensity DEF and, as a result, higher level of expansion in the test Duggan. It is noteworthy that incorporation of metakaolin (8% and 16% and silica fume (5% and 10% showed mitigating potential of expansions. It is important to point out that all factors related to thermal properties and chemical composition of the concrete used in the region converge to a condition of ideal susceptibility for triggering DEF. Therefore, it is essential at least minimum and basic requirements in the design specification in order to avoid high temperatures in the massive concrete elements, preventing them from delayed ettringite formation.

  16. 论斜拉桥墩台基础及桩基施工放样%On the cable-stayed bridge pier foundation and pile foundation construction stakeout

    Institute of Scientific and Technical Information of China (English)

    王成全

    2012-01-01

      结合实例介绍了斜拉桥墩台基础、桩基施工放样技术、墩台定位的方法、索塔施工测量放样以及高塔柱施工测量的施工方法。%  The cable-stayed bridge pier foundation, pile foundation construction stakeout technical positioning pier, Sarasota Construction Setting High Tower Construction Survey Construction Methods with examples.

  17. NONLINEAR STATIC CALCULATION MODEL AND PSEUDO-STATIC TEST OF PILE GROUP BRIDGE FOUNDATIONS%桥梁群桩基础非线性静力计算模型及拟静力试验研究

    Institute of Scientific and Technical Information of China (English)

    张永亮; 陈兴冲; 孙建飞

    2013-01-01

    Horizontal bearing characteristics of bridge pile foundations can be analyzed by using linear elastic subgrade reaction method(m-method) when displacement of pile foundation is generally smaller. However, displacement of pile foundations is often larger under the effect of strong earthquakes. In order to understand the horizontal bearing capacity and deformation characteristics of pile foundations considering nonlinear behaviors of pile shaft and subsoil,a model of pile foundations is constructed. Failure mechanism,bearing capacity, deformation characteristics and hysteresis characteristics of pile foundations are studied by using pseudo-static test. A nonlinear static calculation model of pile group foundations is put forward under horizontal load. The elastoplasticity of pile shafts in variable axial loads is simulated by distributed PMM plastic hinge;and nonlinearity of subsoil is simulated by the curves of p-y,t-z and q-z,respectively,which have been given in the code of American API;where p is horizontal soil resistance at lateral of pile shaft;y is horizontal displacement;t is vertical frictional resistance around piles shaft;q is vertical bearing resistance at pile tip;z is vertical relative displacement of interface between pile and soil. The results show that:(1) The numerical results are in good agreement with those obtained from experiments. (2) Hysteretic characteristics of pile foundations can be simulated using Clough degradation bilinear model. (3) Weak positions of pile shaft are 0-4 times around the radius of pile below pile top. The results can provide references for evaluating seismic performance of bridge pile foundation using capacity spectrum method.%线弹性地基反力法(m 法)仅适用于正常使用时桥梁桩基础变位较小的情况,但在强震作用下基础的变位较大。为了研究桩基础在地基土及桩身进入非线性状态下的水平承载能力及变形特性,通过群桩基础缩尺比例模型,采用拟

  18. 上海中心大厦桩基础变刚度调平设计%Variable rigidity design in the pile foundation of Shanghai Tower

    Institute of Scientific and Technical Information of China (English)

    姜文辉; 巢斯

    2012-01-01

    How to control the settlement and differential settlements of buildings in Shanghai is important. Variable rigidity design is based on the settlement control and is efficient in differential-settlement control of high-rise buildings with piles group and soft bed. Large-diameter post-grouting bored piles are adopted in the foundation of Shanghai Tower. The foundation of Shanghai Tower was designed according to the variable rigidity conception. By selecting length and distance of piles properly, the differential settlements of plate at centre and edges were controlled within the reasonable range, which can optimize the plate design. Pile tests show that post-grouting technique can increase the bearing capacity of the single pile as well as decrease differences among bearing capacities of different piles.%对于上海地区的超厚软弱土层,如何控制建筑沉降和差异沉降是设计的重点。变刚度调平设计是基于沉降控制的基础设计方法,对于群桩基础和软土地基的高层建筑沉降差异控制有显著的效果。介绍了上海中心大厦大直径后注浆钻孔灌注桩基础设计中按照变刚度调平概念,通过合理选择桩长和桩距,使得主楼底板中心和边缘的计算差异沉降控制在合理的范围,优化了底板的设计。经过试桩,认为后注浆的桩端注浆方法能有效提高单桩承载力和减小不同桩承载力间的变异值。

  19. 刚性基础下复合地基桩长计算方法%The Calculating Method for the Pile Length of Composite Foundation under Rigid Ground

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 杨光华

    2011-01-01

    由于刚性基础下的复合地基没有考虑桩土变形协调和土的沉降位移,桩土相对位移计算偏大,导致计算桩侧摩阻力值偏大而设计桩长偏小.针对复合地基传统设计方法的不足,建立了一个考虑桩土变形协调和土的压缩变形对桩体荷载传递影响的双曲线模型函数,以及建立了荷载从桩顶向下传递计算的方法,可更准确计算桩侧摩阻力及桩端荷载,桩底土层沉降采用切线模量法计算,以桩体压缩量及桩端土体沉降量为控制要求,进而可以确定满足复合地基承载力及沉降要求的单桩长度.通过工程实例验证,该方法计算得到的复合地基桩长与实际工程中桩长基本一致,为今后复合地基桩长设计提供参考.%The calculated results of pile-soil relative displacement are much too high mainly due to lack of considering the deformation compatibility of pile-soil and the displacement of soil. Skin friction values of pile are relatively large on the basis of load transfer method, which will lead to the shorter design pile lengths. For the deficiencies of traditional design methodof composite foundation, a hyperbolic model transfer function is established which takes into account load transfer to the pile affected by deformation of soil and the deformation compatibility of pile-soil. And the calculation method of load gradually transferred from top to bottom is also established. It can more accurately calculate the skin friction of pile side and the load under the pile bottom. With the pile compression and the settlement of pile-end soil as the control requirements, so the length of pile which may satisfy composite foundation's capacity and settlement can be determined. An engineering example shows that the pile length of composite foundation calculated by this method is essentially the same as the actual in work. This method provides a reference for the pile length design of composite foundation.

  20. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal

  1. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  2. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  3. 软土地层桥梁群桩基础桩土共同作用性状的非线性有限元分析%Nonlinear finite element analysis of pile-soil interaction of bridge pile group foundation in soft soil stratum

    Institute of Scientific and Technical Information of China (English)

    汪优; 刘建华; 王星华; 蔡君君

    2012-01-01

    A three dimensional nonlinear finite element model of pile group foundation of a high-speed railway bridge was built. Combined with the corresponding data obtained from field tests, the rules of pile axial force, pile side friction force, soil additional stress, pore water pressure distribution, excess pore water pressure dissipation and settlement of pile group foundation were analyzed. The calculation results show that the axial forces of corner piles are larger than the side piles which are larger than the center piles; and the axial forces of corner piles and side piles reduce greatly along the pile body; and the axial forces of center piles decrease slowly. Moreover, the regular pattern of pile side friction is that the pile side friction measurement of corner piles are larger than the side piles which are larger than the center piles generally; and the amount of relative displacement between pile and soil is bigger on the upper and less on the lower. That is to say, the amount of relative displacement between pile and soil on the upper of pile is larger than on the middle and lower of pile. Furthermore, the soil additional stress and excess pore water pressure generated by external loads mainly concentrate in soil under the pile cap within a certain range; and their attenuation gradients decrease along the depth gradually. With the increasing of the consolidation time, the settlement of pile group foundation arrives to be stabilized.%通过对某高速铁路特大桥群桩基础进行三维非线性有限元分析,并结合现场试验得出的规律进行相应的对比分析,研究了软土地层桥梁群桩基础桩身轴力、桩侧摩阻力、基底土体附加应力、孔隙水压力分布、超孔隙水压力消散和群桩基础荷载沉降规律.计算结果表明,基桩所承受的轴力,角桩>边桩>中心桩,角桩和边桩的轴力沿桩身减小的幅度较大,而中心桩的轴力沿桩身减小的幅度稍小;各基桩桩侧摩阻力

  4. 减沉复合疏桩基础在软土地基中的应用%The Application of Composite Foundation with Settlement Reducing Piles

    Institute of Scientific and Technical Information of China (English)

    肖贤

    2011-01-01

    结合某住宅工程地基处理的成与败,强调基础方案的选择,不仅要关注地质条件,还应关注场地条件。介绍了减沉复合疏桩基础在软土地基中的应用。%Combined with the success of foundation treatment in one residential project,in which not only the geological condition should be emphasized in the design of the basement,but also the site condition should be paid some attention.The application of composite foundation with settlement reducing piles is introduced in this paper.

  5. Pile Foundation Treatment Technology of Shield Tunnel beneath Footbridge%盾构隧道下穿人行天桥桩基处理技术

    Institute of Scientific and Technical Information of China (English)

    张火军

    2013-01-01

      武汉轨道交通4号线某区间盾构隧道穿越人行天桥桩基。在盾构穿越天桥前,必须清除隧道开挖范围内的桩基。在无交通疏解和工期紧的条件下,首先搭设临时支架保护天桥,从地面注浆加固土体,在托换承台后,人工挖竖井从竖井中凿除盾构隧道范围内桩基,同时盾构穿越时调整施工参数。整个施工过程中,天桥正常通行,盾构穿越天桥后,承台最大累计沉降在3 mm以内,保证了天桥的安全和盾构施工工期,到达了预期效果。%Line 4 of Wuhan urban rail transit uses shield tunneling across the pedestrian bridge with pile foundation. Before the shielding crossing the footbridge, piles within tunnel excavation region must be cleared. Under heavy traffic without diversion and with a tight project schedule, temporary support to protect the footbridge is erected, with grouting reinforcing soil from the ground. After supporting and changing the abutment, manual shaft dug from the existing shaft to remove pile foundation in the shield tunnel. At the same time shield adjusts construction parameters while tunneling. Throughout the construction process, the footbridge functions as normal passage. After shield crosses the footbridge, the maximum cumulative settlement of the abutment is less than 3 mm, the footbridge safety and shield construction period are ensured, reaching the expected results.

  6. Anti-earthquake mechanism of pervious concrete pile composite foundation%透水性混凝土桩减压减震耦合抗震机理研究

    Institute of Scientific and Technical Information of China (English)

    崔新壮; 王聪; 周亚旭; 张娜; 高智珺

    2012-01-01

    With the advantages of both granular piles and rigid piles, pervious concrete piles were especially suitable for earthquake-resistance foundation. To study the anti-earthquake mechanism of pervious concrete pile composite founda- tion, the acceleration response and the development and dissipation of excess pore water pressure during the earthquake were numerically simulated. The dynamic behaviors of pervious concrete pile were compared with those of gravel pile and plain concrete pile. The surface acceleration amplification coefficient of pervious concrete pile foundation was obvi- ously smaller than two other pile foundations. Meanwhile, pervious concrete pile predominant period was only half of gravel pile and plain concrete pile foundation, which demonstrated that pervious concrete pile foundation was more ef- fective to avoid the upper building resonance. Besides significant damping effect, the pervious concrete pile foundation also had obvious pressure-reduction effect. The excess pore water pressure induced by an earthquake dissipated quickly because of the high permeability of pervious concrete piles, and the foundation liquefaction was effectively inhibited. Consequently, the draining-damping coupling effect of pervious concrete piles could improve the deformation compati- bility of soil during the earthquake.%透水性混凝土桩兼具散体桩和刚性桩的优点,特别适用于地基抗震。为研究其抗震机理,对地震过程中地基的加速度响应和超静孔隙水压力的长消规律等进行了数值模拟,并与碎石桩、素混凝土桩等的动力行为进行了比较分析。研究发现:透水性混凝土桩复合地基表面加速度放大系数明显小于碎石桩和素混凝土桩复合地基,而且其卓越周期仅为碎石桩和素混凝土桩复合地基的1/2,更有利于抑制上部建筑共振的发生;透水性混凝土桩除具有显著的减震效应外,还具有明显的减压效应,其高透水

  7. Research on the Technology of Deep Mixing Pile for Soft Foundation Construction%深层搅拌桩处理软基施工工艺研究

    Institute of Scientific and Technical Information of China (English)

    梁毅

    2014-01-01

    Deep mixing is a method in which mixing foundation soil (soil or sand) with curing agent by using deep mixing machines compulsorily to promote the strength of the foundation. The effect is significant for the soft founda-tion treatment,and has high degree of practical function for silt, sandy soil, powder soil and sandy soil. This article introduces the construction process of deep mixing pile in soft foundation and the matching experiment in the soft foundation treatment.%深层搅拌是通过深层搅拌机械将地基土壤(土或者沙)与固化剂强制的拌和,从而提升地基的强度。该方法在对软基的处理上效果十分显著,对于淤泥、砂土泥炭土、粉性土以及砂土的实用度很高。文中将对深层搅拌桩对于软基的施工工艺和在施工过程中配比实验进行介绍和探究。

  8. 长短桩复合地基应力及沉降规律数值分析%Numerical analysis of stress and deformation law of long-short piles of composite foundation

    Institute of Scientific and Technical Information of China (English)

    王瑞芳; 皮菊华

    2011-01-01

    通过大型有限元ABAQUS软件,进行三维弹性有限元的数值分析.以9根长桩、4根短桩复合地基为例,研究了在竖向荷载下长短桩复合地基中承台--垫层--桩--土的共同作用特性,对长短桩复合地基的桩体荷载传递规律、桩土应力比、沉降及其影响因素进行了系统的分析,得出了相应的结论.%Presents nine long piles and four short piles composite foundation by using of ABAQUS FEM program, characteristics of co-action among pile cap-padding layer-pile-earth in compostion foundation of pile cluster under vertical loading are studied with three dimensional finite element method;and load transmission characteristics and pile-soil stress ratio, settlement and their influence factors in composite foundation are systematically analysed, corresponding conclusions are drawn.

  9. 复合桩基地基极限承载力的下限有限元解%Finite element lower bound limit solutions for ultimate bearing capacity of subsoil under raft of composite piled foundations

    Institute of Scientific and Technical Information of China (English)

    蒋刚; 孙君; 王旭东

    2011-01-01

    When the composite piled foundation reaches the general ultimate bearing capacity status, an increment of the ultimate bearing capacity for natural foundation is induced by "barrier effect" of piles.The analysis of the problem can be simplified for both the sum of the vertical ultimate bearing capacity of foundation and the increment of the ultimate bearing capacity of foundation soil horizontally sliding around piles.Based on the finite element plastic lower bound limit method, the numerical solutions for the vertical ultimate bearing capacity of foundation and the horizontal resistance sliding around piles varying with soil depth are obtained, and the sliding resistance formula is also established.The sliding resistance coefficient &s reduces with the increase of pile spacing.The increment of the ultimate bearing capacity △fu decreases with the increase of pile spacing.The results indicate that the resistance sliding around piles in the composite piled foundation is being and can not be ignored, and that the ultimate bearing capacity of the composite piled foundation has certain increment, which can be regarded as the security reserve of foundation.%复合桩基在达到整体极限承载状态时,因桩的"遮拦作用"使得地基极限承载力较天然地基有一定提高.其分析可简化为地基竖向极限承载力和地基土水平向绕桩作用产生的极限承载力提高值的叠加.利用下限有限元方法,求解得到地基的极限承载力和不同深度处土体绕桩阻力的数值解,并建立了绕桩阻力计算公式.绕桩阻力系数ks随桩间距的增加而逐渐减小.地基极限承载力提高值△fu随桩间距的增加而逐渐降低.计算表明:复合桩基下绕桩阻力存在并不可忽视,承台下地基极限承载力有明确的提高,可以作为地基的安全储备.

  10. Foundation Treatment Construction Technology of Landfill by Super Down Hole Dynamic Compaction Pile Combined with Bored Pile%SDDC桩结合灌注桩的垃圾填埋场地基处理施工技术∗

    Institute of Scientific and Technical Information of China (English)

    毛正君; 陶志怀; 魏荣誉; 韩小明

    2016-01-01

    由于垃圾填埋场地具有性质复杂、厚度变化大、强度较低、压缩系数大、腐蚀性和污染性强等特点,在服务期内和封顶后都会产生大幅度的沉降。结合西安某垃圾填埋场实例,探讨了孔内深层超强夯桩( SDDC桩)结合灌注桩在垃圾填埋场地基处理中的施工技术。实践证明,采用该技术在满足地基承载力的基础上,降低了工程造价、提高了工程质量,取得了良好的社会经济效益。%Due to some characteristics of the landfill such as the complex properties, big change in thickness, low strength, large compressibility, strong corrosion resistance and polluting, it will generate settlement by a large margin during the service period and after capping. This paper cites an example of a landfill site in Xi’ an, probing into the foundation treatment construction technology of landfill by super down hole dynamic compaction pile combined with bored pile. It has been proved in practice that using this technique can meet the bearing capacity of foundation soil, at the same time, it also can reduce the engineering cost, improve the engineering quality and achieve good social and economic benefits.

  11. Pile Foundation Mechanical Characteristic Analysis for Three Types of Wellhead Platforms in East China Sea%东海三种井口平台桩基受力特性分析

    Institute of Scientific and Technical Information of China (English)

    孙友义; 侯金林; 刘明

    2014-01-01

    Wellhead platforms with 4 legs and 8 skirt piles can be classified as three forms inclu-ding single-batter type,double-batter type and batter-to-vertical type according to the jacket leg batter.The pile foundation mechanical characteristic is an important performance of the platform. Pile foundation mechanical characteristics for the three types of platforms were studied,using SACS software,based on nonlinear soil-pile-structure interaction analysis.Influence factor analy-sis on pile foundation mechanical characteristics was performed,and measures for improving the pile foundation bearing capacities were discussed.The results can provide a reference for jacket and pile foundation design for these types of platforms.%4腿8裙桩井口平台按导管架腿斜度可分为单斜式、双斜式与斜变直式3种形式。桩基受力特性是平台的重要性能。以 SACS 程序为分析工具,基于非线性土壤/桩基/结构交互分析,研究了这3种形式平台的桩基受力特性。通过桩基受力影响因素分析,提出了改善桩基受力的措施,可为该类平台的导管架与桩基设计提供参考。

  12. DIFFERENCE OF SEISMIC BEHAVIOR OF HIGH AND LOW CAPS OF PILE FOUNDATIONS%高低承台桩基地震行为差异研究

    Institute of Scientific and Technical Information of China (English)

    马亢; 许强; 李庶林; 陈东霞; 方军; 窦翰杰

    2015-01-01

    The pile foundation could be classified into the high or low types according to the position of cap relative to the surface of grounds. In many engineering practice,the settlement of unconsolidated clay or backfilled soil after construction,the soil rheology or the seismic field subsidence may lead to the separation of the cap from the clay surface,i.e.,the cap was embedded originally into clay to a new state of high cap pile foundation. For the static condition,this kind of separation may result in the negative skin friction force along the piles and reduce the vertical bearing capacity of piles. However,under the seismic shaking condition,the centrifuge shaking table experiments and simulation with ABAQUS on both the cases indicated that piles underwent a higher maximum bending moment and a much larger active depth under high cap case than those at low cap case. This suggested that the embedding condition played an important role in the seismic response of pile-cap foundation. It becomes more disadvantageous when the embedding condition of the cap changes from the low cap case to the high cap case.%对于采用桩基的各类结构,按承台埋没于地基土体与否,可区分之高、低承台桩基形式。在许多实际工程中,因回填土或欠固结土地基的继续沉降,或因土体流变或场地震陷等后沉降效应,均可致使承台与土体接触解除,即先前按设计采用的低承台桩基可能转为高承台形式。在静力条件下,这将导致桩身产生负摩阻力而降低其部分竖向承载能力;然而,在地震作用下,通过开展离心机地震模型试验和 ABAQUS 计算分析发现:当承台与地基土体脱离时,桩基最大弯矩设计值将会增大,且弯矩有效深度也将变深;并且,基础(承台)周期明显延长,充分表明高、低承台桩基形式地震行为差异迥然,高承台桩基形式较之相应低承台情况更为不利,在抗震设计时应充分予以认识、考虑。

  13. Modeling of Batter Pile Behavior under Lateral Soil Movement

    Science.gov (United States)

    Chen, C. Y.; Hsu, H. Q.

    2017-06-01

    Pile foundation is frequently used when structures are located on weak sublayers or are at risk from lateral loadings such as earthquakes. The design of pile foundations has recently become crucial to stop slope movement. To understand the behavior of pile foundations subjected to lateral soil movement, the three-dimensional Fast Lagrangian Analysis of Continua (FLAC3D) program was used to perform numerical simulations, which can reduce the cost of field testing. Vertical piles and batter piles were combined into 3 × 3 pile groups, and the response of batter piles to soil movement was analyzed. The outer batter piles led to an increased bending moment in the middle, vertical pile row. Increasing the pile spacing and the presence of battered piles reduced the pile group’s displacement. The batter pile group’s maximum bending moment was smaller than the vertical pile group’s in sand soil, but 5-8 times higher in clay soil.

  14. Calculation of neutral surface depth and pile-soil stress ratio of rigid pile composite foundation considering influence of negative friction%考虑负摩阻力的刚性桩复合地基中性面深度及桩土应力比计算

    Institute of Scientific and Technical Information of China (English)

    武崇福; 郭维超; 李雨浓; 铁瑞

    2016-01-01

    研究了刚性桩复合地基桩侧摩阻力在线性模式下中性面深度及桩土应力比的计算方法。根据刚性桩复合地基各组成部分的沉降变形关系,推导了垫层–桩–土的变形协调方程。考虑负摩阻力对桩土工作性状的影响,将桩侧摩阻力分布由试验曲线简化为线性模式,同时考虑桩顶刺入褥垫层,桩底刺入下卧层,结合桩土变形协调方程推导了中性面深度、桩顶平面桩土应力比、中性面桩土应力比的计算公式。分析了多种因素对中性面深度及桩土应力比的影响,结果表明:刚性桩复合地基的中性面深度比在0.15~0.35之间,中性面桩土应力比相比桩顶平面桩土应力比增大10%~40%。最后应用于某工程现场载荷试验和某刚性桩复合地基模型试验,计算值与试验值吻合较好。%The computing method for determining the neutral surface depth and pile-soil stress ratio of rigid pile composite foundation is studied under skin friction of pile using a linear model. A cushion-pile-soil deformation compatibility equation is derived based on the settlement deformation relationship among different constituent parts of rigid pile composite foundation. The distribution of the skin friction is simplified from a test curve to a linear model by taking into account the influence of negative friction on working properties of the pile and soil. Additionally, considering the top of the pile piercing into the cushion and the bottom of the pile into the substratum, and using the cushion-pile-soil deformation compatibility equation, a model is created to describe the neutral surface depth and pile-soil stress ratios on the top surface and neutral surface of the pile. Using the proposed method, the effects of various factors on the neutral surface depth and pile-soil stress ratio are analyzed. The results show that the neutral surface depth ratio of the rigid pile composite foundation is within 0

  15. The application of rotary drilling rig drilling technology in building engineering pile foundation construction%旋挖钻机成孔技术在建筑工程桩基施工中的应用

    Institute of Scientific and Technical Information of China (English)

    翟金宝; 郑亚迪

    2014-01-01

    According to the characteristics of rotary drilling rig could automatic positioning,perpendicularity automatic detection,high automation degree,the drill bit could quickly through various stratums,this paper proposed the pile foundation construction technology using rotary drilling pile instead of manual hole digging pile under miscellaneous fill,backfill deep geological condition,through the pile foundation engineering construction cases showed the rotary drilling pile had very big superiority than manual hole digging pile in cost,construction period and other aspects.%针对旋挖钻机能自动定位,垂直度自动检测,自动化程度高,钻头可快速穿过各种复杂地层的特征,提出了在杂填土、回填土较深的地质条件下用旋挖桩来代替人工挖孔桩的桩基施工技术,通过实际桩基工程施工案例显示旋挖桩比人工挖孔桩在成本、工期等方面有着很大的优势。

  16. 水泥深层搅拌桩在处理软地基施工中的应用%The application of cement deep mixing pile in soft foundation treatment construction

    Institute of Scientific and Technical Information of China (English)

    宫晋太

    2016-01-01

    结合水泥深层搅拌桩在工程中的应用实例,分析了水泥深层搅拌桩所具有的优势,探讨了水泥深层搅拌桩在软基加固处理中的准备工作、施工要点以及质量控制方法,有利于促进水泥深层搅拌桩的推广应用。%Combining with the application example of cement deep mixing pile in engineering,this paper analyzed the advantages of cement mix-ing pile,discussed the preparation work,construction key points and quality control methods of cement deep mixing pile in soft foundation rein-forcement treatment,promoted the promotion and application of cement deep mixing pile.

  17. Simulation Analysis on Pile Foundation Excavation of the Tunnel Going through Bridge and Process of Cutting Piles%隧道下穿桥梁桩基开挖和切桩过程仿真分析

    Institute of Scientific and Technical Information of China (English)

    王伟; 贾培栋

    2015-01-01

    对兰州市地铁一号线拱星墩—焦家湾区间隧道下穿烂泥沟桥的工程概况以及数值分析中的有限元的相关理论作了介绍.对隧道直接下穿烂泥沟桥的开挖以及切桩过程进行了详细的数值模拟分析,得到了隧道开挖和切桩过程桩基和土层的力学变化规律,并从控制沉降的角度,分析得出隧道直接下穿烂泥沟桥梁引起的结构沉降不满足规范要求,必须对烂泥沟桥梁进行加固或改造.%The tunnel construction situations of Lanzhou Line No. 1 subway, from Gongxingdun to Jiaojiawan, which goes through the bridge, are introduced and the related theories of finite elements in data analysis are illus-trated. The digging of the tunnel going through Lannigou bridge and the process of cutting piles are numerically modeled, and the mechanical behaviors of pile foundation and soil layer are analyzed. The result shows the struc-tural subsidence caused by bridge doesn' t meet the requirements from the analysis of controlling subsidence, so the bridge must be reinforced and improved.

  18. 海上测风塔单桩基础设计与分析%Design and Analysis of Single Pile Foundation of Offshore Anemometer Tower

    Institute of Scientific and Technical Information of China (English)

    彭才智

    2015-01-01

    This paper induced the design points of the single pile foundation of offshore anemometer tower and proposed its design method combining with the environmental characteristics of offshore anemometer towers . A design example was analyzed , which provides a reference for similar engineering .%在归纳了海上测风塔单桩基础的设计要点的基础上,通过结合某海上测风塔基础设计实例与海上测风塔环境等特点进行了分析,提出了海上测风塔单桩基础的设计方法,为类似工程提供参考。

  19. 盾构隧道旁穿人行天桥桩基的FLAC模拟%FLAC simulation on footbridge pile foundation across shield tunnel

    Institute of Scientific and Technical Information of China (English)

    李晓静

    2011-01-01

    Through establishing numerical analysis model,it analyzes and forecasts footbridge pile foundation ground surface settlement across shield tunnel between Xi'an subway No.1 line Beidajie station-Wulukou station.Calculation results show that the existence of pile foundation prevents the extension of subsider in width in some points.If the two lines are not excavated at the same time,it will leads to certain inclination of the footbridge.It suggests that preventive measures should be taken in construction.The maximum ground surface displacing value is-10 mm,which is in safe domain.Therefore,it is unnecessary to carry on grouting reinforcement for ground layer.%通过建立数值分析模型分析预测了西安地铁一号线北大街站到五路口站区间隧道盾构施工旁穿人行过街天桥桩基础的地表沉降,计算结果显示,桩基的存在一定程度阻止了沉降槽宽度方向上的扩展;两条线路不同时开挖,可能导致天桥有一定量倾斜,建议施工时做好预防应急措施。地表最大竖向位移值为-10 mm,处于安全可控范围之内,因此不需要对地层进行注浆预加固处理。

  20. 复杂岩溶地区桩基施工技术%Techniques for the Construction of Pile Foundation in Complex Karst Regions

    Institute of Scientific and Technical Information of China (English)

    冯雅妮

    2011-01-01

    The geological conditions of the district,where the pile foundation of the third Daya River Mega Bridge of the Tong-Guan Railway is located,are very complex.The upper part of the stratum consists of alluvial coarse(or fine) round gravel soil filled with fine sand or clay,while in the lower part the joints and cracks of rock are much developed,and there are comparatively many big karst cavities.Owing to the above-mentioned poor geological conditions,in the process of the pile foundation construction,the drill often seizes up and stops,the bore bit often gets off the bull rod,the bored holes are often found interlinked,and the wall-retaining slurry is often found lost,all of which may result in the collapse of the hole wall or the collapse of the opening of the hole.Aiming at solving the above-mentioned problems,adopted are various construction techniques and methods,such as pre-slip casting,filling with backfilling materials,laying protecting barrels right after drilling,and pouring concrete under water,which help speed up the formation of piles,and effectively ensure the quantity and quality of the poured concrete.%通灌铁路大雅河3号特大桥桩基施工区域地质条件相当复杂,地层上部为冲洪积粗(细)圆砾土充填细砂及粘土,下部岩石节理裂隙强烈发育,溶洞和溶蚀较多且较大。在桩基施工过程中经常出现卡钻、掉钻、串孔、护壁泥浆流失,造成护壁坍塌或孔口塌陷等现象。针对出现的不同情况采用提前注浆处理、回填材料填充、护筒跟进和水下灌注混凝土等不同的施工方法,使得成桩速度加快,混凝土灌注数量及质量得到有效控制。

  1. 后装可拆式钢抱箍桩柱塔式起重机基础施工技术%Construction Technology of Tower Crane Foundation with Afterinstallation Detachable Steel Embrace Loop Pile

    Institute of Scientific and Technical Information of China (English)

    陆建飞; 刘建平; 张旭洪

    2012-01-01

    桩柱钢抱箍式混凝土承台塔式起重机基础是一种新型塔式起重机基础结构体系.它是由混凝土承台、钻孔灌注桩和桩身的后装钢抱箍组成的塔式起重机基础结构,和钢管桩塔式起重机基础类似,该塔式起重机基础不仅可为土方开挖和混凝土底板浇筑提供垂直和水平运输的机械,而且还可以加大塔式起重机的工作半径,从而节省工期、提高工效.除此之外,该施工技术在施工方面却更为简单,设计更加合理,还具备成本投入低、可循环利用的优势.%Concrete pile cap crane foundation with steel embrace loop pile is a new type of crane foundation structural system. It consists of concrete pile cap, screw holes filling pile and the steel embrace hoop on pile shaft. Similar to steel pipe piles crane foundation, this crane foundation structural system not only can provide vertical and horizontal transportation machinery for casting concrete slabs and soil excavation, but also can increase the work radius of crane tower, which results less construction time and higher efficiency. Compared with other construction technologies, the construction technology is featured by simpler operation,more reasonable design. It also obtains the advantages of as low cost and recyclable.

  2. 软弱地质层桩基旋挖钻机钻孔施工工法%Construction Methods for Rotary Excavating Drilling Machine for Pile Foundation of Weak Geological Layer

    Institute of Scientific and Technical Information of China (English)

    刘佳伟

    2009-01-01

    The paper particularly discusses construction technology and operating essentials for pile foundation drilling with rotary excavating drilling machine at weat geological section.%详细论述了在软弱地质段,采用旋挖钻机进行桩基钻孔施工的施工工艺和操作要点.

  3. Analysis of pile-soil stress ratio of cast-in-place X-section concrete pile composite foundation under rigid base%刚性基础下现浇X形桩复合地基桩-土应力比分析

    Institute of Scientific and Technical Information of China (English)

    吕亚茹; 丁选明; 刘汉龙; 崔允亮

    2012-01-01

    As one of the most important factors, pile-soil stress ratio can reflect the load transfer and deformation mechanism of composite foundation. Up to now, as a new pile, no uniform method has been found to calculate the pile-soil stress ratio for X-section pile. Sedimentation basin and filter chamber are typical buildings with concrete floor plate that is considered to be a rigid base. The bearing capacity of pile composite foundation under the rigid base is different from which under the soft base. The in-situ static load tests are carried out based on the foundation treatment project in Qiaobei sewage treatment plant. Besides, a finite element model is built to simulate the cast-in-place X-section concrete pile composite foundation under the rigid base by software ABAQUS. The pile-soil stress ratios are discussed considering some factors including elastic modulus of pile, compression modulus of surrounding soil, pile lengths, cushion thicknesses and compression modulus. The results reveal that the pile-soil stress ratio increases with the increasing of pile modulus, cushion modulus and pile length, while reduces with the increasing of modulus of surrounding soil and cushion thickness. The reasonable pile-soil stress ratio of X-section pile ranges from 20 to 25, corresponding to the pile modulus from 10 to 20 GPa, the cushion thickness from 20 to 40 cm, and the cushion modulus from 30 to 45 MPa.%桩土应力比是反映复合地基承载特性的重要参数之一,可反映复合地基的荷载传递和变形机制.做为一种新型桩,目前尚未得出统一的计算X形桩复合地基桩土应力比的公式.沉淀池、滤池等构筑物是典型的具有混凝土底板(刚性基础)的结构,刚性基础下桩复合地基的承载性能有别于柔性基础.故结合南京桥北污水处理厂地基处理工程做现场静载荷试验,应用有限元软件ABAQUS建立刚性荷载板下现浇X形混凝土桩复合地基的模型,模拟不同桩身弹性模量

  4. Test Setup for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...... in offshore pile foundations today....

  5. 浅议输电线路工程钻孔灌注桩基础施工与质量监控%Cast-In-Situ Bored Pile Foundation Construction and Quality Monitoring of Engineering of Power Transfer Line

    Institute of Scientific and Technical Information of China (English)

    吕欣

    2015-01-01

    This paper analyzed and discussed construction technology of slurry supporting cast-in-place pile bored pile in slurry wall of pile foundation in electric transmission line iron tower foundation engineering,proposed key points of quality monitoring on pile-forming and underwater pouring concrete of cast-in place pile,summarized means of prevention and treatment of easily occurred trouble in construction through practical experience.%对输电线路铁塔基础工程中的桩基础主要采用的泥浆护壁钻孔灌注桩施工工艺、施工过程进行了分析和探讨,并提出了在钻孔灌筑桩成桩、水下浇筑混凝土的质量监控中应注意的一些要点,通过实践经验总结了如何在施工中预防及处理一些易出现的故障和质量问题的方法。

  6. On control details of pile foundation construction for drilling of auger drills%旋挖钻成孔桩基施工控制细节

    Institute of Scientific and Technical Information of China (English)

    郭振军

    2011-01-01

    主要就旋挖钻成孔桩基施工容易忽视的一些细节、重点难点问题进行了分析,从卡钻、埋钻、钢筋笼声测管的制作及安装、灌注混凝土、桩基泥浆液的使用等方面,对遇到的问题提出了切实可行的解决方案,并取得了良好的效果。%The paper analyzes from details and difficulties which commonly are neglected in the pile foundation construction of drilling of auger drills,points out some feasible solutions from the drill pipe sticking,the burying drilling,the manufacturing and installation of acoustic pipes for reinforcing cages,the grouting concrete,the using foundation mud slurry and the use of mud slurry according to the problems,and achieves better effect.

  7. 高压旋喷桩加固后桩基水平静载原位试验研究%In Situ Experimental Study on Horizontal Load of Pile Foundation after Reinforcement by High -pressure Jet Grouting Piles

    Institute of Scientific and Technical Information of China (English)

    翁雅谷; 王欢; 何奔; 陈国兴

    2015-01-01

    Properties of soil around piles at shallow level show great influences on horizontal carrying capacity of pile bodies,and reinforcement of soil around piles to improve horizontal carrying capacity of pile bodies is an economical and effective way,but at present studies on it are very few at home.This paper studies and analyzes horizontal static loading properties of pouring piles in soft soil after reinforcement by high -pressure jet pouring piles via site full -scale horizontal loading test to provide preconditions and essential bases for further dynamic calculation.The test results show that after soil mass which extension is 5 and 7.5 times the D (D is diameter of pouring piles)is reinforced by high -pressure jet pouring piles,the horizontal carrying capacity of pouring piles is increased by 2 /3 and 1 time respectively,and the bending moment of pile bodies decreases remarkably so as to anti -crack performance of jet pouring piles greatly and guarantee that sectional concrete of pile bodies does not crack at large horizontal action force.%浅层桩周土的性能对桩体水平承载力有很大影响,通过加固桩周土来提高桩体水平承载力是一种经济有效的手段,但目前国内其研究甚少。通过现场全尺度水平加载试验来研究、分析高压旋喷桩加固后灌注桩在软土中的水平静力加载性能,为进一步动力计算提供前提条件和基本依据。试验结果表明:将延深度5倍和7.5倍 D(D 为灌注桩桩径)范围内的土体进行高压旋喷桩加固后,灌注桩水平承载力分别提高了2/3和1倍,且其桩身弯矩显著下降,从而大大提高了旋喷桩的抗开裂性能,保证桩体能在较大水平作用力下截面混凝土不发生开裂。

  8. 水平荷载下导管架平台桩基础的非线性有限元分析%Nonlinear finite element analysis of jacket platform pile foundations under lateral loads

    Institute of Scientific and Technical Information of China (English)

    袁志林; 段梦兰; 陈祥余; 钟超; 王建国

    2012-01-01

    导管架平台桩基础的控制荷载主要为风荷载、波浪荷载、地震荷载等水平荷载,为研究水平荷载下导管架平台桩基础的承载特性,采用非线性有限元分析方法对水平荷载下桩-土之间的相互作用进行研究,提出了有效模拟桩基水平承载特性的有限元模型,分析了模型桩的刚度、直径、土质参数中水平土压力系数、剪胀角对桩基承载特性的影响及水平荷载下群桩承载特性,并将有限元计算结果与API规范及模型试验结果进行对比.研究结果表明,非线性有限元分析方法分析水平荷载下桩-土相互作用是可行的,计算结果可为导管架平台的桩基设计提供参考.%The control loads of jacket platform pile foundations are the wind load, wave load, seismic load and other lateral loads. A fundamental study of the soil response of piles subjected to lateral loads is conducted using the nonlinear finite element analysis. A finite element model is established to simulate the response of a pile subjected to lateral loads effectively. The effects of pile properties, i.e. stiffness and diameter and soil properties, i.e., coefficient of horizontal earth pressure, dilation angle on the response of a pile subjected to lateral loads are investigated. In addition, the response of pile groups under lateral loads is also analyzed. Finally, the results of finite element analysis are compared with API recommendations and the model test results. The results of the study show that the nonlinear finite element analysis is accurate in analyzing soil response of piles subjected to lateral loads. The calculation results can provide reference for the pile foundation design of jacket platform.

  9. Big Pile or Small Pile?

    Science.gov (United States)

    Branca, Mario; Quidacciolu, Rossana G.; Soletta, Isabella

    2013-01-01

    The construction of a voltaic pile (battery) is a simple laboratory activity that commemorates the invention of this important device and is of great help in teaching physics. The voltaic pile is often seen as a scientific toy, with the "pile" being constructed from fruit. These toys use some strips of copper and zinc inserted in a piece…

  10. APPLICATION OF STEEL SHEET PILE AND COMBINED STEEL PILE INNER SUPPORT IN WIDE-SPAN DEEP FOUNDATION PIT CONSTRUCTION%钢板桩与组合钢管内支撑在大跨度深基坑施工中的应用

    Institute of Scientific and Technical Information of China (English)

    吴丽华; 曹昕

    2012-01-01

    Foundation pit of main building of Nengda Building in Nantong City of Jiangsu Province is 11.35m deep. To reduce lateral deformation of steel sheet pile, combined steel pile inner supports are set at certain positions to ensure smooth excavation of local deep foundation pit. Construction period is saved and cost is reduced, because the supports can be recycled.%江苏南通能达大厦主楼基坑深11.35 m,为减少钢板桩侧向变形,在一定位置设组合钢管内支撑,保证了局位深基坑的土方顺利开挖,缩短了工期,且支撑可周转使用,降低了成本.

  11. 考虑砂石桩固结的混凝土芯砂石桩复合地基固结解析解%Analytical solution for consolidation of composite foundation with concrete-cored sand-gravel piles

    Institute of Scientific and Technical Information of China (English)

    石北啸; 杨燕伟; 谢荣星; 吴辛

    2013-01-01

    Considering the annular drainage section of concrete-cored sand-gravel pile composite foundation, both radial and vertical flows within the sand-gravel pile and soil construction disturbance, using the initial condition of load beared by soil and pile, the governing equations of consolidation problem of composite foundation with concrete-cored sand-gravel piles are derived; the analytical solution to the governing equations is obtained;the overall average degree of consolidation defined in terms of stress and deformation is given;and the influences of several factors, such as the permeability coefficient of sand-gravel piles, diameter ratio of concrete-cored pile and sand-gravel pile on the consolidation of composite foundation are analyzed. The results show that the solution of overall average degree of consolidation in terms of stress is not equal to that in terms of deformation;the greater the permeability coefficient of sand-gravel piles is, the faster the consolidation rate is;under the condition of a certain diameter size of sand-gravel piles, with diameter of concrete-cored pile increasing, the consolidation rate is increased at first and then decreased. Finally, a comparison between the present solution and two previous solutions is made. Compared with two previous solutions,the present solution considers the influences of annular drainage section and load beared by soil and pile together, the overall average degree of consolidation calculated by the present solution is between two previous solutions.%考虑了混凝土芯砂石桩复合地基中砂石桩的环形排水通道、砂石桩体内的径、竖向渗流和土体施工扰动,并采用桩土共同分担荷载的初始条件,得到了混凝土芯砂石桩复合地基固结问题的控制方程,给出了控制方程的解答;并分别给出了复合地基按应力和按变形定义的总平均固结度,分析了砂石桩桩体渗透系数、芯桩与砂石桩直径比对地基固结性状

  12. 水中桩基础压注混凝土加大截面施工技术研究%Pile foundation in water pouring concrete to increase the construction technology research section

    Institute of Scientific and Technical Information of China (English)

    徐会超

    2014-01-01

    桩基加大截面是一种较为理想的桩基础加固措施,水深较浅(5m以内)的可采用双层钢护筒的方法施工,但水深较深的桩基加固需要采用其他方法保证施工的安全同时减少工程成本。本文以江门市白藤大桥维修加固工程桩基加固(该桥位水深在8m到17.5m之间)为依托对水下桩基础加大截面的施工工艺进行分析研究,以期取得良好的效果,为类似工程的加固提供技术支持和工艺方面的参考。%increasing section reinforcement pile foundation is an ideal pile foundation, shallow water depth (within 5m) can the construction method ofthe protective tube of double steel pile, but deeper reinforcement requiredby other methods to ensure construction safety and reduce the cost of the project. This paper takes Jiangmen City rattan bridge repair reinforcementreinforcement (bit depth of the bridge in the 8m to 17.5m) for the analysis of underwater pile foundation construction technology section of relying on the increase, and achieved good results in order, to provide technical support and technical aspects of the reference for reinforcement of similar engineering.

  13. Reliability-Based Design and Quality Control of Bored Piles

    NARCIS (Netherlands)

    Bach, D.

    2014-01-01

    Bored piles are a type of deep foundations which have been and are being widely used in construction engineering such as high-rise buildings, bridges, jetties, and so on. Although bored piles have remarkable advantages over driven piles, the quality of bored piles is frequently affected by many caus

  14. Reliability-Based Design and Quality Control of Bored Piles

    NARCIS (Netherlands)

    Bach, D.

    2014-01-01

    Bored piles are a type of deep foundations which have been and are being widely used in construction engineering such as high-rise buildings, bridges, jetties, and so on. Although bored piles have remarkable advantages over driven piles, the quality of bored piles is frequently affected by many

  15. 强夯+CFG桩复合地基在较厚回填土中的应用%Application of dynamic compaction and CFG pile composite foundation in the treatment of thick backfill

    Institute of Scientific and Technical Information of China (English)

    郑宇; 王天勇; 杨铮; 金灿国; 王建华; 张相勇; 董素芹

    2013-01-01

    The design and construction method of dynamic compaction plus cement fly-ash grave ( CFG) pile were introduced to enhance the bearing capacity of foundation and control foundation settlement in thick backfill by an engineering example. The standard penetration test and static loading test were carried out to topsoil compacted by dynamic compaction, and the bearing capacity of the composite foundation processed by dynamic compaction and CFG was detected by static loading test of single pile composite foundation and vertical compression static loading test of single pile. The results show that the bearing capacity and deformation of composite foundation are acceptable and can meet the requirement of related codes. Moreover, the engineering example shows this method can shorten the construction period and is economic, convenient and safe.%通过工程实例,介绍了在较厚回填土中采用强夯+ CFG桩复合地基进行地基处理以提高地基承载力及控制沉降的设计及施工方法.强夯后对表层土进行标准贯入试验及静力载荷试验,打入CFG桩后对复合地基承载力进行单桩复合地基静载荷试验与单桩竖向抗压静载荷试验检测,结果表明地基承载力与变形均满足规范要求.工程实例表明采用此方法可节约造价、缩短工期且安全可靠.

  16. 拉森钢板桩在太化基坑支护工程中的应用探讨%The application discussion of Larsen steel sheet pile in Taihua foundation pit support engineering

    Institute of Scientific and Technical Information of China (English)

    吴文生

    2014-01-01

    以太化新材料园区工程为例,对工程的水文地质条件进行了分析,确立了钢筋混凝土灌注排桩支护+深层搅拌水泥桩作止水帷幕与拉森钢板桩支护两种基坑支护方案,并对两者作了对比研究,指出拉森钢板桩方案可有效节约成本,缩短施工工期,确保施工安全。%Taking the Taihua new materials industrial park project as an example,this paper analyzed the engineering hydrogeology condition, determined two foundation pit support schemes making reinforced concrete bored piles support + deep mixing cement pile as water curtain and Larssen steel sheet pile support,and made comparative research on both,pointed out that Larsen steel sheet pile scheme could effectively save cost,shorten construction period,ensured the construction safety.

  17. Application of Self-made Steel Sheet Piles in Deepwater Foundation Construction%自制钢板桩在深水基础施工中的应用

    Institute of Scientific and Technical Information of China (English)

    赵志刚

    2012-01-01

    The paper introduces the use of self-made steel sheet piles instead of normal Lasson ones in deep-water foundation pit excavation.The self-made steel sheet piles,often used as revolving materials,is characterized by flexible configuration and wide utilization of piles rigidity in different water depths.The wide application and relatively bigger width of self-made sheet pile help reduce cost and speed up construction progress.%介绍了使用自制钢板桩而不是使用常规的拉森钢板桩解决深水基坑开挖问题,自制钢板桩使用常用周转材,配置灵活,可以根据不同的深度制作不同刚度的钢板桩,具有很强的实用性,自制钢板桩宽度大,因此不仅降低了费用还加快了进度。

  18. Pile Driving

    Science.gov (United States)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  19. 全套管钻孔咬合桩在临近地铁基坑工程中的应用%Application of Drilling Occlusive Pile with Full Casing in Foundation Pit Engineering for Adjacent Subway in Suzho u

    Institute of Scientific and Technical Information of China (English)

    朱芝同; 宋志彬; 冯起赠; 和国磊

    2014-01-01

    以苏州某商业大楼咬合桩的施工为例,介绍全套管钻孔咬合桩在临近地铁基坑支护工程中的应用情况以及咬合桩施工技术要点。施工结果表明,全套管钻孔咬合桩对周围环境影响小,对地层扰动小、施工快、造价低,在苏州软土及高水位土层基坑支护中具有广阔的应用前景。%Taking the construction of an occlusive pile in Suzhou as the example, the paper introduces the application of drilling occlusive pile with full casing in foundation pit support engineering for adjacent subway and the main points of con-struction technology.The results show that the drilling occlusive pile with full casing has advantages of little influence on environment, small disturbance to the ground, rapid construction and low cost, which has a broad application prospect for foundation pit support engineering in soft soil and high water level ground of Suzhou.

  20. 桩基低应变检测波型分析及桩身完整性判别%Wave Analysis of Pile Foundation Low Strain Detection and Determination of Pile Body Integrity

    Institute of Scientific and Technical Information of China (English)

    刘福臣; 王文; 张振善; 刘文卿

    2012-01-01

    According to the characteristics of reflect waves on pile cap, pile body and pile tip, analyses are made to find causes for the defects such as segregation, sandwich silt , necking-down, fissure and expanded diameter difference, the measures are discussed to treat the above defects, and the standards are established to determine in-phase and reversed-phase reflected waves. By analyzing a large quantities of field detecting data, the rationality and applicability of the standards are verified, which will improve the precision for determining the integrity of pile body.%根据桩基体系中桩顶、桩身、桩端等各部位反射波的特征,分析产生离析、夹泥、缩径、断裂、扩径差异等缺陷的原因,探讨各类型缺陷的处理措施,建立同相反射波和反相反射波的判别标准.通过对大量现场检测资料的分析,验证判别标准的合理性和适用性,该方法对提高桩身完整性判别检测的精度有较大帮助.

  1. 海上风电机组多桩承台基础结构设计与参数优化分析%Structure Design and Parameter Optimization Analysis on Pile Group Cap Foundation of Offshore Wind Power

    Institute of Scientific and Technical Information of China (English)

    李振作; 田伟辉; 胡永柱

    2015-01-01

    针对适用于软土海床地基条件的近海风电机组多桩承台基础结构型式,依据相关规范及工程经验,确定多桩承台基础结构尺寸设计原则,分析基础结构设计所应考虑的荷载及荷载组合方式,建立多桩承台基础结构分析模型,对基础结构设计的主要参数进行优化分析,为海上风电基础结构设计提供指导。%For studying the structural type of pile group cap foundation for offshore wind turbine which is suitable for soft clay seabed, the size design principles of this foundation are determined, the loads and load combinations of structure design are analyzed and then the structure analysis model of this foundation is established according to the relevant standards and engineering experiences. The main parameters in the structure design of pile group cap foundation are optimized by using the model to provide guidance for the structure design of offshore wind turbine.

  2. Analysis on pile-soil interaction of pile-supported composite foundation%桩承式加网复合地基桩土共同作用分析

    Institute of Scientific and Technical Information of China (English)

    王瑞芳; 王克宇

    2015-01-01

    By the method of shearing displacement analysis, the interactions between single pile with cap and soil are ana-lyzed, the formula of displacement and axial force for pile with cap under uniform loading are obtained. The finite element soft-ware, ABAQUS, is used to analyze the bearing performance of single pile in three dimensions, and the results are compared with those of the analytical calculation method. The comparison shows that the settlements of roadbed surface and pile top as well as the pile axial forces calculated by the above two methods are similar. The analytical calculation result is in consonance with the measured data, which verifies the accuracy of analytical calculation method.%采用剪切位移法分析了桩承式带桩帽单桩与桩间土的相互作用,得出均布荷载下带桩帽单桩的桩身位移、轴力公式. 用ABAQUS有限元软件对带帽单桩进行三维数值分析,将数值计算结果与解析公式结果进行比较,计算表明解析公式计算出的桩身轴力、桩顶沉降、路基表面沉降和有限元计算值接近. 将现场实测数据与解析计算结果进行比较,解析计算的沉降结果和实测沉降数据较吻合,说明所提出的解析法计算公式准确性较好,对工程应用有一定的参考价值.

  3. 浅析预应力砼管桩在建筑基础中的应用优势%On the Application Advantages of Prestressed Concrete Pipe Pile in Buildings Foundation

    Institute of Scientific and Technical Information of China (English)

    周付彬

    2016-01-01

    By comparing prestressed concrete pipe pile with other types from aspects of project cost, design and construction period, and through the market investigation and case analysis, it comes to the conclusion that the prestressed concrete pipe pile has applica-tion advantages in the high-level architecture foundation.%通过预应力混凝土管桩在工程造价、设计施工、施工工期等方面与其它桩型相比较,并通过市场调查和案例分析,得出预应力混凝土管桩在中高层建筑基础中的应用优势.

  4. A semi-analytical method for the analysis of pile-supported embankments

    Institute of Scientific and Technical Information of China (English)

    Wan-huan ZHOU; Ren-peng CHEN; Lin-shuang ZHAO; Zheng-zhong XU; Yun-min CHEN

    2012-01-01

    In this paper,a semi-analytical method for the analysis of pile-supported embankments is proposed.The mathematic model describes the cooperative behavior of pile,pile cap,foundation soil,and embankment fills.Based on Terzaghi's ID consolidation theory of saturated soil,the consolidation of foundation soil is calculated.The embankments with two different types of piles:floating piles and end-bearing piles are investigated and discussed.The results of axial force and skin friction distributions along the pile and the settlements of pile-supported embankments are presented.It is found that it takes a longer time for soil consolidation in the embankment with floating piles,compared with the case using end-bearing piles.The differential settlement between the pile and surrounding soil at the pile top is larger for the embankment with end-bearing piles,compared with the case of floating piles.

  5. DRIVEN POLYSTRONG REINFORCED CONCRETE PILES AND NEW DESIGN OF PILE CAPS

    Directory of Open Access Journals (Sweden)

    I. I. Bekbasarov

    2015-01-01

    Full Text Available The paper presents constructional and technological features for manufacturing driven piles with variable strength of pile shaft. Economical efficiency of their production has been shown in the paper. The paper provides a pile cap design that ensures perception of hammer impacts with the help of lateral edges of the pile cap. Driven reinforced concrete piles which are manufactured from three shaft sections having various strength have been proposed in the paper. Material strength (concrete grade and diameter of bars and length of shaft sections are given on a case by case basis in accordance with nature and rate of stresses in piles during their driving process. Manufacturing of polystrong piles provides an opportunity to select them for a particular construction site with due account of their preservation during driving process.A pile cap has been developed that as opposed to existing analogous designs makes it possible to transmit impact efforts from a hammer to the pile through lateral surface of its head part. The pile cap provides the possibility to increase an area for perception of hammer impact efforts by the pile and in doing so it is possible significantly to reduce a damage risk and destruction of pile concrete during its driving. Application of polystrong piles and their driving with the help of new pile cap are considered as a basis for defect-free and resource-saving technology for pile foundations in the construction.

  6. 刚性桩复合地基荷载传递规律模型试验%Physical model study on load transfer law of rigid pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    吕伟华; 邵光辉

    2016-01-01

    It is difficult to determine the load sharing ratio between rigid pile and soil when a composite foundation un⁃derlain an embankment. In this study, a small scale physical tank was designed to simulate working conditions of a single rigid pile, in which sand was set as the sublayer and clay as the surrounding soil. The load transfer law was adequately analyzed by monitored earth pressures and pile axial stresses. Then assuming only vertical shearing stress at the filled basement , a computational physical model which considered the existence of negative and positive friction force was pres⁃ented. Further, this model could take into account the pile upward and down stick into the soil layers as well as the inter⁃action among embankment, pile and soil. Results indicated that rigid⁃pile composite foundation could efficiently reduce the total embankment settlement. The maximum axial force located at a depth of one or two times of the pile diameter. The maximum negative and positive frictions on the pile increased with the increasing embankment load, and the maxi⁃mum positive friction position moved downward. According to a proportional relationship between the additional stress and friction, a stiffness factor of the sublayer as Winkler foundation was defined. Calculated results of pile⁃soil stress ratio and load share were closed to measured results. This validated the rationality of the proposed method which could provide reference for practical engineering application.%针对刚性桩复合地基所受上覆荷载下难以定量计算桩土间荷载分配的问题,设计了缩尺模型箱试验,通过人工模拟桩端下卧层为砂土、桩身段加固区地基为黏性土的工况,进行桩、土承载特性和桩身荷载传递规律的研究。假设基底桩土相对位移下路堤内土柱间滑移面剪应力垂直分布,考虑桩顶上刺入路堤、桩端下刺入下卧层以及桩侧负、正摩阻力非线性

  7. Pile Load Capacity – Calculation Methods

    Directory of Open Access Journals (Sweden)

    Wrana Bogumił

    2015-12-01

    Full Text Available The article is a review of the current problems of the foundation pile capacity calculations. The article considers the main principles of pile capacity calculations presented in Eurocode 7 and other methods with adequate explanations. Two main methods are presented: α – method used to calculate the short-term load capacity of piles in cohesive soils and β – method used to calculate the long-term load capacity of piles in both cohesive and cohesionless soils. Moreover, methods based on cone CPTu result are presented as well as the pile capacity problem based on static tests.

  8. 77 FR 15045 - Takes of Marine Mammals Incidental to Specified Activities; Pile Placement for ORPC Maine's...

    Science.gov (United States)

    2012-03-14

    ... pile bent arrangement consisting of 10 steel pipe piles. Each foundation pile will have a 76-centimeter... will be located in an area with up to 12 m (40 ft) of marine clay and some thin layers of glacial till... pile will be two m (six ft) in diameter, or consist of an array of three piles not greater than 76 cm...

  9. Foundations

    Science.gov (United States)

    Harteveld, Casper

    A building will more likely collapse if it does not have any proper foundations. Similarly, the design philosophy of Triadic Game Design (TGD) needs to reside on solid building blocks, otherwise the concept will collapse as well. In this level I will elaborate on these building blocks. First I will explain what the general idea of TGD is. It is a design philosophy, for sure, but one which stresses that an “optimum” needs to be found in a design space constituted by three different worlds: Reality, Meaning, and Play. Additionally, these worlds need to be considered simultaneously and be treated equally. The latter requires balancing the worlds which may result in different tensions, within and between two or three of the worlds. I continue by discussing each of the worlds and showing their perspective on the field of games with a meaningful purpose. From this, we clearly see that it is feasible to think of each world and that the idea makes sense. I substantiate this further by relating the notion of player and similar approaches to this framework. This level is quite a tough pill to swallow yet essential for finishing the other levels. Do not cheat or simply skip this level, but just take a big cup of coffee or tea and start reading it.

  10. 桩基成孔施工中防塌泥浆性能试验分析%Analysis on Anti-sloughing Mud Properties in the Pile Foundation Borehole Construction

    Institute of Scientific and Technical Information of China (English)

    郝延周

    2014-01-01

    Hole collapse and diameter shrinkage often occur in the pile foundation borehole construction, the borehole qual-ity directly affects the quality of the bored grouting pile.Except for casing in borehole construction, the most effective wall protection method is by sloughing mud.Through the comparison and analysis on various mud with ingredients, the best for-mula of collapse preventing mud is selected to improve the stability of hole wall in bored grouting pile construction.%塌孔、缩径是桩基成孔施工中经常出现的问题,成孔的质量直接影响钻孔灌注桩桩体的质量。目前的成孔施工中除了下套管之外最有效的护壁方法就是采用防塌泥浆护壁。通过对各种组分泥浆试验性能参数的比较与分析,优选出防塌泥浆最佳配方,从而提高钻孔灌注桩成孔施工中孔壁的稳定性。

  11. Monitoring and Analysis of Pile-anchor Retaining Structure for a Deep Foundation Pit in Beijing%北京某深基坑桩锚支护结构监测及分析

    Institute of Scientific and Technical Information of China (English)

    周宸; 李旭东; 孙愿平

    2011-01-01

    采用桩锚支护结构对北京某深基坑进行支护,在施工过程中进行桩顶位移、地表沉降、锚索轴力监测,并对监测数据分析.结果表明:桩锚支护体系能有效地控制基坑水平位移和周边地表沉降,并且桩顶水平位移变化、沉降变化是比较有规律的.锚索预应力损失值较大,在30%~50%之间,在开挖过程中变化范围在15%以内;第一道锚索在控制位移和沉降发挥着关键的作用,第三道锚索是控制桩身最大弯矩的关键.结合实测值与理论计算值产生差异的原因,对以后类似桩锚支护结构的设计提出了建议.%Based on supporting a deep foundation pit by adopting pile-anchor retaining structure. During the constrction, the displacement of pile head, the surface settlement, the axial load of anchor rope are monitored and analyzes the main monitoring data The results indicate that the pile- anchor retaining structure can control the horizontal displacement of foundation pit and the surface settlement of surrounding structure effectively, and there are some laws in variation of horizontal displacemen and surface settlement. The losses of prestresses of anchors is large, it's about 30%~50% . and the range of variation is about 15% during the constrction; the first anchor rope play an important role in controlling displacement and settlement , the third anchor rope is the key of controlling the maximum bending moment in pile. Giving advice fur the design of similar pile- anchor retaining structure combine with the reasons of the calculating data different from the measuring data

  12. Level Classifications of Foundation Stiffness

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten

    2007-01-01

    This article describes a foundation module developed and implemented in both HAWC and FLEX capable of to simulate the frequency dependent stiffness and damping of foundations e.g. pile, gravitation and bucket foundations.......This article describes a foundation module developed and implemented in both HAWC and FLEX capable of to simulate the frequency dependent stiffness and damping of foundations e.g. pile, gravitation and bucket foundations....

  13. Technical Approaches to Improvement of Application of PHC Pile in Deep Foundation Pit%提高PHC管桩在深基坑支护中应用的技术途径

    Institute of Scientific and Technical Information of China (English)

    张仕; 李欢秋; 王爱勋

    2011-01-01

    城市深基坑支护已从单一的支护方式发展到综合各种支护方式优点的综合治理方式或复合支护方式.预制预应力混凝土管桩因其经济性、施工对环境影响小等优点已在建筑物基础中广为应用,在基坑支护中则由于其抗弯能力小而受到一定的限制.本文研究了PHC500预应力混凝土管桩增强技术及增强后弯矩计算方法、桩锚及喷锚网复合支护技术的应用.通过某软土层中深度为7~9m的地下室基坑支护,探讨了管桩在深基垸工程综合治理中应用的方法和可行性,为相关工程提供了具有参考价值的工程设计及施工实例.%Retaining and protecting method for deep foundation excavation in cities have developed from single to composite approaches combining the advantage of all kinds of retaining and protecting technology. The prefab pre stressed concrete pipe piles have been widely applied in the foundation construction because of its advantage of eco nomical efficiency and little influence on surroundings etc. But they have been restricted due to little bending resist ance in the retaining and protecting for foundation excavation. In this paper,the reinforcing technology and its calcula tion methods of bending,the application of pile-anchors and anchor-shotcrete composite retaining and protecting tech nology were researched. Through a retaining and protecting for foundation excavation in the basement with depth of 7 9 meter in weak soil, the feasibility and methods of the pipe piles in deep foundation pit were discussed. And the val uable design and construction cases were also presented in this paper.

  14. 基桩检测合格率的概率分析及可靠度评估%Probabilistic analysis and reliability assessment for acceptance rate of foundation pile testing

    Institute of Scientific and Technical Information of China (English)

    郑俊杰; 刘勇; 郭嘉; 徐志军

    2009-01-01

    With the aim to overcome some shortcomings in current specifications and codes concerning foundation pile testing, a reliability approach is proposed to evaluate the quality of pile foundations by taking the acceptance rate of foundation piles as a quality index. The prior distribution of this acceptance rate is assumed to follow a Beta distribution and the probability density function of the corresponding posterior distribution, which also follows a Beta distribution, and the acceptance rate is derived by employing the Bayesian approach. The use of the Bayesian approach solves the problem that the quality of pile foundations is evaluated by test results at one time, fully incorporates the existing in-situ data and enables the posterior distribution of acceptance rate not only with solid probabilistic basis but also practical senses. Based on worldwide specifications, codes and papers, a target reliability index of 3.2 is proposed as the criterion for evaluating the quality of pile foundations. The reliability approach conducts quality assessment in a quantitative manner and can be used as a reference for further revisions of relevant standards.%基于概率论,分析了当前桩基工程质量评估的有关规范中存在的问题,建议采用检测合格率作为基桩质量的评估指标,并提出了评估基桩质量的可靠度方法.提出基桩检测合格率的先验分布服从标准Beta分布,并应用Bayesian方法求出该合格率后验分布的概率密度函数,结果表明后验分布也服从标准Beta分布.Bayesian方法的引入,摒弃了传统评估方法中仅根据一次检测结果来确定工程质量的缺点,并充分考虑了已有类似工程中的数据,使合格率后验分布的确定既具有概率统计理论基础,又具有工程实际意义.根据国内外相关规范和文献资料,选取目标可靠度指标3.2作为评估基桩质量的标准.可靠度方法的引入不仅使得桩基工程质量评估更加科学合理,而

  15. Cause Analysis of Wuhan Tianheng Building Pile Accident

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The geological condition and the original structure feature and foundation design of Wuhan Tianheng building are described. The accident appearance of pile foundation in the construction execution of work is illustrated. The generating source of this pile foundation accident is analyzed in great details.``

  16. The Settlement Behavior of Piled Raft Interaction in Undrained Soil

    DEFF Research Database (Denmark)

    Ghalesari, Abbasali Taghavi; Barari, Amin; Amini, Pedram Fardad

    2013-01-01

    Offshore piled raft foundations are one of the most commonly used foundations in offshore structures. When a raft foundation alone does not satisfy the design requirements, the addition of piles may improve both the ultimate load capacity and the settlement performance of the raft. In this paper,...

  17. 鲁西南某2×300MW坑口电厂桩基原位试验研究%IN-SITU TESTS OF PILE FOUNDATION AT POWER PLANT IN SOUTHWEST OF SHANDONG PROVINCE

    Institute of Scientific and Technical Information of China (English)

    周亮; 倪恒; 范延彬

    2012-01-01

    鲁西南某2×300MW坑口电厂地基位于黄河冲积地层中,工程地质性质较差,地基强度不能满足电厂重要建(构)筑物的要求.根据现场的工程地质条件,施工中采用预应力高强混凝土管桩(PHC桩)进行地基处理.本文以鲁西南某2×300MW坑口电厂桩基检测工程为实例,首先采用低应变法对桩身质量进行了检测,然后采用高应变试验和静载试验2种方法确定了单桩竖向极限承载力,并对这2种方法的优点、缺点和影响因素进行了分析和对比.得出结论:(1)采用高应变CAP-WAP法拟合后的试验结果与单桩竖向静载荷试验结果基本吻合,通过选取合适的桩、土参数模型使高应变试验的结果准确可靠,是切实可行的.(2)在现场条件不允许开展静载试验时,高应变试验可作为静载试验的补充手段对桩基进行检测.(3)当能够获得可靠的高应变试验结果(与静载试验基本吻合)时,可以通过严谨计算对规范法设计方案进行一定程度的调整,以节约成本,但要慎重对待.%the foundation of a 2×300MW pithead's power plant in southwest of Shandong province is located in alluvial layers of the Yellow River. The engineering properties of the strata are poor. The low foundation strength can't meet the needs of the key structures and buildings of the power plant. According to the geological conditions, foundation treatment has been conducted by high-strength pre-stressed concrete pipe. In the case study, we test the pile body with low strain integrity testing methods, determine the vertical ultimate bearing capacity of single pile u-sing two methods such as high strain tests and static load tests, and contrast the advantages/disadvantages and affecting factors. Then we conclude the following three results. (1) Testing results by high strain CAPWAP method after fitting agree well with that by the vertical static load of a single pile. So it is likely to enhance the accuracy and

  18. Pullout capacity of batter pile in sand.

    Science.gov (United States)

    Nazir, Ashraf; Nasr, Ahmed

    2013-03-01

    Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21-31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18-75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.

  19. Pullout capacity of batter pile in sand

    Directory of Open Access Journals (Sweden)

    Ashraf Nazir

    2013-03-01

    Full Text Available Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of Pα occurs at batter angle approximately equal to 20°, and it is about 21–31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18–75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.

  20. Seismic response of tall building considering soil-pile-structure interaction

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The seismic behavior of tall buildings can be greatly affected by non-linear soil-pile interaction during strongearthquakes. In this study a 20-storey building is examined as a typical structure supported on a pile foundation for differentconditions: (1) rigid base, i.e. no deformation in the foundation: (2) linear soil-pile system; and (3) nonlinear soil-pile system.The effects of pile foundation displacements on the behavior of tall building are investigated, and compared with the behavior ofbuildings supported on shallow foundation. With a model of non-reflective boundary between the near field and far field,Novak's method of soil-pile interaction is improved. The computation method for vibration of pile foundations and DYNANcomputer program are introduced comprehensively. A series of dynamic experiments have been done on full-scale piles,including single pile and group, linear vibration and nonlinear vibration, to verify the validity of boundary zone model.

  1. Análisis dinámico no lineal para pilotes de cimentación fundidos " in situ " // Non-linear dynamical analysis for foundation piles molten " in situ "

    Directory of Open Access Journals (Sweden)

    E. Fraga Guerra

    1998-01-01

    Full Text Available En la actualidad existen diversas técnicas para controlar el estado técnico de los pilotes de cimentación, una de las másutilizadas es mediante el estudio de sus vibraciones mecánicas, ya que este método resulta muy eficaz pues permite obteneróptimos resultados sin detener el proceso productivo.En el presente trabajo se estudia la influencia de la no linealidad en el sistema pilote-terreno, para lo cual se hace necesarioobtener las soluciones de modelos físico-matemáticos expresados a través de ecuaciones diferenciales ordinarias no linealesnecesarias a tales efectos. Por otra parte, debido a la presencia de un gran número de parámetros que intervienen en el modelose implementa la técnica de elementos finitos, considerando un modelo lineal, para determinar las características estáticas ydinámicas del sistema para las condiciones planteadas en el problema._________________________________________________________________AbstractThere are several techniques nowadays to control the technical state of the foundation piles. One of the most used techniques isthe study of mechanical vibrations of the piles since this method turns out very efficient because it allows obtaining optimumresults without stopping the productive process.Throughout this work, the influence of non-linearity in the ground-pile system is studied, such influence appears because of thedifferent characteristics and great variety of the soils, then, for this study, it is made necessary to obtain the solutions ofmathematics and physical models expressed through non-lineal ordinary-differential equations needed as well. On the otherhand, due to the presence of a great number of parameters acting in the model, the technique of finite element is implemented,taking into account a lineal model to determine the static and dynamic characteristics of the system according for the conditionsstated in the mathematical problem.

  2. Researches on Construction Scheme of Urban Shallow Passenger Dedicated Line Tunnel of Adjacent Pile Foundations%城市浅埋近接桩基客运专线隧道施工方案研究

    Institute of Scientific and Technical Information of China (English)

    崔光耀; 苏昊; 路军富

    2011-01-01

    Finite difference software Flac3D is used to build the 3-d digital model for the project of Jichang road tunnel of Chengdu-Mianyang Leshan passenger dedieated line across Lantian ciaduct in Chengdu.The ground settlement,vertical displacement of pile foundations and difference value of horizontal displacement between pile top and pile bottom caused by tunnel excavation from the tunnel are stueied.It's shown that the undercut construction scheme is superior to the open one.These resrarches provide important guarantee for the normal opreaion of existing viaduet and the constructure of Jiehang road tunnel.And references is provided for similar projects.%依托成绵乐客运专线机场路隧道下穿成都市蓝天立交工程,采用有限差分软件FLAC进行三维数值模拟分析.主要从隧道开挖所造成的地表沉降、桩基下沉量以及桩基端部水平位移差值这三个方面进行研究.研究结果表明:暗挖施工方案明显优于明挖施工方案.研究成果为既有立交桥的正常运营以及机场路隧道施工的顺利进行提供了保证,又可为相似工程提供参考.

  3. 西宝高铁兴平段路基组合桩地基处理技术%Technology of subgrade's foundation treatment by combined piles in Xinping section of Xi'an-Baoji high speed railway

    Institute of Scientific and Technical Information of China (English)

    张华莹

    2015-01-01

    The Xingping section on Xi'an-Baoji high speed railway,laying on the second terrace of western Weihe plateau,faces the challenge of subgrade settlement,as the collapsible loess and saturated loess compose the upper layer,while sand and gravel soil form the lower layer. T he shallow groundwater depth and a maximum filling height of 8 m further pile on the treatment task. T he paper compares the available schemes and proposes the combined pile foundation as a preferable solution. It entails the designing concept and calculation approach,and on this basis,carries out settlement observation,dynamic detection and operation experiment to prove its validity. T he results show that the scheme effectively controls the settlement,creating an enabling environment for ballastless-track pavement. Compared with widely-applied single-pile foundation,this cost-effective solution helps enhance the bearing capacity of the foundation and brings settlement under control.%西安至宝鸡高铁兴平段路基位于关中平原西部渭河二级阶地上,地层上部为湿陷性黄土及饱和黄土,下部为砂层及圆砾土层,地下水位埋深较浅,路堤最大填方高度8 m,路基工后沉降难以控制。经综合方案比选,地基采用组合桩处理。本文详细地阐述了组合桩的设计计算方法,通过沉降观测、动态检测及运营实践证明,组合桩地基处理措施有效控制了路基工后沉降,满足无砟轨道铺设要求,使用效果良好。与传统单一桩型复合地基处理效果相比,组合桩具有节约投资、提高地基承载力、有效控制工后沉降等优势。

  4. Study on Pile-soil Stress Ratio of Composite Foundation Reinforced with Geosynthetic Encased Stone Columns%筋箍碎石桩复合地基桩土应力比的计算与分析∗

    Institute of Scientific and Technical Information of China (English)

    张玲; 陈哲; 赵明华

    2017-01-01

    针对筋箍碎石桩复合地基的受力变形特点,考虑桩土的初始应力状态,假定桩为具有恒定剪胀角的弹塑性体,且满足摩尔库伦屈服准则与非关联流动法则,土体和加筋体为线弹性材料,考虑桩筋材土三者间相互作用,导得了筋箍碎石桩复合地基桩土应力比计算新公式。为验证本文计算公式的可行性,将本文方法计算结果与弹塑性极限分析方法结果进行对比分析,两者吻合良好。在此基础上,分析探讨了筋材刚度、桩周土变形模量、面积置换率等因素对筋箍碎石桩复合地基桩土应力比的影响。分析结果表明:筋材刚度是桩土应力比的主要影响因素,桩土应力比随筋材刚度、面积置换率、桩体内摩擦角的增大而增大,随着桩周土变形模量和桩体剪胀角的增大而减小。%Based on the deformation characteristics of the composite foundation reinforced with encased stone columns under vertical loads,a new calculation formula to estimate the pile-soil stress ratio of geo-synthetic-encased stone columns was proposed with consideration of pile-geosynthetic-soil interactions.In the derivation process,initial stresses in soil and a column were taken into account,the column was con-sidered as an elastic-plastic material with constant dilatancy angle and satisfying both the Mohr-Coulomb yield criterion and non-associated flow rule,and the soil and geosynthetic encasement were considered as linear-elastic materials.The proposed formula was validated by comparison with the results of elasto-plas-tic limit analysis method.Finally,a parametric study was conducted to investigate various parameter effects of encasement stiffness,deformation modulus of soil,and replacement ratio on the behavior of the pile-soil stress ratio.The parametric study shows that the pile-soil stress ratio of the composite foundation with the encased stone column increases with the increase of encasement

  5. Model Test on Concrete Cutting Directly by Shield and Pile Foundation Cutting Technology%盾构切削混凝土模拟试验和切削桩基施工技术

    Institute of Scientific and Technical Information of China (English)

    傅德明

    2014-01-01

    Underground obstacles,such as concrete piles,soil retaining structures,pipes and trenches and underground structures,are often encountered during shield boring in the construction of urban rail transit works.These pile founda-tions are normally underpinned,dismantled or manually cut.However,these conventional treatment methods have such disadvantages as high cost,long construction period and severe influence on the surrounding traffics.A400 mm model shield is used to cut blind concrete,glass fiber concrete and reinforced concrete,so as to study the feasibility of pile foundation cutting directly by shields,to make analysis on the modification of cutter heads and to obtain shield boring control parameters.Furthermore,the experience of the pile foundation cutting directly by shields in the construction of No.7 line and No.10 line of Shanghai rail transit works is described.Conclusions drawn are as follows:1 )It is feasi-ble to cut reinforced concrete directly by shields;2)Before shield launching,the cutter head should be modified,and a number of advance cutting tools and shell tools should be installed on the cutter head;3 )During the cutting of the pile foundations directly by shield,the shield should advance slowly (with less than 10 mm/min advance speed),and the earth pressure,thrust and cutter head torque set should be stable;4)During the cutting of the pile foundations directly by shield,lubricating and friction-reducing materials should be added into the excavation chamber so as to prevent the screw conveyor from being jammed by concrete blocks.After the shield passes the obstacle point,secondary grouting should be made to fill the annulus space behind the segment lining on basis of the monitoring results so as to control the settlement of the ground surface and the nearby buildings;5 )Cutting pile foundations directly by shield has advantages, including low cost,high safety and small environmental influence.%城市轨道交通盾构施工中经常遇到穿

  6. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    NARCIS (Netherlands)

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance

  7. Literature review Quasi-static and Dynamic pile load tests: Primarily report on non-static pile load tests

    NARCIS (Netherlands)

    Huy, N.Q.

    2010-01-01

    Pile testing, which plays an importance role in the field of deep foundation design, is performed by static and non-static methods to provide information about the following issues: (Poulos, 1998) - The ultimate capacity of a single pile. - The load-displacement behavior of a pile. - The performance

  8. Test Procedure for Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The test procedure described in the following is used when examining the effects of static or cyclic loading on the skin friction of an axially loaded pile in dense sand. The pile specimen is only loaded in tension to avoid any contribution from the base resistance. The pile dimensions are chosen...... to resemble full scale dimension of piles used in offshore pile foundations today. In this report is given a detailed description of the soil preparation and pile installation procedures as well data acquisition methods....

  9. Wavelet analyses for stress wave detection of piles

    Institute of Scientific and Technical Information of China (English)

    WANG; Jingtao; (王靖涛)

    2003-01-01

    The theoretical foundation for application of wavelet analysis to pile integrity detection has been presented. The mechanism of spectral variations of reflected pulse from various defects in piles is explained by using the wave scattering theory. The theoretical analyses have been verified through the tests of model piles and a lot of engineering piles. A quantitative evaluation method for estimating damage degree of piles is proposed. The characteristic indexes describing spectrum variations of reflected signals and their critical values are given. They can be used not only to evaluate the damage degree but also to identify the kinds of pile defects.

  10. 滑动测微计在桩身内力测试中的分析应用%Analysis and Application of Sliding Micrometer in Internal Forces Measurement of Pile Foundation

    Institute of Scientific and Technical Information of China (English)

    李戟; 马若龙; 王志勇

    2011-01-01

    This paper briefly introduces the work principle and data processing methods of sliding micrometer in the internal forces measurement of pile foundation. Through an example of project, the regularities of elasticity modulus changed with strain are analyzed when the piles body are loaded,and the internal forces distribution is calculated under different load levels. Programmed using Matlab language,the three-dimensional graphics of the side friction resistance and end resistance are drew in different stratum,so as to provide the basis for engineering design.%该文简要说明了滑动测微计在桩身内力测试中的工作原理及资料处理方法.通过工程实例,分析桩身受荷时弹性模量随应变的变化规律,计算出各级荷载作用下桩身内力分布情况,并运用Matlab语言进行编程,绘制出各地层的桩侧摩阻力和端阻力等三维图形,为工程设计提供依据.

  11. 地震作用下桥梁桩基与土层相互作用的模型试验研究%Model Test and Study of Pile Foundation of Bridge-Soil Interaction Acted by Earthquake

    Institute of Scientific and Technical Information of China (English)

    方卫民; 汤永净; 王炳龙

    2000-01-01

    采用有限元方法可建立地震反应计算模型。为进一步验证理论计算的可行性以及分析地震对桥梁桩基的影响,在1:50的基础动力结构模型试验中,应用相似原理将模拟地震波作用于桥梁桩基模型上来研究模型桩身不同深度处的轴力和土层位移的变化情况。试验结果表明模型桩轴力、土层位移与用两维四节点有限元预测原型的相应指标是相似的。%This paper provides a model test which simulates pile foundation of bridge-soil interaction by an earthquake wave to verify that the theoretical analysis is possible with the help of finite element. The model test scaled 1:50 presents results of pile axis forces and soil displacement. The results have proved to be similar to calculating values given by computer in the ease of two-dimensional and quad-node finite element.

  12. 采空区不良效应下桥梁桩基的风险评价%Risk evaluation approach to the bridge pile foundation based on the adverse effects in the goaf

    Institute of Scientific and Technical Information of China (English)

    亓晓贵; 宋世芬; 陈一洲

    2016-01-01

    The paper takes the risk assessment of the bridge pile foundation in the goaf of an expressway,for instance,by establishing a finite element numerical model with the engineering procedure based on the MIDAS/GTS.As is known,in engineering practice,it is of great necessity to assess the goaf's adverse effects on the bridge pile foundation by resolving to further innovative methods and improved measures so as to work out the risk impacts accurately and ensure the bridge foundation construction quality.Just for the said purpose,we have done the risk estimation of the bridge pile foundation in the goaf of one expressway for instance,and built up the finite element numerical model with the procedure based on MIDAS/GTS.In addition,we have also gained the influential effects in different conditions and put forward some corresponding effective countermeasures for the risk control of the settlements of the goaf so as to protect the coal seams still under mining by the gravity stress and the settlement of the bridge pile foundation under loading after grouting in the goaf,etc.The results we have obtained show that the evaluation method helps to reduces the safeless factors influencing the bridge pile foundation construction and provides us with rich research experience and approach for the similar engineering prosperity in terms of safety risk assessment.Based on the simulation of the mechanism and the effects formed by the multi-stage progress of mined-out area,it can be concluded that the influence of the adverse effects on the risk management of the pile foundation construction can be of great significance and serious hardship to be overcome.As well,the paper can be expected to provides a beneficial supplement to the Assessment Guidelines for the Safety Risk evaluation for the Highway Bridge Project Construction under the goaf area (Trial Implementation).Furthermore,it is also of great theoretical and practical significance for controlling and predicting the risk aversion

  13. The foundation pile improved finite bar element method under oblique eccentric loading%倾斜偏心荷载作用下基桩改进有限杆单元法

    Institute of Scientific and Technical Information of China (English)

    朱永波; 郭秋香

    2009-01-01

    在分析探讨相关文献资料的基础上,结合算例对倾斜偏心荷载作用下基桩的受力特性以及改进有限杆单元法进行了较系统深入的研究,指出改进有限元的分析在国内外具有重要的理论与工程实际意义.%Based on analysis and discussing related references and data, combined with calculation example, the foundation pile mechanical characteristics under oblique eccentric loading and improved finite bar element method were researched systematically and profoundly. It point-ed out that improved finite element analysis had important theoretical and engineering practical meanings at home and abroad.

  14. Study on pile drivability with one dimensional wave propagation theory

    Institute of Scientific and Technical Information of China (English)

    陈仁朋; 王仕方; 陈云敏

    2003-01-01

    Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.

  15. Field test and numerical analysis on behaviors of low-cap pile foundation supporting bridged abutment subjected to embankment load%低承台桥台桩基侧向受力性状试验与数值分析

    Institute of Scientific and Technical Information of China (English)

    聂如松; 冷伍明; 杨奇; 岳健

    2012-01-01

    Based on field test results, a three-dimensional finite element method was set up to explore the settlement of the pile foundation, the bending moment of the piles, the horizontal movement of pile head, shear force and earth pressure on pile shafts with increasing embankment load behind the abutment wall. The results show that the calculated and measured results agree well; the lateral deformation of pile head and maximum bending moment of pile with the increase of embankment load increases linearly. In 20 m depth, the distribution of shear force along the pile depth is in "S" shaped pattern, the distribution of the earth pressure along the depth direction is of a parabola. The mechanical model of low-cap pile foundation is equivalent with the statically indeterminate beam of the pile head and pile embedded in a certain depth soil. The conclusions can be helpful and give references for pile design and construction.%基于现场测试结果,采用三维有限元技术分析低承台桥台桩基在台后路基填土过程中桩基沉降、桩身弯矩、桩顶水平变形、桩身剪力和桩侧附加水平挤压力随台后填土荷载增加的变化规律.研究结果表明:计算结果与实测结果吻合较好:桩顶水平变形和桩身最大弯矩随填土荷载的增加近似呈线性增加:深度方向20m范围内,桩身剪力图呈“S”型,桩侧附加水平挤压力图呈抛物线型.低承台桥台桩基力学模型等同于桩项和桩端嵌入一定深度、具有一定变位的超静定梁结构.本文所得结论可以为桥台桩基的设计和施工提供参考.

  16. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    Directory of Open Access Journals (Sweden)

    Wang Duanduan

    2015-01-01

    Full Text Available Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.

  17. Friction effects on lateral loading behavior of rigid piles

    DEFF Research Database (Denmark)

    Zania, Varvara; Hededal, Ole

    2012-01-01

    The adequacy of the p -y curves used in the current practice for the design of rigid pile foundations with large diameter, like in the case of monopile foundations of offshore wind turbines, has been widely questioned. The current study aims at analyzing the lateral behavior of rigid piles, while...... taking into account the shear frictional resistance along the pile. For this purpose efficient three dimensional finite element models of different diameter have been developed. The increase of the side friction and of the diameter of the pile is shown to alter the failure pattern and increase...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...

  18. 桥梁桩基钢筋笼定位的方案探讨%Discussion of the Plan of Reinforcement Cage Positioning for Bridge Pile Foundation

    Institute of Scientific and Technical Information of China (English)

    李衍宁

    2014-01-01

    本文呢从桩基钢筋笼偏位对施工所造成的影响作为问题的突破口,深入分析了钢筋笼偏位的原因。缤纷根据笔者切身的实践经验,总结了控制钢筋笼偏位的施工方案,如“抽浆法”、“钢筋笼接长法”等方法。经过现场实践检验,控制效果明显。%Taking the impact of construction which is caused by the deviation of the pile reinforcement cage as the breach of the problem, this article analyzes the reason of the deviation of reinforcement cage. Based on the author’s own experience, the article summarizes the construction schemes to control deviat-ion of reinforcement cage, such as "Pumping slurry method","extending the link of reinforcement cage method", etc. Thro-ugh practical test, the control ef ect is obvious.

  19. Experimental study on corrosion prevention of concrete pile foundation of a large power plant in Shandong%山东某大型电厂桩基混凝土防腐蚀性试验

    Institute of Scientific and Technical Information of China (English)

    李吉林

    2013-01-01

    为研究桩基混凝土在腐蚀性地下水环境中的耐久性,依据山东某大型电厂中等~强腐蚀性地下水地质条件,在Cl-与SO2-4共存的地下水环境与只存在SO2-4的水环境中进行桩基混凝土防腐蚀性试验。结果表明:在Cl-与SO2-4共存的地下水环境中,混凝土受硫酸盐侵蚀的程度比只存在SO2-4的水环境中轻微;掺加防腐剂并没有明显提高混凝土抗蚀能力;抗硫酸盐水泥的抗硫酸盐侵蚀性与普通硅酸盐水泥接近,但抗氯离子侵入性难以满足耐久性要求;采用普通硅酸盐水泥、大掺量掺和料、低水胶比的高性能混凝土能满足桩基耐久性要求。%In order to study the durability of concrete piles in a corrosive groundwater environment, concrete corrosion resistant test of pile foundation in the environments with Cl- and SO2-4 coexistance and with only SO2-4 existance was performed, according to medium-highy corrosive groundwater geological conditions of a large power plant in Shandong. The results show that in the Cl-and SO2-4 coexistence groundwater environment, sulfate attack concrete situation is slightly lower than in the presence of SO2-4 only environment, the conventional doped preservatives does not significantly increase corrosion resistance, and resistance to sulfur cement and sulphate resistance of ordinary Portland cement remain close, but resistance to chloride ion invasive can not meet durability requirements. Finally, the ordinary Portland cement and admixture with low water-cement ratio, high-performance concrete pile can be used to meet durability requirements.

  20. 砂石桩与素混凝土桩复合地基桩处理软弱吹填土地基%Treatment on Soft Dredger Fill Foundation for Composite Foundation Between Gravel Pile and Plain Concrete Pile

    Institute of Scientific and Technical Information of China (English)

    焦占生; 雷洋

    2014-01-01

    Taking a project in Caofeidian manufacturing district as an example, the difficulties of soft ground treatment for blowing and filling, the complex use of gravel pile and plain concrete pile are analyzed in this thesis. Not only can it improve the bearing capacity, but also eliminate liquefaction. It is very economical and applicable.%以曹妃甸工业区某项目为例,分析了吹填土软弱地基处理的难点,提出砂石桩与素混凝土桩复合使用,不仅提高承载力,消除液化,又经济适用。

  1. Transient response of piles-bridge under horizontal excitation

    Institute of Scientific and Technical Information of China (English)

    朱斌; 陈仁朋; 陈云敏

    2003-01-01

    Moving ships and other objects drifting on water often impact a bridge's pile foundations. The mechanical model of the piles-bridge structure under horizontal forcing was established, and a time-domain approach based on Finite-difference Method was developed for analyzing the dynamic response of the piles-bridge structure. For a single pile, good agreement between two computed results validated the present approach. The slenderness ratio of the pile, the pile-soil stiffness ratio and the type of the structure influence the dynamic response of the piles-bridge structure. The computed results showed that the stiffness of the structure determines the dynamic response of the piles-bridge structure under horizontal forcing.

  2. Transient response of piles-bridge under horizontal excitation

    Institute of Scientific and Technical Information of China (English)

    朱斌; 陈仁朋; 陈云敏

    2003-01-01

    Moving ships and other objects drifting on water often impact a bridge' s pile foundations. The mechanical model of the piles-bridge structure under horizontal forcing was established, and a time-domain approach based on Finite-difference Method was developed for analyzing the dynamic response of the piles-bridge structure. For a single pile, good agreement between two computed results validated the present approach.The slenderness ratio of the pile, the pile-soil stiffness ratio and the type of the structure influence the dynamic response of the piles-bridge structure. The computed results showed that the stiffness of the structure determines the dynamic response of the piles-bridge structure under horizontal forcing.

  3. Model Tests of Pile Defect Detection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The pile, as an important foundation style, is being used in engineering practice. Defects of different types and damages of different degrees easily occur during the process of pile construction. So,dietecting defects of the pile is very important. As so far, there are some difficult problems in pile defect detection. Based on stress wave theory, some of these typical difficult problems were studied through model tests. The analyses of the test results are carried out and some significant results of the low-strain method are obtained, when a pile has a gradually-decreasing crosssection part, the amplitude of the reflective signal originating from the defect is dependent on the decreasing value of the rate of crosssection β. No apparent signal reflected from the necking appeares on the velocity response curve when the value of β is less than about 3.5 %.

  4. 2D Forward Simulation of Grouting Karst for Pile Foundation with High-density Resistivity Method%桩基岩溶注浆模型高密度电法二维正演模拟

    Institute of Scientific and Technical Information of China (English)

    张吉; 师学明; 辛民高

    2011-01-01

    研究目的:高密度电法是一种常用的桩基岩溶注浆质量无损检测方法,为使该方法更好地应用于生产实践,本文采用RES2DMOD软件(版本号3.0)对桩基岩溶注浆地质-地球物理模型进行了高密度电法二维正演数值模拟.研究结论:数值模拟结果表明,完整注浆体和岩溶注浆缺陷在高密度电法视电阻率断面图上均有反应,分别为高阻异常和低阻异常.温纳装置高密度电法对于异常的反应相对明显,异常的范围比较大,但幅值相对较小;施伦贝谢装置对于异常的反应幅值较大,但范围较小,且呈垂向分布,相对不易识别.%Research purposes; The high -density resistivity method (HDR) is a commonly used method for detecting the quality of grouting karst of pile foundation. In order to guide the production practice, RES2DM0D 3.0 was used for 2D forward simulation with high - density resistivity for grouting karst of pile foundation to the geology - earth physical model . Research conclusions: The result of numerical simulation shows the full grouting body and defects of grouting karst can be reflected on the resistivity profile drawing respectively by abnormal high resistance and low resistance. The geophysical anomaly is obvious with large abnormal range and small amplitude when using the Wenner array HDR method, and the geophysical anomaly is weaker with small reflection amplitude and vertical distribution when using the Wenner - Schlumberger array and it is difficult to distinguish.

  5. 高填土路堤对既有大跨度桥梁桩基的影响分析与监测%Analysis and Field Monitoring on the Effect of High Earth Embankment on the Existing Large Span Bridge Pile foundations

    Institute of Scientific and Technical Information of China (English)

    宋春雨; 季永兴; 孙磊

    2015-01-01

    哈尔滨市松花江北岸滨江大道工程穿越松花江跨江大桥。为减轻路堤填筑对桥桩的影响,基于垂向二维有限元模型及现场监测,研究了土工格栅加筋、钻孔灌注桩隔离及注浆处理等综合措施的可行性,并分析了路堤填筑过程中地基土及桥桩的变形。结果表明:土体加筋、钻孔灌注桩隔离及注浆处理等综合措施可有效减轻路堤填筑对桥桩的影响;路堤填筑对桥桩的影响主要集中在桥墩桩身的上部,桩身下部影响较小;桩基础附加沉降主要由承台上部填土所致,主动区加固措施对减小桥桩的水平位移效果比较明显。研究同时表明,垂向二维有限元模型因桩基简化为板桩墙,使得地层附加应力全部由桩基承担,被动区土层变形的计算结果偏小,桩基变形计算结果偏大。%Bingjiang Avenue is built along the north bank of Songhua River and runs through the Songpu Bridge in Haerbin city ,the provincial capital of Heilongjiang .The high embankment causes additional stresses in the ground layers affecting on the adjacent piles for the bridge abutment .In this paper ,a 2D FEM model was used to analyze the deforma-tions of soil layers and the performances of bridge piles during the construction .The field monitored data of settlements and lateral displacements were reported and discussed .The synthetic implements including geogrid ,bore piles for stress isolation and compaction grouting were studied for their feasibility on controlling the influences of high embankment on the bridge piles ,as well as the deformation of the foundation and the bridge piles .The results of computations and measure-ments in situ can be summarized as follows :the synthetic implements mentioned above can alleviate the influence of em-bankment construction on the adjacent bridge piles ;high embankment mainly affects on the performance of upper part of the piles ,while the lower parts are

  6. FORECASTING PILE SETTLEMENT ON CLAYSTONE USING NUMERICAL AND ANALYTICAL METHODS

    Directory of Open Access Journals (Sweden)

    Ponomarev Andrey Budimirovich

    2016-06-01

    Full Text Available In the article the problem of designing pile foundations on claystones is reviewed. The purpose of this paper is comparative analysis of the analytical and numerical methods for forecasting the settlement of piles on claystones. The following tasks were solved during the study: 1 The existing researches of pile settlement are analyzed; 2 The characteristics of experimental studies and the parameters for numerical modeling are presented, methods of field research of single piles’ operation are described; 3 Calculation of single pile settlement is performed using numerical methods in the software package Plaxis 2D and analytical method according to the requirements SP 24.13330.2011; 4 Experimental data is compared with the results of analytical and numerical calculations; 5 Basing on these results recommendations for forecasting pile settlement on claystone are presented. Much attention is paid to the calculation of pile settlement considering the impacted areas in ground space beside pile and the comparison with the results of field experiments. Basing on the obtained results, for the prediction of settlement of single pile on claystone the authors recommend using the analytical method considered in SP 24.13330.2011 with account for the impacted areas in ground space beside driven pile. In the case of forecasting the settlement of single pile on claystone by numerical methods in Plaxis 2D the authors recommend using the Hardening Soil model considering the impacted areas in ground space beside the driven pile. The analyses of the results and calculations are presented for examination and verification; therefore it is necessary to continue the research work of deep foundation at another experimental sites to improve the reliability of the calculation of pile foundation settlement. The work is of great interest for geotechnical engineers engaged in research, design and construction of pile foundations.

  7. Concept Study of Foundation Systems for Wave Energy Converters

    DEFF Research Database (Denmark)

    Molina, Salvador Devant; Vaitkunaite, Evelina; Ibsen, Lars Bo

    Analysis of possible foundation solution for Wave Energy Converters (WEC) is presented by investigating and optimizing novel foundation systems recently developed for offshore wind turbines. Gravity based, pile and bucket foundations are innovative foundation systems that are analyzed. Concept...

  8. Optimization of pile foundation program based on Analytic Hierarchy Process%基于AHP的基坑支护方案的优选研究

    Institute of Scientific and Technical Information of China (English)

    贺晨; 陈建宏

    2011-01-01

    基坑工程是一个复杂的系统工程,支护方案的优劣受很多因素影响,应用层次分析法原理,将复杂的深基坑支护方案决策问题层次化,并且,根据深基坑支护系统的特点建立层次结构模型,通过层次分析法比较,选出最优支护方案.实例研究表明,层次分析法简便、高效、科学合理,是一种处理复杂的多目标决策问题的实用方法.通过层次总排序得到各个备选方案的优劣排序,使选择过程更加全面、科学、公正、准确.%Deep foundation pit was a complex systematic project, supporting the merits of the program affected by many factors. This paper, through using analytic hierarchy principle, discusses the complex program of deep foundation pit hierarchical decision - making problems, and, under the Sbenzhen - based pit support system, it is characterized by the establishment of a hierarchical model and through the comparison of AHP to select the optimal supporting program. Case studies show: AHP is simple, efficient, scientific and rational, and it is a complex multi -objective decision - making problem in practical ways. Total sorting through the layers to be pros and cons of various options will make the selection process become more comprehensive, scientific, fair and accurate.

  9. 浮箱平台抢修水中钢桩基础技术研究%Technical Research on Using the Floating Platform for Repairing Steel-Pile Foundation in Water

    Institute of Scientific and Technical Information of China (English)

    谢爱华

    2012-01-01

    水中基础受水深、地质的影响,会增加抢修的难度和时间,是桥梁抢修的关键。现有的水中基础抢修技术和器材,难以满足快速抢修、保障交通畅通的要求。提出了一种水中桥梁基础抢修的新技术和新器材,即采用浮箱平台抢修水中钢桩基础,并着重介绍了浮箱平台的结构组成、施工方法及结构计算。该浮箱平台结构简单、施工速度快,是一种新式平台结构和新的平台施工方法。%Owing to the fact that the foundation in water is usually affected by the depth of water and its geological conditions,which increases the difficulty of rush-repair and the time for rush-repair,and thus,is the key factor of rush-repairing bridges.Since the existing rush-repairing techniques and equipments for rush-repairing the foundation in water are hard to meet the requirements of quickly rush-repairing and ensuring the smooth traffic,a new kind of technology and equipment for rush-repairing the bridge foundation in water,namely,using the floating platform for rush-repairing the steel pile foundation in water,is put forward in the paper,with greater stress placed on the introduction to the structural composition of the floating box platform,the construction methods of it and its structure calculations.Being simple in structure and quick in construction,the floating platform is a new structure of platform and a new construction method for the construction of platforms.

  10. Construction Techniques for the Treatment of the Collapse of Bored Holes for Large-Diameter Foundation Piles%大直径基桩坍孔处理施工技术

    Institute of Scientific and Technical Information of China (English)

    尤春颖

    2011-01-01

    新月铁路分离式立交桥21-1基桩紧邻电气化铁路,振动较大且砂土层较厚,在试桩过程中发生坍孔。分析工程具体情况,决定采用预制钢筋混凝土沉井护壁处理。介绍了沉井的设计、加工与下沉,大直径冲击钻成孔过程及相应的质量控制措施,处理后的基桩质量良好。可为类似工程处理提供有益借鉴。%Owing to the fact that the No. 21-1 foundation pile of the Xinyue Railway Separate Overpass is near an electrified railway, where the vibration is very strong and the sand layer is thick, the wall of the bored hole collapsed in the course of test-boring

  11. Key Construction Techniques and Bearing Behaviors of Railway Foundation Treatment with Screw Pile in Saline Soil Area%螺杆桩在盐渍土地区铁路地基处理中的施工关键技术与承载特性分析

    Institute of Scientific and Technical Information of China (English)

    万鹏洲

    2016-01-01

    Combined with practical construction of screw pile from Hohhot to Zhunger Railway Engineering,key construc-tion techniques and bearing behaviors of railway foundation treatment with screw pile in saline soil area are mainly re-searched by combining field test and theoretical analysis of numerical simulation.The construction technology and technical parameters are summarized and bearing mechanism of screw pile and settlement rate of subgrade are analyzed,which is beneficial to the formation of the complete set of construction technology of railway foundation treatment with screw pile in saline soil area.Based on the research,it is found that the screw pile has many characteristics such as high bearing capaci-ty,low sedimentation rate,high efficiency of forming pile and remarkable economic benefits,which fully reflects the appli-cation advantages of this new style pile in railway foundation treatment.%结合呼和浩特至准格尔铁路工程螺杆桩实际施工,采用现场试验和模型数据理论分析相结合的研究方法,重点研究了盐渍土地区螺杆桩的施工关键技术和承载受力特性,总结了施工工艺和技术参数,分析了螺杆桩的承载机理和路基沉降速率,形成了螺杆桩在盐渍土地区铁路地基处理的成套施工技术。通过研究发现螺杆桩具有承载力高、沉降率低、成桩效率高、经济效益显著等诸多特点,充分体现了这种新型桩在铁路地基处理中推广应用的优势。

  12. Development technology of rigidity-drain pile and numerical analysis of its anti-liquefaction characteristics

    Institute of Scientific and Technical Information of China (English)

    刘汉龙; 陈育民; 赵楠

    2008-01-01

    Pile foundation is widely used in the offshore engineering. The pile can be seriously destroyed by the soil liquefaction during strong earthquakes. The potentials of liquefaction and damages of pile foundation due to the liquefaction can be reduced by the implementation of the drainage in the liquefiable foundation. A patented pile technology, named rigidity-drain pile, was introduced. The partial section of the pile body was filled by materials with higher penetrability which forms some effective drainage channels in the pile. The principles and construction methods were presented. 3D models for both rigidity-drain pile and ordinary pile were built in FLAC3D code. The dynamic loadings were applied on the bottom of the model. According to the numerical results, in the case of the rigidity-drain pile, the water in the relevant distance range around the pile flows toward the pile drainage, the contour of the pore pressure shows a funnel form. Contrast to the ordinary pile, the rigidity-drain pile can dissipate the accumulated excess pore water, maintain effective stress and obviously reduce the possibility of surrounding soil liquefaction.

  13. The pile EL3; Pile EL3

    Energy Technology Data Exchange (ETDEWEB)

    Robert, J.; Raievski, V. [Commissariat a l' Energie Atomique, Paris (France). Centre d' Etudes Nucleaires; Hainzelin, J. [Chantiers de l' Atlantique (Penhoet-Loire), 75 - Paris (France)

    1959-07-01

    The programme of the high flux laboratory pile EL3 was laid down in october 1954. It is a heavy-water moderated and cooled pile. The fuel rods are of uranium metal with 1.6 per cent - 2 per cent of molybdenum, with aluminium canning. The maximum thermal flux in the moderator is 10{sup 14} n/cm{sup 2}/s. Studies began in january 1955, construction in may 1955, and the first divergence took place in July 1957. This report gives a general description of the pile and its adjacent buildings, the physical study of the pile, and certain technological studies carried out for the construction of EL3. (author) [French] Le programme de la pile laboratoire a haut flux EL3, a ete fixe en octobre 1954. C'est une pile moderee et refroidie a l'eau lourde. Les barres de combustible sont en uranium metal a 1,6 pour cent - 2 pour cent de molybdene, gainees a l'aluminium. Le flux thermique maximum dans le moderateur est de 10{sup 14} n/cm{sup 2}/s. Les etudes ont commence en janvier 1955, la construction en mai 1955, la premiere divergence a eu lieu en juillet 1957. On trouvera dans ce rapport, une description generale de la pile et de ses batiments annexes, l'etude physique de la pile et un certain nombre d'etudes technologiques executees pour la construction d'EL3. (auteur)

  14. Influence of pile inclination on the lateral capacity of batter piles in clays

    Energy Technology Data Exchange (ETDEWEB)

    Rao, S.N.; Veeresh, C. [Indian Inst. of Tech., Madras (India)

    1994-12-31

    In many coastal and offshore areas, there are several soft clay deposits and in such soils pile foundations are used to support structures. The foundations of these structures are usually subjected to large amounts of lateral loads. In such cases, inclined piles or batter piles are better suited to resist lateral loads as a part of lateral load is converted into axial load. This paper refers to an experimental investigation carried out on model piles installed in soft clayey soils. Tests were conducted on model aluminum pile of diameter 12mm embedded in soft clay bed with batter angle (angle of inclination with vertical varying from {minus}30 to +30) and at each of these inclinations piles were tested for embedment ratios of 30, 40 and 50. The results indicate that the lateral capacity of pile is influenced by angle of inclination and the direction of the load application, and depth of embedment. A method is proposed to predict the load deflection behavior with different inclinations using the results of load tests conducted at a particular inclination.

  15. 运用FLAC3D对水泥土桩加固液化砂土地基的分析%ANALYSIS ON LIQUESCENT SAND FOUNDATION SOIL REINFORCED BY CEMENT PILE WITH FLAC3D

    Institute of Scientific and Technical Information of China (English)

    牛琪瑛; 刘峰; 郭英; 刘少文

    2013-01-01

    该文运用三维有限差分软件FLAC3D(Fast Lagrangian Analysis of Continua)对水泥土桩加固的液化砂土地基建立模型并进行地震响应分析,从计算机数值模拟的角度对水泥土桩加固模型地基竖向位移、超静孔隙水压力、孔压比、剪应变增量、接触面剪力及表面加速度作了较系统地分析,总结了这些参数的变化规律,得到了一些有价值的结论,对实际工程有一定的指导意义.%The three-dimensional finite difference program FLAC3D (Fast Lagrangian Analysis of Continua) is used to establish the model of the improved foundation soil by cement piles and to analyze seismic response.From the point of the numerical analysis,it adopts a visualized way to make a systematic analysis about the vertical displacement,the excess pore water pressure,the pore pressure ratio,the shear strain increment,the shear stress on interface elements and the surface acceleration.It helps us to obtain some valuable conclusions by summarizing the changing patterns of above parameters.It has definite instruct meaning for practical projects in the future.

  16. Computerised analysis of sulphate action on model concrete piles

    Digital Repository Service at National Institute of Oceanography (India)

    Deshmukh, A.M.; Balasubramanian, S.; Venugopal, C.

    Sulphate action severely affects the durability of marine structures. It is imperative to study precisely the effects of magnesium sulphate on pile foundations in the marine environment. In the present paper an attempt is made to assess and analyse...

  17. 单层土地基中静压桩连续贯人的数值模拟%On numeric simulation of continuous of static pressure piles in single-layer foundation

    Institute of Scientific and Technical Information of China (English)

    贺晓明; 唐鹏; 寇海磊

    2012-01-01

    摘要:在ABAQUS平台上利用位移贯入法,模拟了PHC管桩连续贯入的全过程,求得了贯入时桩侧土体位移变化以及应力变化,研究发现桩土之间的摩擦系数对桩侧土体应力场以及位移场的变化具有重要影响。%The paper adopts the displacement penetration method on ABAQUS platform, simulates the general process for the continuous penetra- tion of the PHC pipe pile, achieves the displacement changes of the pile side soil body and its stress changes, and finds by the research that the friction coefficient between the pile and soil has the important influence on the stress field of the pile side soil body and the changes of the dis- placement field.

  18. Experimental study on DX pile performance in frozen soils under lateral loading

    Institute of Scientific and Technical Information of China (English)

    XiaoBing Liu; LiHong Chen; ZhongYang Yu; JianXiao Hu; Wen Peng

    2013-01-01

    Experiments about working mechanism and mechanical characteristics of the DX model pile foundation under lateral dynamic and static loading were conducted by using a model system of the dynamic frozen soil-pile interaction. The horizontal displacement-force relationship of the pile head and bending moment distribution along the body in frozen soils of different temperatures were discussed. According to test results, both the horizontal displacement-force relationship of the DX pile head and bending moment distribution of the DX pile body are smaller than that of equal-diameter piles under same lateral loads. The piles with different plate positions show different displacements and bending moments. This phenomenon is mainly related to the soil temperature and bearing plates locations. Thus, dynamic response analysis of the pile foundation should be taken into account.

  19. Influence of pile-raft foundation reinforcement on subgrade of adjacent existing railway%桩筏地基加固对紧邻既有线路基的影响

    Institute of Scientific and Technical Information of China (English)

    刘维正; 徐林荣; 左珅; 刘长虹; 陈鹏飞

    2015-01-01

    在新建线桩筏地基加固过程中,采用应力铲、水平向土应变计与测斜管对紧邻既有线路基的变形与应力进行原位监测,分析了不同施工阶段紧邻既有线路基变形规律与受力特性。为减小测试误差,建立了路基变形与稳定计算有限元模型,得到了坡脚水平位移换算系数,计算了不同开挖深度的路基最大剪应力与边坡安全系数。基于监测与计算结果,提出了施工期跳槽浇筑、更换桩型与路基坡面喷浆挂网等既有线路基防护措施。为验证防护效果,利用评分法与标准差法分析了轨检车数据。分析结果表明:施工期间紧邻既有线路基累积坡脚水平位移为24.25 mm,平均每天的侧向位移小于0.59 mm,路基坡脚水平位移对施工过程反应敏感,可作为监控既有线路基稳定状况的关键指标;两线之间9 m 深度范围地基土水平应力随不同施工阶段出现挤压回缩变化,压应力小于10 kPa,但不同施工阶段水平应力变化不明显;浸泡条件下基坑开挖至2.2 m 时边坡安全系数由1.08减小为0.54,路基失稳破坏,因此,施工现场必须采取既有线路基坡面防护。施工期间既有线轨检的轨道质量指数(TQI)增幅达129.58%,既有线轨道几何线性波动较大,但 TQI 小于安全限值,即对路基防护优化后既有线路基变形得到有效控制。%During the process of pile-raft foundation reinforcement of new railway, the deformation and stress of subgrade for adjacent existing railway were measured in situ by using stress spade,horizontal strain gauge and inclinometer,and the mechanical characteristics and deformation laws of subgrade were analyzed.In order to minimize test error,a finite element model (FEM)was built to calculate the subgrade deformation and stability,the conversion factor of slope horizontal displacement was obtained,and the maximum shear stress and slope

  20. Underwater noise generated by offshore pile driving

    NARCIS (Netherlands)

    Tsouvalas, A.

    2015-01-01

    Anthropogenic noise emission in the marine environment has always been an environmental issue of serious concern. In particular, the noise generated during the installation of foundation piles is considered to be one of the most significant sources of underwater noise pollution. This is mainly attri

  1. Application of Gujiao Cofferdam in the Construction of Pile Foundations in Deep-water and Slope Rock Condition%固脚围堰在深水坡岩条件下桩基施工中的应用

    Institute of Scientific and Technical Information of China (English)

    姚伟

    2012-01-01

    Cutian Creek Super Major Bridge is located in Cutian county in Fukien province and Minqing county in Fujian province to hand over boundary place, among them 7# main piers are lacated in the central Cutian construction,water depth about 43m, river bed is weak weathered standstone, without overburden and highly level off.within the scope of pile caps is terrain elevation to achieve 5m-7m, cause the steel pipe piles and casings of drilling platforms can not be inserted into the rock steadly.In addition, because of the influence of downstream Shuikou hydropower shiplock, large floating crane can not get into the area,selection of construction equipment severely limited. After the alternative schemes, decide to carry on the construction by lmmersioning the Gujiao cofferdam with Floating gantry. According to the measured data of the elevation of the river, process the steel cofferdam with high and low blade foot.and put together on Floating gantry and sink into the river, use the Floating gantry and crane sink down the steel casings, pouring underwater concrete bottom sealing,and use the steel casings to construct the drilling platforms of the main pier foundations by Floating crane.%古田溪特大桥位于福建省古田县和闽清县交界处,其中7#主墩位于古田溪库区中央,施工水深约43米,河床为弱风化砂岩,无覆盖层而且极不平整,承台范围内地形高差达到5m-7m,造成钻孔平台钢管桩、钢护筒无法插打入岩稳固.此外,因受桥址下游水口电站船闸影响,大型浮吊等施工设备无法进入施工区,施工设备选择严重受限.经过方案比选,决定采用浮龙门下放固脚围堰的方式进行施工.根据已测得的河床标高数据分片加工高低刃脚钢围堰,在浮龙门上拼组成整体并下沉至河床,利用浮龙门和浮吊下放钢护筒,然后浇筑水下封底混凝土,再利用浮吊以稳固好的钢护筒为承力基础,搭设钻孔平台进行承台桩基施工.

  2. The Effects of Time on Soil Behaviour and Pile Capacity

    DEFF Research Database (Denmark)

    Augustesen, Anders

    this into account. This implies that the design methods used today do not in general make use of the full capacity of piles. This thesis is based on a number of scientific papers and reports that deal with elements of pile design and time effects in soils in general. With regard to pile design, focus is placed...... foundations. Further, design methods that take no account of time will be subject to considerable error unless they consider a tightly specified age range. Time functions (relation between time after installation and capacity), which have been offered for quantifying set-up for piles in clay, are investigated....... Therefore, the design of piles has remained a constant source of attention, especially with regard to the methodology for predicting the capacity. Three very different design methods for piles in both clay and sand are assessed by comparing predicted capacities with measured capacities from established...

  3. Experimental Investigations of Tension Piles in Sand Subjected to Static and Cyclic Loading

    DEFF Research Database (Denmark)

    Thomassen, Kristina

    The present thesis regards the behavior of the piles in jacket pile foundations used for offshore wind turbines. The piles are often loaded in tension because of the combination of wind and wave conditions and the low self-weight of the wind turbine. The repeated cyclic loading can lead...... to accumulated upwards displacement of the piles and, thus, undesired deflection of the wind turbine structure. This study concerns the effect of cyclic loading on a pile installed in dense sand and loaded in tension. A new laboratory test setup was constructed to make these pile load tests. The thesis discusses...... the advantages and disadvantages of the test setup. The results of cyclic loading tests showed that the loading conditions are very important for the behavior of piles. Some wind and wave conditions can be beneficial and increase the pile capacity while other conditions can be damaging and reduce the pile...

  4. Behavior of instrumented model batter piles in clay

    Energy Technology Data Exchange (ETDEWEB)

    Narasimha Rao, S.; Veeresh, C. [Indian Inst. of Technology, Madras (India). Ocean Engineering Centre

    1995-12-31

    Pile foundations in several coastal and offshore structures are subjected to significant amounts of lateral loads due to wave action. Usually batter piles are adopted to resist large lateral loads. In this investigation an attempt has been made to study the behavior of batter pile in clayey soils through an experimental program carried out on instrumented model aluminium piles of 26 mm diameter in a test tank of size, 1,200 mm x 800mm x 1,100 mm. The pile was instrumented with electrical resistance type strain gauges to determine the bending moment variations along the depth of embedment of pile. Bending moment vis depth relationships were used to determine the Soil reaction (p) and lateral displacement (y) along the length of the pile for the applied load. From the bending moment vs depth curves it is found that depth of maximum bending moment is greater for negative batter pile than for vertical and positive batter pile. The data of soil reaction and lateral displacement against depth can be used to develop p-y relationships which are useful in the design of laterally loaded piles.

  5. Concept design for sub-system of resisting horizontal forces in pile foundation%建筑桩基抵抗水平力分体系的概念设计

    Institute of Scientific and Technical Information of China (English)

    陈孝堂

    2009-01-01

    Starting from the concept of understanding low capping piles and high capping piles,combined with the earthquake force pile resistance mechanism,it analyzes the reasons for lateral deformation and lateral instability of the pile under the lateral actions,introduces the core issue of piles,soil level of power-sharing,and proposes four sub-systems of resisting horizontal force,including the soil pressure of the side soil layer of the platform or basement and rubed resistance,the axle pressure of batter piles,shear and bending resistance ability of piles,bom platform,underground wall,one and worked and undertaken with the elastic reactance strength of the land in coordination.%从低桩承台、高桩承台的概念理解人手,结合桩基抵抗地震水平力的机理,分析桩基在水平力作用下的侧向变形及失稳的原因,阐述由桩、土分担水平力的核心问题,提出建筑桩基抵抗水平力分体系的系统设计思路,提出由承台或地下室的侧面土层的土压力及摩阻力承担,由斜桩的轴向力承担,由桩的抗剪及抗弯能力承担,由承台、地下墙体、基桩协同工作和土的弹性抗力承担四种分体系.

  6. Prediction of bearing capacity of CFG piles composite foundation based on wavelet neural network%基于小波神经网络的CFG桩复合地基承载力预测

    Institute of Scientific and Technical Information of China (English)

    李万庆; 闫冠勇; 孟文清; 石华旺

    2011-01-01

    针对BP神经网络学习时间长、收敛速度慢等缺陷,借助小波分析理论,将母小波平移和伸缩构成的小波基作为神经网络的激励函数,通过指导网络的初始化和参数选取,使网络以较简单的拓扑结构实现函数逼近,利用网络训练建立起承载力与其影响因素之间的非线性关系.在相同结构和参数下,与BP神经网络进行分析对比.结果表明:利用小波变换对数据时频局域化分析的能力并结合人工神经网络的自学习功能,使得小波神经网络预测模型具有较强的逼近和容错能力,预测结果比传统的BP神经网络具有更快的收敛速度和更高的精度.%Aiming at the long training time and slow convergence rate of BP neural network, wavelet basis consisted by the translation and stretch of mother wavelet constitutes the activation function of neural network basing on the theory of wavelet analysis. The neural network can use simple topology to approximate function by the guidance of network initialization and parameters selection. The nonlinear relationship between the bearing capacity of CFG piles composite foundation and its main factors is established by using the trained network. Under the same structure and parameters, the prediction results are analyzed and compared with the BP neural network. The result shows that this forecast model makes full use of the wavelet transformation to analysis the data of time - frequency localization and is combined with the self- learning function of artificial neural network,which makes it have a strong a-bility to approach and fault tolerance. The precision and speed by using the trained wavelet neural network is higher and its predicting result is more accurate than that of BP network.

  7. 声波透射法在基桩检测中影响因素的深入分析%Analysis and Discussion About the Influencing Factors in the Pile Foundation Test by Acoustic Wave Transmission Method

    Institute of Scientific and Technical Information of China (English)

    赵守全; 赵常要; 朱兆荣

    2016-01-01

    This article is based on sound wave transmission method,analyzes the influence factors of pile foundation testing and points out the factors of the testing instrument,acoustic detecting tube material,temperature of testing environment, blocking pipe and tubes which are not parallel will affect the test results.Therefore,the influence degree of the influence factors on the test results and its mechanism are carried on analysis thoroughly,such as sound velocity anomaly problems caused by the acoustic detection tube is not parallel,although correction method is more,there are some limitations and shortcomings.The paper,adopts the correction method based on acoustic detecting tube space position relations,has achieved good correction effect,and consequently presents the corresponding processing methods or measures to reduce the influence degree of these factors on the test results,and finally the reliability of the testing results of sound wave transmis-sion method is improved.%本文就声波透射法在基桩检测中的影响因素这一问题进行了深入分析,指出了检测仪器、声测管材质、检测环境的温度、堵管、声测管不平行等因素都会对结果分析产生影响,并针对这些因素对检测结果的影响程度及机理进行了深入分析,如声测管不平行引起的声速异常问题,虽然修正方法较多,但都有一定的局限性和弊端,本文采用了基于声测管空间位置关系的修正方法取得了良好的修正效果,进一步给出了相应的处理方法或措施,使这些因素对检测结果的影响程度有效降低,提高了声波透射法检测结果的可信度。

  8. 酸性水环境下桥梁桩基混凝土的配制与耐久性研究%Preparation and Durability of Concrete for Bridge Pile Foundation in Acidic Water Environment

    Institute of Scientific and Technical Information of China (English)

    刘江; 曾逢春; 蔡老虎; 王在喜; 邵然; 李北星

    2012-01-01

    Aiming at the preparation of bridge pile foundation concrete in acidic water environment,the effect of mineral admixtures, water-binder (w/b) ratio and pH value of erosion environment on acid resistance of concrete is studied. Cement is replaced by fly ash (FA) with the incorporation amount from 20% to 50% or by ground granulated blast-furnace slag (GGBS) from 35% to 65%. The w/b ratio is 0. 35,0. 39 and 0. 43 respectively. The acidic environmental conditions are simulated by using sulfuric acid solution with the pH value 1,2 or 4. The corrosion process was monitored by measuring the compressive strength for a period of one year. The results showed that a reduce in the w/b ratio improved the acid resistance of concrete. It was found that the improvement effect of mineral admixture on acid attack of concrete is dependent on the type and dosage mixture admixture and the pH value of simulation erosion solution. The high volume fly ash concrete mixtures performed better than high volume ground granulated blast-furnace slag concrete mixtures.%针对酸性水环境下桥梁桩基混凝土的配制,研究了矿物掺合料、水胶比以及侵蚀溶液pH值对混凝土抗酸侵蚀性能的影响.混凝土的粉煤灰掺量从20%~50%变化,矿粉掺量从35 %~65%变化,水胶比分别取0.35、0.39、0.43,酸性水侵蚀环境通过pH值分别为1、2、4的硫酸溶液模拟,抗酸性能通过测定1年龄期的混凝土抗压强度变化率表征.结果表明,降低水胶比有利于提高混凝土的抗酸侵蚀性能;矿物掺合料对混凝土耐酸性能的改善作用与其品种、掺量及模拟侵蚀溶液的pH值大小有关.大掺量粉煤灰混凝土比大掺量矿渣粉混凝土具有更好的耐酸性能.

  9. Piles of objects

    KAUST Repository

    Hsu, Shu-Wei

    2010-01-01

    We present a method for directly modeling piles of objects in multi-body simulations. Piles of objects represent some of the more interesting, but also most time-consuming portion of simulation. We propose a method for reducing computation in many of these situations by explicitly modeling the piles that the objects may form into. By modeling pile behavior rather than the behavior of all individual objects, we can achieve realistic results in less time, and without directly modeling the frictional component that leads to desired pile shapes. Our method is simple to implement and can be easily integrated with existing rigid body simulations. We observe notable speedups in several rigid body examples, and generate a wider variety of piled structures than possible with strict impulse-based simulation. © 2010 ACM.

  10. 柔性基础下筋箍碎石桩复合地基变形机理及其沉降分析方法%Deformation mechanism and settlement analysis method of reinforced-hoop-gravel-pile composite ground under flexible foundation

    Institute of Scientific and Technical Information of China (English)

    曹文贵; 赵聚才; 贺敏; 王江营

    2014-01-01

    筋箍碎石桩复合地基是一种新型的软土地基处理方法,其沉降分析是地基处理加固设计的重要依据。因此,首先结合柔性基础下筋箍碎石桩复合地基的工程特点,通过深入研究筋箍碎石桩复合地基变形力学机理,将复合地基划分为碎石桩筋箍段、非筋箍段和下卧层三部分,建立出筋箍碎石桩复合地基沉降计算模型。然后,通过考虑筋箍碎石桩复合地基筋箍段桩土相对滑移和非筋箍段桩土径向变形即“鼓胀效应”特点,引入典型桩土单元分析模型,分别建立出碎石桩筋箍段和非筋箍段压缩变形计算方法,进而提出了柔性基础下筋箍碎石桩复合地基沉降分析新方法。最后,通过工程实例计算,并与实测值及现有方法计算结果进行对比分析,表明该方法更能反映工程实际情况,克服了现有方法分析结果偏于危险的缺陷。%The reinforced-hoop-gravel-pile composite ground is a new method for treating soft soil ground, and its settlement analysis method is an important basis of the ground foundation reinforcement design. Firstly, the mechanical mechanism of the reinforced-hoop-gravel-pile composite ground under flexible foundation is discussed based on its engineering characteristics. The composite ground is divided into three sections: reinforced-hoop section, unreinforced-hoop section of gravel-pile and substratum section. A settlement analysis model for the reinforced-hoop-grave-pile composite ground is developed. Secondly, the pile-soil relative slip of the reinforced-hoop section and the radial deformation (e.g., lateral displacement of gravel pile) of the unreinforced-hoop section are taken into account. An analytical model with typical pile-soil element is imported, and the compressive deformation analysis methods for the reinforced-hoop and unreinforced-hoop sections are established respectively. Therefore, a new settlement analysis method

  11. 盐水环境下水泥土桩劣化效应及其对道路复合地基沉降的影响%Deterioration Effect of Soil-cement Pile Under Saltwater Environment and Its Influence on Composite Foundation Settlement of Road

    Institute of Scientific and Technical Information of China (English)

    崔新壮; 龚晓南; 李术才; 汤潍泽; 张炯

    2015-01-01

    In order to reveal deterioration effect of soil-cement pile in saltwater environment and its influence on road composite foundation settlement,the deterioration effect of soil-cement in Yellow River Delta in saltwater environment was investigated by model test.The deterioration depth of soil-cement and evolution laws of compressive strength in non-deteriorated regions were analyzed.Based on the conclusion of previous researches on soil-cement deterioration,a practical prediction method for entire life-cycle bearing capacity of soil-cement piles in saltwater environment was proposed based on soil-cement early strength test.At the same time,influence of deterioration of soil-cement pile on composite foundation settlement was investigated by model test and numerical simulation.The results show that during reinforcing the soft subsoil with high salinity groundwater,soil-cement piles are deteriorated from outside to inside.Deterioration of soil-cement has a great influence on bearing capacity of mixed pile,which increases settlement of composite foundation.Furthermore,the pile defects will aggravate deterioration effect of soilcement pile.In order to ensure sustainable stability of subgrade and control its long-term settlement,deterioration of soil-cement should be considered during the design of composite foundation in saltwater region.%为了揭示盐水环境下水泥土桩的劣化效应及其对道路复合地基沉降的影响,通过室内模型试验研究了黄河三角洲盐水环境下水泥土的劣化效应,分析了水泥土劣化深度和未劣化部分抗压强度的演化规律.通过对已有水泥土劣化研究成果进行总结分析,提出了基于水泥土早期强度试验的盐水环境下水泥土桩全寿命周期承载力实用预测方法;同时,通过模型试验和数值模拟研究了水泥土桩劣化对复合地基沉降的影响.研究结果表明:在加固地下水矿化度高的软弱地基时,水泥土桩会从外向内逐渐劣化;

  12. Vertical Dynamic Stiffness of Offshore Foundations

    DEFF Research Database (Denmark)

    Latini, Chiara; Cisternino, Michele; Zania, Varvara

    2016-01-01

    Nowadays, pile and suction caisson foundations are widely used to support offshore structures which are subjected to vertical dynamic loads. The dynamic soil-structure interaction of floating foundations (foundations embedded in a soil layer whose height is greater than the foundation length...

  13. Analysis on Safety during Construction Process for Large-Scale and Super-Long Steel Sheet Pile Cofferdam of Deepwater Foundation%深水基础大规模超长钢板桩围堰施工过程安全性分析

    Institute of Scientific and Technical Information of China (English)

    汤劲松; 熊保林

    2013-01-01

    以阜阳至六安铁路颍河特大桥主墩深水基础超长钢板桩围堰施工为例,考虑钢板桩、内支撑和周围土体相互作用,运用ANSYS软件,建立其三维整体有限元模型,分别对静水和流水条件下超长钢板桩围堰施工过程进行力学行为及安全性分析.结果表明:钢板桩桩身水平位移随着工序的推进不断增大,最大水平位移位于基坑开挖面附近;每道内支撑最大轴向应力出现在该道内支撑施工完成以后的第1个抽水吸泥工序,并随工序的推进而波动变化;施工过程中应该特别注意最后2个工序的施工安全;流水压力对钢板桩围堰的影响主要体现在迎水面的钢板桩桩身水平位移有所增大;基底抗隆起和围堰整体抗倾覆安全系数均满足相关规范要求,施工过程结构是安全的.%A case study was done for the super-long steel sheet pile cofferdam construction practice of the main pier deepwater foundation at Ying River super major bridge of Fuyang-Lu'an Railway.Three-dimen-sional finite element model was established by ANSYS software considering the interactions among steel sheet pile,internal bracing and surrounding soil mass.The mechanical behaviors and safety were analyzed during construction process by simulation analysis for super-long steel sheet pile cofferdam under still water and running water conditions respectively.The results show that the horizontal displacement of steel sheet pile increases constantly with the driving on of construction procedures,and the position of maximum horizontal displacement is located next to the excavation face of foundation pit.The maximum axial stress of each internal bracing appears at the first construction procedure of water pumping and mud suction after its installation,and it fluctuates with the advancement of construction procedures.The construction safety of the last two procedures should be paid special attentions during construction process

  14. Vertical Dynamic Impedance of Tapered Pile considering Compacting Effect

    Directory of Open Access Journals (Sweden)

    Wenbing Wu

    2013-01-01

    Full Text Available Based on complex stiffness transfer model, the vertical vibration of tapered pile embedded in layered soil is theoretically investigated by considering the compacting effect of the soil layer surrounding the tapered pile in the piling process. Allowing for the stratification of the surrounding soil and variable crosssection of the tapered pile, the pile-soil system is discretized into finite segments. By virtue of the complex stiffness transfer model to simulate the compacting effect, the complex stiffness of different soil segments surrounding the tapered pile is obtained. Then, substituting the complex stiffness into the vertical dynamic governing equation of tapered pile, the analytical solution of vertical dynamic impedance of tapered pile under vertical exciting force is derived by means of the Laplace technique and impedance function transfer method. Based on the presented solutions, the influence of compacting effect of surrounding soil on vertical dynamic impedance at the pile head is investigated within the low frequency range concerned in the design of dynamic foundation.

  15. Distributed fibre optic strain measurements on a driven pile

    Science.gov (United States)

    Woschitz, Helmut; Monsberger, Christoph; Hayden, Martin

    2016-05-01

    In civil engineering pile systems are used in unstable areas as a foundation of buildings or other structures. Among other parameters, the load capacity of the piles depends on their length. A better understanding of the mechanism of load-transfer to the soil would allow selective optimisation of the system. Thereby, the strain variations along the loaded pile are of major interest. In this paper, we report about a field trial using an optical backscatter reflectometer for distributed fibre-optic strain measurements along a driven pile. The most significant results gathered in a field trial with artificial pile loadings are presented. Calibration results show the performance of the fibre-optic system with variations in the strain-optic coefficient.

  16. Application of PCC pile in soil improvement of highway

    Institute of Scientific and Technical Information of China (English)

    刘芝平; 刘汉龙; 谭慧明

    2008-01-01

    The construction process and load-bearing behaviors of Cast-in-place concrete thin-wall pipe piles are analyzed based on its application on Yantong Expressway Project. The low strain test, static load test and field excavation were also carried out, and the bearing capacity of the new pile can meet the requirements of design. With the increase of pile diameter, the bearing capacity is increased. The settlement of composite foundation is decreased, when the replacement ratio of pile is increased. The test results also show that the load carried by inner soils is neglectable. According to the tests and application, it can be concluded that the new type of pile is convenient to construction with high bearing capacity and reliable quality, which has great potential in practical engineering.

  17. Suitability Analysis of Pile-column Pier Foundation Using Low Strain Method and In Situ Experiments%桥梁桩柱式基础低应变法检测适宜性分析及现场试验

    Institute of Scientific and Technical Information of China (English)

    杨宇; 马晔

    2014-01-01

    The propagation of stress waves in a pile-column system was analyzed using the elastic-ity theory and was verified by in situ experimentation.This study first analyses the propagation of a semi-spherical stress wave after transient shock in a column-pile system according to the Saint-Venant principle.The results indicate that the stress wave caused by shock on top of the bent cap or on a combined section of pile and column can still satisfy the plane section.A method is intro-duced to verify this assumption in which shock is applied to a certain point in a pile-column sys-tem,and the peak time of the stress wave is collected in the same section by conducting a multi-channel equipment.If the difference of each peak time is less than a certain value,it can be conclu-ded that the wave propagation is unanimous and satisfies the plane section.Two groups of in situ tests were performed on a pile-column system in which shock was applied to the top of the bent cap and to a combined section of pile and column.Stress waves were collected on the section at the top of the column,the combined section of pile and column,and the pile section under the tie beam.When shock was applied to the top of the bent cap,the wave velocity value was in a com-mon range,and the stress waves reached the outer edge of the pile section synchronously.It was considered that the stress wave reached the center of the same section at the same time by calcu-lating the difference in peak time of the stress wave at the outer edge and at center of the section. Thus,it was concluded that the plane section can be applied in such a mode.However,this conclu-sion is not completely valid when the stress wave in the pile is caused by shock on the combined section of the pile.In the pile section near the tie beam,the value of the peak time of the stress wave in each channel varied;therefore,the stress wave did not reach the center of the section at the same time.However,in the pile section slightly far from the

  18. Residual settlement calculation of geocell cushion over gravel piles

    Institute of Scientific and Technical Information of China (English)

    陈昌富; 杨宇; 肖淑君; 周志军

    2008-01-01

    The calculation of residual settlement of bidirectional reinforced composite foundation, which is composed of geocell cushion over gravel piles, was studied. The geocell cushion was modeled as a thin flexible plate with large deflection. Based on the Kirchhoff hypothesis, the governing differential equations and boundary conditions of the deformation of geocell cushion under working load were founded using von Karman method and solved by Galerkin method. On theses bases, the gravel piles and inter-pile soils were assumed as Winkler ground with variable spring stiffness so as to execute the approximate calculation of the residual settlement of the bidirectional reinforced composite foundation. The calculation method was verified by two laboratory experiments concerning settlement of embankments. One experiment was with just geocell cushion installed to treat the soft clay under embankments; another one was with both geocell cushion and gravel piles installed. The results show that the calculated settlement curve and the maximum settlement are closed to the observed ones.

  19. Analysis of static and dynamic pile-soil-jacket behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Mohammad Reza Emami

    1998-12-31

    In the offshore industry, recent extreme storms, severe earthquakes and subsidence of the foundation of jacket platforms have shown that new models and methods must take into account the jacket- pile-soil foundation interaction as well as the non-linear dynamic performance/loading effects. This thesis begins with a review of the state of art pile-soil interaction model, recognizing that most existing pile-soil models have been established based on large diameter pile tests on specific sites. The need for site independent and mechanistic pile-soil interaction models led to the development of new (t-z) and (p-y) disk models. These are validated using the available database from recent large diameter pile tests in the North Sea and Gulf of Mexico. The established static disk models are applied for non-linear static analysis of the jacket-pile-soil system under extreme wave loading. Dynamic pile-soil interaction is studied and a new disk-cone model is developed for the non-linear and non-homogeneous soils. This model is applied to both surface and embedded disks in a soil layer with non-linear properties. Simplified non-linear as well as more complex analysis methods are used to study the dynamic response of the jacket platform under extreme sea and seismic loading. Ductility spectra analysis is introduced and used to study the dynamic performance of the jacket systems near collapse. Case studies are used to illustrate the effects of structural, foundation failure characteristics as well as dynamic loading effects on the overall performance of the jacket-pile-soil systems near ultimate collapse. 175 refs., 429 figs., 70 tabs.

  20. Comparative Model Tests of SDP and CFA Pile Groups in Non-Cohesive Soil

    Science.gov (United States)

    Krasiński, Adam; Kusio, Tomasz

    2015-02-01

    The research topic relates to the subject of deep foundations supported on continuous flight auger (CFA) piles and screw displacement piles (SDP). The authors have decided to conduct model tests of foundations supported on the group of piles mentioned above and also the tests of the same piles working as a single. The tests are ongoing in Geotechnical Laboratory of Gdaňsk University of Technology. The description of test procedure, interpretation and analysis of the preliminary testing series results are presented in the paper.

  1. Comparative Model Tests of SDP and CFA Pile Groups in Non-Cohesive Soil

    Directory of Open Access Journals (Sweden)

    Krasiński Adam

    2015-02-01

    Full Text Available The research topic relates to the subject of deep foundations supported on continuous flight auger (CFA piles and screw displacement piles (SDP. The authors have decided to conduct model tests of foundations supported on the group of piles mentioned above and also the tests of the same piles working as a single. The tests are ongoing in Geotechnical Laboratory of Gdaňsk University of Technology. The description of test procedure, interpretation and analysis of the preliminary testing series results are presented in the paper.

  2. A Pile of Legos.

    Science.gov (United States)

    DePino, Andrew, Jr.

    1994-01-01

    Describes the relationships a high school built with neighborhood industry, a national laboratory, a national museum, and a large university while trying to build a scale model of the original atomic pile. Provides suggestions for teachers. (MVL)

  3. Visualization of soil arching in flexible piled embankments

    Indian Academy of Sciences (India)

    Tuğba Eskışar

    2015-10-01

    Piled embankments rely on soil arching, but, when geogrid reinforcements are used, membrane action within the reinforcement contributes to load distribution. The arching of soil in unreinforced and reinforced piled embankments is evaluated in this study. A small-scale test apparatus is used to model the settlement up to 5 mm in an embankment with four pile elements. Visual inspection of the soil settlement and soil-reinforcement interaction is important to explain the mechanism of arching. In this study, X-ray Computed Tomography (CT) method was used as a non-destructive technique. The arching of soil between the piles was observed in the case of rigid piles and in the case of flexible piles with grid type of reinforcement. The load carrying capacity increased up to 33% in the case of geogrid reinforcement, and the differential settlement decreased around 35%, proving the efficiency of piled embankments with geogrid reinforcements. It is also shown that, using X-ray CT method and visualization techniques provides a better understanding of soil behavior in a reinforced embankment with the flexible pile foundation system.

  4. Foundation stiffness in the linear modeling of wind turbines

    Science.gov (United States)

    Chiang, Chih-Hung; Yu, Chih-Peng; Chen, Yan-Hao; Lai, Jiunnren; Hsu, Keng-Tsang; Cheng, Chia-Chi

    2017-04-01

    Effects of foundation stiffness on the linear vibrations of wind turbine systems are of concerns for both planning and construction of wind turbine systems. Current study performed numerical modeling for such a problem using linear spectral finite elements. The effects of foundation stiffness were investigated for various combinations of shear wave velocity of soil, size of tower base plate, and pile length. Multiple piles are also included in the models such that the foundation stiffness can be analyzed more realistically. The results indicate that the shear wave velocity of soil and the size of tower base plate have notable effects on the dominant frequency of the turbine-tower system. The larger the lateral dimension, the stiffer the foundation. Large pile cap and multiple spaced piles result in higher stiffness than small pile cap and a mono-pile. The lateral stiffness of a mono-pile mainly depends on the shear wave velocity of soil with the exception for a very short pile that the end constraints may affect the lateral vibration of the superstructure. Effective pile length may be determined by comparing the simulation results of the frictional pile to those of the end-bearing pile.

  5. Response of carrying capacity of piles induced by adjacent Metro tunneling

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-jie; DENG Fei-huang; WU Jia-jia; LIU Jian; WANG Fu-qiang

    2009-01-01

    Construction of tunnels in urban areas requires assessment of the impact of tunneling on the stability and integrity of existing pile foundations. We have focused our attention to the analysis of the carrying capacity of pile foundations provided by the impact of construction of urban tunnels on adjacent pile foundations, under the engineering background of the construction of the # 2 Line of the Guangzhou subway. It is carried out using a fast Lagrangian analysis of a continuum in a 3D numerical code, which is an elastoplastic three-dimensional finite difference model, to simulate the response of piles under the entire process of metro tun-neling (deactivation of soil element and activation of the lining). The adjacent stratum around the tunnel is classified into three re-gions: Zone Ⅰ(upper adjacent stratum of tunnel), Zone Ⅱ (45°-upper-lateral adjacent stratum of tunnel) and Zone Ⅲ (lateral adjacent stratum of tunnel). In each region one typical pile is chosen to be calculated and analyzed in detail. Numerical simulations are mainly conducted at three points of each pile shaft: the side-friction force of the pile, the tip resistance of the pile and the axial loading of the pile. A contrasting analysis has been conducted both in the response of typical piles in different regions and from computer calculated values with site monitoring values. The results of numerical simulations show that the impact on carrying ca-pacity of the piles lies mainly in the impact of construction of urban tunnels on the side-friction forces and the tip resistance of piles. The impact differs considerably among the different strata zones where the pile tips are located. The complicated rules of side-friction force and tip resistance of piles has resulted in complicated rules of pile axial loading thus, in the end, it impacts the carrying capacity of pile-foundations. It is necessary to take positive measures, such as stratum grouting stabilization or foundation underpinning, ete

  6. Numerical analysis of pile lateral behavior of pile supported embankment

    Institute of Scientific and Technical Information of China (English)

    荆志东; 刘力; 郑刚; 姜岩

    2008-01-01

    A finite difference numerical method was adopted to evaluate the pile lateral behavior of pile supported embankment. A published case history was used to verify the proposed methodology. By simulating the case history, the determination of parameters needed were verified. Then three embankments constructed on different ground conditions with different soil-pile relative stiffnesses were analyzed to study pile lateral behaviors including pile deflection and bending moment. The results show that pile deflections and bending moments induced by soil lateral deformation and embankment vertical load are different for piles at different positions under the same embankment. The relative stiffness between pile and soil affected by the properties of different reinforcing piles such as concrete pile and deep mixing method pile exert important effects on the pile lateral behavior and the pile’s failure modes. Consequently, it is necessary to consider the different piles lateral behaviors and possible failure modes at different positions and the different piles proprieties with different reinforcing methods in the embankment stability analysis.

  7. Behavior of Pile Group with Elevated Cap Subjected to Cyclic Lateral Loads

    Institute of Scientific and Technical Information of China (English)

    陈云敏; 顾明; 陈仁朋; 孔令刚; 张浙杭; 边学成

    2015-01-01

    The pile group with elevated cap is widely used as foundation of offshore structures such as turbines, power transmission towers and bridge piers, and understanding its behavior under cyclic lateral loads induced by waves, tide water and winds, is of great importance to designing. A large-scale model test on 3×3 pile group with elevated cap subjected to cyclic lateral loads was performed in saturated silts. The preparation and implementation of the test is presented. Steel pipes with the outer diameter of 114 mm, thickness of 4.5 mm, and length of 6 m were employed as model piles. The pile group was cyclic loaded in a multi-stage sequence with the lateral displacement controlled. In addition, a single pile test was also conducted at the same site for comparison. The displacement of the pile cap, the internal forces of individual piles, and the horizontal stiffness of the pile group are presented and discussed in detail. The results indicate that the lateral cyclic loads have a greater impact on pile group than that on a single pile, and give rise to the significant plastic strain in the soil around piles. The lateral loads carried by each row of piles within the group would be redistributed with loading cycles. The lateral stiffness of the pile group decreases gradually with cycles and broadly presents three different degradation patterns in the test. Significant axial forces were measured out in some piles within the group, owing to the strong restraint provided by the cap, and finally lead to a large settlement of the pile group. These findings can be referred for foundation designing of offshore structures.

  8. Behavior of pile group with elevated cap subjected to cyclic lateral loads

    Science.gov (United States)

    Chen, Yun-min; Gu, Ming; Chen, Ren-peng; Kong, Ling-gang; Zhang, Zhe-hang; Bian, Xue-cheng

    2015-06-01

    The pile group with elevated cap is widely used as foundation of offshore structures such as turbines, power transmission towers and bridge piers, and understanding its behavior under cyclic lateral loads induced by waves, tide water and winds, is of great importance to designing. A large-scale model test on 3×3 pile group with elevated cap subjected to cyclic lateral loads was performed in saturated silts. The preparation and implementation of the test is presented. Steel pipes with the outer diameter of 114 mm, thickness of 4.5 mm, and length of 6 m were employed as model piles. The pile group was cyclic loaded in a multi-stage sequence with the lateral displacement controlled. In addition, a single pile test was also conducted at the same site for comparison. The displacement of the pile cap, the internal forces of individual piles, and the horizontal stiffness of the pile group are presented and discussed in detail. The results indicate that the lateral cyclic loads have a greater impact on pile group than that on a single pile, and give rise to the significant plastic strain in the soil around piles. The lateral loads carried by each row of piles within the group would be redistributed with loading cycles. The lateral stiffness of the pile group decreases gradually with cycles and broadly presents three different degradation patterns in the test. Significant axial forces were measured out in some piles within the group, owing to the strong restraint provided by the cap, and finally lead to a large settlement of the pile group. These findings can be referred for foundation designing of offshore structures.

  9. Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model

    OpenAIRE

    Guodong Deng; Jiasheng Zhang; Wenbing Wu; Xiong Shi; Fei Meng

    2014-01-01

    By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solu...

  10. Bending behavior of double-row stabilizing piles with constructional time delay

    Institute of Scientific and Technical Information of China (English)

    Yang YU; Yue-quan SHANG; Hong-yue SUN

    2012-01-01

    The bending behavior of double-row stabilizing plies is associated with the constructional time delay (CTD),which can be defined as the time interval between the installations of the front stabilizing pile and the rear stabilizing pile.This paper investigates the effect of CTD on the bending moments of double-row stabilizing piles and a method for determining the optimal CTD is proposed.The stabilizing pile is modeled as a cantilever pile embedded in the Winkler elastic foundation.A triangular distributed earth pressure is assumed on the pile segment in the sliding layer.The front stabilizing pile and the rear stabilizing pile are connected by a beam with pinned joints.The analytical solutions of bending moments on the front and the rear stabilizing piles are derived and the accuracy of bending moment solutions is validated by comparing the tensile strain measured from the Hongyan landslide project,Taizhou,Zhejiang,China.It is concluded that CTD has a significant influence on the bending moments of double-row stabilizing piles.An optimal CTD can be obtained when the maximum tensile stress in the front stabilizing pile is equal to that in the rear stabilizing pile,which is 1.4 months for the Hongyan landslide project.

  11. Field test and numerical simulation of pile-slab foundation of 500 kV transmission line tower in silt%软基中500kV输电桩板塔基现场试验与数值模拟

    Institute of Scientific and Technical Information of China (English)

    刘振平; 贺怀建; 白世伟; 张华; 邹丹; 李火兵

    2012-01-01

    A new foundation type called pile-slab base is introduced for the 500kV transmission line tower according to the geological conditions of silt. Then the field mechanical tests of heap loading and uplifting are done for this new foundation after the pile integrity testing. At the same time, the pressure of the slab, the stress of steel bar meters and the displacement deformation of four corners of the slab and pile are monitored. The results show that the compressive and uplifting resistance performance is excellent and the foundation can function as a whole to resist deformation; the engineering demand also can be satisfied. Moreover, the field test is simulated by the ABAQUS software; the conclusions are verified further on the basis of consistence between numerical calculation results and test data; therefore, the numerical model can be applied to other mechanical simulation reliably.%针对软弱淤泥地质条件下500kV输电线铁塔桩板基础型式,在对桩进行完整性检测后,又对整个桩板基础进行了现场堆载、上拔力学试验,同时监测板底压力与桩身钢筋计的受力状况以及大板4脚、基柱的位移变形.试验结果表明,桩板基础具有良好的抗压、抗拔性能,在抵御外载荷作用时,表现出良好的整体性,能够很好地满足工程的需要;通过ABAQUS建立计算模型,在模拟结果与试验数据基本一致的基础上,进一步验证了现场试验的结论,为模拟桩板基础其他受力工况提供了可靠的模型依据.

  12. Contribution to Estimating Bearing Capacity of Pile in Clayey Soils

    Science.gov (United States)

    Drusa, Marián; Gago, Filip; Vlček, Jozef

    2016-12-01

    The estimation of real geotechnical parameters is key factor for safe and economic design of geotechnical structures. One of these are pile foundations, which require proper design and evaluation due to accessing more deep foundation soil and because remediation work of not bearable piles or broken piles is a crucial operation. For this reason, geotechnical field testing like cone penetration test (CPT), standard penetration (SPT) or dynamic penetration test (DP) are realized in order to receive continuous information about soil strata. Comparing with rotary core drilling type of survey with sampling, these methods are more progressive. From engineering geologist point of view, it is more important to know geological characterization of locality but geotechnical engineers have more interest above the real geotechnical parameters of foundation soils. The role of engineering geologist cannot be underestimated because important geological processes in origin or during history can explain behaviour of a geological environment. In effort to streamline the survey, investigation by penetration tests is done as it is able to provide enough information for designers. This paper deals with actual trends in pile foundation design; because there are no new standards and usable standards are very old. Estimation of the bearing capacity of a single pile can be demonstrated on the example of determination of the cone factor Nk from CPT testing. Then results were compared with other common methods.

  13. Contribution to Estimating Bearing Capacity of Pile in Clayey Soils

    Directory of Open Access Journals (Sweden)

    Drusa Marián

    2016-12-01

    Full Text Available The estimation of real geotechnical parameters is key factor for safe and economic design of geotechnical structures. One of these are pile foundations, which require proper design and evaluation due to accessing more deep foundation soil and because remediation work of not bearable piles or broken piles is a crucial operation. For this reason, geotechnical field testing like cone penetration test (CPT, standard penetration (SPT or dynamic penetration test (DP are realized in order to receive continuous information about soil strata. Comparing with rotary core drilling type of survey with sampling, these methods are more progressive. From engineering geologist point of view, it is more important to know geological characterization of locality but geotechnical engineers have more interest above the real geotechnical parameters of foundation soils. The role of engineering geologist cannot be underestimated because important geological processes in origin or during history can explain behaviour of a geological environment. In effort to streamline the survey, investigation by penetration tests is done as it is able to provide enough information for designers. This paper deals with actual trends in pile foundation design; because there are no new standards and usable standards are very old. Estimation of the bearing capacity of a single pile can be demonstrated on the example of determination of the cone factor Nk from CPT testing. Then results were compared with other common methods.

  14. Application of Pile Anchor System in Super Deep Foundation Excavation of the People’ s Daily Project%桩锚体系在人民日报社报刊综合业务楼超深基坑支护中的应用

    Institute of Scientific and Technical Information of China (English)

    白志华; 郭金武; 李哲琳; 赵海军

    2014-01-01

    结合人民日报社报刊综合业务楼项目,通过支护方案比选,最后确定采用护坡桩结合预应力锚杆体系(简称桩锚体系)进行支护,就其在超深基坑支护中的应用进行了总结和分析。最终确定了桩锚体系的设计参数,并对护坡桩桩间土支护进行了设计。实践表明本工程中的支护方案较为合理,符合安全可靠性要求。%In the People’ s Daily Integrated Business Building project, by using the results generated by plan comparison, a combination system with slope wall piling and prestressed anchor has been used for the basement supporting. This paper introduces the application and utilization of the combination system which is used in the deep foundation excavation site. Finally, design parameters of the combination system have been conducted. It helps to design a support system of the soil among the piles. The real practice shows that the plan is reasonable. It is consistent with safety requirements.

  15. The Application and Design of High Pressure Jet Grouting Pile in the Sluice Foundation Treatment of Both Sides of Qiantang River%高压旋喷桩在钱塘江两岸水闸地基处理中的应用设计

    Institute of Scientific and Technical Information of China (English)

    王立新

    2013-01-01

      Along with the use of sluice operation, it exposed the defects of the tidal gate: the uneven settlement between each part of the sluice is serious. According to the investigation and analysis of risks, the main reason of the situation formation is that the sluice foundation is washed away by the tide. High pressure jet grouting pile can be used not only as the foundation reinforcement of existing buildings and new buildings, but also can be used as a temporary measure in construction (such as retaining soil and water, waterproof of deep foundation pit side etc. ), especially as the best way of the sluice foundation reinforcement of both sides of Qiantang River. The use of high pressure jet grouting pile technology in sluice foundation treatment has achieved satisfying results.%  随着水闸的运行使用,暴露出一个这一带挡潮闸的通病:水闸各段各部位之间不均匀沉降严重。根据险情调查分析,出现该状况的主要原因是潮水对水闸地基的冲刷所致。高压旋喷桩不仅可作为既有建筑和新建建筑的地基加固之用,也可作为施工中的临时措施(如深基坑侧壁挡土或挡水、防水帷幕等),尤其是目前钱塘江两岸水闸的地基加固、防渗处理的最佳方法。目前在该地区相关水闸地基处理中采用高压旋喷桩技术,取得了令人较满意的结果。

  16. Analysis of Wave Fields induced by Offshore Pile Driving

    Science.gov (United States)

    Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.

    2015-12-01

    Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.

  17. Flexible pile thermal barrier insulator

    Science.gov (United States)

    Anderson, G. E.; Fell, D. M.; Tesinsky, J. S. (Inventor)

    1978-01-01

    A flexible pile thermal barrier insulator included a plurality of upstanding pile yarns. A generally planar backing section supported the upstanding pile yarns. The backing section included a plurality of filler yarns forming a mesh in a first direction. A plurality of warp yarns were looped around said filler yarns and pile yarns in the backing section and formed a mesh in a second direction. A binder prevented separation of the yarns in the backing section.

  18. Laterally Loaded Piles in Clay

    DEFF Research Database (Denmark)

    Christensen, Helle; Niewald, Gitte

    1992-01-01

    The ultimate lateral resistance of a pile element moved horizontally can be analyzed by the theory of plasticity. At a certain depth the movements around the pile are purely horizontal and upper bound solutions can be estimated theoretically under undrained circumstances. Model tests...... in the laboratory show ultimate resistances close to the estimated limits and p - y curves close to curves based on test results from full-scale piles. Rough and smooth piles with circular and square cross sections are investigated....

  19. Small-Scale Cyclic Tests on Nonslender Piles Situated in Sand

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

    In the period from August 2011 till October 2011 a series of small-scale tests on pile foundations has been conducted at Aalborg University. In all the tests, the piles have been exposed to cyclic loading consisting of 20-25 load cycles and all the tests have been conducted in a pressure tank...

  20. Small-Scale Quasi-Static Tests on Non-Slender Piles Situated in Sand

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

    In the period from February 2009 till March 2011 a series of small-scale tests on pile foundations has been conducted at Aalborg University. In all the tests the piles have been exposed to quasi-static loading and all the tests have been conducted in a pressure tank. The objective of the tests has...

  1. The Influence of Time on Bearing Capacity of Driven Piles

    DEFF Research Database (Denmark)

    Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.

    2004-01-01

    In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay......, a regeneration factor appears. The regeneration factor accounts for effects of dissipation of pore pressure due to pile driving and true time effects such as ageing on the ultimate bearing capacity. Normally the factor is 0.4 but in this paper, the influence of the undrained shear strength and time...... on the regeneration factor is investigated. A relation between the quantities is proposed, which in the end may imply an economical benefit in the design of pile foundations....

  2. 基于小波变换的侧面激振法对在役基桩检测%Pile-Side Excitation Integrity Testing for Existing Foundation Based on Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    张敬一; 陈龙珠; 高飞

    2012-01-01

    通过建立桩-土-柱-梁三维有限元模型,分别对柱侧进行横向、斜向下45°、竖向激振,对模拟信号小波变换后,研究了不同的激振形式、激振-检波配置方式对识别桩底深度的影响.结果表明:在激振侧面检波,信号干扰最小;检波器宜在激振高度附近,且激振点应远离上部结构,以减小上部结构的干扰;相对于横向激振,竖向激振与斜向激振时桩底反射更明显,在实际检测中以采用斜向激振为宜.%Three-dimensional (3-D) finite element model of pile-soil-pillar-beam system was used to simulate the testing, and wavelet transform was employed to deal with the simulated signal processing. The effects of the excitation-receiver configuration and the excitation mode, including transverse direction, longitudinal direction and oblique direction, were investigated. It is good to place the receiver in the side wall of the excitation face. Keeping the receiver close to excitation height and a certain distance from the superstructure can reduce the interferences of the superstucture. Compared to transverse direction exciation, longitudinal and oblique direction exciations are much better to identify the pile length. To strike in oblique direction is strongly recommended because of much convenience in practical procedure.

  3. Deformation Analysis of Dual Steel Sheet Pile Cofferdam with Weak Foundation in Water%软弱基础水中双排钢板桩围堰变形分析

    Institute of Scientific and Technical Information of China (English)

    张广东; 刘雄; 熊剑

    2015-01-01

    As temporary building envelope ,the stability of steel sheet pile cofferdam in water is of self-evident im-portance to construction safety .Researching the deformation monitoring of the cofferdam ,grasping deformation conditions and controlling construction risk can prevent accidents during construction ,and have great meaning to saving the project cost at the same time .The paper analyzed and discussed the deformation monitoring data of the temporary double steel sheet pile cofferdam in a lake tunnel construction project ,focusing on the relationship between deformation of cofferdam and the water head in the pumping period .By best polynomial approximation ,the result provides experience for similar projects.%作为临时围护结构,水中钢板桩围堰的稳定性对工程施工安全的重要性不言而喻. 对围堰进行变形监测研究,掌握变形状况,控制施工风险,不仅能够防范施工期间事故的发生,还能节约工程成本. 通过分析某湖中大型通道项目施工中临时双排钢板桩围堰变形监测数据,研究围堰变形量和抽水过程中水位差的联系,经过拟合分析得出结论,可为类似水上工程设计和施工提供参考.

  4. 基于数值模拟的海上风电大直径桩桩土相互作用研究%Study on Pile-soil Interaction of Large Diameter Pile Foundation of Offshore Wind Power Based on Numerical Simulation

    Institute of Scientific and Technical Information of China (English)

    孙希; 黄维平

    2015-01-01

    As a method that can describe the non-linear characteristics of pile-soil, the p-y curve method is widely used for the analysis of laterally loaded piles. Because the recommended p-y curve formulations are based on the results of lateral load test on instrumented piles with diameter less than or equal to 3 m, the suitability of p-y method for the monopile with diameter of 4-6 m or even more used in offshore wind farms needs to be proved. The simulated data are processed and analyzed, then using the finite element software of ABAQUS and SACS to analyze the monopile with a diameter of 6.2 m. Through the comparative analysis of examples, the validity and applicability of the simulated data are proved. The simulation results show that the p-y curves recommended by standards is more safe.%p-y曲线能够反映桩土非线性特征,是分析水平受荷桩常采用的方法。但现场多为3m以内的试桩,对于4~6m甚至更大的海上风电单桩基础结构而言,其适用性值得商榷。为此,采用数值仿真技术对海上风电基础结构大直径钢管桩现场试桩试验进行了有限元数值模拟,分别采用ABAQUS和SACS软件对6.2 m直径桩进行了对比分析,证明了数值实验得到的大直径桩p-y数据的有效性;并将数值实验得到大直径桩p-y数据通过软件SACS与规范推荐的p-y曲线计算结果进行对比,结果表明,规范推荐的p-y曲线偏安全。

  5. A seismic performance evaluation method for a pile-foundation RC girder bridge considering three kinds of SSI effect%考虑SSI三种效应的桩基础RC梁式桥抗震性能评估方法研究

    Institute of Scientific and Technical Information of China (English)

    江辉; 李杰; 杨庆山; 朱晞; 刘林

    2012-01-01

    The dynamic interaction among pile-soil-bridge system is a hot spot and a difficult problem of aseismic design of bridges, and the flexible foundation effect, kinematics effect and foundation damping effect should be reasonably considered. Here, by introducing a seismic demand spectrum modification algorithm of kinematics interaction effect and foundation damping one with FEMA440, an aseismic performance evaluation method taking effectively three kinds of SSI effect for a pile-foundation RC girder bridge into account was developed based on structural nonlinear static analysis method. With a highway RC continuous girder bridge as an example, the nonlinear static and dynamic analysis were conducted respectively for the aim of comparison with three kinds of design spectra and the corresponding artificial waves as inputs. The results under two earthquake levels showed that the seismic response of the bridge taking the 2nd and the 3rd kinds of effect into account with the proposed method is slightly smaller than that of the bridge taking the 1st kind of effect into account with the dynamic time-history method, and the proposed method can be used to evaluate effectively the aseismic performance of a pile-foundation bridge under the anticipated earthquake demand.%桩-土-桥动力相互作用是桥梁抗震研究的热点和难点问题,需合理考虑地基土柔度效应、运动学效应及阻尼效应的影响.采用基于性能点轨迹法的结构非线性静力分析方法,引入FEM A440针对土-结相互作用运动学效应、地基阻尼效应的地震动需求谱修正算法,探讨建立综合考虑桩-土相互作用三种效应的桩基础RC桥梁的抗震性能评估方法.以某高速公路RC连续梁桥为算例,分别以三种设计谱及相应的人工波为输入进行非线性静、动力方法验算对比,两个水准下的计算结果表明所建议方法在补充考虑后两种效应后,地震响应略小于以考虑第一种效应为主

  6. Test Exponential Pile

    Science.gov (United States)

    Fermi, Enrico

    The Patent contains an extremely detailed description of an atomic pile employing natural uranium as fissile material and graphite as moderator. It starts with the discussion of the theory of the intervening phenomena, in particular the evaluation of the reproduction or multiplication factor, K, that is the ratio of the number of fast neutrons produced in one generation by the fissions to the original number of fast neutrons, in a system of infinite size. The possibility of having a self-maintaining chain reaction in a system of finite size depends both on the facts that K is greater than unity and the overall size of the system is sufficiently large to minimize the percentage of neutrons escaping from the system. After the description of a possible realization of such a pile (with many detailed drawings), the various kinds of neutron losses in a pile are depicted. Particularly relevant is the reported "invention" of the exponential experiment: since theoretical calculations can determine whether or not a chain reaction will occur in a give system, but can be invalidated by uncertainties in the parameters of the problem, an experimental test of the pile is proposed, aimed at ascertaining if the pile under construction would be divergent (i.e. with a neutron multiplication factor K greater than 1) by making measurements on a smaller pile. The idea is to measure, by a detector containing an indium foil, the exponential decrease of the neutron density along the length of a column of uranium-graphite lattice, where a neutron source is placed near its base. Such an exponential decrease is greater or less than that expected due to leakage, according to whether the K factor is less or greater than 1, so that this experiment is able to test the criticality of the pile, its accuracy increasing with the size of the column. In order to perform this measure a mathematical description of the effect of neutron production, diffusion, and absorption on the neutron density in the

  7. Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model

    Directory of Open Access Journals (Sweden)

    Guodong Deng

    2014-01-01

    Full Text Available By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solution of velocity response in time domain are derived by means of Laplace transform technique and separation of variables technique. Based on the obtained solutions, the influence of parameters of pile end soil on the dynamic response is studied in detail for different designing parameters of pile. Lastly, the fictitious soil-pile model and other pile end soil supporting models are compared. It is shown that the dynamic response obtained by the fictitious soil-pile model is among the dynamic responses obtained by other existing models if there are appropriate material parameters and thickness of pile end soil for the fictitious soil-pile model.

  8. When Rubble Piles Collide...

    Science.gov (United States)

    Richardson, D. C.; Leinhardt, Z. M.; Quinn, T.

    1999-09-01

    There is increasing evidence that many km-sized bodies in the Solar System may be rubble piles, gravitationally bound collections of solid material (Richardson, Bottke, & Love 1998, Icarus 134, 47). If true, then collisions may occur in free space between rubble piles. Here we present results from a project to map the parameter space of collisions between km-sized spherical rubble piles. The results will assist in parameterization of collision outcomes for Solar System formation models and may give insight into catastrophic disruption scaling laws. We use a direct numerical method (Richardson, Quinn, Stadel, & Lake 1999, Icarus, in press) to evolve the positions and velocities of the rubble pile particles under the constraints of gravity and physical collisions. We test the dependence of the collision outcomes on impact speed and angle, spin, mass ratio, and dissipation parameter. Speeds are kept low so that the maximum strain on the component material does not exceed the crushing strength, appropriate for dynamically cool systems such as the primordial disk during early planet formation. We compare our results with analytic estimates, laboratory experiments, hydrocode simulations, and stellar system collision models. We find that net accretion dominates the outcomes in head-on, slow encounters while net erosion dominates for off-axis, fast encounters. The dependence on impact angle is almost equally as important as the dependence on impact speed. Off-axis encounters can result in fast-spinning elongated remnants or contact binaries while fast encounters result in smaller fragments overall. Reaccumulation of debris escaping from the remnant can occur, leading to the formation of smaller rubble piles. Less than 2% of the system mass ends up in orbit around the remnant. Initial spin can reduce or enhance collision outcomes, depending on the relative orientation of the spin and orbital angular momenta. We derive a relationship between impact speed and angle for

  9. Discussions and Measures to Several Drill Pile Foundation Problems of the Qinghai-Tibet Railway in Permafrost Regions%青藏铁路多年冻土区钻孔桩基础个别问题探讨及设计对策

    Institute of Scientific and Technical Information of China (English)

    高翰青

    2004-01-01

    Part of soil around cast-in-place pile will thaw because the heat of hydration produced by concrete during construction. In this paper soil upfreezing action to pile during refreezing process is analyzed, and the measures to the action are put forward. Furthermore, soil frictional forces to pile due to the thawing of part of soil around pile and the slowness of refreezing after construction is discussed and a rational method is suggested.

  10. 30 CFR 816.83 - Coal mine waste: Refuse piles.

    Science.gov (United States)

    2010-07-01

    .... Critical construction periods shall include at a minimum: (i) Foundation preparation including the removal... revegetated upon completion of construction. (c) Placement. (1) All vegetative and organic materials shall be... professional engineer, shall inspect the refuse pile during construction. The professional engineer...

  11. 30 CFR 817.83 - Coal mine waste: Refuse piles.

    Science.gov (United States)

    2010-07-01

    .... Critical construction periods shall include at a minimum: (i) Foundation preparation including the removal... revegetated upon completion of construction. (c) Placement. (1) All vegetative and organic materials shall be... professional engineer, shall inspect the refuse pile during construction. The professional engineer...

  12. 深基坑桩锚支护工程中预应力锚索施工技术%Analysis on pre-stressed anchor cable construction technology in deep foundation pit pile anchor support engineering

    Institute of Scientific and Technical Information of China (English)

    张宏伟

    2016-01-01

    基于预应力锚索施工的工艺原理,介绍了预应力锚索在桩锚支护施工中的准备工作,并从钻孔、清孔、预应力锚索制作、安放、注浆等方面,阐述了预应力锚索的施工技术要点,指出该技术安全可靠、施工方便、成本低廉,值得推广应用。%Based on the process principle of pre-stressed anchor cable construction,this paper introduced the preparatory work of pre-stressed an-chor cable in pile anchor support construction,and from the hole drilling,hole cleaning,pre-stressed anchor cable production,installation,grou-ting and other aspects,elaborated the construction technology key points of pre-stressed anchor cable,pointed out that the technology was safe and reliable,convenient construction,low cost,worthy of popularization and application.

  13. Mechanical response of bridge piles in high-steep slopes and sensitivity study

    Institute of Scientific and Technical Information of China (English)

    赵衡; 尹平保; 李夕兵

    2015-01-01

    The bridge piles located in high-steep slopes not only endure the loads from superstructure, but also the residual sliding force as well as the resistance from the slope. By introducing the Winkler foundation theory, the mechanical model of piles−soils−slopes system was established, and the equilibrium differential equations of pile were derived. Moreover, an analytic solution for identifying the model parameters was provided by means of power series method. A project with field measurement was compared with the proposed method. It is indicated that the lateral loads have great influences on the pile, the steep slope effect is indispensable, and reasonable diameter of the pile could enhance the bending ability. The internal force and displacements of pile are largely based upon the horizontal loads applied on pile, especially in upper part.

  14. Case Study of CPT-based Design Methods for Axial Capacity of Driven Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2012-01-01

    Today the design of onshore axially loaded driven piles in cohesionless soil is commonly made on basis of CPT-based methods because field investigations have shown strong correlation between the local shaft friction and the CPT cone resistance. However, the recommended design method for axially....... Thus, several CPT-based methods have been proposed for the design of offshore driven piles in cohesionless soil such as the UWA-05, ICP-05, and NGI-99 methods. This article treats a case study where the API-method as well as the UWA-05 and NGI-99 methods are compared using CPT-data from an offshore...... location with dense to very dense sand. The design of the piles in the jacket foundation shows that API-00 for both the tension and the compression loads predicted much longer piles than the CPT-based methods. Variation of the pile length and pile diameter shows that NGI-99 and UWA-05 predicts almost...

  15. EURIPIDES, load tests on large driven piles in dense silica sands

    Energy Technology Data Exchange (ETDEWEB)

    Zuidberg, H.M.; Vergobbi, P.

    1996-12-31

    In 1995 an extensive load testing program was conducted on 30 inch pipe piles in dense silica sands similar to those found in the southern North Sea. A highly instrumented pile was driven at one location, extracted and redriven at a second location. A total of twelve static compression and tension load tests were performed at three penetration depths between 30 and 47 meters. Test objectives included acquiring reliable data on capacity of offshore type piles in sands which hitherto were hardly available and to understand the failure mechanisms in order to improve current foundation design. The paper describes the design of the testing program and project organization and funding. Details of the test pile and instrumentation to measure the loads in the pile and the pile-sand interaction are highlighted with an emphasis on quality of the measurements. The field-work and innovative testing facilities are also described.

  16. Field study of plastic tube cast-in-place concrete pile

    Institute of Scientific and Technical Information of China (English)

    陈永辉; 曹德洪; 王新泉; 杜海伟; 张霆

    2008-01-01

    The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.

  17. PROCESS DIAGRAMS FOR INSTALLATION OF DRIVEN PILES IN PENETRATED WELLS

    Directory of Open Access Journals (Sweden)

    Kovalev Vladimir Aleksandrovich

    2017-03-01

    Full Text Available This article presents the main options of improved and newly devised designs and process diagrams for installation of foundations made of driven, or jack, piles in the penetrated wells with expanded shoe, mainly in weak wet (waterlogged and water-saturated soils. The article presents six options of process diagrams for installation of driven piles in penetrated wells, listing the main procedures: for well-compacted weak soils, for the case when the water ingress is excluded, for the case when it is necessary to increase the load-bearing capacity of pile's bearing face in the waterlogged soils, for the case when the load-bearing capacity of the pile shall be increased both for the end and for the sides, for the case when peat or other biogenous water-saturated soils are present at the bottom of the well, and for the case when there is no contracted zone nor practical possibility to ensure the stability of the walls. The proposed six options of process diagrams for installation of the driven piles in penetrated wells provide expansion of their area of application regarding the soil conditions, increase of load-bearing capacity, and possibility of using jack systems for driving the piles under conditions of dense urban development.

  18. 考虑加载过程及桩体固结变形的碎石桩复合地基固结解析解%ANALYTICAL SOLUTION FOR CONSOLIDATION OF STONE COLUMN-REINFORCED FOUNDATIONS TAKING INTO ACCOUNT CONSOLIDA-TION DEFORMATION OF PILE UNDER PROGRESSIVE LOADING

    Institute of Scientific and Technical Information of China (English)

    郭彪; 龚晓南; 李亚军

    2016-01-01

    For the sake of improvement of the composite foundations consolidation theory , an analytical solution is obtained for consolidation of stone column -reinforced foundations taking into account the consolidation deformation of pile under progressive loading .Column consolidation and deformation are considered with the following two assumptions:(1)the quantity of water flowing through the disturbed soil zone into the column is not equal to that flowing out from the column and (2)the difference between them is equal to the volume change of the column .In addition, the linear distribution pattern of the horizontal permeability of soil in the disturbed zone is also taken into account for the disturbance effect of columns construction on the surrounding soil .To prove the correctness of the solution, a discussion is performed in the article.If the loading time tends to zero, the obtained solution can be convert to the solution in the condition of constant load .Furthermore, if the loading time and the size of stone columns tend to zero at the same time , the obtained solution can be convert to the one -dimensional solution obtained by Terzaghi.In the end, the average degree of consolidation of a composite foundation is obtained and discussed . The results show that the influence of loading process on the consolidation is obvious .The consolidation rate under the linear distribution pattern of the horizontal permeability of soil in the disturbed zone is faster than the consolidation rate in the condition of constant permeability .The consolidation rate considering deformation of pile is slower than consolidation rate using traditional assumptions .So that it is unsafe to ignore deformation of pile . Furthermore, the differences increase gradually as the loading time , the radius ratio, the stress ratios and the permeability coefficient ratios decrease.%为了完善碎石桩复合地基固结理论,通过假设从桩体排出的水量等于流入桩体的水量与桩

  19. Numerical Modelling of Large-Diameter Steel Piles at Horns Rev

    DEFF Research Database (Denmark)

    Augustesen, Anders Hust; Brødbæk, K. T.; Møller, M.;

    2009-01-01

    Today large-diameter monopiles are the most common foundation type used for large offshore wind farms. This paper aims to investigate the behaviour of monopiles under monotonic loading taking the interaction between the pile and the subsoil into account. Focus is paid to a monopile used as founda......Today large-diameter monopiles are the most common foundation type used for large offshore wind farms. This paper aims to investigate the behaviour of monopiles under monotonic loading taking the interaction between the pile and the subsoil into account. Focus is paid to a monopile used...... as foundation for a wind turbine at Horns Rev located in the Danish sector of the North Sea. The outer diameter of the pile is 4 m and the subsoil at the location consists primarily of sand. The behaviour of the pile is investigated under realistic loading conditions by means of a traditional Winkler...

  20. Vibration Based Wind Turbine Tower Foundation Design Utilizing Soil-Foundation-Structure Interaction

    Science.gov (United States)

    Al Satari, P. E. Mohamed; Hussain, S. E. Saif

    2008-07-01

    Wind turbines have been used to generate electricity as an alternative energy source to conventional fossil fuels. This case study is for multiple wind towers located at different villages in Alaska where severe arctic weather conditions exist. The towers are supported by two different types of foundations; large mat or deep piles foundations. Initially, a Reinforced Concrete (RC) mat foundation was utilized to provide the system with vertical and lateral support. Where soil conditions required it, a pile foundation solution was devised utilizing a 30″ thick RC mat containing an embedded steel grillage of W18 beams supported by 20″-24″ grouted or un-grouted piles. The mixing and casting of concrete in-situ has become the major source of cost and difficulty of construction at these remote Alaska sites. An all-steel foundation was proposed for faster installation and lower cost, but was found to impact the natural frequencies of the structural system by significantly softening the foundation system. The tower-foundation support structure thus became near-resonant with the operational frequencies of the wind turbine leading to a likelihood of structural instability or even collapse. A detailed 3D Finite-Element model of the original tower-foundation-pile system with RC foundation was created using SAP2000. Soil springs were included in the model based on soil properties obtained from the geotechnical consultant. The natural frequency from the model was verified against the tower manufacturer analytical and the experimental values. Where piles were used, numerous iterations were carried out to eliminate the need for the RC and optimize the design. An optimized design was achieved with enough separation between the natural and operational frequencies to prevent damage to the structural system eliminating the need for any RC encasement to the steel foundation or grouting to the piles.

  1. 锚杆静压桩群桩效应分析%Analysis of effect for anchored silent group pile

    Institute of Scientific and Technical Information of China (English)

    韩红娟; 郑七振

    2012-01-01

    In order to improve comprehension for the rule of interaction between pile, soil and pile caps, the software ABAQUS was applied to stimulate the different working properties of anchored silent group piles'foundation under different pile length, side length, pile spacing, number of pile and thickness of piles cap. The effect coefficient of group pile and undertaking ratio of pile cap will decreased with the increase of pile length and number of piles, but not the pile spacing. The results will be useful to the guidance of pile foundation design and make the design of pile to accord with real working conditions.%为促进对桩-土-承台相互作用规律的认识,本文主要运用ABAQUS模拟了锚杆静压桩(方桩)的不同桩长、桩边长、桩间距、桩数以及承台厚度情况下,锚杆静压桩群桩基础的工作性状.桩长的增长和桩数的增加,都会导致群桩效应系数和承台荷载分担比的降低;而随着桩间距增大群桩效应系数和承台荷载分担比增大.这些结论都有助于指导桩基设计,使得桩基设计更符合其实际工作状况.

  2. Edge scour at scour protections around offshore wind turbine foundations

    DEFF Research Database (Denmark)

    Petersen, Thor Ugelvig; Sumer, B. Mutlu; Fredsøe, Jørgen

    2014-01-01

    When building offshore wind turbines with mono-pile foundations, scour protection is typically placed to avoid scouring of the soil close to the mono-pile. An important aspect is that the scour protection itself causes erosion, inflicted by the local increase in the hydrodynamic field and in turn...

  3. Scour Around Monopile Foundations for Off-shore Wind Turbines

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Frigaard, Peter B.; Martinelli, Luca;

    2006-01-01

    Since the first offshore wind farm had been built (Vindeby Lolland 1991) the dimensions of the turbines are rising quickly: by now the diameter of the rotor reaches 90m and the pile diameter exceeds 4m. Monopile foundations, preferred to gravity ones for large pile diameters and shallow waters, s......, suffers from severe scour and the toe needs to be protected....

  4. Behaviour of Single Pile in Reinforced Slope Subjected to Inclined Load

    Directory of Open Access Journals (Sweden)

    Dr. A. I. Dhatrak

    2016-09-01

    Full Text Available Deep foundations, including driven piles, are used to support vertical loads of structures and lateral forces. Typical structures subjected to lateral loads include bridge abutments, transmission tower, sand offshore platforms. Traffic, wind, wave, and seismic forces are common types of lateral loads subjected to pile foundations. The present work is focused on understanding the lateral load capacity of vertical piles located near crest of the slope and subjected to the lateral and inclined loads. The experimental investigation was carried out to study the effect of reinforcing an earth slope on the inclined loading behavior of a single vertical pile located near the slope. Layers of geogrid were used to reinforce a sandy slope of 1V:2H. The parametric studies were performed by varying the length of pile(L, angle of inclination of load (θ, number of geogrid reinforcement (Nr and crest distance. It was observed that the lateral load capacity of pile depends upon these parameters. The lateral load capacity of pile increases with increase in inclination of load, length of pile(L, number of geogrid reinforcement (Nr and crest distance.

  5. Pressured Grouting Method (PGM) in Pile Engineering

    Institute of Scientific and Technical Information of China (English)

    吴兴序; 于志强; 王旭

    2002-01-01

    Application of pressured grouting method (PGM) in pile engineering can tackle problems encountered during construction of bored piles. Bearing capacity of piles can be increased through compaction of subsoils around piles. This paper reports research efforts of this technique by the pile research team in Southwest Jiaotong University in last decade with respect to the construction process, test findings, and primary research conclusions. The social-economical benefits of this method and application market in pile engineering are also analyzed.

  6. Application of ANSYS in pile-soil contact non-linearity%ANSYS在桩土接触非线性中的应用

    Institute of Scientific and Technical Information of China (English)

    俞轩; 郭小刚

    2012-01-01

    Taking the finite element ANSYS as the platform, the paper discusses the modeling concept of ANSYS used in pile-soil interaction, the pile-soil constitutive model and pile-soil contact surface analysis, and finally analyzes the impact of elastic pile modulus and elastic soil modulus upon pile foundation subsidence, points out that elastic soil modulus has greater impact upon pile foundation subsidence than elastic pile modulus.%以有限元ANSYS为平台,论述了ANSYS用于桩土相互作用的建模思路,以及桩土本构模型,桩土界面的接触分析,最后分析了桩弹性模量与土的弹性模量对桩基沉降的影响,指出土的弹性模量对桩基沉降影响很大。

  7. Lumped-parameter Model of a Bucket Foundation

    DEFF Research Database (Denmark)

    Andersen, Lars; Ibsen, Lars Bo; Liingaard, Morten

    2009-01-01

    As an alternative to gravity footings or pile foundations, offshore wind turbines at shallow water can be placed on a bucket foundation. The present analysis concerns the development of consistent lumped-parameter models for this type of foundation. The aim is to formulate a computationally effic...

  8. Small-Scale Testing of Laterally Loaded Non-Slender Piles in a Pressure Tank

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo

    2012-01-01

    The monopile foundation concept is often employed as the foundation for offshore wind turbines. Typically, piles with diameters of 4-6 m and embedded lengths of 15-30 m are em¬ployed. Hence, the length to diameter ratio is around 5. The design method recommended by the American Petroleum Institute...

  9. Experimental study on settlement of model piles in frozen soil under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    张建明; 朱元林; 张家懿

    1999-01-01

    Test results show that the settlement process of model piles is mainly the rheological process of frozen soil under shear loading. The settlement rate of model piles increases with increasing temperature of frozen soil, decreasing roughness of pile surface and increasing rigidity of pile foundation. As the water content of frozen soil reaches its saturation value, the settlement rate is the least. When the level of loading is higher, the settlement rate under dynamic loading is less than that under static loading. With the level of loading lowering, the effect between dynamic and static loading on the settlement rate becomes close gradually. Under the present test conditions, the settlement rate of model piles is independent of the frequency of dynamic loads.

  10. Introduction to Single Piles under Lateral Loading

    DEFF Research Database (Denmark)

    Augustesen, Anders; Ibsen, Lars Bo

    The purpose of this chapter is to give a short introduction to single piles subjected to lateral loading. First, the observed behaviour of laterally loaded piles is described, i.e. the effects of loading conditions, installation procedure, pile type etc. on pile behaviour are presented (section 1...

  11. Microbiologically Influenced Corrosion of Pilings

    Science.gov (United States)

    2014-03-04

    reported in all climatic conditions on unprotectej suJ pilings m contact with saline water (ie scawater and hrackisli ’.vater’’ tliat is siibj^ct... Pilings 6. AUTHOR(S) Brenda J. Little and Richard I. Ray 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Research Laboratory...ACRONYM(S) ONR 11. SPONSOR/MONITOR’S REPORT NUMBER(S| 13. SUPPLEMENTARY NOTES Ao/£/o/3lz<l 14. ABSTRACT Sheet piles , used as retaining walls

  12. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  13. The Method of Calculating the Settlement of Weak Ground Strengthened with the Reinforced Sandy Piles

    Directory of Open Access Journals (Sweden)

    Maltseva Tatyana

    2016-01-01

    Full Text Available The paper presents an engineering method for calculating the weak clay base, strengthened with sandy piles reinforced along the contour. The method is based on the principle of layer-by-layer summation, which is used when designing the bases and foundations. The novelty of the suggested method lies in the taking account of the soil reaction along the pile lateral surface and the impact of external vertical loads on the vertical displacement of the base.

  14. Experimental study of reinforced concrete pile caps with external, embedded and partially embedded socket with smooth interface

    Directory of Open Access Journals (Sweden)

    R. Barros

    Full Text Available On Precast concrete structures the column foundation connections can occur through the socket foundation, which can be embedded, partially embedded or external, with socket walls over the pile caps. This paper presents an experimental study about two pile caps reinforced concrete with external, partially embedded and embedded socket submitted to central load, using 1:2 scaled models. In the analyzed models, the smooth interface between the socket walls and column was considered. The results are compared to a reference model that presents monolithic connections between the column and pile cap. It is observed that the ultimate load of pile cap with external sockets has the same magnitude as the reference pile cap, but the ultimate load of models with partially embedded and embedded socket present less magnitude than the reference model.

  15. Viscoelastic behavior of concrete pile

    Institute of Scientific and Technical Information of China (English)

    丁科; 唐小弟

    2008-01-01

    Based on constitutive theory of viscoelasticity,the viscoelastic behaviour of concrete pile was investigated.The influence of viscosity coefficient on the stress,displacement and velocity response was discussed.With the increase of viscosity coefficient,the amplitude of stress wave decreases,and the maximum value of the stress wave shifts to deeper position of the pile.In other words,the viscosity coefficient behaves as lag effect to stress wave.

  16. 均匀黏弹性地基中现浇 X 形桩低应变动测响应数值模拟%Numerical Simulation of Low Strain Dynamic Test Response for X-section Cast-in-place Concrete Pile on Homogeneous Viscoelastic Foundation

    Institute of Scientific and Technical Information of China (English)

    范玉明; 丁选明; 朱振生; 付强

    2015-01-01

    A three dimensional finite model of an X-section cast-in-place concrete pile-soil system is established to simulate wave propagation in a low strain integrity X-section cast-in-place concrete pile (XCC pile).Velocity responses in the time domain at the top of the intact and defective piles are obtained.The velocity response characteristics of the intact pile are analyzed in addition to the velocity response curves of the defective piles.The results reveal that the velocity response at the top of the XCC pile during low strain integrity testing shows serious 3D effects,resulting in the peak value of the incident wave close to the pile center being largest,and the arrival time of the peak value of the incident wave close to the pile center being earliest.The farther a point is from the pile center,the more hysteretic is the peak of the arriving incident wave.The peak value of the incident waves first increases and then reduces from the pile center to the pile boundary.The inci-dent and reflected waves at different points along the ring direction at the top of the intact pile are very similar,but the disturbing waves of different points are not the same.The arrival time of the incident waves in the pile with variable modulus are the same as those in the intact pile,but the arrival time of the peak of the reflection wave at the bottom of the pile with variable modulus is later than that in the intact pile,and the peak value is smaller.The first defective reflected waves at different points along ring direction at the top of the defective XCC pile shows little differ-ences,but the second one shows larger differences.%建立现浇 X 形桩(XCC 桩)桩-土体系三维有限元模型,对 XCC 桩低应变检测动力响应进行数值模拟,得到完整桩和缺陷桩的桩顶速度响应结果,并分析完整桩及缺陷 XCC 桩桩顶速度响应特性及规律。计算结果表明:XCC 桩低应变瞬态动测时桩顶速度响应存在明显的三维效应,桩

  17. DETERMINING DRIVING RESISTANCE WITH REBOUND OF PILE-TOP DURING PILE DRIVING

    Institute of Scientific and Technical Information of China (English)

    陈仁朋; 胡亚元; 陈云敏

    2001-01-01

    This paper presents a method to determine driving resistance with rebound of pile-top during pile driving. The soil around the pile shaft is assumed to be rigid-plastic, while that under the pile-tip is assumed to be ideally elastoplastic. The driving force acting on the pile-top is simplified to a triangular impact force. The kinematic equation of the pile-tip is established. From the one-dimensional wave equation, the movements of the pile-tip and pile-top are determined. The rebound at the pile-top can be written in a very concise form. It is shown that the shaft resistance makes the rebound at the pile-top decrease. In particular, when the pile is very long or the soil around the pile is very stiff, the decrease is very obvious.

  18. Three-dimensional numerical simulation and earth pressure analysis on double-row piles with consideration of spatial effects

    Institute of Scientific and Technical Information of China (English)

    Zi-han WANG; Jian ZHOU

    2011-01-01

    As a new kind of technology in retaining structures,the characteristics of double-row piles are significantly affected by spatial effects.In this paper,double-row piles as a retaining structure are simulated numerically in three-dimension by finite element software PLAXIS 3D FOUNDATION.The behavior differences of piles in different positions around the foundation pit are analyzed.By changing the parameters,including the length-width ratio,the excavation depth,the distance between rows and the diameter of piles,the variations of the lateral deformation,the bending moment and the earth pressure around the piles are determined.The reasonable values of parameters and some suggestions with consideration of earth pressure are proposed for the design of double-row piles as a retaining structure.The results show that the lateral deformation and bending moment are the largest in the middle of long side of the foundation pit,which is identified as the most unfavorable position.It is indicated that the earth pressure between rows above pit bottom is close to active earth pressure,while the earth pressure between rows under pit bottom is close to static earth pressure.It is suggested that 1/2-2/3 of pile length,0.6-1.2 m,3d-6d,and 2d-2.5d be chosen as embedded depth of piles,diameter of piles,distance between rows,and distance between piles,respectively,where d is the pile diameter.

  19. Method of calculating pilestrip foundations in case of karst hole formation

    Directory of Open Access Journals (Sweden)

    Gotman Al'fred Leonidovich

    2014-02-01

    Full Text Available The paper presents pile strip foundations in the areas with karst risk. The analysis of karst hole formation mechanism shows the lateral soil pressure on the piles caused by the downfallen soil on the hole rims, which transfers around the hole edges during karst hole formation. In this case, the horizontal pressure of the pile reactive force in the area of the pile connection with the raft is transferred to the raft. Pile failure at the hole boundaries will lead to the increase of the raft bearing distance above the karst hole. The inadequate raft bearing capacity can provoke the emergency situation. The existing Codes on karst protective foundations design do not contain the analysis of pile and raft horizontal pressure under the downfallen soil.The goal of this work is to develop the method of pile strip foundations analysis in the areas with karst risk in case of karst hole formation. The analysis of stress-strain state of the system “foundation soil — pile foundation” was carried out using numerical modeling in geotechnical program MIDAS GTS. As a result of numerical investigations, the diagrams of lateral soil pressure onto the piles and the raft are plotted. The pile pressure is approximated with the linear or bilinear function in dependence on geometrical dimensions of the karst hole and strength characteristics of soil that generates the horizontal pressure.In the Codes, the analysis of a pile under lateral soil pressure is given for a pile with the free end. In the problem examined, the pile head has the hinged bearing in place of the connection with the raft. In view of the given boundary data, the pile design scheme is plotted. The inner forces and displacements of the pile are determined by integrating the differential equation of a pile bending. The consistent integrations are evaluated out of the boundary conditions. The boundary values of inner forces and displacements are evaluated from the equality conditions of

  20. Simulation analysis for O-cell test of pile and the interaction of upper pile and lower pile

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ying-jie; ZHANG Ke-xu; ZHANG Er-qi

    2009-01-01

    In this paper, the soil-pile system of O-cell test of pile is simplified as an axi-symmetrie problem.By using aggregation of quadrilateral isoparametrie elements to simulate pile and soil, setting Goodman' s elements between pile and soils, a method of numerical simulation analysis on O-cell test of pile is presented with the consideration of nonlinear mechanical behavior of soils and pile-soil interface.The method is applied to the a-nalysis of a case of O-cell test of pile.The load-displacement curves and axial force curves of upper pile and lower pile obtained from the O-cell test of pile are fitted, and parameters of the mechanical model of soils and interface are determined.Analysis results validate that the numerical simulation analysis method put forward in this paper is applicable.Furthermore, the interaction and influence of upper pile and lower pile in the O-cell test are also studied with the method.The result shows that if load box is located in a soil layer with fine me-chanical behavior, the interaction of upper pile and lower pile in O-cell test can be ignored generally.

  1. Effect of Passive Pile on 3D Ground Deformation and on Active Pile Response

    OpenAIRE

    Bingxiang Yuan; Rui Chen; Jun Teng; Tao Peng; Zhongwen Feng

    2014-01-01

    Using a series of model tests, this study investigated the effect of a passive pile on 3D ground deformation around a laterally loaded pile and on that laterally loaded pile’s response in sand. The active pile head was subjected to lateral loads, and the passive pile was arranged in front of the active pile. In the model tests, the distance between the two pile centers was set to zero (i.e., a single pile test), 2.5, 4, and 6 times the pile width (B). The 3D ground surface deformations around...

  2. Review of Laterally Loaded Monopiles Employed as the Foundation for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Brødbæk, Kristian Thoustrup; Møller, Martin;

    Monopiles are often used foundation concepts for offshore wind turbine converters. These piles are highly subjected to latereal loads and overturning moments due to wind and wave forces. Typically, monopiles with diameters of 4 to 6 m and embedded pile lenghts of 15 to 30 m are necessart. In curr......Monopiles are often used foundation concepts for offshore wind turbine converters. These piles are highly subjected to latereal loads and overturning moments due to wind and wave forces. Typically, monopiles with diameters of 4 to 6 m and embedded pile lenghts of 15 to 30 m are necessart...

  3. Analysis of Interaction Factors Between Two Piles

    Institute of Scientific and Technical Information of China (English)

    CAO Ming; CHEN Long-zhu

    2008-01-01

    A rigorous analytical method is presented for calculating the interaction factor between two identical piles subjected to vertical loads. Following the technique proposed by Muki and Sternberg, the problem is decomposed into an extended soil mass and two fictitious piles characterized respectively by Young's modulus of the soil and that of the difference between the pile and soil. The unknown axial forces along fictitious piles are determined by solving a Fredholm integral equation of the second kind, which imposes the compatibility condition that the axial strains of the fictitious piles are equal to those corresponding to the centroidal axes of the extended soil. The real pile forces and displacements can subequally be calculated based on the determined fictitious pile forces, and finally, the desired pile interaction factors may be obtained. Results confirm the validity of the proposed approach and portray the influence of the governing parameters on the pile interaction.

  4. Dynamic stiffness and damping of foundations for jacket structures

    DEFF Research Database (Denmark)

    Latini, Chiara; Zania, Varvara; Johannesson, Björn

    2015-01-01

    Foundation for offshore jacket structures may comprise of long floating piles. The dynamic response of floating piles to horizontal load is herein investigated. The analytical solution of horizontally vibrating end bearing piles by Novak & Nogami (1977) has been modified. At first the soil resist...... study clarifies the role of the parameters involved i.e. the depth of the soil layer, the pile diameter and the soil layer shear wave velocity. Results are presented in terms of dimensionless graphs which highlight the frequency dependency of the dynamic stiffness and damping.......Foundation for offshore jacket structures may comprise of long floating piles. The dynamic response of floating piles to horizontal load is herein investigated. The analytical solution of horizontally vibrating end bearing piles by Novak & Nogami (1977) has been modified. At first the soil...... resistance as defined by Nogami & Novak (1977) is determined, considering 3D wave propagation within linear soil layer with hysteretic damping. Thereafter, the dynamic response of the pile is estimated assuming soil pressure equal to the soil resistance and imposing displacement compatibility. A parametric...

  5. Physical modeling and numerical analyses of vibro-driven piles with evaluation of their applicability for offshore wind turbine support structures

    OpenAIRE

    Foglia, Aligi; Kohlmeier, Martin; Wefer, Maik

    2016-01-01

    Vibro-driven piles can potentially become cost-reducing alternatives to standard impact-driven piles for offshore wind turbine support structures. If these foundations are to be used to support jacket sub-structures, their bearing behaviour in tension has to be explored. In a novel geotechnical testing facility two large-scale vibro-driven piles for jacket sub-structures have been axially tested in tension. In this contribution the experimental tests are thoroughly described and the test resu...

  6. Pile-up glass microreactor.

    Science.gov (United States)

    Kikutani, Yoshikuni; Hibara, Akihide; Uchiyama, Kenji; Hisamoto, Hideaki; Tokeshi, Manabu; Kitamori, Takehiko

    2002-11-01

    We made a 'pile-up' microreactor in which ten levels of microchannel circuits were integrated to form a single glass entity. Solutions were distributed to each layer via cylindrical holes with a diameter much larger than that of the microchannel. Fabrication of the pile-up reactor was completed using only conventional photolithography, wet etching and thermal bonding techniques, and no special facilities or instruments were required. An amide formation reaction between amine in aqueous solution and acid chloride in organic solution was carried out using the pile-up reactor. The yield of the amide formation reaction is dependent on the size of the specific surface area between the two solutions, and the small space inside the microchannels is good for acquiring a large specific surface area without any stirring processes. The maximum throughput for the ten-layered pile-up reactor was ten times larger than that of a single-layered one, yet the reaction yield was still high. Productivity of the pile-up reactor for the reaction was as high as on a gram per hour scale. This value suggests that many conventional plants producing fine chemicals can be replaced by microreactors through the numbering-up technology.

  7. Energy piles. A fundamental energy pile; Energiepfaehle. Eine fundamentale Energiequelle

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Holger; Beldermann, Nico [GF-Tec GmbH, Roedermark (Germany)

    2013-03-01

    The Maintower, the new airport in Berlin/Brandenburg, a lot of Ikea buildings, and also small office buildings or residential buildings may exchange energy with the underground by means of pile fundaments. At the correct planning and execution, energy piles are low-cost geothermal power plants which sustainable generate heating and cooling for the buildings standing on them. Even more energy can be generated safely under compliance with the groundwater protection by means of a new development of the material and the transfer.

  8. Airborne sound propagation over sea during offshore wind farm piling.

    Science.gov (United States)

    Van Renterghem, T; Botteldooren, D; Dekoninck, L

    2014-02-01

    Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario.

  9. A numerical study of the effect of groundwater on spiral coil energy piles

    Science.gov (United States)

    Kim, Seong-Kyun; Lee, Youngmin

    2016-04-01

    Numerical simulations were performed to investigate effects of groundwater on the thermal performance of the geothermal energy pile. Energy piles, a part of the closed-loop geothermal heat pump systems, are used to exchange heat between the ground and the heat pump. A heat-carrying fluid circulates the ground through a coiled pipe installed in pile foundations. The COMSOL multiphysics was used as a simulator, which can solve the equations for the temperature and fluid flow in the pipe system, as well as those in the ground. Water temperatures at the pipe outlet after 90-day injection of warm water (30℃) were calculated from following cases: (1) one energy pile installed at the fully saturated medium with regional groundwater flow (100 m/year), (2) one energy pile installed at the partially saturated medium (water table is located 13.5 m below the ground surface) with regional groundwater flow (1,000 m/year), (3) one energy pile installed at the fully saturated medium with no regional groundwater flow, (4) one energy pile installed at the partially saturated medium with no regional groundwater flow, (5), (6), (7) four energy piles (distance between energy piles is 10, 5 ,2 m) installed at the fully saturated medium with regional groundwater flow, and (8), (9), (10) four energy piles installed at the partially saturated medium with regional groundwater flow. The outlet temperature of each case is (1) 28.11℃, (2) 28.84℃, (3) 28.97℃, (4) 29.09℃, (5) 28.19℃ (mean value), (6) 28.24℃ (mean value), (7) 28.33℃ (mean value), (8) 28.84℃ (mean value), (9) 28.90℃ (mean value), and (10) 29.10℃ (mean value), respectively. The thermal power ratio of the energy pile of each case (standard case is case 1) is (1) 0%, (2) -46%, (3) -39%, (4) -52%, (5) -4%, (6) -7%, (7) -12%, (8) -39%, (9) -42%, and (10) -53%, respectively. Numerical results show that the performance of the energy pile installed at the fully saturated medium with regional groundwater flow (case 1

  10. Displacement and deformation analysis for uplift piles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    On the assumptions that the shear resistance increases linearly with increasing shear displacement between the uplift pile and surrounding soil,that the axis force is distributed as parabola along the pile length,that elastic distortion occurs when the pile is loaded,that the displacement of pile is in accord with that of the soil,and that the uplift pile failure is regarded as the soil failure,arational calculation method was proposed for calculating the deformation,ultimate displacement and shear resistance of piles.The distributions of frictional resistance and the shear displacement along the pile length were obtained with the method.The comparisons were made between the measurement results and the present results.The present theoretical results agree well with the measurement results,with the average difference being less than 12% before failure.The comparisons show that the proposed method is reasonable for uplift design and engineering construction of piles.

  11. Refreezing of cast-in-place piles under various engineering conditions

    Institute of Scientific and Technical Information of China (English)

    Lei Guo; QiHao Yu; XiaoNing Li; XinBin Wang; YongYu Yue

    2015-01-01

    In the construction of the Qinghai-Tibet Power Transmission Line (QTPTL), cast-in-place piles (CIPPs) are widely applied in areas with unfavorable geological conditions. The thermal regime around piles in permafrost regions greatly affects the stability of the towers as well as the operation of the QTPTL. The casting of piles will markedly affect the thermal regime of the surrounding permafrost because of the casting temperature and the hydration heat of cement. Based on the typical geological and engineering conditions along the QTPTL, thermal disturbance of a CIPP to surrounding permafrost under different casting seasons, pile depths, and casting temperatures were simulated. The results show that the casting season (summer versus winter) can influence the refreezing process of CIPPs, within the first 6 m of pile depth. Sixty days after being cast, CIPPs greater than 6 m in depth can be frozen regardless of which season they were cast, and the foundation could be refrozen after a cold season. Comparing the refreezing characteristics of CIPPs cast in different seasons also showed that, without considering the ground surface conditions, warm seasons are more suitable for casting piles. With the increase of pile depth, the thermal effect of a CIPP on the surrounding soil mainly expands vertically, while the lateral heat disturbance changes little. Deeper, longer CIPPs have better stability. The casting temperature clearly affects the thermal disturbance, and the radius of the melting circle increases with rising casting temperature. The optimal casting temperature is between 2 °C and 9 °C.

  12. Postmortem analysis of sand grain crushing from pile interface using X-ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Silva, I. Matias; Combe, Gaeel; Foray, Pierre; Flin, Frederic; Lesaffre, Bernard [Universite de Grenoble, 3SR Lab, UMR 5521 Grenoble-INP, UJF-Grenoble 1, CNRS, Grenoble, France CEN, CNRM-GAME UMR 3589, Meteo France - CNRS, Grenoble (France)

    2013-06-18

    Pile foundations of offshore platforms, wind and water turbines are typically subjected to a variety of cyclic loading paths due to their complex environment. While many studies focus on global pile behaviour, the soil-pile interface is explored here by a micromechanical study of the soil layer in contact with the pile surface. This work is devoted to the analysis of frozen post-mortem silica sand samples recovered at the pile interface following installation and cyclic loading tests in a calibration chamber using x-ray tomography. An experimental procedure developed for three dimensional (3D) snow imaging was adapted for the recovery of the in-situ sand samples to preserve their structure during tomography scans. 3D images at a pixel size of 7 {mu}m were then obtained using a cryogenic cell. Results confirm the presence of a shear band at the pile surface as well as void ratios changes in the direction of the pile's radius.

  13. Simulating pile load-settlement behavior from CPT data using intelligent computing

    Science.gov (United States)

    Alkroosh, I.; Nikraz, H.

    2011-09-01

    Analysis of pile load-settlement behavior is a complex problem due to the participation of many factors involved. This paper presents a new procedure based on artificial neural networks (ANNs) for simulating the load-settlement behavior of pile foundations embedded in sand and mixed soils (subjected to axial loads). Three ANN models have been developed, a model for bored piles and two other models for driven piles (a model for each of concrete and steel piles). The data used for development of the ANN models is collected from the literature and comprise a series of in-situ piles load tests as well as cone penetration test (CPT) results. The data of each model is divided into two subsets: Training set for model calibration and independent validation set for model verification. Predictions from the ANN models are compared with the results of experimental data and with predictions of number of currently adopted load-transfer methods. Statistical analysis is used to verify the performance of the models. The results indicate that the ANN model performs very well and able to predict the pile load-settlement behaviour accurately.

  14. Reliability analysis of beams on random elastic foundations

    NARCIS (Netherlands)

    Griffiths, D.V.; Paiboon, J.; Huang, J.; Fenton, G.A.

    2012-01-01

    The classical problem of a beam on an elastic foundation has long been of practical interest to geotechnical engineers, because it provides a framework for computing deflections not only of foundations, but also of vertically oriented laterally loaded piles. The supporting soil can be modelled as an

  15. On construction scheme of bored piles%谈灌注桩施工方案

    Institute of Scientific and Technical Information of China (English)

    刘立创

    2012-01-01

    The paper points out the bored pile is the common foundation treatment,and fully introduces the craft procedure and craft methods of the bored pile construction by taking the engineering example of the bored pile construction,so as to enhance the application of the bored pile.%指出灌注桩是常用的一种地基处理方法,通过灌注桩施工的一个工程实例,较全面地介绍了灌注桩施工的工艺流程、工艺方法,从而促进灌注桩的推广应用。

  16. Erective Sea Embankment with PCC Piles

    Institute of Scientific and Technical Information of China (English)

    LIU Han-long; FEI Kang; DENG An; ZHANG Ting

    2005-01-01

    The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, this technique integrates PCC pile installation, PVDs drainage systems, and geotextile reinforcements, resulting in sea embankments with PCC piles. In the application of a sea embankment with PCC piles, PCC piles are employed as the retaining structures;the soft sea ground inside PCC piles is drained and improved by PVDs and vacuum-surcharge combined preloading; geotextile-reinforced backfills lying over the improved soft ground form the embankment body. Brief descrptions of the fundamentals, design and construction of the sea embankment with PCC piles are presented. A case study on the stability of sea embankment with PCC piles is presented as well.

  17. 桩侧热交换能量桩技术开发及应用%Technology Development and Application of Energy Pile with Heat Exchange at the Pile Side

    Institute of Scientific and Technical Information of China (English)

    黄吉永

    2014-01-01

    Combined with the local reality of pile foundation and the exploration on energy pile technology, a new kind of energy pile technology with heat exchange at the pile side is presented. The main feature of the technology is bundling the ground source heat pump pipe to a precast pile buried underground by pile ramming and hooks traction. Engineering practice shows that the new construction technology has some advantages,including no squeezing effect, no damage to the pile, low noise, long pile controllable and with convenient heat exchange tube on setting. Among them, the heat exchange tubes laid on the pile almost have no impact on the construction of precast piles, overcoming the major obstacles at the respects of the traditional pre-energy pile in construction.%结合本地区的桩基工程实际和对能量桩技术的摸索,提出了在桩侧实现热交换的新型能量桩技术。该技术的主要特点是将地源热泵管绑扎于预制桩的桩侧,并通过桩体的下沉和挂钩的牵引埋入地下。通过对一个工程案例的总结分析,发现新型能量桩技术在施工方面具有无挤土效应、对桩无损伤、低噪声、桩长可控、热交换管设置方便等优点。其中,热交换管的布设对预制桩的接桩几乎无影响,克服了传统预制能量桩在施工方面的主要障碍。

  18. Observed variations of monopile foundation stiffness

    DEFF Research Database (Denmark)

    Kallehave, Dan; Thilsted, C.L.; Diaz, Alberto Troya

    2015-01-01

    The soil-structure stiffness of monopile foundations for offshore wind turbines has a high impact on the fatigue loading during normal operating conditions. Thus, a robust design must consider the evolution of pile-soil stiffness over the lifetime of the wind farm. This paper present and discuss...... full-scale measurements obtained from one offshore wind turbine structure located within Horns Reef II offshore wind farm. Data are presented for a 2.5 years period and covers normal operating conditions and one larger storm event. A reduction of the pile-soil stiffness was observed during the storm...... events, followed by a complete regain to a pre-storm level when the storm subsided. In additional, no long term variations of the pile-soil stiffness was observed. The wind turbine is located in dense to very dense sand deposits....

  19. Applying of Concrete-cored DCM Pile in Thick Soft Soil Foundation at Northeast Segment of Circle Express Way, Nanjing%混凝土芯水泥土搅拌桩在绕越高速公路东北段深厚软土地基中的应用

    Institute of Scientific and Technical Information of China (English)

    朱翔

    2011-01-01

    混凝土芯水泥土搅拌桩作为一种新型的高速公路软土地基加固方法,承栽力远远高于相同桩径的水泥土搅拌桩,其造价又比相应的钢筋混凝土桩低,且没有泥浆污染,应用推广前景广阔,有较好的经济效益和社会效益。结合南京绕越东北段高速公路先导段RY—DB3标,对混凝土芯水泥土搅拌桩的结构、作用机理和施工方法、质量控制、检测方法等做简单阐述。%As a new reinforcing method of soft soil in express way, Concrete-cored DCM (Deep Cement Mixing) pile has preferable economic and social benefit for its bearing capacity outclass DCM pile with the same diameter, and its cost is lower than corresponding concrete pile. It avoids slop pollution and has extensive applying foreground. This paper introduced the structure, effect mechanism, quality control, test mesures of Concrete-cored DCM pile connected with RY-DB3 bid of the Northeast segment of circle express way, Nanjing.

  20. Optimization Mathematical Model of Pile Forces for Offshore Piled Breasting Dolphins

    Institute of Scientific and Technical Information of China (English)

    周锡礽; 王东芹; 王晖; 朱福明

    2004-01-01

    An optimization mathematical model of the pile forces for piled breasting dolphins in the open sea under various loading conditions is presented. The optimum layout with the well distributed pile forces and the least number of piles is achieved by the multiplier penalty function method. Several engineering cases have been calculated and compared with the result of the conventional design method. It is shown that the number of piles can be reduced at least by 10% ~ 20%and the piles' bearing state is improved greatly.

  1. Corporate Foundations

    DEFF Research Database (Denmark)

    Herlin, Heidi; Thusgaard Pedersen, Janni

    2013-01-01

    This paper aims to explore the potential of Danish corporate foundations as boundary organizations facilitating relationships between their founding companies and non-governmental organizations (NGOs). Hitherto, research has been silent about the role of corporate foundations in relation to cross......-sector partnerships. The results of this paper are based on interviews, participant observations, and organizational documents from a 19-month empirical study of a Danish corporate foundation. Findings suggest that corporate foundations have potential to act as boundary organizations and facilitate collaborative...... action between business and NGOs through convening, translation, collaboration, and mediation. Our study provides valuable insights into the tri-part relationship of company foundation NGO by discussing the implications of corporate foundations taking an active role in the realm of corporate social...

  2. Thermal Conductivity Of Rubble Piles

    CERN Document Server

    Luan, Jing

    2015-01-01

    Rubble piles are a common feature of solar system bodies. They are composed of monolithic elements of ice or rock bound by gravity. Voids occupy a significant fraction of the volume of a rubble pile. They can exist up to pressure $P\\approx \\epsy\\mu$, where $\\epsy$ is the monolithic material's yield strain and $\\mu$ its rigidity. At low $P$, contacts between neighboring elements are confined to a small fraction of their surface areas. As a result, the effective thermal conductivity of a rubble pile, $\\kcon\\approx k(P/(\\epsy\\mu))^{1/2}$, can be orders of magnitude smaller than, $k$, the thermal conductivity of its monolithic elements. In a fluid-free environment, only radiation can transfer energy across voids. It contributes an additional component, $\\krad=16\\ell\\sigma T^3/3$, to the total effective conductivity, $\\keff=\\kcon +\\krad$. Here $\\ell$, the inverse of the opacity per unit volume, is of order the size of the elements and voids. An important distinction between $\\kcon$ and $\\krad$ is that the former i...

  3. Fiber Bragg Grating-Based Performance Monitoring of Piles Fiber in a Geotechnical Centrifugal Model Test

    Directory of Open Access Journals (Sweden)

    Xiaolin Weng

    2014-01-01

    Full Text Available In centrifugal tests, conventional sensors can hardly capture the performance of reinforcement in small-scale models. However, recent advances in fiber optic sensing technologies enable the accurate and reliable monitoring of strain and temperature in laboratory geotechnical tests. This paper outlines a centrifugal model test, performed using a 60 g ton geocentrifuge, to investigate the performance of pipe piles used to reinforce the loess foundation below a widened embankment. Prior to the test, quasidistributed fiber Bragg grating (FBG strain sensors were attached to the surface of the pipe piles to measure the lateral friction resistance in real time. Via the centrifuge actuator, the driving of pipe piles was simulated. During testing, the variations of skin friction distribution along the pipe piles were measured automatically using an optical fiber interrogator. This paper represents the presentation and detailed analysis of monitoring results. Herein, we verify the reliability of the fiber optic sensors in monitoring the model piles without affecting the integrity of the centrifugal model. This paper, furthermore, shows that lateral friction resistance developed in stages with the pipe piles being pressed in and that this sometimes may become negative.

  4. Numerical simulation of liquefaction susceptibility of soil interacting by single pile

    Directory of Open Access Journals (Sweden)

    Ahmad Asaadi

    2015-06-01

    Full Text Available Previous case histories have shown that soil liquefaction severely damaged many structures supported on pile foundations during earthquakes. As a result, evaluating the potential for instability is an important consideration for the safe and resistant design of deep foundation against earthquakes. In this study, the liquefaction susceptibility of saturated sand interacting by single concrete pile was simulated by means of finite difference method. A nonlinear effective stress analysis was used to evaluate soil liquefaction, and the soil-pile interaction was considered using interface elements. The parameter Ru was defined as the pore water pressure ratio to investigate liquefaction in the soil mass during time. A set of numerical models were carried out by three types of soil mass with various condensation (loose, semi-dense and dense under three ground motion with different predominant frequencies and peak accelerations. The effect of these parameters was studied using excess pore pressure, lateral movement and settlement time histories. It was found that the pile can affect the liquefaction susceptibility of soil by comparing the near pile and free field responses. However, for various soil and earthquake characteristics, it was found that the depth of soil liquefaction and triggering, varies.

  5. Mechanical analysis about the influence of tunnel excavation on vertical effect of adjacent bridge pile

    Science.gov (United States)

    Tian, Xiaoyan

    2017-08-01

    Tunnel excavation will bring additional deformation and internal force of adjacent bridge piles, if the deformation is large, it will threat the upper structure safety of the bridge. According to the complexity of the existing three - dimensional numerical simulation modeling and the time - consuming calculation, a two - stage analysis method of tunnel excavation based on Winkler foundation model was proposed. Firstly, Loganathan and Polous solutions were used to obtain the vertical displacement of the soil free field at the pile position when tunnel excavated, and the corresponding polynomial fitting displacement curve was taken. Secondly, the differential equation was established by means of the equilibrium condition of micro - element physical force and considering the pile group effect. Then, through the logical derivation, the calculation expressions of the tunnel excavation on the effect of the adjacent bridge pile (settlement, axial force and friction resistance) were obtained. Finally, based on the background of the tunnel project of Yanxing Door Station ∼ Xianning Road Station in Xi’an Metro Line 3, the feasibility and applicability of the proposed method were proved by comparing the calculated values with the numerical simulation values. It provides theoretical guidance for the effective analysis about the influence of tunnel excavation on the adjacent pile foundation effect.

  6. Experimental Investigations on the Efficiency Coefficient of Pile Groups

    Directory of Open Access Journals (Sweden)

    Sara Darsi

    2016-06-01

    Full Text Available Several factors influence on behavior of piles group such as type of soil, number of piles in the group and the distance between piles. In this paper, using a small laboratory model, the influence of these factors on the behavior of piles group has been examined.For this purpose a group of piles in different distances and variable number of piles was allocated in sand under anpressure axial load. The piles are preferably metal; thus to reduce weight a hollow type has been selected.In order to calculate the coefficient of piles group efficiency, a single pile has been experimented. Experimental observations show that the number of piles in the group and the distances between piles in sand have considerable effect on bearing capacity and the coefficient of pile group efficiency and the coefficient of efficiency in this type of soil have constantly been more than 1 and limited to 1 by increasing the distance between piles.

  7. Static Tension Tests on Axially Loaded Pile Segments in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...

  8. Noise reduction by the application of an air-bubble curtain in offshore pile driving

    Science.gov (United States)

    Tsouvalas, A.; Metrikine, A. V.

    2016-06-01

    Underwater noise pollution is a by-product of marine industrial operations. In particular, the noise generated when a foundation pile is driven into the soil with an impact hammer is considered to be harmful for the aquatic species. In an attempt to reduce the ecological footprint, several noise mitigation techniques have been investigated. Among the various solutions proposed, the air-bubble curtain is often applied due to its efficacy in noise reduction. In this paper, a model is proposed for the investigation of the sound reduction during marine piling when an air-bubble curtain is placed around the pile. The model consists of the pile, the surrounding water and soil media, and the air-bubble curtain which is positioned at a certain distance from the pile surface. The solution approach is semi-analytical and is based on the dynamic sub-structuring technique and the modal decomposition method. Two main results of the paper can be distinguished. First, a new model is proposed that can be used for predictions of the noise levels in a computationally efficient manner. Second, an analysis is presented of the principal mechanisms that are responsible for the noise reduction due to the application of the air-bubble curtain in marine piling. The understanding of these mechanisms turns to be crucial for the exploitation of the maximum efficiency of the system. It is shown that the principal mechanism of noise reduction depends strongly on the frequency content of the radiated sound and the characteristics of the bubbly medium. For piles of large diameter which radiate most of the acoustic energy at relatively low frequencies, the noise reduction is mainly attributed to the mismatch of the acoustic impedances between the seawater and the bubbly layer. On the contrary, for smaller piles and when the radiated acoustic energy is concentrated at frequencies close to, or higher than, the resonance frequency of the air bubbles, the sound absorption within the bubbly layer

  9. Global and local scour at pile groups

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Bundgaard, Klavs; Fredsøe, Jørgen

    2005-01-01

    This paper presents the results of an experimental investigation on scour around pile groups with different configurations exposed to steady current. Two kinds of tests were carried out: rigid-bed tests and actual scour tests. In these, the mean and turbulence properties of the flow were measured...... across the pile groups. The pile-group configurations were such that the global scour was distinguished from the local scour. The results show that the global scour can be quite substantial....

  10. Global and local scour at pile groups

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Bundgaard, Klavs; Fredsøe, Jørgen

    2005-01-01

    This paper presents the results of an experimental investigation on scour around pile groups with different configurations exposed to steady current. Two kinds of tests were carried out: (1) Rigid-bed tests, and (2) Actual scour tests. In the former tests, the mean and turbulence properties...... of the flow were measured across the pile groups. The pile group configurations were such that the global scour was distinguished from the local scour. The results show that the global scour can be quite substantial....

  11. Vertical Capacity of Bucket Foundations in Undrained Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo

    2014-01-01

    Offshore wind turbine structures are traditionally founded on gravity concrete foundations or mono-piles. Bucket foundations were developed for the offshore oil and gas industry and are now being used in wind turbine construction. The loading in this application is characterized by a vertical load...... due to the slender construction combined with horizontal forces inducing a large overturning moment. Field tests on bucket foundations were performed to gain insight into the vertical load response of bucket foundations in clay soils. The field tests were accompanied by finite element numerical...... simulations in order to provide a better understanding of the parameters influencing bucket foundation behavior....

  12. Influence of reaction piles on test pile response in a static load test

    Institute of Scientific and Technical Information of China (English)

    Qian-qing ZHANG; Shu-cai LI; Zhong-miao ZHANG

    2013-01-01

    This work presents a new analytical method to analyze the influence of reaction piles on the test pile response in a static load test.In our method,the interactive effect between soil and pile is simulated using independent springs and the shear displacement method is adopted to analyze the influence of reaction piles on test pile response.Moreover,the influence of the sheltering effect between reaction piles and test pile on the test pile response is taken into account.Two cases are analyzed to verify the rationality and efficiency of the present method.This method can be easily extended to a nonlinear response of an influenced test pile embedded in a multilayered soil,and the validity is also demonstrated using centrifuge model tests and a computer program presented in the literature.The present analyses indicate that the proposed method will lead to an underestimation of the test pile settlement in a static load test if the influence of the presence of reaction piles on the test pile response is neglected.

  13. P–y curves for bucket foundations in sand using finite element modeling

    DEFF Research Database (Denmark)

    Østergaard, Martin Underlin; Knudsen, Bjørn S.; Ibsen, Lars Bo

    2015-01-01

    Pile foundations for offshore wind turbines are often designed using p−y curves, where the soil reaction is given as a function of the pile displacement. The p−y curves are based on experiments done using slender piles, normally used in the oil and gas-industry. The monopiles commonly used today...... than a monopile, thus the before mentioned mismatch is even more pronounced. The purpose of this paper is to use 3D finite element modelling in PLAXIS 3D to establish a new p−y curve formulation for the bucket foundation in sand. The new formulation is based on the results of 18 numerical models...

  14. On Bearing Behavior of Rigid - flexible Multi-pile Composite Sub-grades%刚柔多元桩复合地基承载性能有限元分析

    Institute of Scientific and Technical Information of China (English)

    阎风翔

    2014-01-01

    The present research imitates the bearing behavior of rigid - flexible multi - pile composite foundation using finite element software ABAQUS and obtains the pile body stress characteristics and deformation law. The load of rigid pile is obviously bigger than that of the flexible pile. As for the same type pile,stress of angle pile is the largest,stress of side pile is smaller,and stress of center pile is the smallest. The biggest pile body stress is not at the top of piles,but in a certain position of them. Laws of deformation and bearing capacity of composite foundation are opposite:the deformation of pile top is largest,the deformation of pile group center is the largest,that of the side pile is smaller,and that of the angle pile is the smallest.%采用有限元软件ABAQUS模拟刚柔多元桩复合地基,得出其桩顶、桩身应力特点和变形规律。刚性桩承担的荷载明显大于柔性桩承担的荷载;对于同种桩型,角桩的应力最大,边桩次之,中桩最小;沿桩身应力最大部位不在桩顶,而是位于桩身的某一位置;复合地基的变形规律与承载力规律恰好相反,桩顶处变形最大,并且群桩中心处变形最大,边桩次之,角桩最小。

  15. Vasculitis Foundation

    Science.gov (United States)

    ... Read More Click here to view full calendar Vasculitis Patient-Powered Research Network The V-PPRN seeks ... with various forms of vasculitis. Join The Network! Vasculitis Foundation News Introducing our 2017-2018 VCRC-VF ...

  16. Glaucoma Foundation

    Science.gov (United States)

    ... IMPORTANT RESEARCH FINDING First Cellular Model of Exfoliation Glaucoma Research is advancing in the quest to find ... cure for exfoliation syndrome and its associated exfoliation glaucoma, the current focus of The Glaucoma Foundation. Exfoliation ...

  17. Foundation Structure

    OpenAIRE

    Schakenda, Bruno; Nielsen, Søren Andreas; Ibsen, Lars Bo

    2009-01-01

    Method of installing a bucket foundation structure comprising one, two, three or more skirts, into soils in a controlled manner. The method comprises two stages: a first stage being a design phase and the second stage being an installation phase. In the first stage, design parameters are determined relating to the loads on the finished foundation structure; soil profile on the location; allowable installation tolerances, which parameters are used to estimate the minimum diameter and length of...

  18. Effect of pile-cap connection on behavior of torsionally loaded pile groups

    Institute of Scientific and Technical Information of China (English)

    Ling-gang KONG; Li-min ZHANG

    2008-01-01

    To evaluate the respouses of fixed and pinned pile groups under torsiun, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and τ-θ curves, the far-field interactions through Mindlin's and Randolph's elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixedand pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%~64% of those for the corresponding fixed-head pile groups at a twist angle of 2°. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.

  19. Tension Tests On Bored Piles In Sand

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

    2006-01-01

    The lengths of the bored piles varied from 2 m to 6 m and all were of a diameter of 140 mm. The piles were tested to failure in tension and the load-displacement relations were recorded. The investigation has shown pronounced differences between the load bearing capacities obtained by different...

  20. Steel Sheet Pile Walls in Soft Soil

    NARCIS (Netherlands)

    Kort, D.A.

    2002-01-01

    For almost a century, steel sheet pile walls are applied worldwide as earth retaining structures for excavations and quay walls. Within the framework of the development of European structural codes for Civil Engineering works, the Eurocodes, Eurocode 3 Part 5 for design of steel sheet pile walls was

  1. Analysis of pile load-transfer under pile-side softening

    Institute of Scientific and Technical Information of China (English)

    刘杰; 张可能

    2003-01-01

    A set of analytical equations for the variation of the axial force along depth and the pile-top load-settle-ment curve were established, using tri-linear softening model to pile-side soil and bilinear hardening model to pile-end soil . Influences of the pile-side and pile-end soil behavior on the load-settlement curve were discussed, indica-ting that the lowering reason for the variation step degree of the axial force along depth is the softening of the pile-side soil to result in the side friction lowering when the pile-top load is increased. To verify the reliability of thismethod, the parameters used in calculation are obtained from the test in Zhuzhou area. The obtained results are thencompared with the tested results. Contrast shows that the calculated results and the tested values are very close,which illustrates that the proposed method is reliable.

  2. Analytical Evaluation of Reinforced Concrete Pier and Cast-in-Steel-Shell Pile Connection Behavior considering Steel-Concrete Interface

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2016-01-01

    Full Text Available The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS pile where a reinforced concrete (RC member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the steel casing, both the cost and size of CISS pile can be reduced. In this study, the structural behavior of the RC pier and the CISS pile connection is simulated by using an advanced 3D finite element (FE method, where the interface between the steel and concrete is also modeled. Firstly, the FE model is verified. Then, the parametric study is conducted. The analysis results suggest that the embedment length and the friction coefficient between the steel casing and the infilled concrete affect the structural behavior of the RC pier. Finally, the minimum embedment length with reference to the AASHTO design guideline is suggested considering the composite action of the CISS pile.

  3. Prediction of unknown deep foundation lengths using the Hilbert Huang Transform (HHT

    Directory of Open Access Journals (Sweden)

    Ahmed T.M. Farid

    2012-08-01

    Full Text Available Prediction of unknown deep foundation embedment depth is a great deal nowadays, especially in case of upgrading or rehabilitation of old structures. Many old bridges and marine or pier structures in the United States are established using deep foundations system of timber piles and their foundation records do not exist. Non-Destructive Testing (NDT or Non-Destructive Evaluation (NDE method for a great variety of materials and structures has become an integral part of many tests. However, the process of testing long piles, deeply embedded in the ground, is more complex than (NDT of the other structural materials. This paper summarizes some of the most common non-destructive test methods for deep foundations and presents a new method called the Hilbert Huang Transform (HHT. This Hilbert Huang Transform (HHT method is used now by a wide range in a different health monitoring of many systems. In this paper, some field tests on the timber Piles of one bridge at North Carolina was performed to verify the using the (HHT method for predicting the embedded depth of the unknown piles. Percentage of the accuracy achieved using HHT method for pile length compared to the actual pile length data was performed. Finally, a recommendation is presented for the limitation of using this new method as a new non-destructive method for deep foundations.

  4. Simulation Studies on the Settlement of Composite Foundation with Contact Element of Zero Thickness

    Institute of Scientific and Technical Information of China (English)

    Dong Bichang; Wang Jingtao; Cheng Tao

    2005-01-01

    The various factors influencing the settlement of composite foundation have been more completely studied through numerical simulation. The influence on the settlement of composite foundation of the geometry and mechanical properties of the pile, soil, cushion, and the interface between pile and soil have been investigated through computer simulation, in which the contact elements with zero thickness are used. Some valuable conclusions for the settlement of composite foundation have been obtained: (1) The method using the contact element of zero thickness is successful when used in the simulation of the settlement of composite foundation; (2) Among the factors influencing the settlement of composite foundation, the compression modulus of the soil is the largest, and the cohesion of the soil is the second largest; (3) The effects on settlement of the internal friction angle of the soil, the elastic modulus, the radius, and the length of the pile, and the elestic modulus of the cushion are also more obvious.

  5. Environmentally Friendly Solution to Ground Hazards in Design of Bridges in Earthquake Prone Areas Using Timber Piles

    Science.gov (United States)

    Sadeghi, H.

    2015-12-01

    Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.

  6. Deformation Measurement of a Driven Pile Using Distributed Fibre-optic Sensing

    Science.gov (United States)

    Monsberger, Christoph; Woschitz, Helmut; Hayden, Martin

    2016-03-01

    New developments in distributed fibre-optic sensing allow the measurement of strain with a very high precision of about 1 µm / m and a spatial resolution of 10 millimetres or even better. Thus, novel applications in several scientific fields may be realised, e. g. in structural monitoring or soil and rock mechanics. Especially due to the embedding capability of fibre-optic sensors, fibre-optic systems provide a valuable extension to classical geodetic measurement methods, which are limited to the surface in most cases. In this paper, we report about the application of an optical backscatter reflectometer for deformation measurements along a driven pile. In general, pile systems are used in civil engineering as an efficient and economic foundation of buildings and other structures. Especially the length of the piles is crucial for the final loading capacity. For optimization purposes, the interaction between the driven pile and the subsurface material is investigated using pile testing methods. In a field trial, we used a distributed fibre-optic sensing system for measuring the strain below the surface of an excavation pit in order to derive completely new information. Prior to the field trial, the fibre-optic sensor was investigated in the laboratory. In addition to the results of these lab studies, we briefly describe the critical process of field installation and show the most significant results from the field trial, where the pile was artificially loaded up to 800 kN. As far as we know, this is the first time that the strain is monitored along a driven pile with such a high spatial resolution.

  7. Dynamic Instability of Pile-Supported Structures in Liquefiable Soils during Earthquakes

    Directory of Open Access Journals (Sweden)

    S. Adhikari

    2008-01-01

    Full Text Available Piles are long slender columns installed deep into the ground to support heavy structures such as oil platforms, bridges, and tall buildings where the ground is not strong enough to support the structure on its own. In seismic prone zones, in the areas of soft soils (loose to medium dense soil which liquefies like a quick sand piles are routinely used to support structures (buildings/ bridges. The pile and the building vibrate, and often collapse, in liquefiable soils during major earthquakes. In this paper an experimental and analytical approach is taken to characterize this vibration. The emphasis has been given to the dynamic instability of piled foundations in liquefied soil. The first natural frequency of a piled-structure vibrating in liquefiable soil is obtained from centrifuge tests. The experimental system is modelled using a fixed-free Euler-Bernoulli beam resting against an elastic support with axial load and tip mass with rotary inertia. Natural frequencies obtained from the analytical method are compared with experimental results. It was observed that the effective natural frequency of the system can reduce significantly during an earthquake.

  8. Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles

    Directory of Open Access Journals (Sweden)

    Haibin Yang

    2017-04-01

    Full Text Available Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.

  9. Numerical simulation of the influence of soil core on the bearing capacity of pipe pile

    Directory of Open Access Journals (Sweden)

    G.Ya. Bulatov

    2010-03-01

    Full Text Available The cost of the foundation can be up to 20-30% of the total building cost. Reducing consumption of materials and quality selection of the required characteristics of the pile can reduce both the estimated cost and time of work.In terms of compact construction and the high land prices the most relevant is high-rise building. But it is hard to build in soft ground conditions (for example, in St. Petersburg. The situation is complicated by insufficiently explored methods of selection and design of piles (especially steel-tube piles for specific cases of construction, as well as by the absence of regulatory documents related to the high-performance technology.The article considers the clarification methods for calculating the bearing capacity of tubular steel piles. An additional contribution of soil core to the overall bearing capacity due to accounting an effect of its "natural" selflocking in the cavity of the steel pipe is considered.The conclusions about the effectiveness of the piles, depending on different initial parameters are made.

  10. Vertical vibration of a large diameter pipe pile considering transverse inertia effect of pile

    Institute of Scientific and Technical Information of China (English)

    郑长杰; 刘汉龙; 丁选明; 周航

    2016-01-01

    Considering the transverse inertia effect of pile, the vertical dynamic response of a large diameter pipe pile in viscoelastic soil layer is studied. The wave propagations in the outer and inner soil are simulated by three-dimensional elastodynamic theory and those in the pile are simulated by Rayleigh-Love rod theory. The vertical and radial displacements of the outer and inner soil are obtained by utilizing Laplace transform technique and differentiation on the governing equations of soils. Then, based on the continuous conditions between the pile and soils, the displacements of the pile are derived. The frequency domain velocity admittance and time domain velocity response of the pile top are also presented. The solution is compared to a classical rod model solution to verify the validity. The influences of the radii and Poisson ratio of pile on the transverse inertia effect of pile are analyzed. The parametric study shows that Poisson ratio and outer radius of pile have significant influence on the transverse inertia effect of large diameter pipe piles, while the inner radius has little effect.

  11. 3D finite element analysis on pile-soil interaction of passive pile group

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; LIU Dun-ping; ZHANG Ling; JIANG Chong

    2008-01-01

    The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and cousiderable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.

  12. Analysis of effect of different construction methods of piles on the end effect on skin friction of piles

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hongbo; CHEN Zhuchang

    2007-01-01

    Based on the comparative analysis of end effect on skin friction of displacement-pile (driven pile),the end effect on skin friction of bored pile is studied.The end effect on skin friction between driven pile and bored pile is different and the end effect on skin friction of bored pile is reduce of skin friction in the soil layer adjacent to the pile end.The degradation degree of skin friction is deduced with the increase of the distance from pile end.The concept of additional mud cake formed by the effect of cushion at the bottom of borehole during pouring concrete is introduced to explain the mechanism of end effect on skin friction of the bored pile.The test results of post-grouting piles indicate that the post-grouting technique is an effective way to improve the end effect on skin friction of bored pile.

  13. The Construction Technologies and Quality Control Measures of Rotary Drilling Bored Piles%旋挖桩的施工工艺及质量保证措施

    Institute of Scientific and Technical Information of China (English)

    孙晓元

    2015-01-01

    ABSTRACT:The construction of rotary drilling bored piles is more advanced way of pile foundation construction, and the rotary drilling bored pile has the the characteristics of good quality and high construction efficiency. This paper introduces in detail the construction technologies of rotary drilling bored pile, and probes into the quality control measures for the construction of rotary drilling bored piles.%旋挖桩施工是现今我国建筑施工中一种较为先进的桩基施工方式,具有质量好、施工效率高的特点。详细介绍了旋挖桩的施工工艺,探讨了旋挖桩的工程质量保证措施。

  14. Applied Foundations

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich

    2002-01-01

    A central theme in the foundations of mathematics, dating back to D. Hilbert, can be paraphrased by the following question "How is it that abstract methods (`ideal elements´) can be used to prove `real´ statements e.g. about the natural numbers and is this use necessary in principle?"...

  15. Bucket foundations

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    In this report, bearing behaviour and installation of bucket foundations are reviewed. Different methods and standards are compared with the experimental data presented in Foglia and Ibsen (2014a). The most important studies on these topics are suggested. The review is focused on the response...

  16. Safety precautions in atomic pile control (1962); Securite dans le controle des piles atomiques (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Furet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    We have been led to study the problem of safety in atomic pile control as a result of our participation on the one hand in the planning of C.E.A. atomic piles, and on the other hand in the pile safety sub omission considering atomic pile safety of operational or planned C.E.A. piles. We have thus had to consider the wishes occurring in piles during their operation and also their behaviour in the dynamic state The present work deals mainly with the importance of intrinsic safety devices, with the influence of reactivity variations on the power fluctuations during accidental operation, and with the development of robust and reliable safety appliances. The starting p accident has been especially studied both for low-flux piles where a compromise is necessary between the response time of the safety appliances and the statistical fluctuations and for high lux piles where xenon poisoning has an effect on the lower limit of the velocity of reactivity liberation. The desirability has been stressed of automation as a safety factor in atomic pile control. The details required for an understanding of the diagrams of the apparatus are given. (author) [French] Nous avons aborde le probleme de la securite dans le controle des piles atomiques a la suite de notre participation d'une part aux avant rojets de piles atomiques du CE.A. et d'autre part a l'examen au sein de la sous ommission de surete des piles, de la securite des piles du CE.A. en fonctionnement ou en projet. Nous avons ete amenes a nous interesser alors aux risques encourus par les piles pendant leur fonctionnement et par la meme a leur comportement en regime dynamique. Ce travail traite principalement de l'importance des securites intrinseques, de l'influence des variations de reactivite sur les evolutions de puissance en regime d'accident et du developpement d'appareillages de securite robustes et de fonctionnement tres sur. L'accident de demarrage a ete particulierement

  17. 30 CFR 77.214 - Refuse piles; general.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; general. 77.214 Section 77.214... Installations § 77.214 Refuse piles; general. (a) Refuse piles constructed on or after July 1, 1971, shall be..., tipples, or other surface installations and such piles shall not be located over abandoned openings...

  18. 30 CFR 77.215-4 - Refuse piles; abandonment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; abandonment. 77.215-4 Section 77... MINES Surface Installations § 77.215-4 Refuse piles; abandonment. When a refuse pile is to be abandoned... refuse pile shall be abandoned in accordance with a plan submitted by the operator and approved by...

  19. Numerical Analysis of Piles in Layered Soils: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Reddy C

    2015-04-01

    Full Text Available In this paper, numerical analysis of a pile-soil interaction problem is presented considering the parameters influencing the axial load-deformation behavior of the pile embedded in a layered soil medium. The analysis is demonstrated with parametric solutions of a pile with underlain model soil strata under the axial force. An attempt is made to ascertain the extent of influence of elastic properties of the pile, geometry of the pile, end conditions of the pile and the elastic properties of the underlain soil strata on the response of the piles under axial loads lying in a model soil layers in terms of the settlement of the pile and the internal deformation of the pile. The study revealed that the increase in modulus of elasticity of pile improves the settlement resistance of the pile, increase in the ratio of cross sectional dimensions causes decrease in the top deformations of the pile, the settlement of the pile reduced to a great extent when the cross section of the pile adopted is non circular instead of circular and increase in the elastic modulii of top and bottom layers of soil has decreased the settlement of the pile to a great extent, but elastic modulus of soil layers other than top and bottom has got negligible influence on the settlement of the pile.

  20. Efficient stock piling of 40mm shells

    Directory of Open Access Journals (Sweden)

    J. N. Nanda

    1958-10-01

    Full Text Available A problem was posed as to discuss efficient stock-piling of 40mm shells. There is, in fact no data from which emergency requirements can be deduced. A figure has been quoted by Army authorities that E rounds per month are required during an emergency. The size of the emergency stock pile will depend upon the difference of the normal peace time production, and also on the time taken for the crash programme of emergency production to come into fulfillment. In addition the delivery time from factories to the stock piles is also kept in view.

  1. Research on method of pressure grouting piling of driven tube

    Institute of Scientific and Technical Information of China (English)

    Dianqi PAN; Zupei ZHANG; Diancai PAN; Yong CHEN; Maosen TAN

    2006-01-01

    The pressure grouting pile of driven tube can improve the load bearing capacity of the single pile from the mechanism of pressure grouting pile of driven tube. On the basis of analyzing the mechanism, the authors designed the machines and tools of pressure grouting, determined the operating manufacture and technology parameter on the pressure grouting secondly. The result shows that the pressure grouting pile of driven tube not only changes the pile type but also reduce the length of the pile and its engineering cost, it enhances the load bearing capacity of single pile an the same time.

  2. Ground vibrations due to pile and sheet pile driving : prediction models of today

    OpenAIRE

    Deckner, Fanny; Viking, Kenneth; Hintze, Staffan

    2012-01-01

    As part of aconstruction work pile and sheet pile driving unavoidably generates vibrations.As of today construction works are often located in urban areas and along withsociety’s increasing concern of environmental impact the need for vibrationprediction prior to construction is of immediate interest. This study presents a review of the predictionmodels existing today. For prediction of ground vibrations from pile and sheetpile driving there are roughly three different types of models; empiri...

  3. Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany

    NARCIS (Netherlands)

    Daehne, M.; Gilles, A.; Lucke, K.; Peschko, V.; Adler, S.; Kruegel, K.; Sundermeyer, J.; Siebert, U.

    2013-01-01

    The first offshore wind farm 'alpha ventus' in the German North Sea was constructed north east of Borkum Reef Ground approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundations of 12 wind turbines. Visual monitoring of harbour porpoises was conducted p

  4. The Effect of Soil-Pile Interface Behaviour on Laterally Loaded Piles

    DEFF Research Database (Denmark)

    Zania, Varvara; Hededal, Ole

    2011-01-01

    In current practice it is either the p – y curve concept, or analytical solutions assuming different formulations for ultimate soil resistance that are being used to evaluate the lateral pile response. The adequacy of the p – y curves or of the assumed pressure distribution and ultimate soil...... resistance have been questioned. In this study the lateral capacity of three-dimensional numerical models of rigid piles embedded in cohesionless soil was estimated. The potential variability of the friction properties along the perimeter of the pile was considered. The interface properties affect...... the ultimate soil resistance and the stiffness of the soil–pile response....

  5. Introduction of effective piles in a base structure

    Directory of Open Access Journals (Sweden)

    В.Б. Кашка

    2005-03-01

    Full Text Available  Design features of effective piles such as СВ and their advantages in use are considered at the device of the pile bases in comparison with widely widespread types of piles. From results of comparative tests of piles under static pressing loading in different earth conditions the tendency of redistribution of bearing (carrying ability between a trunk and expansions an effective pile such as СВ was determined on earth conditions.

  6. ATLAS Pile-up and Overlay Simulation

    CERN Document Server

    Novak, Tadej; The ATLAS collaboration

    2017-01-01

    The high luminosity of the LHC results in a significant background to interesting physics events known as pile-up. ATLAS uses several methods for simulating the effects of pile-up. The mostly used method is a direct simulation of background events where multiple simulated background events are combined for each physics event. For some physics processes, a more accurate simulation can be achieved by overlaying real proton-proton collisions on a simulated hard-scatter process. Overlay is also being investigated for a premixed pile-up background to reduce CPU usage and I/O stress during the simulation. Embedding replaces the muons found in Z→mumu decays in data with simulated taus at the same 4-momenta, thus preserving the underlying event and pileup from the original data event. This talk compares the pile-up simulation methods used at the ATLAS experiment pointing their benefits and drawbacks.

  7. Buckling of Monopod Bucket Foundations – Influence of Boundary Conditions and Soil-structure Interaction

    DEFF Research Database (Denmark)

    Madsen, Søren; Pinna, Rodney; Randolph, M. F.

    2015-01-01

    Using large monopod bucket foundations as an alternative to monopiles for offshore wind turbines offers the potential for large cost savings compared to typical piled foundations. In this paper, numerical simulations are carried out to assess the risk of structural buckling during installation...... is investigated. The effects of including soil restraint and soil–structure interaction on the buckling analysis are also addressed....

  8. Wave radiation from vibratory and impact pile driving in a layered acousto-elastic medium

    OpenAIRE

    Tsouvalas, A.; Metrikine, A.

    2014-01-01

    A steel monopile is the most common foundation type of a wind turbine installed offshore and is driven into place with the help of vibratory or impact hammers. Underwater noise generated during the installation of steel monopiles has recently received considerable attention from international environmental organizations and regulatory bodies in various nations. Collected data regarding underwater noise measurements indicate that pile driving operations, especially when impact hammers are used...

  9. Local Scour Around Piles Under Wave Action

    Institute of Scientific and Technical Information of China (English)

    陈国平; 左其华; 黄海龙

    2004-01-01

    The model tests are performed with regular waves, and the effect of wave height, wave period, water depth, scdiment size and pile diameter is evaluated. The shape and size of local scour around piles are studied. There are three typical scour patterns due to wave action. It is found that a relationship exists between the erosion depth and the wave number. An empirical formula of the maximum local scour is thus derived.

  10. Model Test Research on the End Bearing Behavior of the Large-Diameter Cast-in-Place Concrete Pile for Jointed Rock Mass

    Directory of Open Access Journals (Sweden)

    Jingwei Cai

    2016-01-01

    Full Text Available For large-diameter, cast-in-place concrete piles, the end bearing capacity of a single pile is affected by discontinuous surfaces that exist in natural rock masses when the bearing layer of the pile end is located in the rock layer. In order to study the influence of the jointed dip angle on the bearing characteristics of the pile end, the discrete element models are adopted to simulate the mechanical characteristics of the jointed rock masses, and the model tests of the failure mode of the jointed rock masses were also designed. The results of the numerical calculations and modeling tests show that the joints, which have a filtering effect on the internal stress of the bedrock located at the pile end, change the load transferring paths. And the failure mode of the jointed rock foundation also changes as jointed dip angle changes. The rock located at the pile end generally presents a wedge failure mode. In addition, the Q-S curves obtained by model tests show that the ultimate end bearing capacity of a single pile is influenced by the jointed dip angle. The above results provide an important theoretical basis for how to correctly calculate end resistance for a cast-in-place concrete pile.

  11. Nonlinear calculating method of pile settlement

    Institute of Scientific and Technical Information of China (English)

    贺炜; 王桂尧; 王泓华

    2008-01-01

    To study calculating method of settlement on top of extra-long large-diameter pile, the relevant research results were summarized. The hyperbola model, a nonlinear load transfer function, was introduced to establish the basic differential equation with load transfer method. Assumed that the displacement of pile shaft was the high order power series of buried depth, through merging the same orthometric items and arranging the relevant coefficients, the solution which could take the nonlinear pile-soil interaction and stratum properties of soil into account was solved by power series. On the basis of the solution, by determining the load transfer depth with criterion of settlement on pile tip, the method by making boundary conditions compatible was advised to solve the load-settlement curve of pile. The relevant flow chart and mathematic expressions of boundary conditions were also listed. Lastly, the load transfer methods based on both two-broken-line model and hyperbola model were applied to analyzing a real project. The related coefficients of fitting curves by hyperbola were not less than 0.96, which shows that the hyperbola model is truthfulness, and is propitious to avoid personal error. The calculating value of load-settlement curve agrees well with the measured one, which indicates that it can be applied in engineering practice and making the theory that limits the design bearing capacity by settlement on pile top comes true.

  12. Assessment of pile response due to deep excavation in close proximity—A case study based on DTL3 Tampines West Station

    Directory of Open Access Journals (Sweden)

    C.G. Chinnaswamy

    2015-12-01

    Full Text Available Ground movements during deep excavations and tunnelling, especially in urban areas, may potentially have major impact on adjacent buildings, structures and utilities. This impact on buildings and structures needs to be assessed by considering the horizontal and vertical displacements induced by deep excavations to determine the necessary mitigation measures. One major factor affecting the degree of severity the impact due to deep excavation may have on the buildings and structures is the type of foundation systems. While methodology in determining the damage category for the buildings on shallow foundation has been quite well established, the methodology for assessing the impact on the pile foundation is not straightforward due to the geometry and complexity of soil structure interaction. Often simplified two-dimensional (2D or comprehensive three-dimensional (3D finite element analyses would be carried out for the stage excavation to predict the displacement and stresses in the piles. Suitable protective and preventive measures would need to be designed and implemented for the existing buildings/structures if the damage category falls within the unacceptable range. This paper discusses the analysis and methodology to assess the effect on the pile foundation of a high-rise building due to the deep excavation of the Down Town Line Stage 3 (DTL3 Tampines West (TPW Station. The approach to assess the geotechnical capacity of the pile as a result of the deep excavation is presented in this paper. Based on the assessment of pile response, predicted movement, structural and geotechnical capacities of the pile, it was found to be within the acceptable limit and the pile foundation has adequate factor of safety with the deep excavation in close proximity.

  13. The Effect of the Propeller Jet on Pile Groups

    Institute of Scientific and Technical Information of China (English)

    Kubilay Cihan

    2014-01-01

    The objective of this study is to determine the effect of jet propeller on the damage of berthing structures combined of armoured slope with pile groups. For this purpose, scour measurements were performed for four types berthing structures, which were armoured slope with tandem arrangements of piles for two and three piles and with side by side arrangements of piles for two and three piles. The effect of gap between piles on damage was investigated. The damage level induced by propeller jet between piles was determined. The gaps were 1, 2, 3, and 4 times the pile diameter. Three different values of Rpm (690, 820, and 950) were chosen for the tests. The diameter of circular piles is 40 mm. The slope ratio was 1/3 and the diameter of propeller was 10 cm.

  14. Characterizing Axial Stiffness of Individual Batter Piles with Emphasis on Elevated, Laterally Loaded, Clustered Pile Groups

    Science.gov (United States)

    2016-11-01

    Ebeling1 investigated the minimum required depth of embedment for an example vertical pile bent system founded in a cohesionless sandy soil with two...vertical to 1 horizontal (4V:1H), angled toward shore . Prior to pile driving, the river bottom was dredged, or filled if needed, to elevation 650 ft

  15. Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany

    Science.gov (United States)

    Dähne, Michael; Gilles, Anita; Lucke, Klaus; Peschko, Verena; Adler, Sven; Krügel, Kathrin; Sundermeyer, Janne; Siebert, Ursula

    2013-06-01

    The first offshore wind farm ‘alpha ventus’ in the German North Sea was constructed north east of Borkum Reef Ground approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundations of 12 wind turbines. Visual monitoring of harbour porpoises was conducted prior to as well as during construction and operation by means of 15 aerial line transect distance sampling surveys, from 2008 to 2010. Static acoustic monitoring (SAM) with echolocation click loggers at 12 positions was performed additionally from 2008 to 2011. SAM devices were deployed between 1 and 50 km from the centre of the wind farm. During aerial surveys, 18 600 km of transect lines were covered in two survey areas (10 934 and 11 824 km2) and 1392 harbour porpoise sightings were recorded. Lowest densities were documented during the construction period in 2009. The spatial distribution pattern recorded on two aerial surveys three weeks before and exactly during pile-driving points towards a strong avoidance response within 20 km distance of the noise source. Generalized additive modelling of SAM data showed a negative impact of pile-driving on relative porpoise detection rates at eight positions at distances less than 10.8 km. Increased detection rates were found at two positions at 25 and 50 km distance suggesting that porpoises were displaced towards these positions. A pile-driving related behavioural reaction could thus be detected using SAM at a much larger distance than a pure avoidance radius would suggest. The first waiting time (interval between porpoise detections of at least 10 min), after piling started, increased with longer piling durations. A gradient in avoidance, a gradual fading of the avoidance reaction with increasing distance from the piling site, is hence most probably a product of an incomplete displacement during shorter piling events.

  16. Increase of In-Situ Measured Shear Wave Velocity in Sands with Displacement Pile and Stone Column Inclusions

    Directory of Open Access Journals (Sweden)

    Franciscus Xaverius Toha

    2017-04-01

    Full Text Available Seismic downhole and MASW measurements were conducted at a potentially liquefiable site, where PC piles and stone column inclusion were provided to remediate the foundation soil. The selected site is part of a refinery located in high seismicity zone. The seismic measurements were done prior and after the PC piles and stone columns were installed. The densification, reinforcing, and dissipation contribution to the overall mitigation was elaborated herein. The measurement results are essentially consistent with the most recent theoretical developments and indicate that the strengthening due to mitigation is higher than predicted.

  17. The forecast of a temperature regime of soils containing the pile foundation of a pithead on diamond-mining mines of cryolithic zone%冻土地带钻石矿区含桩基础坑口的土壤温度状况预测

    Institute of Scientific and Technical Information of China (English)

    Urii A.Khokholov; Dmitrii E.Solovev; Alexander S.Kurilko; Alexander V.Drozdov

    2014-01-01

    构建了冻土区垂直井轴套环的环绕岩石部分与空气热交换的三维数学模型。模型充分考虑了冷却器的存在、冻结液体的温度、冻结孔的长度及其数量和位置、大气温度、矿内的空气不均匀度以及所包含岩石的盐分程度。模型可以计算并预测坑口桩承载能力的变化,并将该变化作为影响冷冻系统工作的一个因素。通过使用这种三维数学模型,可确定出最合理的冷冻系统状态(针对于ALROSA证券公司矿山的条件)。这些系统状态数据包括坑口桩的承载能力和尺寸<0.5 m坑轴阻尼解冻环轮保护混凝土衬砌免受坑轴冻结和可能发生的变形侵害。%The three-dimensional mathematical model of heat exchange of air ventilating with environing rocks in collar part of vertical pit shafts of cryolithic zone was developed .It also consider existence of coolers, temperature of freezing liquid , length of freezing holes , their quantity and location , temperatures of atmosphere and mine air , inhomogeneity and degree of salinity of containing rocks .This model allows to calculate and predict change of carrying capacities of pit-head piles taking into account work of freezing system .With use of this three-dimensional mathematical model the most rational regime of freezing system were determined ( for conditions of mines of stock company ALROSA ) .These regimes allow to provide a carrying capacity of pit-head piles and existence of a damping thawed ring round a pit shaft in size less than 0.5 m for protection of concrete lining of pit shaft from freezing and wherein possible deformations .

  18. Effect of soil-foundation-structure interaction on the seismic response of wind turbines

    Directory of Open Access Journals (Sweden)

    Sam Austin

    2017-09-01

    Full Text Available Soil-foundation-structure interaction can affect the seismic response of wind turbines. This paper studies the effects of soil-foundation-structure interaction on the seismic response of 65 kW, 1 MW, and 2 MW horizontal-axis wind turbines with truncated cone steel towers. Four types of foundations with frequency-based design were analyzed, including spread foundation, mono pile, pile group with cap, and anchored spread foundation. Soil is modeled both implicitly (subgrade reaction modulus and explicitly. The finite element model developed using the ANSYS program was first validated using experimental data. Numerical models are then analyzed in both frequency and time domains using the Block Lanczos and generalized HHT-α formulations. Recommendations were given to simplify the soil-foundation-structure interaction analysis of wind turbines subjected to seismic loading.

  19. Heat piles - a combination of geotechnical and geothermal engineering; Energiepfaehle - Verbindung von Geotechnik und Geothermie

    Energy Technology Data Exchange (ETDEWEB)

    Katzenbach, R.; Rueckert, A. [Technische Univ. Darmstadt (Germany). Inst. fuer Geotechnik; Knoblich, K.; Sanner, B. [Giessen Univ. (Germany). Inst. fuer Angewandte Geowissenschaften; Mands, E. [Prof. Dr. Knoblich und Partner GmbH, Wetzlar (Germany)

    1997-12-01

    The numerical programs used for borehole heat exchangers are also suitable to simulate the performance of heat piles, provided they permit a differentiation of thermal properties in the vicinity of the heat exchanger pipes. Adaptations of known programs for heat piles have been described by PAHUD and FROMENTIN (1997). For simple pile geometries, the program EED can be used as well (HELLSTROeM et al., 1997), as it permits very quick determination of the potentials for heat extraction and energy supply. Because of their geotechnical function, such systems should only be made use of where heating and cooling can be planned with sufficient accuracy, giving an idea of the likely temperatures in the piles. Further, the static function of the piles needs to be kept in mind. If adequately used, heat piles offer a huge potential for practically all types of buildings erected in sites requiring deep foundations or where the excavation for the foundation needs to be enclosed. In Germany alone 5000 buildings are erected each year which would permit non-depleting use of the thermal energy bottled up in the ground and ground water via heat piles. (orig.) [Deutsch] Zur Simuliation des Betriebsverhaltens von Energiepfahlanlagen eigenen sich die auch fuer Erdwaermesonden verwendeten numerischen Programme, vorausgesetzt, sie lassen eine Differenzierung der thermischen Eigenschaften im Nahbereich der Waermetauscherrohre zu. Anpassungen von bekannten Programmen im Hinblick auf Energiepfaehle schildern PAHUD and FROMENTIN (1997). Fuer einfache Pfahlgeometrien kann auch das Programm EED herangezogen werden (HELLSTROeM et al., 1997), mit dem sich sehr schnell die moeglichen Entzugs- und Einspeiseleistungen ermitteln lassen. Wegen der vorrangigen geotechnischen Bedeutung sollten Energiepfaehle nur im Rahmen einer ausreichend genauen Heizungs-/Kuehlungsplanung vorgesehen werden, die einen Eindruck der zu erwartenden Temperaturen in den Phaehlen geben kann. Ausserdem ist immer zu beachten

  20. Vertical dynamic response characteristics of single pile in non-homogeneous soil layers

    Institute of Scientific and Technical Information of China (English)

    KONG De-sen; LUAN Mao-tian; LING Xian-zhang

    2008-01-01

    A computational method and a mechanical model for evaluating the vertical dynamic harmonic response characteristics of a single pile embedded in non-homogeneous soil layers and subjected to harmonic loadings were established based on a certain assumption and the improved dynamic model of beam-on-Winkler foundation by using the principle of soil dynamics and structure dynamics. Both non-homogeneity of soil strata and softening effect of soil layer around the pile during vibration were simultaneously taken into account in the pro-posed computational model. It is shown through the comparative study on a numerical example that the numerical results of dynamic response of the single pile computed by the proposed method are relatively rational and can well agree with the numerical results computed from the well-known software of finite element method. Finally the parametric studies were conducted for a varied range of main parameters to discuss the effects of relevant factors on dynamic responses of the single pile embedded in non-homogeneous layered soils excited by harmonic loading with different frequencies.

  1. Geotechnical maps for recommendation on bored pile capacity in Nakhon Ratchasima municipality, Thailand

    Directory of Open Access Journals (Sweden)

    Suksun Horpibulsuk

    2013-08-01

    Full Text Available This paper presents the development of geotechnical maps in Nakhon Ratchasima municipality, Nakhon Ratchasima province, Thailand based on the boring logs and in situ test results collected from public and private sector sources. The standard penetration number, N was used to identify the soil type. The soil deposits in Nakhon Ratchasima municipality are divided into three layers: medium-to-stiff silty clay with N 50. The medium-to-stiff silty clay layer has a thickness varying from 1.8 to 7.5 metres and an average N value of 14 with a relatively low standard deviation of 1.08. The first hard silty clay layer has a thickness varying from 1.2 to 3.0 metres and an average N value of 42 with a standard deviation of 1.37. For a practical application in foundation engineering in which the pile tips of the bored piles are located in the second hard stratum with N > 50, eight pile tip zones with approximated load capacity are recommended for pile lengths of 3-10 metres.

  2. Comparison of Design Schemes of Inclined Pile and Vertical Pile in Embedded Rock Pile of Thin Walled Abut-ment%薄壁桥台嵌岩桩基础斜桩与直桩设计方案的比较

    Institute of Scientific and Technical Information of China (English)

    张利强

    2012-01-01

      According to the pile foundation engineering of 2nd section of Monapo bridge foundation project in Nampula-Cua-mbaroad road upgrading and regeneration in Mozambique, calculation analysis was made on the stress and reinforcement of different base heights and pile lengths of embedded rock pile of thin walled abutment with Prokon 2.5 structure analysis software, so as to provide the basis for rational selection of pile foundation type based on different formation conditions and base heights in the design.%  结合莫桑比克Nampula-Cuamba道路升级改造项目第二标段Monapo桥基础桩基工程,采用Prokon 2.5结构分析软件对薄壁桥台嵌岩斜桩和直桩在不同台高和不同桩长的受力和配筋情况分别进行计算分析,从而为设计中根据不同地层条件和不同台高选择合理的桩基形式提供依据.

  3. Determination of p-y Curves for Bucket Foundations in Sand Using Finite Element Modeling

    OpenAIRE

    Knudsen, Bjørn S.; Østergaard, Martin Underlin; Ibsen, Lars Bo; Clausen, Johan

    2013-01-01

    Cylindrical offshore wind turbine foundations, such as bucket foundations and monopiles, have up till now been designed using analytical methods based on experiments done with piles much more slender than the ones used in today’s industry. Compared to the widely used monopile foundation, the suction bucket has a much smaller ratio between length and diameter, and the suction buckets will thus act more as a rigid object during rotation in the soil. To improve the design of suction buckets thro...

  4. Picking up Clues from the Discard Pile

    Science.gov (United States)

    2008-01-01

    As NASA's Phoenix Mars Lander excavates trenches, it also builds piles with most of the material scooped from the holes. The piles, like this one called 'Caterpillar,' provide researchers some information about the soil. On Aug. 24, 2008, during the late afternoon of the 88th Martian day after landing, Phoenix's Surface Stereo Imager took separate exposures through red, green and blue filters that have been combined into this approximately true-color image. This conical pile of soil is about 10 centimeters (4 inches) tall. The sources of material that the robotic arm has dropped onto the Caterpillar pile have included the 'Dodo' and ''Upper Cupboard' trenches and, more recently, the deeper 'Stone Soup' trench. Observations of the pile provide information, such as the slope of the cone and the textures of the soil, that helps scientists understand properties of material excavated from the trenches. For the Stone Soup trench in particular, which is about 18 centimeters (7 inches) deep, the bottom of the trench is in shadow and more difficult to observe than other trenches that Phoenix has dug. The Phoenix team obtained spectral clues about the composition of material from the bottom of Stone Soup by photographing Caterpillar through 15 different filters of the Surface Stereo Imager when the pile was covered in freshly excavated material from the trench. The spectral observation did not produce any sign of water-ice, just typical soil for the site. However, the bigger clumps do show a platy texture that could be consistent with elevated concentration of salts in the soil from deep in Stone Soup. The team chose that location as the source for a soil sample to be analyzed in the lander's wet chemistry laboratory, which can identify soluble salts in the soil. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed

  5. Pile-up detector for LHCb

    CERN Document Server

    Baskov, V A; Kim, V; Polyansky, V V; Verdi, A; Verdi, A.

    1999-01-01

    99-014 In this article we propose to use a dedicated pile-up detector --- 180 degree Cherenkov calorimeter which measures energies of gamma-quanta being produced in ppinteractions by the Cherenkov radiation intensity --- to ensure the conditions which will allow LHCb to work with luminosity 4--5 10 32 cm -2 s -1 . The calorimeter consists of a multiplicator with the width corresponding to the maximum of particles in an electromagnetic shower, behind which a quartz plate is situated where shower particles produce Cherenkov radiation. The pile-up detector is situated at the 180 degree angle relative to the LHCb spectrometer.

  6. Applicability of recycled aggregates in concrete piles for soft soil improvement.

    Science.gov (United States)

    Medeiros-Junior, Ronaldo A; Balestra, Carlos Et; Lima, Maryangela G

    2017-01-01

    The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.

  7. MODERN METHODS OF DESIGN AND ARRANGEMENT OF RAMMING PILES IN PUNCHED HOLES

    Directory of Open Access Journals (Sweden)

    ZOTSENKO N. L.

    2015-10-01

    Full Text Available Problem statement. Ramming piles in punched holes (RPPH differ of high degree of use of supporting capacity of base because of forming in it a compacted zone at the expense of displacement of soil in the volume rammer and compacted material of expansion. The method of their construction almost exclude excavation and formwork, reducing the consumption of concrete, metal, accelerates zero cycle compared to the foundations raised and excavation and immersion into the soil of precast elements. The expansion of the normative base, their design and construction should be for further implementation of of natural objects. The correctness of the geomechanical model of plane and spatial version of finite element method (FEM should be proved for the calculation of cooperative work of RPPH as part of grillages with base. The most effective kinds of equipment and technological schemes of construction of RPPH should be noticed. Conclusions. The paper presents the main regulations on the design and the arrangement RPPH, corresponding of construction norms of Ukraine. The results of experimental and theoretical studies conducted by the authors for over thirty years, and the experience of the use of these piles on the objects of civil engineering, industrial and agricultural construction made their base. The use of the elastoplastic model with the criterion of Mohr-Coulomb strength for designing of the system "grillage -RPPH- soil" was substantiated. The designing in plane and spatial problems of FEM is proved that in the distance between the axes of adjacent piles up to five diameters is a correct choice of a flat version and simplifying of calculating scheme to the conventional strip foundation. An improved. The method of calculating of RPPH as part of grillages ribbon, where as the width of the foundation was taken a diameter of the broadening of the pile, and the depth of its inception corresponds to the bottom of it. The supporting layer of base under the

  8. 30 CFR 77.215-3 - Refuse piles: certification.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles: certification. 77.215-3 Section... COAL MINES Surface Installations § 77.215-3 Refuse piles: certification. (a) Within 180 days following written notification by the District Manager that a refuse pile can present a hazard, the person...

  9. 30 CFR 77.215-1 - Refuse piles; identification.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; identification. 77.215-1 Section... COAL MINES Surface Installations § 77.215-1 Refuse piles; identification. A permanent identification marker, at least six feet high and showing the refuse pile identification number as assigned by...

  10. 30 CFR 77.215-2 - Refuse piles; reporting requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; reporting requirements. 77.215-2... COAL MINES Surface Installations § 77.215-2 Refuse piles; reporting requirements. (a) The proposed location of a new refuse pile shall be reported to and acknowledged in writing by the District...

  11. 30 CFR 77.215 - Refuse piles; construction requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refuse piles; construction requirements. 77.215... COAL MINES Surface Installations § 77.215 Refuse piles; construction requirements. (a) Refuse deposited on a pile shall be spread in layers and compacted in such a manner so as to minimize the flow of...

  12. 29 CFR 1926.603 - Pile driving equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Pile driving equipment. 1926.603 Section 1926.603 Labor... Operations § 1926.603 Pile driving equipment. (a) General requirements. (1) Boilers and piping systems which are a part of, or used with, pile driving equipment shall meet the applicable requirements of...

  13. 30 CFR 77.209 - Surge and storage piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Surge and storage piles. 77.209 Section 77.209... Installations § 77.209 Surge and storage piles. No person shall be permitted to walk or stand immediately above a reclaiming area or in any other area at or near a surge or storage pile where the...

  14. Stress wave propagation in reinforced concrete piles during driving

    NARCIS (Netherlands)

    Zorn, N.F.

    1983-01-01

    The aim of this report is to give an insight into what happens in a reinforced concrete pile during driving, and to contribute to design requirements for the loading case pile driving. Since the behaviour of stress waves in piles is influenced by a various number of parameters, the fewest of which r

  15. Stress wave propagation in reinforced concrete piles during driving

    NARCIS (Netherlands)

    Zorn, N.F.

    1983-01-01

    The aim of this report is to give an insight into what happens in a reinforced concrete pile during driving, and to contribute to design requirements for the loading case pile driving. Since the behaviour of stress waves in piles is influenced by a various number of parameters, the fewest of which

  16. The Tensile Capacity Of Bored Piles In Frictional Soils

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Andersen, Allan; Damkilde, Lars

    2008-01-01

    Three series of 10 piles each were installed in two different locations. The length of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The pi...

  17. Pile anchor Supporting System Combined with Priestesses Anchor Cables and Bored Piles%预应力锚索与钻孔咬合桩相结合的桩锚支护体系*

    Institute of Scientific and Technical Information of China (English)

    褚锡星; 殷建

    2013-01-01

    预应力锚索与钻孔咬合桩结合的桩锚支护体系能有效的降低排桩间漏水,减少搭设和拆除深基坑内支撑工程成本,拓宽机械工作面,确保工程工期,避免角撑、对撑施工。通过具体工程案例,系统论述了预应力锚索与钻孔咬合桩结合的桩锚支护体系工艺流程、施工要点及其监测方法,为其在工程中的应用提供理论支撑。%The pile anchor supporting structure combined with prestressed anchor cables and bored piles can effectively reduce water leakage between rowed piles and the cost of erecting and dismantling supporting engineering in deep foundation pits.It can also,expand mechanical working surface,ensure project schedule and avoid gusset and supporting construction.The paper analyses the technological process,key points of construction and monitoring methods of the pile anchor supporting structure combined with prestressed anchor cables bored piles, so as to provide theoretical support for its application in engineering.

  18. Centrifuge modelling of large diameter pile in sand subject to lateral loading

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    Large-diameter (4 to 6 m) rigid monopiles are often used as foundations for offshore wind turbines. The monopiles are subjected to large horizontal forces and overturning moments and they are traditionally designed based on the p-y curve method. The p-y curves recommended in offshore design...... and cyclic behaviour of large diameter rigid piles in dry sand by use of physical modelling. The physical modelling has been carried out at Department of Civil Engineering at the Danish Technical University (DTU.BYG), in the period from 2005 to 2009. The main centrifuge facilities, and especially...... the equipment for lateral load tests were at the start of the research in 2005 outdated and a major part of the work with the geotechnical centrifuge included renovation and upgrading of the facilities. The research with respect to testing of large diameter piles included:  Construction of equipment...

  19. Numerical Investigation on the Thermo-mechanical Behavior of a Quadratic Cross Section Pile Heat Exchanger

    DEFF Research Database (Denmark)

    Pagola, Maria Alberdi; Madsen, Søren; Jensen, Rasmus Lund

    2017-01-01

    and shaft resistances; ii) the maximum upward/downward displacements. A one-year time span is considered under operational and extreme thermal boundary conditions. The results show that a typical geothermal utilization of the energy foundation does not generate significant structural implications...... and, therefore, there is a need to develop guidelines to design them properly. This paper contributes by studying the thermo-mechanical behavior of the precast piles which are 15-meter long and have a quadratic cross section and a W-shape pipe heat exchanger. This article aims to numerically assess...... on the geotechnical capacity of a single energy pile. However, ground thermal loads need to be considered in the design phase to account for potential extreme temperature changes, which could generate thermal stresses that equalize the mechanically generated ones....

  20. Consolidation behavior of cement—and lime/cement—mixed column foundations

    Institute of Scientific and Technical Information of China (English)

    蔡袁强; 徐长节

    2002-01-01

    The consolidation behavior of mixed in place cement-and lime /cement-mixed column was studies.COnsolidation of the composite foundation was modeled as a three-dimensional axi-symmetric problem.The authors used the finite difference method to obtain the pore pressure variation with time at and location below the surface.A computer program developed by the authors was used to draw some interesting conclusions about the consolidation behaviors of cement-mixed pile foundation.Finally,a combined model including the permeability coefficients of cement-mixed piles and soil,was studied and its feasibility was evaluated.

  1. On the Modelling of Pile Installation

    NARCIS (Netherlands)

    Dijkstra, J.

    2009-01-01

    This thesis introduces two different types of physical model tests to investigate the stress and density change in the soil during installation of a jacked pile as well as two numerical modelling approaches to model the same process in a finite element code capable of large deformations.

  2. Full size testing of sheet pile walls

    NARCIS (Netherlands)

    Kuilen, J.W.G. van de; Linden, M.L.R. van der; Katsma, H.; Stolle, P.

    1996-01-01

    Azobé (Lophira alata) is widely used in timber sheet pile walls in the Netherlands. The boards in these walls are coupled and therefore load-sharing can be expected. A simulation model based on the finite element method DIANA (DIANA, 1992) was developed and load-sharing could be calculated. To check

  3. Displacement pile installation effects in sand

    NARCIS (Netherlands)

    Beijer-Lundberg, A.

    2015-01-01

    Installation effects govern the post-installation behaviour of displacement piles in sand. These effects are currently not completely understood. Suitable experimental techniques to model these installation effects include field, laboratory and experimental models. In the current thesis a small-scal

  4. Determination of p-y Curves for Bucket Foundations in Silt and Sand Using Finite Element Modelling

    DEFF Research Database (Denmark)

    Vethanayagam, Vinojan; Ibsen, Lars Bo

    Design of offshore wind turbine foundations are today based on analytical formulas, which describes the link between a displacement, y, and the associated soil pressure, p. The formulas are empirically developed on slender piles with a slenderness ratio L=D > 30, but foundations of today are less...

  5. Seismic Response Analysis of Portal Water Injection Sheet Pile

    Institute of Scientific and Technical Information of China (English)

    WANG Yuanbin; GUO Haiyan; ZHANG Chunhui

    2007-01-01

    To further the study on the newly developed portal water injection sheet pile under static loads, in this paper, by adopting the nonlinear calculation module of FEM software ANSYS, a model for the interaction between the soil and the sheet piles is set up,and the seismic response analysis for this type of space-retaining structure is performed. The effects of the embedded depth and the distance between the front pile and the back pile on the dynamic characteristics of the portal water injection sheet pile are studied.

  6. NONLINEAR DYNAMICAL CHARACTERISTICS OF PILES UNDER HORIZONTAL VIBRATION

    Institute of Scientific and Technical Information of China (English)

    HU Yu-jia; CHENG Chang-jun; YANG Xiao

    2005-01-01

    The pile-soil system is regarded as a visco-elastic half-space embedded pile. Based on the method of continuum mechanics, a nonlinear mathematical model of pilesoil interaction was established-a coupling nonlinear boundary value problem. Under the case of horizontal vibration, the nonlinearly dynamical characteristics of pile applying the axis force were studied in horizontal direction in frequency domain. The effects of parameters, especially the axis force on the stiffness were studied in detail. The numerical results suggest that it is possible that the pile applying an axis force will lose its stability. So, the effect of the axis force on the pile is considered.

  7. Comparison of Foundation Systems for Wave Energy Converters Wavestar

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl;

    2013-01-01

    In order to deliver cost competitive solutions, Wave Energy Converters (WEC) must be optimized in several fields, e.g. transportation, installation, structure, machinery etc. Large expenses lie on the superstructure support, i.e. the offshore foundation. Geotechnical analysis and optimization....... In such a solution horizontal wind and wave loads are dominant. Gravity based, pile and bucket foundations are universally applied solutions for the offshore structures. The suitability of these types for a WEC is analysed and commented. The foundations are designed to satisfy ultimate and serviceability limit state...... of six possible foundation solutions for WEC are presented in this article. The study is performed for WEC superstructure supported by two or four foundations. In the four-column system horizontal wind and wave loads are transformed as a pair of vertical forces, acting in tension and compression. When...

  8. On the instability of offshore foundations: theory and mechanism

    Science.gov (United States)

    Gao, FuPing; Li, JinHui; Qi, WenGang; Hu, Cun

    2015-12-01

    As the offshore engineering moving from shallow to deep waters, the foundation types for fixed and floating platforms have been gradually evolving to minimize engineering costs and structural risks in the harsh offshore environments. Particular focus of this paper is on the foundation instability and its failure mechanisms as well as the relevant theory advances for the prevailing foundation types in both shallow and deep water depths. Piles, spudcans, gravity bases, suction caissons, and plate anchors are detailed in this paper. The failure phenomena and mechanisms for each type of foundations are identified and summarized, respectively. The theoretical approaches along with sophisticated empirical solutions for the bearing capacity problems are then presented. The major challenges are from flow-structure-soil coupling processes, rigorous constitutive modeling of cyclic behaviors of marine sediments, and the spatial variability of soil properties for large-spreading structures. Further researches are suggested to reveal the instability mechanisms for underpinning the evolution of offshore foundations.

  9. Working mechanism of two-direction reinforced composite foundation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling; ZHAO Ming-hua; HE Wei

    2007-01-01

    Based on the discussion about working mechanism of horizontal reinforcement and that of vertical reinforcement,respectively, the working mechanism of two-direction reinforced composite foundation was studied. The enhancing effect of horizontal reinforcement on vertical reinforced composite foundation was analyzed. A simplified calculation method for such two-direction reinforced working system was presented. A model experiment was carried out to validate the proposed method. In the experiment, geocell reinforcement worked as the horizontal reinforcement, while gravel pile composite foundation worked as the vertical reinforcement. The results show that the calculated curve is close to the measured one. The installation of geosynthetic reinforcement can increase the bearing capacity of composite foundation by nearly 68% at normal foundation settlement, which suggests that the enhancing effect by geosynthetic reinforcement should be taken into account in current design/analysis methods.

  10. Foundation design of vertical steel storage tank%立式钢制储罐基础设计

    Institute of Scientific and Technical Information of China (English)

    杨文武

    2014-01-01

    以某罐区立式钢制储罐基础设计为例,探讨预制桩、灌注桩和浅基础应用于储罐基础的设计方法。储罐基础设计可比拟为"板-柱结构"体系,借助pkpm结构软件分析两种桩型承载力、浅基础设计、场地条件影响及桩-土共同作用。储罐桩基设计应对水平承载力、竖向承载力和配筋量三控制设计,对于端承型桩基,一般情况下单桩水平承载力起控制作用。相同桩数时,采用方形布桩的边桩配筋比环形布桩的更易产生突变。应用于软土场地的砼预制桩不仅应进行桩基承载力计算,还应加强桩基配筋验算。%Based on a foundation design of vertical steel storage tank in a tank farm , the application of precast piles , pile and shallow foun-dation design method on the basis of the tank were discussed .Tank foundation design can be compared to "plate -column structure"sys-tem, by using PKPM structure software , analysis of bearing capacity , shallow foundation design , site condition and pile -soil interaction of two kinds of pile type were carried out .The horizontal bearing capacity , vertical bearing capacity and reinforcement amount should be controlled in the tank design .For end bearing type piles , single pile horizontal bearing capacity plays a general controlling role .The edge pile reinforcement ratio of square pile arrangement produces mutation more likely than annular arrangement under same number of pile .It is necessary to calculate not only foundation bearing capacity of pile but also foundation reinforcement when precast concrete piles are ap -plied in the soft soil ground .

  11. On gravel pile construction at salinization geological areas%谈盐碱地质碎石桩施工

    Institute of Scientific and Technical Information of China (English)

    张春宝

    2012-01-01

    以盐碱地质碎石桩施工为例,为了正确指导大面积碎石桩施工,对桩进行了工艺性试验,总结和分析了软弱土层碎石桩施工控制各项参数,提出施工控制措施,从而有效解决了软弱地基承载力不足的难题,对地基处理提供了宝贵的经验。%Taking the gravel pile construction on salinization geological areas as the example,the paper undertakes the craft experiment on the pile in order to direct the large-scale gravel pile construction,sums up and analyzes all sorts of parameter in the gravel pile construction control at weak strata,and points out the construction controlling measures,so as to solve the insufficient loading capacity at the weak foundation and provide the precious experience for the foundation treatment.

  12. Foundation works for construction of Danube Bridge II Vidin (Bulgaria)-Calafat (Romania); Puente internacional sobre el rio Danubio entre las localidades de Vidin (Bulgaria) y Calafat (Rumania)

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Martin, J.

    2011-07-01

    The Foundations works of the bridge over the the Danube River II has involved a new technical challenge due to the cathartics of depth and diameter of the piles, and the logistical and human, due to the hard environmental conditions for the execution. This work, awarded to FCC. Construction company in its two contracts. Access to the bridge and Main Bridge has required on the differenced sites, the use of a wide range of foundation systems, since driven precast piles to in in situ pile with permanent casing, installed by vibrating systems and excavated with benoto grabs systems. The enormous responsibility of this phase is evident in the intense camping of characterization tests with static load tests, dynamic and Osterberg cells, as well as control the campaign with Cross-hole tests in 100% of the piles in situ executed, that has allowed no only ensure the highest level of quality on the foundation elements, but also to take the most of the mechanical characteristics of soils provided. The complexity of the execution of more than 24,000 ml pile executed along the more than 2 years duration of the work reach the maximum expression in the more than 6,900 ml of in situ pile made from marine resources, with a maximum depths up to 80 m with 2 m diameter pile. The article intends to give an overview of the site and the execution, associating the different foundation methods used, and the problems that were detected. (Author)

  13. Laboratory Test Setup for Cyclic Axially Loaded Piles in Sand

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2017-01-01

    conditions for all tests. For verifications purposes six static tension tests conducted at three different vertical effective stress levels of 0, 35 and 70 kPa. The load-displacement curves showed that the test setup provides repeatable test results. A preliminary comparison between the unit shaft friction......This paper presents a comprehensive description and the considerations regarding the design of a new laboratory test setup for testing cyclic axially loaded piles in sand. The test setup aims at analysing the effect of axial one-way cyclic loading on pile capacity and accumulated displacements....... Another aim was to test a large diameter pile segment with dimensions resembling full-scale piles to model the interface properties between pile and sand correctly. The pile segment was an open-ended steel pipe pile with a diameter of 0.5 m and a length of 1 m. The sand conditions resembled the dense sand...

  14. The mechanical response of piles with consideration of pile-soil interactions under a periodic wave pressure

    Institute of Scientific and Technical Information of China (English)

    朱峰; 徐卫亚; 王环玲

    2014-01-01

    The pile-soil interaction under wave loads is an extremely complex and difficult issue in engineering. In this study, a physical model test is designed based on the principle of the gravity similarity to obtain time histories of wave forces of unsteady regular waves, and to measure the magnitude and the distribution of wave forces acting on the piles. A numerical model and relevant numerical methods for the pile-soil contact surface are adopted based on the principles of elastic dynamics. For a practical project, the time histories of wave forces on the piles are obtained through physical model tests. The deformations of the piles in the pile-soil interactions and the distribution of the bending moment on the piles are studied. It is shown that, with the increase of the period of wave pressures, the absolute value of the horizontal displacement of the piles increases, the embedment depth of the piles increases, and the scope of influence of soils increases. The change of the bending moment on the piles is consistent with that of its theoretical results, and the proposed numerical method can very well simulate the properties of the piles.

  15. 土工织物散体桩加固粉土路基机理研究%Research on Reinforcement Mechanism of Silt Embankment Using Geotextile Discrete Material Pile

    Institute of Scientific and Technical Information of China (English)

    张京京; 孙立强; 闫澍旺

    2014-01-01

    Sixu expressway is located in the Huaibei Plain,which is covered by silt or silty sand. However,because this type of soil is prone to liquefaction under seismic loading,liquefaction re-sistance measures should be considered when engineering projects are planned for this region.The liquefaction resistance of a geotextile discrete material pile and the bearing capacity of a composite foundation are examined in this study.In addition,the reinforcement mechanism of the geotextile discrete material pile with a silt subgrade is determined.The pore water pressure dissipation,bear-ing capacity of the composite foundation,pile-soil stress ratio,and pile body stress were re-searched by using the finite difference method and field testing,which is beneficial for obtaining the reinforcement mechanism of the composite foundation.Moreover,this paper presents design proposals of a geotextile discrete material pile.The results indicate that under seismic loading,a geotextile discrete material pile can effectively drain and successfully achieve anti-liquefaction.The excess pore pressure ratio increases with distance from the pile axis,and the silt becomes more in-clined to liquefaction.An engineering example is used with numerical calculation to determine that effective pile spacing is 2 m,or approximately 3.3 times the pile diameter.Further,in the silt foun-dation,the bearing capacity of the single geotextile discrete material pile is 50% larger than that of gravel pile under the same conditions,and the composite foundation bearing capacity of the geo-textile discrete material pile is 25% more than that of gravel pile.In static load testing of the com-posite foundation,soil pressure boxes are respectively buried at the top of the pile,at the bearing plate,and at the contact surface of the pile and soil to determine the bearing capacity of the pile and soil under the action of static load.In the two types of composite foundations,the pile-soil stress ratio increases with an

  16. 桥梁在役桩的竖向动力响应特性及损伤识别研究%Study on Vertical Dynamic Response Characteristics and Damage Identification of Existing Bridge Pile

    Institute of Scientific and Technical Information of China (English)

    卢韦男; 张鸿儒

    2014-01-01

    Integrity detection of the pile foundations of existing structures is a difficult problem worldwide.Integrity testing of newly constructed pile foundations includes detection methods such as mining with the observation method,drilling core method,low-strain test method,and ultra-sonic method.However,for damage detection of pile foundations in service,the existence of plat-forms and bridge structures above pile foundations makes the observation method difficult be-cause the mining depth of the soil around the pile is very limited.Drilling core methods cannot be achieved because drill core must be drilled from the pile top.For ultrasonic detection,there is no channel available for installing ultrasonic transducers.For the low-strain test method,velocity sen-sors cannot be placed at the top of the pile;therefore,vertical vibration cannot be recorded.In this paper,vertical impact load is applied on the upper cap surface above the detected pile.According to the vertical velocity response of the cap surface and pile head,we analyze the integrity of the bridge pile foundation in-service. Bridge pier-cap-pile-soil explicit dynamic finite element models are based on ANSYS LS-DY-NA.In the finite element models,impact load is applied on the cap surface,and the vertical veloci-ty responses of the complete pile and the cracked pile are both recorded.Two types of pier-cap-pile-soil numerical models are used in this study with six and eight piles,respectively.The results show that when the impact load is applied at the cap surface on top of the pile to be detected,the stress wave goes through the cap and propagates downward along the pile.Similar to the principle of sonic echo in pile integrity testing,the stress wave reflects at the pile bottom or fracture surface where impedance changes significantly.From the vertical velocity response curve of the pile head, the reflected stress wave from the pile bottom or the fracture surface can be identified to deter-mine whether the pile

  17. Are cometary nuclei primordial rubble piles?

    Science.gov (United States)

    Weissman, P. R.

    1986-01-01

    Whipple's icy conglomerate model for the cometary nucleus has had considerable sucess in explaining a variety of cometary phenomena such as gas production rates and nongravitational forces. However, as discussed here, both observational evidence and theoretical considerations suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or even frequent disruptive events. The proposed model is analogous to the 'rubble pile' model suggested for the larger main-belt asteroids, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case. The concept of cometary nuclei as primordial rubble piles is proposed as a modification of the basic Whipple model, not as a replacement for it.

  18. Empirical Design of Scour Protections around Monopile Foundations

    DEFF Research Database (Denmark)

    De Vos, L.; De Rouck, J.; Troch, P.;

    2011-01-01

    Together with new opportunities, offshore wind farms raise new engineering challenges. An important aspect relates to the erosion of bottom material around the foundation of the wind turbines, caused by the local increase of the wave and current induced flow velocities by the pile's presence....... Typically, the expected scour has a considerable impact on the stability and dynamic behavior of the wind turbine and a scour protection is placed to avoid erosion of the soil close to the foundation. Although much experience exists on the design of scour protections around bridge piers (which are placed...

  19. Bearing Behaviors of Stiffened Deep Cement Mixed Pile

    Institute of Scientific and Technical Information of China (English)

    WU Mai; ZHAO Xin

    2006-01-01

    A series of investigations were conducted to study the bearing capacity and load transfer mechanism of stiffened deep cement mixed (SDCM) pile.Laboratory tests including six specimens were conducted to investigate the frictional resistance between the concrete core and the cementsoil.Two model piles and twenty-four full-scale piles were tested to examine the bearing behavior of single pile.Laboratory and model tests results indicate that the cohesive strength is large enough to ensure the interaction between core pile and the outer cement-soil.The full-scale test results show that the SDCM piles exhibit similar bearing behavior to bored and cast-in-place concrete piles.In general, with the rational composite structure the SDCM piles can transmit the applied load effectively, and due to the addition of the stiffer core, the SDCM piles possess high bearing capacity.Based on the findings of these experimental investigations and theoretical analysis, a practical design method is developed to predict the vertical bearing capacity of SDCM pile.

  20. Hydrodynamic Behavior of Curtainwall-Pile Breakwaters

    Institute of Scientific and Technical Information of China (English)

    O.Nejadkazem; A.R.M.Gharabaghi

    2012-01-01

    A numerical model is developed that can predict the interaction of regular waves normally incident upon a curtainwall-pile breakwater; the upper part of which is a vertical wall and the lower part consists of an array of vertical piles.The numerical model is based on an eigenfunetion expansion method,and utilizes a boundary condition nearby the vertical piles that accounts for wave energy dissipation.Numerical solution comprises a finite number of terms,which is a superposition of propagating waves and a series of evanescent waves.The modeling is validated by comparison with previous experimental studies and overall agreement between measurement and calculation is fairly good.The numerical results are related to reflection,transmission,and dissipation coefficient; wave run-up,wave force,and wave overturning moment are also presented.Effect of porosity,relative draft,and relative water depth are discussed; the choice of suitable range of them is described.The relative draft is more effective for shallow water waves.Model shows decrease in relative draft and leads to reduction of relative wave force,overturning moment,and nunup.It is shown that curtainwallpile breakwaters can operate both effectively and efficiently in the range of relative draft between 0.15 and 0.75.The range 0.5 to 0.2 is also recommended for porosity.

  1. Morphological clues to wet granular pile stability

    Science.gov (United States)

    Scheel, M.; Seemann, R.; Brinkmann, M.; di Michiel, M.; Sheppard, A.; Breidenbach, B.; Herminghaus, S.

    2008-03-01

    When a granular material such as sand is mixed with a certain amount of liquid, the surface tension of the latter bestows considerable stiffness to the material, which enables, for example, sand castles to be sculpted. The geometry of the liquid interface within the granular pile is of extraordinary complexity and strongly varies with the liquid content. Surprisingly, the mechanical properties of the pile are largely independent of the amount of liquid over a wide range. We resolve this puzzle with the help of X-ray microtomography, showing that the remarkable insensitivity of the mechanical properties to the liquid content is due to the particular organization of the liquid in the pile into open structures. For spherical grains, a simple geometric rule is established, which relates the macroscopic properties to the internal liquid morphologies. We present evidence that this concept is also valid for systems with non-spherical grains. Hence, our results provide new insight towards understanding the complex physics of a large variety of wet granular systems including land slides, as well as mixing and agglomeration problems.

  2. Soil Plug Effect Prediction and Pile Driveability Analysis for Large-Diameter Steel Piles in Ocean Engineering

    Institute of Scientific and Technical Information of China (English)

    LIU Run; YAN Shu-wang; LI Zhi-hua

    2009-01-01

    Long steel piles with large diameters have been more widely used in the field of ocean engineering.Owing to the pile with a large diameter,soil plug development during pile driving has great influences on pile driveability and beating capacity.The response of soil plug developed inside the open-ended pipe pile during the dynamic condition of pile-driving is different from the response under the static condition of loading during service.This paper addresses the former aspect.A numerical procedure for soil plng effect prediction and pile driveability analysis is proposed and described.By taking into consideration of the pile dimension effect on side and tip resistance,this approach introduces a dimensional coefficient to the conventional static equilibrium equations for the plug differential unit and proposes an improved static equity method for the plug effect prediction.At the same time,this approach introduces a simplified model by use of one-dimensional stress wave equation to simulate the interaction between soft ping and pile inner wall.The proposed approach has been applied in practical engineering analyses.Results show that the calculated plug effect and pile driveability based on the proposed approach agree well with the observed data.

  3. H型长钢桩尖在密实土层中的应用%Application of long H?type steel pile tip in compact soil layer

    Institute of Scientific and Technical Information of China (English)

    孟晓宁; 于云山

    2016-01-01

    在钢筋混凝土桩基施工时,如果遇到工程区域地质持力层较密实且埋藏较浅或者持力层上面有较密实的覆盖层的情况,往往会造成沉桩困难、桩的入土深度不能满足使用要求等问题.结合具体工程的实践经验对此类工程问题进行分析,提出钢筋混凝土桩组合H型长钢桩尖的解决方案,并与普通钢筋混凝土桩基方案进行对比、通过计算及试桩试验对方案进行验证、对方案优点及适用性进行总结.%During the reinforced concrete pile foundation construction process, when the bearing stratum of engineering region is more compact and shallow buried or be covered by dense layer, the problems are tend to hap?pen, such as pile?sinking difficultly or embedded depth of pile cannot meet operating requirement. Combined with specific engineering practice experience and the analysis of such problems, the solution of reinforced concrete pile with long H?type steel pile tip was mentioned in this paper. The advantage and applicability of this solution was summarized by contrast with common reinforced concrete pile foundation, and it was verified by calculation and test piles.

  4. SCOUR MITIGATION AT BRIDGE PIERS USING SACRIFICIAL PILES

    Institute of Scientific and Technical Information of China (English)

    M. Anisul HAQUE; Md. Munsur RAHMAN; G.M. Tarekul ISLAM; M. Asad HUSSAIN

    2007-01-01

    To mitigate scour around bridge piers, sacrificial piles are economic method where natural processes are involved. The arrangement should be such that scoured materials from the sacrificial piles should have enough volume to fill the scour hole created upstream of the pier in such a way that sediments are trapped inside the scour hole. This concept differs from earlier study made with sacrificial piles that mainly deals to reduce the strength of horseshoe vortex. To determine the effect of sacrificial piles for scour mitigation, alternative arrangements of piles were tested in front of a rectangular pier under clear-water condition and found that when the group of piles is placed at a distance of twice the projected width of the pier, for which percentage of blockage of the pier width is 60%, the scour volume can be reduced upto 61% while the maximum scour depth can be reduced upto 50%.

  5. Vertical bearing capacity of pile based on load transfer model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; YANG Ming-hui; ZOU Xin-jun

    2005-01-01

    The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.

  6. Instability during Installation of Foundations for Offshore Structures

    DEFF Research Database (Denmark)

    Madsen, Søren; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2012-01-01

    caisson”. During installation, suction is applied inside the bucket. The suction creates a pressure differential across the bucket lid, effectively increasing the downward force on the bucket while the water flow reduces the skirt tip resistance. The bucket foundation is constructed as a thin shell......If current technology is used when wind turbines are located in deeper water, the cost of the foundations will increase dramatically. Thus, a new technology is needed to reduce the total cost of offshore wind turbines. A candidate technology could be the bucket foundation, also called a “suction...... as the pile is penetrating through a soil of high stiffness. This paper deals with structural instability issues related to slender, circular cylindrical offshore foundations during installation. The authors present the previous work done by other authors within this field, highlighting the key issues...

  7. 基于荷载传递法的单桩沉降解析解%Calculation of Single Pile Settlement Based on Load Transfer Method

    Institute of Scientific and Technical Information of China (English)

    刘忠; 唐漾; 杜欢欢; 朱思静; 彭刚

    2013-01-01

    In accordance with the performance characteristics of single pile under axial load and based on load transfer method,the bilinear load transfer function,which describes the characteristics of pile-soil interaction,is applied to obtain the analytical solution for load-settlement relation of single pile during the whole pile-soil deformation.This analytical solution is adopted in specific calculation and discussion about the value range of model parameters,the result of which agrees well with the experimental curve.It shows that the method described in this paper well describes the load transfer process of single pile.On the basis of specific parameters obtained from static load experiment,the load-settlement relation of single pile under axial load is calculated and the pile bearing capacity is estimated,which can offer references for the design of pile foundation.%针对轴向荷载作用下的单桩工作特性,基于荷载传递法,采用了描述桩-土相互作用特性的双折线荷载传递函数,得到了针对桩-土变形全过程的单桩荷载-沉降关系解析解.利用该解析解,计算了具体案例,讨论了模型参数的取值范围,计算结果与实验曲线吻合较好.结果表明,本文方法能较好地描述单桩荷载传递过程,根据静载实验获得的具体参数,计算轴向荷载作用下单桩荷载-沉降关系,并估算单桩的承载力,为桩基础设计提供参考依据.

  8. The behaviour of the stiff monopile foundation subjected to the lateral loads

    DEFF Research Database (Denmark)

    Lada, Aleksandra; Ibsen, Lars Bo; Nicolai, Giulio

    The article focuses on the analysis of a large-diameter monopile foundation for offshore wind turbine based on the numerical model results. The case describes the behaviour of a monopile in sand subjected to a lateral loading conditions. The effects of the pile diameter, the length and the load e...

  9. The reactor Cabri; La pile cabri

    Energy Technology Data Exchange (ETDEWEB)

    Ailloud, J.; Millot, J.P. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1964-07-01

    exceptional circumstances... - experimental investigations on power excursions linked with precise initial conditions: the aim of this work is to define the basis for theoretical research, and the limits beyond which the risks of explosion cease to be negligible. The research work will be done so as to enable checking with outside reactor experiments and to continue them in the explosion field. - studies of the behaviour of the reactor control-instrumentation. - experimental investigations related with transient operation with initial short life (study of boiling, temperature measurements, vacuum pressure and fraction...) with the aim of defining the hypotheses of a theory on swimming-pool reactor kinetics related to heat transfer phenomena, - investigations of the behaviour of fuels in reactors (these experiments are planned to be carried out in loops) Preliminary experimental results. CABRI went critical on the 21 December 1963. The first transient experiments are expected for March 1964. (authors) [French] II devenait necessaire de construire en France une pile qui permette d'etudier les conditions de fonctionnement des installations futures, de choisir, tester et mettre au point les dispositifs de securite a adopter. On a choisi une pile a eau, type de pile qui correspond aux constructions les plus nouvelles du CEA en matiere de piles laboratoire ou d'universite; il importe en effet de pouvoir evaluer les risques presentes et d'etudier les possibilites d'augmentation de puissance constamment demandees par les utilisateurs: il est particulierement interessant d'eclaircir les phenomenes d'oscillation de puissance et les risques de calefaction (burn out). Les programmes de travaux sur CABRI seront harmonises avec les travaux effectues sur les Spert americains de meme type; lors de sa construction des contacts fructueux ont ete etablis avec les specialistes americains qui ont defini les premiers de ces reacteurs. La communication donne une

  10. Assessment of Time Functions for Piles Driven in Clay

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars; Sørensen, Carsten Steen

    The vertical bearing capacity of piles situated in clay is studied with regard to the long-term set-up. A statistical analysis is carried out on the basis of data from numerous static loading tests. The database covers a wide range of both soil and pile properties, which ensures a general....... Hence, it is suggested that a constant set-up factor should be applied for the prediction of pile capacities at a given time after initial driving....

  11. The Danish Industrial Foundations

    DEFF Research Database (Denmark)

    Thomsen, Steen

    Industrial foundations are foundations that own companies. Typically, they combine charitable and business goals. This book is about industrial foundation ownership of business companies and what we can learn about it from the Danish evidence. It is about how foundation ownership is ruled, taxed...... and governed, what role it plays in the Danish economy, and how industrial foundation-owned companies perform. The book is the result of a large collaborative research project, led by the author, on industrial foundations. Some global companies such as IKEA, Robert Bosch or the Tata Group are foundation...

  12. Bearing Capacity of Mixed Pile with Stiffness Core

    Institute of Scientific and Technical Information of China (English)

    YUE Jianwei; JIANG Xinliang; LING Guangrong

    2006-01-01

    To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core (MPSC), which is formed by inserting a precast reinforced concrete pile (PRCP), in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out.Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained.The load transfer between cement soil and PRCP was analyzed by finite element method (FEM).Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil.The length and the section area on PRCP of an MPSC both have an optimum value.Adopting MPSC is effective in improving the bearing capacity of soft soil ground.

  13. 竖向荷载下群桩-土-承台相互作用数值分析%Numerical analysis of interaction of pile group-soil-raft under vertical load

    Institute of Scientific and Technical Information of China (English)

    杜家庆; 杜守继; 赵丹蕾; 唐文勇

    2013-01-01

    Besides the interaction of the multiple stress superposition from piles shaft friction, pile bottom resistance and contact stress between low caps and soil, the clamping action makes the cap-pile-soil interaction more complicated in pile foundation with large pile diameter and small spacing. 3D finite difference program is employed to evaluate the pile-soil-cap interaction with the change of vertical load, while the pile spacing and pile diameter remain constant in the analysis procedure. Analysis is carried out to explain the interaction of cap-pile-soil from the following aspects such as the lateral friction of soil in each layer, load on the top of characteristic piles, load-settlement relationship, vertical displacement of soil between piles, etc. The results show that: the clamping action on the upper soil among piles will decrease, and the pile shaft friction in the upper part will increase when the load exceeds 117.8 MN which is slightly larger than Pu/2 (Pu means ultimate bearing capacity of piles group); the lower part of pile shaft friction shows a trend of decrease due to the influence of the multiple stress superposition, and the decrease trend in characteristic piles has different influence scope; the load, which makes settlement of piles group achieve 5% of pile diameter, can be regarded as the vertical ultimate bearing capacity of piles group, and it is reasonable; when the ratio of piles group’s settlement to pile diameter exceeds 1%, the proportion of the load carried by piles decreases because of the cap contribution.%  在大桩径、小桩距的群桩条件下,不仅有来自桩侧、桩端和承台传递的多重应力叠加,还有群桩对桩间土的夹持作用影响,桩-土-承台之间作用更加复杂。用有限差分软件模拟固定桩距、桩径,变化竖向荷载下桩-土-承台的相互作用。从各层土的侧摩阻力、不同位置桩的桩顶荷载、荷载-沉降关系、桩间土体位移等方面的计算

  14. 后注浆灌注桩在某工程中的应用及经济分析%Application and Economic Analysis of Post-grouting Bored Concrete Pile in a Project

    Institute of Scientific and Technical Information of China (English)

    刘军; 洪峰

    2011-01-01

    Combined with the actual construction the principle and application of post-pressure grouting technology in pile tip and pile lateral of reinforced concrete bored cast-in pilate piles are introduced.There are many factors affecting pile foundation selection for construction works.Through the cost analysis and evaluation on the pile foundation of the construction works, some economic indicators for the selection of pile foundation under the present productive force and price level are gained.Which will be beneficial to improve the cost effectiveness and rationality of selection of it.The base-grouting treatment technique of bored concrete pile can improve the bearing capacity, so the application of this kind of pile become broad useage day by day.%结合工程实例,介绍了钢筋混凝土钻孔灌注桩桩端桩侧后压浆技术的原理及应用。影响建筑工程桩基选型的因素很多,通过典型工程桩基的造价分析与评价,得出当前生产力和物价水平条件下桩基选型的若干经济指标.有助于提高建筑工程桩基选型的经济性及合理性水平。由于灌注桩后注浆处理技术可使承载力显著提高.因而这种桩基日益得到广泛应用。

  15. Bored pile construction%冲孔灌注桩施工要点

    Institute of Scientific and Technical Information of China (English)

    陈明晓; 洪小灵

    2012-01-01

    Bored pile foundation as a mature technology,because of its simple installation,construction machinery import and the convenience,fast pile forming speed,quality and reliable,widely used.The bored pile construction process may produce problems in detail,for coastal mud layer too thick,too many boulder distribution of geological environment,the old city construction site is small,it may encounter problems,especially the pile press machine,the punching process emerged in the mud circulation plugging,probe stone underwater concrete,quality control,reasonable solutions and preventive measures.%冲孔灌注桩作为一种成熟的桩基工艺,因其施工机械安装简单、进出场地方便,成桩速度快、桩身质量可靠,得到广泛的应用。本文对冲孔灌注桩施工过程中可能产生的问题进行详细阐述,针对沿海淤泥层过厚,孤石分布偏多的地质环境,老城区施工场地偏小,就可能遇到的问题,特别是桩机走机、冲孔过程中出现的泥浆循环堵管、探头石、水下混凝土质量控制,提出合理的解决方法及预防措施。

  16. Experimental studies on local scour of offshore wind turbine pile%海上风电桩基局部冲刷试验研究

    Institute of Scientific and Technical Information of China (English)

    祁一鸣; 陆培东; 曾成杰; 陈可锋

    2015-01-01

    The foundation of a wind turbine pile is the load of the wind turbine itself and the lateral pressure of the blade rotation, and the stability of a pile foundation is very important. The offshore wind turbine pile is not only influenced by the tidal current and wave interaction, but also the scale of the pile foundation, which is usually between the pier and the pile foundation, and its local scour has some particularity. By establishing a normal model of 1∶60, the local scour of the offshore wind turbine pile foundation under the action of wave, tidal current and wave current is studied. The research results show that:①the tidal current is the dominant factor in controlling the local scour of the pile foundation in the sea area;②under the action of the alternating flow, the shape of the scour hole is oval, and the maximum scour depth is about 0. 8 of the steady flow;③under the wave⁃current interaction, due to the role in the front of the pile wave oscillating flow, sediment is easier to move than the current action, the local scour is significantly enhanced, and the maximum scour depth is 2. 0 and 1. 7 times under the action of tidal current and constant flow;④the calculated values given by the Han Hai⁃qian formula are in good agreement with the experimental values of the scour depth of the pile foundation under the influence of the coefficient 0. 75. According to the test results, it is suggested that the riprap protection of local scour around the pile foundation pit should be done in order to ensure the security and stability of the offshore wind turbine.%风电桩基既承担风机自身荷载,又受到叶片转动的侧向压力,桩基稳定性至关重要。海上风电桩基不仅受潮汐双向水流和波浪共同作用的影响,而且桩基尺度介于通常的桥墩和码头桩基之间,局部冲刷具有一定特殊性。通过建立1∶60的正态模型,研究了洋口海域海上风电桩基在波浪、潮流及波流共同

  17. 一类双排桩支护结构内力计算%CALCULATION FOR A TYPE OF RETAINING STRUCTURE WITH DOUBLE-ROW PILES

    Institute of Scientific and Technical Information of China (English)

    范秋雁; 许胜才; 崔峰

    2012-01-01

    For the reason that the retaining space suffers from the restraint, a type of retaining structure with double-row piles is designed as the structure without soil solum between the pre-row pile and post-row pile, to form the soil-retaining spatial door-frame structure in the post-row pile. At present, there is no calculation method for internal force of such kind of retaining structure with double-row piles. For this type of double-row piles, the pre-row pile and the post-row pile are both considered as elastic foundation beam placing upright. The soil spring is employed to simulate the soil resistance under excavation surface. The sections of double-row pile are divided on the basis of differential equations of elastic foundation beam deflection to establish internal force equations of sections. The power series method is used to determine the internal force and deformation of the pile body below the excavation surface with the boundary condition of pile tip. Under the deformation compatibility condition of middle section of coupling beam, a equation of force method is established to get the internal force of middle section of coupling beam; and then the internal forces of different sections of the pre-row pile and the post-row pile are obtained. Finally, combining with the engineering examples, this type of retaining structure with double-row piles is calculated and the calculation results are compared with the measured statistics. Some valuable suggestions are put forward for design of this type of retaining structure with double-row piles.%由于支护空间受到限制等原因,一类双排桩支护型式设计为前后排桩之间没有土体,形成只有后排桩挡土的空间门架式结构,国内外目前尚无此类双排桩支护结构内力计算方法.针对这类双排桩,把前后排桩看作是竖放的弹性地基梁,用土弹簧模拟基坑开挖面以下的土抗力,根据弹性地基梁的挠曲微分方程对双排桩进行分段,建立各自

  18. Longitudinal vibration of pile in layered soil based on Rayleigh-Love rod theory and fictitious soil-pile model

    Institute of Scientific and Technical Information of China (English)

    Lü Shu-hui; WANG Kui-hua; WU Wen-bing; C. J. LEO

    2015-01-01

    The dynamic response of pile in layered soil is theoretically investigated when considering the transverse inertia effect. Firstly, the fictitious soil-pile model is employed to simulate the dynamic interaction between the pile and the soil layers beneath pile toe. The dynamic interactions of adjacent soil layers along the vertical direction are simplified as distributed Voigt models. Meanwhile, the pile and fictitious soil-pile are assumed to be viscoelastic Rayleigh-Love rods, and both the radial and vertical displacement continuity conditions at the soil-pile interface are taken into consideration. On this basis, the analytical solution for dynamic response at the pile head is derived in the frequency domain and the corresponding quasi-analytical solution in the time domain is then obtained by means of the convolution theorem. Following this, the accuracy and parameter value of the hypothetical boundaries for soil-layer interfaces are discussed. Comparisons with published solution and measured data are carried out to verify the rationality of the present solution. Parametric analyses are further conducted by using the present solution to investigate the relationships between the transverse inertia effects and soil-pile parameters.

  19. 等径桩、挤扩支盘桩相互作用系数数值研究%Numerical Analysis on Pile-pile Interaction Coefficient Between Equal Pile , Squeezed Branch Pile

    Institute of Scientific and Technical Information of China (English)

    丰土根; 宋海洋; 王路博; 陈阳; 胡松

    2015-01-01

    Using Abaqus numerical analysis method,double equal piles,one equal pile and one squeezed branch pile,double squeezed branch piles models were built. Through lots of numerical simulation,analysis of the pile interaction coefficient under different situations,including pile load,pile spacing,soil Poisson's ratio and analysis of the influence to different double piles in surrounding load were carried out. Result shows that the pile-pile influence coefficient is approximately constant value in liner elastic deformation of loading piles ,and irrelevant to the load level and piles characters,but it decreased gradually until close to 0 in plase state,with the Poisson's ratio becomes large. The interaction coefficient gradually decreases,under the same conditions,the surrounding load have a greater impact on double equal piles than double squeezed branch piles and gradually decreases with the increase of poisson's ratio. The study provides a reference in practical engineering between different piles.%采用Abaqus数值分析方法,建立双等径桩、一等径桩一支盘桩、双挤扩支盘桩模型,通过大量的数值模拟计算,分析在不同桩顶荷载、不同桩间距、不同土体泊松比条件下桩的相互影响系数以及在桩周荷载条件下对不同双桩的影响,分析表明,在线弹性变形阶段,桩与桩的影响系数近似为恒定值,与荷载水平及桩的性状无关,进入塑性阶段后,则逐渐减小最后趋于0,随着泊松比的变大,桩之间的相互作用系数逐渐减小,在相同条件下,桩周荷载对双支盘桩的影响大于双等径桩且随泊松比的增大而减小. 研究结果为实际工程中桩之间的影响情况提供参考.

  20. Shaking table testing of hard layered soil-pile-structure interaction system

    Institute of Scientific and Technical Information of China (English)

    LI Peizhen; REN Hongmei; CHEN Yueqing; LU Xilin; SONG Heping

    2007-01-01

    Shaking table tests on a dynamic interaction system of hard layered soil,pile foundation and frame structure were carried out.The earthquake damage of the super-structure and foundation was reproduced.Based on these tests,several key issues about the seismic response of the dynamic soil-structure interaction (SSI) system were studied.The natural frequency of the system was less than that of the structure on rigid foundation if the SSI is not taken into account,while its damping ratio was larger than that of the structure.The mode shape of the system was different from that of the structure on the fixed base in that there were rocking and swinging at the foundation.Magnification or reduction of vibration transferred by soil was related to soil characteristic,excitation magnitude,and so on.Generally,sand magnifies vibration,while viscous powder soil dampens vibration.The components of the acceleration response at the top of the superstructure were based on the relative magnitude of the rocking stiffness,the swing stiffness of the foundation and the stiffness of the super-structure.The multi-direction excitations have little effect on the key issues of the horizontal SSI.

  1. The homogenisation of bulk material in blending piles.

    NARCIS (Netherlands)

    Gerstel, A.W.

    1979-01-01

    In this thesis the homogenisation of bulk material in three types of piles is dealt with. The homogenisation implies that the fluctuations of a material proprety in the input flow of the pile are transformed into output fluctuations, whereby the latter ones are evened out. Analyses are presented con

  2. Effect of piles on the seismic response of mosques minarets

    Directory of Open Access Journals (Sweden)

    Mohamed Ahmed Abdel-Motaal

    2014-03-01

    Minaret (60.0-m height was studied to investigate the effects of soil stiffness, pile length, diameter, and arrangement, on the minaret and pile dynamic behavior. Comparison between study results and conventional analysis method is illustrated. Study results, discussion, and conclusion are given.

  3. Perturbation analysis on post-buckling behavior of pile

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The nonlinear large deflection differential equation, based on the assumption that the subsoil coefficient is the 2nd root of the depth, was established by energy method. The perturbation parameter was introduced to transform the equation to a series of linear differential equations to be solved, and the deflection function according with the boundary condition was considered. Then,the nonlinear higher-order asymptotic solution of post-buckling behavior of a pile was obtained by parameter-substituting. The influencing factors such as bury-depth ratio and stiffness ratio of soil to pile, slenderness ratio on the post-buckling behavior of a pile were analyzed. The results show that the pile is more unstable when the bury-depth ratio and stiffness ratio of soil to pile increase,and although the buckling load increases with the stiffness of soil, the pile may ruin for its brittleness. Thus, in the region where buckling behavior of pile must be taken into account, the high grade concrete is supposed to be applied, and the dynamic buckling behavior of pile needs to be further studied.

  4. Assessment of timber piles in Clallam County, Washington

    Science.gov (United States)

    Pandey, Arun K.; Tyler, Ross; Arnette, Clyde G.; Anthony, Ronald W.

    1998-03-01

    Timber bridges are very common in state and rural highway systems. According to the National Bridge Inventory (NBI), there are 41,743 timber bridges in the United States and another 42,102 bridges with timber decks as a part of the superstructure. As these bridges age, there is a critical need for reliable inspection and assessment methods for evaluating timber members. Under an FHWA mandate, these bridges also need to be evaluated for scour susceptibility. Knowledge of the length of timber piles supporting the bridge is a vital component in calculating scour resistance of a bridge. However, records of timber pile lengths are often nonexistent or incomplete due to the construction practices for timber piles. This paper presents nondestructive evaluation (NDE) techniques used for assessing timber piles on 10 bridges in Clallam County, Washington. Stress wave velocity and resistance drilling techniques were used to determine the presence of and quantify the extent of decay in the piles. A longitudinal stress wave technique was used for determining the length of timber piles. Determination of piles with decay aided in establishing maintenance and repair needs on the bridge substructures. Pile length estimates enabled Clallam County Road Department to determine the scour-susceptibility of these bridges.

  5. Physical Modelling of Cyclic Laterally Loaded Pile in Cohesionless Soil

    DEFF Research Database (Denmark)

    Hansen, Mette; Wolf, Torben K.; Rasmussen, Kristian L.

    Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical in the service...

  6. 水平静力荷载作用下桩伴侣工作性状有限元模拟及与无伴侣构造形式的比较分析%FINITE ELEMENT ANALYSIS OF COMPARATIVE PERFORMANCE OF LATERALLY LOADED PILE WITH OR WITHOUT PARTNER

    Institute of Scientific and Technical Information of China (English)

    薛江炜; 葛忻声; 杨勇; 蔡景珞

    2013-01-01

    Reference on lateral load test and numerical simulation of large diameter pipe pile by using cast-in-place concrete(PCC),finite element model of a single pile with or without pile partner under lateral load is established. Comparison calculations show that pile partner can ensure lateral loads delivering from pile cap to foundation soil, and double reduce stress and displacement of pile. Pile partner can also make some improvement on lateral bearing characters for the pile foundation with low cap even though the modulus of foundation soil is small. When pile partner is equipped,and the connection mode between pile cap and pile changing from rigid connection to hinge joint,pile body internal force can also be drastically reduced;and pile and pile caps by distance can only be considered to meet the requirement of vertical bearing capacity or optimization design of pile foundation stiffness to reduce differential settlement. Pillow is not necessary and can be cancelled in composite foundation when pile partner is applied. The height of pile partner has little influence on internal force and displacement of pile. Under rare earthquake action,pile partner may sacrifice firstly to keep pile perform well.%借鉴现浇混凝土大直径管桩(PCC 桩)水平承载足尺试验和数值模拟的成果,建立水平荷载作用下多个构造形式有无伴侣的单桩有限元数值模型。对比计算与分析表明,对于低承台桩基设置桩伴侣可确保承台向地基土传递水平荷载,成倍减小基桩的应力和位移;对于桩身范围地基土模量低的低承台桩基的水平承载性状也有一定的改善;配备桩伴侣后,将桩与承台的连接方式由刚接改为铰接也能大幅度减小桩身内力,桩顶与承台的距离可单纯考虑竖向承载力和变刚度调平基础底板沉降的需要;设置桩伴侣后可取消褥垫层;桩伴侣的高度变化对水平荷载作用下桩内力和位移影响很小;在罕遇

  7. Ice load on offshore wind turbine foundations; Ice load on offshore wind turbine foundations

    Energy Technology Data Exchange (ETDEWEB)

    Voelund, P.; Joergensen, L.B. [Energi E2, Koebenhavn (Denmark); Gravesen, H.; Soerensen, S.L. [Carl Bro, Glostrup (Denmark); Pedersen, B.; Lorenz, R.S.; Miller, R.; Oestergaard, S.; Riber, H.J. [LIC Engineering, Hellerup (Denmark); Pedersen, J.; Gjerding, J.B. [Tripod, Soeborg (DK)

    2003-12-01

    conical foundation. (13) Design requirements for a vertical cylindrical structure. (14) Composition of extreme ice loads and wind loads. (15) Prediction methods for ice loads and ice ridge loads on offshore wind turbine foundations. The main findings of the project are: (1) Additional netto-costs of using an ice tone on gravitational foundations are limited, because the weight of the cone is needed to stabilise the foundation. (2) For piled foundation types like mono piles and tripods an ice tone will simply add to the cost of the structure. For larger (>5MW) offshore wind turbine foundations it may prove advantageous to omit the use of ice cones since design to withstand wave loads will cover against ice loads. (3) The laboratory tests and foliowing analysis covers all relevant aspects of design of constructions With ice cone. (4) Ice loads on monopile construcdons without ice cone are covered to a certain degree, but not in all details. Important is that loads are in the order of 5 times larger than on conical constructions, and that lock-in between construction vibration at foundation eigenfrequency and ice crushing load frequency can occur and cause critical cyclic loading on the construction. (5) Loads from ice ridges will in general be lower than the load from the undisturbed ice (au)

  8. Kessler Foundation Research Center

    Science.gov (United States)

    ... you, Kessler Foundation researchers have been studying wearable robotic exoskeletons in people with paralysis and weakness, and ... info@kesslerfoundation.org Kessler Foundation 2015 © | accessibility statement | careers | privacy policy | press releases

  9. American Hospice Foundation

    Science.gov (United States)

    American Hospice Foundation Skip to content Home Caregiving Learning About Hospice Grief Grieving Children Grief at School Grief at ... for all who come after us. The American Hospice Foundation (AHF) closed its doors in June 2014. ...

  10. Pediatric Brain Tumor Foundation

    Science.gov (United States)

    ... you insights into your child's treatment. LEARN MORE Brain tumors and their treatment can be deadly so ... Cancer Foundation joins the PBTF Read more >> Pediatric Brain Tumor Foundation 302 Ridgefield Court, Asheville, NC 28806 ...

  11. Cooley's Anemia Foundation

    Science.gov (United States)

    ... role in their lives. Welcome to the Cooley's Anemia Foundation Website The Cooley's Anemia Foundation is dedicated to serving people afflicted with ... major form of this genetic blood disease, Cooley's anemia/thalassemia major. Our mission is advancing the treatment ...

  12. Foundation for Sarcoidosis Research

    Science.gov (United States)

    ... a Clinical Trial Our mission is to stop sarcoidosis — join us. The sarcoidosis community needs your help ... receive periodic emails from the Foundation. Foundation For Sarcoidosis Research 1820 W. Webster Ave., Ste 304 Chicago, ...

  13. American Vitiligo Research Foundation

    Science.gov (United States)

    ... life can acquire vitiligo Welcome to The American Vitiligo Foundation 2017 AVRF Calendars Order your calendar with ... animal testing. Please Visit Our Donations Page American Vitiligo Research Foundation "We Walk By Faith, Not By ...

  14. Skin Cancer Foundation

    Science.gov (United States)

    ... Host a Fundraising Event | About Us | Store The Skin Cancer Foundation The Skin Cancer Foundation is the only ... Handbook A "Sunscreen Gene"? Skin Cancer Facts & Statistics Skin Cancer Treatment Glossary Information on medications and procedures The ...

  15. Toxicology Education Foundation

    Science.gov (United States)

    ... bodies and our world. Welcome to the Toxicology Education Foundation! Our mission is to enhance public understanding ... In with us, follow our Tweets, choose Toxicology Education Foundation as your preferred charity through Smile.Amazon. ...

  16. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Directory of Open Access Journals (Sweden)

    Krasinski Adam

    2015-02-01

    Full Text Available The application of screw displacement piles (SDP is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  17. Method of extracting coal from a coal refuse pile

    Science.gov (United States)

    Yavorsky, Paul M.

    1991-01-01

    A method of extracting coal from a coal refuse pile comprises soaking the coal refuse pile with an aqueous alkali solution and distributing an oxygen-containing gas throughout the coal refuse pile for a time period sufficient to effect oxidation of coal contained in the coal refuse pile. The method further comprises leaching the coal refuse pile with an aqueous alkali solution to solubilize and extract the oxidized coal as alkali salts of humic acids and collecting the resulting solution containing the alkali salts of humic acids. Calcium hydroxide may be added to the solution of alkali salts of humic acid to form precipitated humates useable as a low-ash, low-sulfur solid fuel.

  18. Pre-Stressed Rope Reinforced Anti-Sliding Pile

    Institute of Scientific and Technical Information of China (English)

    XU Jun; WANG Chenghua

    2006-01-01

    Pre-stressed rope reinforced anti-sliding pile is a composite anti-sliding structure. It is made up of pre-stressed rope and general anti-sliding pile. It can bring traditional anti-sliding pile's retaining performance into full play, and to treat with landslide fast and economically. The difference between them is that the pre-stressed rope will transfix the whole anti-sliding pile through a prearranged pipe in this structure. The working mechanics, the design method and economic benefit are studied. The results show that the pre-stressed rope reinforced anti-sliding pile can treat with the small and middle landslides or high slopes well and possess the notable advantage of technology and economic.

  19. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Science.gov (United States)

    Krasinski, Adam

    2015-02-01

    The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  20. Centrifuge modelling of drained lateral pile - soil response

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte

    of rigid piles. The tests have been performed in homogeneously dense dry or saturated Fontainebleau sand in order to mimic simplified drained offshore soil conditions. Approximately half of the tests have been carried out to investigate the centrifuge procedure in order to create a methodology of testing...... for monopiles today. Therefore it appears that the methodology for monopiles lacks scientific justification and a better understanding of rigid piles is needed. More than 70 centrifuge tests on laterally loaded rigid model piles have been carried out in connection with this thesis to get a better understanding...... that enables the transformation of result from tests in model scale to prototype scale. The grain size to pile diameter ratio, the non-linear stress distribution and the pile installation was identified from this investigation as important parameters in reliable scaling of centrifuge results. The remaining...

  1. Influence of ground subsidence on working behavior of composite foundation%地基土沉降对复合地基工作性状的影响

    Institute of Scientific and Technical Information of China (English)

    夏力农; 苗云东; 苗伟波; 周靖; 补国斌; 李训根

    2012-01-01

    采用数值分析方法,考虑桩-土-褥垫层的共同作用,对复合地基在地基土沉降前后的沉降、桩侧摩阻力和桩身轴向应力等工作性状进行了研究.结果表明:与常规条件下相比,在相同上部荷载作用下,地下水位下降使基础和桩顶的沉降增加,桩身轴向应力增大,桩-土应力比提高,上部荷载的增大会加剧这些现象.随着降水造成的地基土沉降增加,加固桩体中负摩阻力的影响逐渐增大,中性点位置下移,负摩阻力引起的下拉力增大,桩侧摩阻力发挥更加充分.%Considering the pile-soil-cushion interaction, the working behaviors of composite foundation fore and after ground subsidence, such as the displacement of soil and reinforced piles, skin friction distribution of pile and pile axial stress are studied by finite element method. The results show that, compared with conventional conditions, the settlement of foundation, including soil and reinforced pile increases, axial stress in pile enhances, pile-soil stress ratio improves while groundwater level lowering in the same applied load. Increase of load acted on the foundation would promote the above-mentioned phenomena. In reinforced piles, the influences of negative skin friction increase gradually, neutral point moves down, down drag caused by negative skin friction increases, skin friction along the piles develops more fully along with the increase of the ground subsidence caused by groundwater level lowering.

  2. Influence of space of double row piles on soil arching effect

    Directory of Open Access Journals (Sweden)

    Zhao bo

    2015-02-01

    Full Text Available FLAC3d software, based on continuous theory, is used to analysis influence of space of double row piles on soil arching effect. The result shows that different from single row pile, double row piles will produce soil arching effect at front pile and rear pile severally, this phenomenon is called multiple soil arching effect; the residual load of front of front row pile will increase,the soil arch zone and the soil arching effect will decrease with the continuous increase of double row pile spacing.At the same time the soil arching effect of rear pile decreases, while the soil arching effect of front pile increases and finally the soil arching effect between front pile and rear pile will be equal.

  3. The influence of connecting pile cap-column in the mechanisms of break in the two pile caps

    Directory of Open Access Journals (Sweden)

    A. C. MESQUITA

    Full Text Available Abstract The paper analyzes the two pile caps with partially embedded socket and subject a center load. Three models were experimentally tested, varying the type of conformation of the column and walls of the socket, with a smooth, the other rough, and a monolithic two pile cap, used for reference. The roughening of the column-socket interface was examined with the aim of verifying the difference of the distribution of compressive and tensile stresses in the strut an tie model used for design. The experimental test to show that the two pile caps with conformation rough of the column and walls of the socket, support more load in comparison with two pile caps with smooth of the column and walls of the socket. Both however underperformed the monolithic two pile cap, with values of 66% and 36% respectively.

  4. Heat piles: the `MAIN TOWER` in Frankfurt on the Main; Einsatz von Energiepfaehlen am Beispiel des MAIN TOWER in Frankfurt am Main

    Energy Technology Data Exchange (ETDEWEB)

    Kapp, C. [NEK Umwelttechnik AG, Zuerich (Switzerland); Hude, N. von der [Bilfinger und Berger Bauaktiengesellschaft, Mannheim (Germany). Service Center Technik

    1997-12-01

    In the inner-city banking quarter of Frankfurt on the Main, one of the highest and most modern office buildings of Europe has been being erected since the summer of 1996. The intersecting rows of drill-foundation piles required to secure the deep excavation and the load-bearing piles were designed as heat piles. Thereby the harnessing of shallow geothermal energy was integrated into the overall HVAC concept, realizing a highly innovative project. Although the erection of heat piles had only been decided on when planning for a conventional energy system was completed, the decision permitted to dispense with some of the usual components in the control station. As executed simulations show, integration of the piles into the overall concept of the building is not easy because the piles are exclusively used to provide cooling energy. But the project demonstrates that heat piles can nowadays be used also on a large scale. (orig.) [Deutsch] Im Bankenviertel in der Innenstadt von Frankfurt am Main entsteht seit dem Sommer 1996 eines der hoechsten und modernsten Buerogebaeude Europas. Die zur Sicherung der tiefen Baugrube erforderlichen Pfaehle der ueberschnittenen Bohrpfahlwand sowie diejenigen zum Lastabtrag wurden als Energiepfaehle ausgebildet. Damit wurde die Nutzung der untiefen Geothermie in das Gesamtkonzept der Haustechnik integriert und so ein innovatives Energiekonzept umgesetzt. Obwohl der Einsatz der Energiepfaehle erst dann beschlossen worden ist, als bereits eine konventionelle Energieversorgung vorgesehen und planerisch umgesetzt worden war, konnte dank der Energiepfaehle auf einige herkoemmliche Komponenten in der Energiezentrale verzichtet werden. Aufgrund der durchgefuehrten Simulationsberechnungen gestaltet sich die Einbindung ins Gesamtgebaeudekonzept nicht einfach, da die Energiepfaehle lediglich zu Kuehlzwecken verwendet werden. Trotzdem zeigt dieses Beispiel, dass heute Energiepfahlsysteme auch in grossem Massstab eingesetzt werden koennen. (orig.)

  5. The Monopod Bucket Foundation

    DEFF Research Database (Denmark)

    Bakmar, Christian LeBlanc; Ahle, Kim; Nielsen, Søren A.;

    2009-01-01

    Following the successful installation of a prototype of a monopod bucket foundation, also called a “monopod suction caisson”, at Horns Rev 2 Offshore Wind Farm, Denmark, in 2009, DONG Energy is currently developing a commercialization strategy. The monopod bucket foundation is a promising...... foundation concept for offshore wind turbines and can be installed using suction assisted penetration, combined with other installation methods. This selfinstalling foundation concept, may avoid the use of expensive jack-ups and scour protection, and thus significantly reduces installation costs. However......, further research, development and prototype testing are required, before the monopod bucket foundation can be commercialized....

  6. Environmental Foundations in Germany

    Directory of Open Access Journals (Sweden)

    Thomas Krikser

    2015-05-01

    Full Text Available Foundations in Germany were examined in the context of environmental issues. Data from environmental foundations show that there is huge difference between private and public foundations concerning financial settings. Furthermore, environment is often not the only objective and sometimes not even processed. Our analysis shows that there are different types of foundations with regard to environmental scopes and activities. Although “attractive topics” such as biodiversity and landscape conservation seem to be more important to foundations, less visible topics such as pollution prevention remain merely a “blind spot.” Together, these findings suggest that there is only a limited potential of private foundations compared with public foundations. Nevertheless, there might be an impact on environmental awareness and local sustainability.

  7. Lateral displacement of silty clay under cement-fly ash-gravel pile-supported embankments:Analytical consideration and field evidence

    Institute of Scientific and Technical Information of China (English)

    张崇磊; 蒋关鲁; 刘先峰; 王智猛

    2015-01-01

    Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported (GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment (HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements;2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation;and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.

  8. 轴向荷载对斜桩水平承载特性影响试验及理论研究%Test and theoretical research on influence of axial load on lateral bearing capacity of batter piles

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      斜群桩受水平荷载作用时,群桩中的基桩受到径向荷载、轴向荷载和弯矩的共同作用。为研究轴向荷载对斜桩水平承载特性的影响,完成了3根单桩以及1组1×2斜桩的大尺寸模型试验。试验结果表明:轴向拉力作用会降低斜桩的水平刚度和极限承载力;而轴向压力作用则会使其水平刚度和极限承载力提高。基于桩侧浅层土体楔形破坏假定,推导了考虑轴向荷载影响的斜桩水平极限土抗力计算公式,提出了桩侧土抗力的p-y曲线方法,并通过模型试验及现场试验验证其合理性。%When batter pile group are under lateral load, the foundation piles in pile group are subjected to radial load, axial load and bending moment. In order to study the influence of axial load on lateral bearing capacity of batter piles, large-scale model tests of three single piles and a 1×2 batter pile group have been conducted in a larger soil tank. It is found that the upward axial force on the pile top decreases the lateral stiffness and the lateral ultimate bearing capacity of batter pile; while the downward axial force enhances the horizontal stiffness and the lateral ultimate bearing capacity of batter pile. Based on the assumption of wedge failure of the shallow soil around piles, considering the influence of axial load on piles, a formula for calculating the lateral ultimate resistance force of soil is deduced. Then, a p-y curve method for resistance force of soil around piles is proposed. Finally, the formula and the proposed p-y curve method for batter pile are verified by model tests and field tests.

  9. Three-dimensional analysis of slopes reinforced with piles

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 叶茂; 张飞

    2015-01-01

    Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.

  10. Analysis of Pile Deformation Characters and Settlement of Pile Group Including New and Old Piles Considering Pile Timeliness%考虑沉桩时效性的新旧桩变形特性与沉降分析

    Institute of Scientific and Technical Information of China (English)

    孙晓晨; 朱杰江

    2016-01-01

    The bearing capacity of residue pile should be reassessed and then the internal relations and differences between the new pile and the residue one should be analyzed in soft soil area. Load⁃settlement relationship is expected to be obtained from above research. A three dimensional elastic⁃plastic finite element model is established by ABAQUS, old and new pile effect and the corresponding differential settlement are studied, and the load influencing factors of old and new piles are discussed. Research results show that with the increase of length to diameter ratio, the old and new pile settlement difference is slightly decreasing. With the increase of new pile diameter, pile of old and new different settlement are substantially reduced. With the increase of pile spacing and diameter ratio, the old pile settlement decreases sharply.%软土地区旧桩重新利用时须重新评估其承载能力,计算明确旧桩承载力与新桩承载力之间的内在联系与差异。采用ABAQUS软件构建新旧桩共同作用的三维弹塑性有限元分析模型,研究了新旧桩共同作用效应及相应的差异沉降,并对影响新旧桩荷载⁃沉桩关系的影响因素进行讨论。研究成果表明:随着长径比的增加,新旧桩的沉降差小幅减小;随着新桩桩径的增加,新旧桩的沉降差大幅减小;随着桩距与直径比值的增加,旧桩沉降大幅减小。

  11. Study of Ground Treatment on Improvement of Pile Foundation Response in Liquefiable Soils

    OpenAIRE

    Yulong, Chen

    2016-01-01

    International audience; In light of the disastrous the 2011 Tohoku Pacific Earthquake, the government of Japan has conducted studies to revise the seismic design code, and elevated peak ground accelerations have been adopted. Consequently, revisions on existing design to comply with the updated code are required for public projects that are still undergoing. The design safety needs to be reassessed, and implementation of strengthening measures is required if deemed necessary. For liquefaction...

  12. Examination of Interaction Spring and Damping Model connecting Ground and Piled Foundations in Liqueaction Ground

    Science.gov (United States)

    Okada, Yoshihisa; Ogawa, Yoshimi

    There are many bridges in lowland areas in East Tokyo and soft ground in Tokyo Bay Coast. A bare possibility is that these structures might suffer disastrous damage due to liquefaction when the area is hit by a large earthquake. In this paper, interaction spring and damping model considering a process of liquefaction and relationship between natural period of ground and pier are proposed, and it is verified by using the dynamic centrifugal model test in level 2 earthquake motion. As the result, it is verified that the response of pier and footing behaviors of the test and the analysis can be well corresponded, the interaction spring and damping model considering the process of liquefaction and the relationship between natural period of ground and pier is suitable for the purpose.

  13. The effect of loading rate on pile bearing capacity of saturated sand

    NARCIS (Netherlands)

    Archeewa, E.

    2005-01-01

    Pile load tests are commonly used by engineers to determine its bearing capacity. At present, there are three methods of pile load tests: the static, the dynamic and the quasi-static test. The static pile load test is done by applying an axial load on the pile with a long duration. The dynamic and q

  14. 40 CFR 761.347 - First level sampling-waste from existing piles.

    Science.gov (United States)

    2010-07-01

    ... existing piles. 761.347 Section 761.347 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... from existing piles. (a) General. Sample piles that are either specifically configured for sampling... alternate sampling plan in accordance with § 761.62(c). (b) Specifically configured piles. A...

  15. Pile mixing increases greenhouse gas emissions during composting of dairy manure

    Science.gov (United States)

    The effect of pile mixing on greenhouse gas (GHG) emissions from stored dairy manure was determined using large flux chambers designed to completely cover pilot-scale manure piles. GHG emissions from piles that were mixed four times during the 80 day trial were about 20% higher than unmixed piles. ...

  16. The effect of loading rate on pile bearing capacity of saturated sand

    NARCIS (Netherlands)

    Archeewa, E.

    2005-01-01

    Pile load tests are commonly used by engineers to determine its bearing capacity. At present, there are three methods of pile load tests: the static, the dynamic and the quasi-static test. The static pile load test is done by applying an axial load on the pile with a long duration. The dynamic and q

  17. Laboratory Testing of Cyclic Laterally Loaded Pile in Cohesionless Soil

    DEFF Research Database (Denmark)

    Roesen, Hanne Ravn; Ibsen, Lars Bo; Hansen, Mette;

    2013-01-01

    Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical...... in the serviceability limit state. In this paper small-scale testing of a pile subjected to cyclic, lateral loading is treated in order to investigate the effect of cyclic loading. The test setup, which is an improvement of a previous setup, is described and the first results of testing are compared with previous...

  18. Discrimination of pile up in a fission fragment detection experiment

    CERN Document Server

    Dematte, L; Bax, H

    2002-01-01

    In this work the problem introduced in a fission experiment by the pile-up due to a strong alpha-background has been addressed. A novel scheme has been developed, able to reject more than 90% of pile-up affected pulses in a plutonium sample with an activity of approx 1 MBq. This procedure is necessary in order to improve the resolution to an acceptable level. With a proper calibration, however, the global mean energy and mass of the fragments are correctly reproduced both with and without pile-up rejection.

  19. 复合地基技术在软土路基处理中的应用%A Study of Composite Foundation Technology Applied in Soft Soil Foundation Treatment

    Institute of Scientific and Technical Information of China (English)

    吴祯

    2013-01-01

      通过工程实例,介绍采用“深层搅拌法”形成水泥土桩复合地基处理软土路基的设计、施工及检测结果。%  Combined with some project case, cement soil pile composite foundation by deep mixing method is introduced in detail about its design, construction and detection results in treating soft soil foundation.

  20. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan

    2015-01-01

    Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.

  1. The Monopod Bucket Foundation

    DEFF Research Database (Denmark)

    Bakmar, Christian LeBlanc; Ahle, Kim; Nielsen, Søren A.

    2009-01-01

    Following the successful installation of a prototype of a monopod bucket foundation, also called a “monopod suction caisson”, at Horns Rev 2 Offshore Wind Farm, Denmark, in 2009, DONG Energy is currently developing a commercialization strategy. The monopod bucket foundation is a promising...... foundation concept for offshore wind turbines and can be installed using suction assisted penetration, combined with other installation methods. This selfinstalling foundation concept, may avoid the use of expensive jack-ups and scour protection, and thus significantly reduces installation costs. However...

  2. Wave Run-Up on Offshore Windturbine Foundations

    DEFF Research Database (Denmark)

    Frigaard, Peter; De Vos, Leen

    2005-01-01

    In the last decade, several offshore wind-farms are built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there still are some engineering challenges in placing the wind turbine foundations offshore. For example, unexpected damage to boat landing...... facilities and platforms has been caused by wave run-up and wave impacts on the platforms. To be able to assess the forces caused by the wave run-up, it is necessary to know the maximum run-up height and the destribution of the run-up along the pile. This article describes a physical model study...

  3. Condition Assessment Survey (CAS) Program. Deficiency standards and inspections methods manual: Volume 1, 0.01 Foundations and footings

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    General information is presented for asset determinant factor/CAS repair codes/CAS cost factors; guide sheet tool & material listing; testing methods; inspection frequency; standard system design life tables; system work breakdown structure; and general system/material data. Deficiency standards and inspection methods are given for footings - spread/strip/grade beams; foundation walls; foundation dampproofing/waterproofing; excavation/backfill/ and piles & caissons.

  4. Airborne thermography of temperature patterns in sugar beet piles

    Science.gov (United States)

    Moore, D. G.; Bichsel, S.

    1975-01-01

    An investigation was conducted to evaluate the use of thermography for locating spoilage areas (chimneys) within storage piles and to subsequently use the information for the scheduling of their processing. Thermal-infrared quantitative scanner data were acquired initially on January 16, 1975, over the storage piles at Moorhead, Minnesota, both during the day and predawn. Photographic data were acquired during the day mission to evaluate the effect of uneven snow cover on the thermal emittance, and the predawn thermography was used to locate potential chimneys. The piles were examined the day prior for indications of spoilage areas, and the ground crew indicated that no spoilage areas were located using their existing methods. Nine spoilage areas were interpreted from the thermography. The piles were rechecked by ground methods three days following the flights. Six of the nine areas delineated by thermography were actual spoilage areas.

  5. As Traffic Piles Up, So Does Air Pollution

    Science.gov (United States)

    ... 160914.html As Traffic Piles Up, So Does Air Pollution To minimize exposure, researchers recommend shutting windows and ... Doing so can reduce your exposure to toxic air pollution from a traffic jam by up to 76 ...

  6. New Mathematical Modelling of Stabilizing Pile with Prestressed Tieback Anchors

    Directory of Open Access Journals (Sweden)

    Cheng Huang

    2013-01-01

    Full Text Available This paper presents a novel mathematical modelling for analyzing stabilizing piles with prestressed tieback anchors. The new differential equations governing the mechanical response of the stabilizing pile are formulated and the boundary conditions considering the tie-back anchors are mathematically specified. Then, the system of differential equations is numerically solved by the high-accuracy Runge-Kutta finite difference method. A simple computer program has been written on the platform of MATLAB to run the procedure of the proposed algorithm. This approach is entirely different from the traditional finite element method used to design the anchored piles. The FEM is employed to verify the feasibility of the developed method. The comparative case study indicates that the proposed method has more higher modeling and computing efficiency than the FEM and can be an alternative method for designing the anchored pile used for slope stabilization.

  7. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    in dry sand by use of centrifuge modelling and to compare the findings with the standard p-y curves. It has been chosen to apply piles with an embedment length of 6 to 10 times the diameter of the applied piles. The general static behaviour of monopiles in dry sand has based on centrifuge tests been...... in sand by use of physical modelling and comparison of the findings with standard p-y curves. The present research is based on use of the centrifuge facilities at Danish Technical University (DTU), the sole geotechnical centrifuge in Scandinavia. It became evident in the initial phase of the research...... that the available centrifuge facilities at DTU was outdated and the focus was changed to establish up-to-date centrifuge facilities for medium to large diameter piles, and to initiate the research on the behaviour of large diameter piles in sand under static and cyclic loading. Key elements in the establishment...

  8. Processing Satellite Imagery To Detect Waste Tire Piles

    Science.gov (United States)

    Skiles, Joseph; Schmidt, Cynthia; Wuinlan, Becky; Huybrechts, Catherine

    2007-01-01

    A methodology for processing commercially available satellite spectral imagery has been developed to enable identification and mapping of waste tire piles in California. The California Integrated Waste Management Board initiated the project and provided funding for the method s development. The methodology includes the use of a combination of previously commercially available image-processing and georeferencing software used to develop a model that specifically distinguishes between tire piles and other objects. The methodology reduces the time that must be spent to initially survey a region for tire sites, thereby increasing inspectors and managers time available for remediation of the sites. Remediation is needed because millions of used tires are discarded every year, waste tire piles pose fire hazards, and mosquitoes often breed in water trapped in tires. It should be possible to adapt the methodology to regions outside California by modifying some of the algorithms implemented in the software to account for geographic differences in spectral characteristics associated with terrain and climate. The task of identifying tire piles in satellite imagery is uniquely challenging because of their low reflectance levels: Tires tend to be spectrally confused with shadows and deep water, both of which reflect little light to satellite-borne imaging systems. In this methodology, the challenge is met, in part, by use of software that implements the Tire Identification from Reflectance (TIRe) model. The development of the TIRe model included incorporation of lessons learned in previous research on the detection and mapping of tire piles by use of manual/ visual and/or computational analysis of aerial and satellite imagery. The TIRe model is a computational model for identifying tire piles and discriminating between tire piles and other objects. The input to the TIRe model is the georeferenced but otherwise raw satellite spectral images of a geographic region to be surveyed

  9. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders

    This document is the second of four notes concerning the effects of time (in this case ageing) on the vertical capacity of piles. It includes a critical review of the relevant publications described in note a.......This document is the second of four notes concerning the effects of time (in this case ageing) on the vertical capacity of piles. It includes a critical review of the relevant publications described in note a....

  10. 20051655 - Petronas, Capacity of Driven Piles Offshore Malaysia

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars

    This document is the third of four notes concerning the vertical capacity of piles. It includes an assessment of the effect of previous static load testing upon the measured capacity, i.e. preshearing effects.......This document is the third of four notes concerning the vertical capacity of piles. It includes an assessment of the effect of previous static load testing upon the measured capacity, i.e. preshearing effects....

  11. Pile Structure Program, Projected Start Date : January 1, 2010 (Implementation).

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Chris; Corbett, Catherine [Lower Columbia River Estuary Partnership; Ebberts, Blaine [U.S. Army Corps of Engineers

    2009-07-27

    The 2008 Federal Columbia River Power System Biological Opinion includes Reasonable and Prudent Alternative 38-Piling and Piling Dike Removal Program. This RPA directs the Action Agencies to work with the Estuary Partnership to develop and implement a piling and pile dike removal program. The program has since evolved to include modifying pile structures to enhance their habitat value and complexity by adding large woody debris. The geographic extent of the Pile Structure Program (PSP) includes all tidally-influenced portions of the lower Columbia River below Bonneville Dam; however, it will focus on the mainstem. The overarching goal of the PSP is to enhance and restore ecosystem structure and function for the recovery of federally listed salmonids through the active management of pile structures. To attain this goal, the program team developed the following objectives: (1) Develop a plan to remove or modify pile structures that have lower value to navigation channel maintenance, and in which removal or modification will present low-risk to adjacent land use, is cost-effective, and would result in increased ecosystem function. (2) Determine program benefits for juvenile salmonids and the ecosystem through a series of intensively monitored pilot projects. (3) Incorporate best available science and pilot project results into an adaptive management framework that will guide future management by prioritizing projects with the highest benefits. The PSP's hypotheses, which form the basis of the pilot project experiments, are organized into five categories: Sediment and Habitat-forming Processes, Habitat Conditions and Food Web, Piscivorous Fish, Piscivorous Birds, and Toxic Contaminant Reduction. These hypotheses are based on the effects listed in the Estuary Module (NOAA Fisheries in press) and others that emerged during literature reviews, discussions with scientists, and field visits. Using pilot project findings, future implementation will be adaptively managed

  12. Review of the literature on leachates from coal storage piles

    Energy Technology Data Exchange (ETDEWEB)

    Davis, E.C.; Boegly, W.J. Jr.

    1978-01-01

    Runoff from coal storage piles associated with coal conversion or combustion facilities may represent a potential source of environmental pollution. This report is an assessment of existing information on coal pile leachate. The assessment indicates that few detailed studies have been conducted to date, and these are limited and the results are highly variable. More detailed long-range studies using various types of coal are recommended. These studies should be carried out both in the laboratory and in field-scale experiments.

  13. Numerical modeling of centrifuge cyclic lateral pile load experiments

    Institute of Scientific and Technical Information of China (English)

    Nikos Gerolymos; Sandra Escoffer; George Gazetas; Jacques Gamier

    2009-01-01

    To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimental p-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including: soil plastification at an early stage of loading, "pinching" behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. (1974) for sand, is also presented.

  14. Emissions from prescribed burning of timber slash piles in Oregon

    Science.gov (United States)

    Aurell, Johanna; Gullett, Brian K.; Tabor, Dennis; Yonker, Nick

    2017-02-01

    Emissions from burning piles of post-harvest timber slash (Douglas-fir) in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5), black carbon, ultraviolet absorbing PM, elemental/organic carbon, filter-based metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins/dibenzofurans (PCDD/PCDF), and volatile organic compounds (VOCs) were sampled to determine emission factors, the amount of pollutant formed per amount of biomass burned. The effect on emissions from covering the piles with polyethylene (PE) sheets to prevent fuel wetting versus uncovered piles was also determined. Results showed that the uncovered ("wet") piles burned with lower combustion efficiency and higher emission factors for VOCs, PM2.5, PCDD/PCDF, and PAHs. Removal of the PE prior to ignition, variation of PE size, and changing PE thickness resulted in no statistical distinction between emissions. Results suggest that dry piles, whether covered with PE or not, exhibited statistically significant lower emissions than wet piles due to better combustion efficiency.

  15. Slime thickness evaluation of bored piles by electrical resistivity probe

    Science.gov (United States)

    Chun, Ok-Hyun; Yoon, Hyung-Koo; Park, Min-Chul; Lee, Jong-Sub

    2014-09-01

    The bottoms of bored piles are generally stacked with soil particles, both while boreholes are being drilled, and afterward. The stacked soils are called slime, and when loads are applied on the pile, increase the pile settlement. Thus to guarantee the end bearing capacity of bored piles, the slime thickness should be precisely detected. The objective of this study is to suggest a new method for evaluating the slime thickness, using temperature compensated electrical resistivity. Laboratory studies are performed in advance, to estimate and compare the resolution of the electrical resistivity probe (ERP) and time domain reflectometry (TDR). The electrical properties of the ERP and TDR are measured using coaxial type electrodes and parallel type two-wire electrodes, respectively. Penetration tests, conducted in the fully saturated sand-clay mixtures, demonstrate that the ERP produces a better resolution of layer detection than TDR. Thus, field application tests using the ERP with a diameter of 35.7 mm are conducted for the investigation of slime thickness in large diameter bored piles. Field tests show that the slime layers are clearly identified by the ERP: the electrical resistivity dramatically increases at the interface between the slurry and slime layer. The electrical resistivity in the slurry layer inversely correlates with the amount of circulated water. This study suggests that the new electrical resistivity method may be a useful method for the investigation of the slime thickness in bored piles.

  16. Moebius Syndrome Foundation

    Science.gov (United States)

    ... to Moebius syndrome Who we are Mission and History Foundation leadership Scientific advisory board Press room Our stories Financial ... to Moebius syndrome » Who we are » Mission and History » Foundation leadership » Scientific advisory board » Press room » Our stories » Financial ...

  17. Foundations for Critical Thinking

    Science.gov (United States)

    Bers, Trudy; Chun, Marc; Daly, William T.; Harrington, Christine; Tobolowsky, Barbara F.

    2015-01-01

    "Foundations for Critical Thinking" explores the landscape of critical-thinking skill development and pedagogy through foundational chapters and institutional case studies involving a range of students in diverse settings. By establishing a link between active learning and improved critical thinking, this resource encourages all higher…

  18. Modelling Foundations and Applications

    DEFF Research Database (Denmark)

    This book constitutes the refereed proceedings of the 8th European Conference on Modelling Foundations and Applications, held in Kgs. Lyngby, Denmark, in July 2012. The 20 revised full foundations track papers and 10 revised full applications track papers presented were carefully reviewed...

  19. Corrosion Activity on CFRP-Strengthened RC Piles of High-Pile Wharf in a Simulated Marine Environment

    Directory of Open Access Journals (Sweden)

    Ning Zhuang

    2017-01-01

    Full Text Available We report test results from an experimental study to investigate the effectiveness of carbon fiber-reinforced polymer (CFRP against reinforcing steel bar corrosion. Twelve reinforced-concrete pile specimens of 180 mm square by 1,600 mm long were cast. Three pile specimens were corroded to 5% steel mass loss and then strengthened with CFRP sheets; four specimens were strengthened by using CFRP sheets, whereas the remaining five specimens were not strengthened. The specimens were placed in a simulated marine environment, and corrosion was induced by an impressed current technique. At different theoretical corrosion degrees, nondestructive tests were performed to investigate the corrosion activity of the pile specimens, and destructive tests were performed to determine reinforcing steel bar mass loss. Based on the findings, the effectiveness of the CFRP-strengthened RC piles under aggressive marine environmental conditions was established.

  20. A Snapshot of Present Research at AAU and DTU on Large-Diameter Piles in Coarse-Grained Materials

    DEFF Research Database (Denmark)

    Leth, C. T.; Sørensen, Søren Peder Hyldal; Klinkvort, Rasmus Tofte

    2012-01-01

    Large-diameter (4 to 6 m) monopiles are often used as foundations for offshore wind turbines. The monopiles are subjected to large horizontal forces and overturning moments and they are traditionally designed based on the p-y curve method. The p-y curves recommended in offshore design regulations...... conducted at Aalborg University (AAU) and at the Technical University of Denmark (DTU). The piles have been investigated by means of physical and numerical modelling. The former consists of both centrifuge tests and tests in a so-called pressure tank (1G tests but with an applied overburden pressure...

  1. 原料堆场地基加固设计%Foundation Strengthening Design Of Raw Material Storage Yard

    Institute of Scientific and Technical Information of China (English)

    王荣杰; 彭国萍

    2012-01-01

    The raw material storage yard located in the intermediate zone between plain and mountains and kop and its foundation need to be strengthened to avoid large -area sliding unstability and settlement. The foundation deep strengthening scheme ineluding the methods of plastic drainage board and surcharge preloading, dynamic gravel pile replacement, sand gravel pile replacement; CFG pile, plain concrete pile and cement mixing pile.%某原料堆场建设场地地貌属海积平原及残山孤丘山前过渡带,需进行地基加固处理,处理后地基要求不发生大面积滑动失稳,并适当控制沉降。地基深层加固方案一般有插塑板堆载预压法、强夯碎石桩置换法、砂桩置换法、CFG桩法、素砼桩法、水泥搅拌桩法等。

  2. Preliminary report on coal pile, coal pile runoff basins, and ash basins at the Savannah River Site: effects on groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-04-28

    Coal storage piles, their associated coal pile runoff basins and ash basins could potentially have adverse environmental impacts, especially on groundwater. This report presents and summarizes SRS groundwater and soil data that have been compiled. Also, a result of research conducted on the subject topics, discussions from noted experts in the field are cited. Recommendations are made for additional monitor wells to be installed and site assessments to be conducted.

  3. Offshore wind turbine foundations. Development of a special vibratory hammer with enhanced function; Gruendung von Offshore Windenergieanlagen. Entwicklung einer speziellen Vibrationsramme mit erweiterter Funktion

    Energy Technology Data Exchange (ETDEWEB)

    Koecher, Johannes; Ulrich, Dirk [ThyssenKrupp Tiefbautechnik GmbH, Alsfeld (Germany)

    2013-11-01

    To ensure that steel jacket foundations for offshore wind turbines are securely anchored, they are fixed to the seabed by means of ''pins''. The pins consist of pipe piles weighing up to 140 metric tons, and are driven into the seabed by a vibratory hammer and then anchored by impact driving. ThyssenKrupp Tiefbautechnik has modified a vibratory hammer so that it can pick up the piles horizontally directly from the working ship or pontoon and then vibrate them vertically into the ground. This significantly reduces installation times and foundation costs. (orig.)

  4. The Supercritical Pile Model for GRBs

    Science.gov (United States)

    Kazanas, Demos

    2006-01-01

    We present the spectral and temporal radiative signatures expected within the Supercritical Pile model of Gamma Ray Bursts (GRB). This model is motivated by the need for a process that provides the dissipation necessary in GRB and presents a well defined scheme for converting the energy stored in the relativistic protons of the Relativistic Blast Waves (RBW) associated with GRB into radiation; at the same time it leads to spectra which exhibit a peak in the burst nuF(sub nu) distribution at an energy E(sub p) approximately equal to 1 MeV in the observer s frame, in agreement with observation and largely independent of the Lorentz factor GAMMA of the associated relativistic outflow. Furthermore, this scheme does not require (but does not preclude) acceleration of particles at the shock other than that provided by the isotropization of the flow bulk kinetic energy on the RBW frame. In the present paper we model in detail the evolution of protons, electrons and photons from a RBW to produce detailed spectra of the prompt GRB phase as a function of time from across a very broad range spanning roughly 4 log10 GAMMA decades in frequency. The model spectra are in general agreement with observations and provide a means for the delineating of the model parameters through direct comparison with trends observed in GRB properties.

  5. Parametric study on the effects of pile inclination angle on the response of batter piles in offshore jacket platforms

    Science.gov (United States)

    Aminfar, Ali; Ahmadi, Hamid; Aminfar, Mohammad Hossein

    2016-06-01

    Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile's inclination angle, and its interaction with the geometrical properties of the pile and the geotechnical characteristics of the surrounding soil on the behavior of the inclined piles supporting the jacket platforms. Results show that the inclination angle is one of the main parameters affecting the behavior of an offshore pile. We investigated the effect of the inclination angle on the maximum von Mises stress, maximum von Mises elastic strain, maximum displacement vector sum, maximum displacement in the horizontal direction, and maximum displacement in the vertical direction. The pile seems to have an operationally optimal degree of inclination of approximately 5°. By exceeding this value, the instability in the surrounding soil under applied loads grows extensively in all the geotechnical properties considered. Cohesive soils tend to display poorer results compared to grained soils.

  6. Flow and bed shear stresses in scour protections around a pile in a current

    DEFF Research Database (Denmark)

    Nielsen, Anders Wedel; Liu, Xiaofeng; Sumer, B. Mutlu

    2013-01-01

    with uniformly distributed coarse stones and a lower filter layer with finer stones. For the numerical simulations, the Flow-3D software was used. The scour protection layers were simulated with different numerical approaches, namely regularly arranged spheres, porous media, or their combinations (hybrid models...... on it in an unfavourable manner. Using physical models and 3D computational fluid dynamic (CFD) numerical simulations, the velocity and bed shear stresses are investigated in complex scour protections around mono piles in steady current. In the physical model the scour protections consisted of an upper cover layer......). Numerical simulations with one or four layers of cover stones without filter layer were first computed. Three additional simulations were then made for a scour protection with a cover layer and a single filter layer. Finally, a simulation of a full scale foundation and scour protection was made with porous...

  7. Numerical Analysis of the Stability of Embankment Slope Reinforced with Piles

    Institute of Scientific and Technical Information of China (English)

    CUI Wei; ZHANG Zhigeng; YAN Shuwang

    2007-01-01

    The effects of stabilizing piles on the stability of an embankment slope are analyzed by numerical simulation. The shear strength reduction method is used for the analysis, and the soil - pile interaction is simulated with zero-thickness elasto-plastic interface elements. Effects of pile spacing and pile position on the safety factor of slope and the behavior of piles under these conditions are given. The numerical analysis indicates that the positions of the pile have significant influence on the stability of the slope, and the pile needs to be installed in the middle of the slope for maximum safety factors. In the end, the soil arching effect closely associated with the space between stabilizing piles is analyzed. The results are helpful for design and construction of stabilizing piles.

  8. Analytical model of vertical vibrations in piles for different tip boundary conditions: parametric study and applications

    Institute of Scientific and Technical Information of China (English)

    Ning WANG; Kui-hua WANG; Wen-bing WU

    2013-01-01

    In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load.

  9. Capacity and failure mechanism of laterally loaded jet-grouting reinforced piles: Field and numerical investigation

    Institute of Scientific and Technical Information of China (English)

    HE Ben; WANG LiZhong; HONG Yi

    2016-01-01

    This study presents the results of field and numerical investigations of lateral stiffness,capacity,and failure mechanisms for plain piles and reinforced concrete piles in soft clay.A plastic-damage model is used to simulate concrete piles and jet-grouting in the numerical analyses.The field study and numerical investigations show that by applying jet-grouting surrounding the upper 7.5D (D =pile diameter) of a pile,lateral stiffness and bearing capacity of the pile are increased by about 110% and 100%,respectively.This is partially because the jet-grouting increases the apparent diameter of the pile,so as to enlarge the extent of failure wedge and hence passive resistance in front of the reinforced pile.Moreover,the jet-grouting provides a circumferential confinement to the concrete pile,which suppresses development of tensile stress in the pile.Correspondingly,tension-induced plastic damage in the concrete pile is reduced,causing less degradation of stiffness and strength of the pile than that of a plain pile.Effectiveness of the circumferential confinement provided by the jet-grouting,however,diminishes once the grouting cracks because of the significant vertical and circumferential tensile stress near its mid-depth.The lateral capacity of the jet-grouting reinforced pile is,therefore,governed by mobilized passive resistance of soil and plastic damage of jet-grouting.

  10. Wave Run-Up on Cylindrical and Cone Shaped Foundations for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    De Vos, Leen; Frigaard, Peter; De Rouck, Julien

    2007-01-01

    During the last decade, several offshore wind-farms were built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there are still some engineering challenges in placing the foundations of offshore wind turbines. For example, wave run-up and wave impacts...... of foundations for offshore wind turbines, including both regular and irregular waves. The influence of wave steepness, wave height and water depth on run-up is investigated. The measured run-up values are compared with applicable theories and previous experimental studies predicting run-up on a circular pile...... cause unexpected damage to boat landing facilities and platforms. To assess the forces due to wave run-up, the distribution of run-up around the pile and the maximum run-up height need to be known. This article describes a physical model study of the run-up heights and run-up distribution on two shapes...

  11. Seismic Demands for Pile-Supported Wharf Structures with Batter Piles

    Directory of Open Access Journals (Sweden)

    Rouhollah Amirabadi

    2012-09-01

    Full Text Available This study develops an optimal Probabilistic Seismic Demand Model (PSDM for pile-supported wharves whit batter plies. Four bins with twenty non-near-field ground motions and three typical pile-supported wharf structures from western United States ports are used to determine an optimal PSDM by using Probabilistic Seismic Demand Analysis (PSDA. PSDA is used to compute the relationship between Engineering Demand Parameters (EDPs and earthquake Intensity Measures (IMs. An optimal PSDM should be practical, sufficient, effective and efficient-all tested through several IM-EDP pairs. It has been found that for these types of structures, the optimal model comprises a spectral IM, such as spectral acceleration and one of several EDPs. These EDPs are considered for local (moment curvature ductility factor, intermediate (displacement ductility factor and horizontal displacement of embankment and global (differential settlement between deck and behind land response quantities. The considered PSDMs are a critical component in performance-based seismic design and seismic risk assessment. Results can be used in probabilistic framework for performance-based design developed by Pacific Earthquake Engineering Research (PEER center.

  12. 能源桩的荷载-温度联合测试技术∗%IN-SITU MECHANICAL-THERMO COMBINED TESTING TECHNIQUE OF GEOTHERMAL ENERGY PILES

    Institute of Scientific and Technical Information of China (English)

    王昊; 路宏伟; 洪鑫; 史春乐; 龚红卫; 蒋刚

    2016-01-01

    Energy pile is a new artifical foundation technology with which pipe loops are incorporated in the pile foundation for ground⁃source heat⁃pump systems, but there have been little information regarding the researching and testing of bearing behavior of energy piles under the pile⁃soil heat exchange. Combined with the conventional static load test and the ground thermal response test, established the methods and requirements for the testing technique of energy piles under the mechanical thermo coupling effect were established, the testing scheme was determined by load level of energy piles and the operating of pile⁃soil heat exchange. It was suggested the testing items, contents, equipment selection and the point of testing. Combined with an engineering example of energy piles, it was introduced the scheme, contents and heat exchange equipment of the field testing, combined with the characteristics of soil in layers,the layout of the temperature and stress sensors on energy piles were also introduced. According to the testing process, the pile top settlement and the axial stresses of energy piles with the change of the temperature of pile shaft were presented.%能源桩是在桩基中埋设地源热泵换热器的新型桩基础。但目前对能源桩因桩-土热交换引起的桩身承载性状变化的研究和测试却极为有限。结合常规桩基静荷载试验和岩土热响应试验,建立了荷载-温度作用下能源桩的联合测试技术方法,提出以能源桩荷载水平和桩-土热交换工况等因素作用来确定荷载-温度联合测试方案,建议了相应的测试项目和内容、测试设备的选择及测试要点。结合某能源桩工程实例,介绍能源桩荷载-温度现场测试方案、内容及热交换设备;结合土层分布特征,介绍了桩身温度、应力传感器的布置的设计,并给出与桩身温度相关的桩顶沉降、桩身应力等数据。

  13. Design of a New Foundation for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Brincker, Rune

    2004-01-01

    The gravitation platform and the monopile have in the previous major offshore wind turbine projects been dominating. A four-year research and development project has proven the bucket foundation to be feasible in suitable soil condition in water depth from near shore to app. 40 meters. A prototype...... was installed at the test field in Frederikshavn in late 2003, with a 3 MW wind turbine in normal operation. The R&D work is continued the complete the bucket concept and having the design standards for the construction and installation methodologies recognised. The design saves about half of the steel weight...... as compared to a traditional pile foundation, it is much easier to install and it can easily be removed when the wind turbine is taken down. However, the new design is suffering from uncertainties in the accumulated fatigue in the both the steel structure and the surrounding earth material. Therefore an on...

  14. Thermo active piles and diaphragm walls building process and thermal response test; Pilotes y pantallas termoactivas. Proceso constructivo y caracterizacion termica

    Energy Technology Data Exchange (ETDEWEB)

    Mazariegos, A.; Anton, L. C.; Valle, R.; Urchueguia, J.; Quilis, S.; Martinez, S.; Magraner, T.

    2009-07-01

    Thermo active foundation technology uses building foundation piles diaphragm wall slabs as ground heat exchangers to provide building with heating and cooling. This type of foundation is based on the use of the ground temperature to enhance the heat pump coefficient of performance (COP). In this kind of structures, the heat exchange can be done through a closed circuit installed on the reinforced of the foundation. This closed circuit is made up of HDPE pipes geothermal probes, through which water or brine circulates producing a heat exchange between this fluid and the ground. this fluid is led to a geothermal heat pump GHP, generating the energy required for air-conditioning a building. ENERGESIS, leading company in the air-conditioning field using geothermal energy and RADIO KRONSA, leading company in the engineering field of soil and subsoil, with the collaboration of the Universidad Politecnica de Valencia (UPV) and the Escuela Universitaria de Ingenieria Tecnica de Obras Publicas (UPM), have developed an action line to design and implement saving energy facilities by using geothermal energy associated with the foundations. A series of tests at work have been done in order to have a procedure to implement the thermal response of thermo active piles and diaphragm walls. (Author) 7 refs.

  15. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2015-01-01

    Full Text Available The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain reference value for theoretical research and technical application of the technique.

  16. INTERACTION OF A LONG SINGLE PILE THAT HAS A DOUBLE-LAYER BASE WITH ACCOUNT FOR COMPRESSIBILITY OF THE PILE SHAFT

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan Zaven Grigor'evich

    2012-07-01

    The authors provide their solution to the problem of interaction of a long compressible pile that has a double-layer linear deformable base. The paper demonstrates that taking account of compressible properties of the pile material leads to qualitatively new distribution of shearing stresses over the surface of a cylindrical pile. It is noteworthy that increase of the pile length and stiffness of the upper section of the base raise the share of the load perceived by the surface of the pile. Besides, in particular conditions of the soil environment, the load perceived by the lower section of the base may reach approximately 20-30 % of the total load.

  17. Réparation des pieux battus dans les sables carbonatés Repair of Driven Piles in Calcareous Formations

    Directory of Open Access Journals (Sweden)

    Nauroy J. F.

    2006-11-01

    Full Text Available Les formations carbonatées rencontrées en de nombreuses zones d'activités pétrolières en mer posent de difficiles problèmes de dimensionnement et de mise en place des pieux. Sur plusieurs sites de sable carbonaté, la capacité portante des pieux battus se révèle beaucoup plus faible que prévu et des techniques de réparation doivent être étudiées. Dans ce contexte, l'ARGEMA (Association de Recherche en Géotechnique Marine, groupement français d'organismes de recherche, de compagnies pétrolières et de contracteurs offshore, a expérimenté une réparation d'un pieu expérimental de 30 cm de diamètre et 23 m de long battu dans un sable carbonaté. Le frottement latéral de ce pieu mobilisé juste après battage était très faible. La réparation a consisté à injecter du coulis de ciment à partir d'un forage situé à 40 cm du pieu. Cet article décrit les procédures et les caractéristiques des injections réalisées et leurs conséquences sur la capacité portante du pieu. Le frottement entre le pieu et le terrain s'accroît avec le volume de ciment injecté; les valeurs maximales obtenues sont du même ordre de grandeur que celles observées avec un pieu foré-cimenté. The calcareous formations encountered in many zones of offshore petroleum activity raise difficult problems for designing and installing foundation piles. On several sites with calcareous sands, the bearing capacity of driven piles proves to be much less than had been planned, and repair techniques have to be examined. Within this context, ARGEMA (Association de Recherche en Géotechnique Marine, a french group of research organizations, oil companies and offshore contractors, has tested a repair of an experimental pile 30 cm in diameter and 23 m long driven into a calcareous sand. The skin friction of this pile, mobilized just after driving, was found to be very low. The repair-job consisted in injecting grout from a drilled borehole located at some tens

  18. Hepatitis B Foundation

    Science.gov (United States)

    ... worldwide 2 Billion People have been infected with Hepatitis B Worldwide The Hepatitis B Foundation is working on ... of people living with hepatitis B. Learn About Hepatitis B in 11 Other Languages . Resource Video See More ...

  19. Prostate Cancer Foundation

    Science.gov (United States)

    ... P 2 rovocative Questions PCCTC Scientific Retreat Coffey-Holden Research News Faces of Prostate Cancer [4] Survivors ... Foundation News The Prostate Cancer Foundation’s 2016 Coffey-Holden Prostate Cancer Academy Meeting accelerates advances in the ...

  20. Patient Advocate Foundation

    Science.gov (United States)

    ... Resources CoPay Resources Healthcare Reform Prevention View Resource Click here to submit a resource Subscribe Copyright © 2012 Patient Advocate Foundation Headquarters: 421 Butler Farm Road, Hampton, VA 23666 Phone: (800) 532-5274 - ...