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  • Rock and Soil Mechanics
    Supervised by: Chinese Academy of Sciences
    Publisher: Science China Press
    Period:Monthly Publication
    Editor-in-Chief:KONG LingWei
    Sponsored by :Institute of Rock and Soil Mechanics, Chinese Academy of Sciences
    Journal Tags: EI
    Language: Chinese
    Release Date: 1979
    ISSN 1000-7598 CN 42-1199/O3
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Table of Content
10 April 2007, Volume 28 Issue 4
Fundamental Theroy and Experimental Research
Bifurcation condition of crack pattern in two-dimensional parallel cracks under far field shear stress
ZHOU Xiao-ping ,WANG Jian-hua ,ZHANG Yong-xing
. 2007, 28 (4):  639. 
Abstract ( 1542 )   PDF (384KB) ( 1158 )  
The interaction among cracks is studied by using pseudo-traction method. Bifurcation condition of crack growth pattern can be expressed by the crack length/ spacing ratio, . The interution among cracks leads to bifurcation of crack growth patterns if is larger than a critical value . Bifurcation condition for arrays of 2 parallel cracks, arrays of 3 parallel cracks and arrays of infinite arrays of cracks subjected to shear stress is analysed theoretically. The value of is 0.816 497 5,0.717 572 8 and 0.636 638 5 for arrays of 2 parallel cracks, arrays of 3 parallel cracks and arrays of infinite arrays of cracks respectively. The numerical results show that the value of decreases with increasing the number of cracks.
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Two dimensions study of internal length scales for rate dependent and gradient-dependent models
CHEN Gang, ZHANG Hong-wu
. 2007, 28 (4):  643-648. 
Abstract ( 1379 )   PDF (402KB) ( 1079 )  
Both rate dependent and gradient-dependent models introduce internal length scales in dynamic initial value problems.The paper studies strain localization and stability of material by simple harmonic motion for rate dependent and gradient-dependent models. The laws of internal length scales and conditions of material stability are obtained at two dimensions condition for two mixture models. And more, formula of strain localization band width at the one and two dimensions conditions is derived.
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Constitutive model for clay considering complex stress paths
LU De-chun,YAO Yang-ping
. 2007, 28 (4):  649-654. 
Abstract ( 2277 )   PDF (719KB) ( 1544 )  
According to the characteristics of stress-strain curve of clay and the relating characteristics of its stress path, a sand stress path constitutive model established by authors is extended to clay; thus a clay stress path constitutive model is proposed. Through the transformed stress method, the SMP criterion is applied to the clay stress path constitutive model; then the model can describe the general stress states reasonably. The clay stress path constitutive model is identical with the modified Cam-clay model when they are in the condition of bidirectional loading (area A) and unloading (area D); there are different methods for computing plastic strain in the condition of single-direction loading (area B and F); specially, in the area C and E, the clay stress path constitutive model can compute plastic strain which will be zero if the modified Cam-clay model is used. Compared with the prediction of the modified Cam-clay model on the test data of Fujinomori clay, the superiority of the clay stress path constitutive model is demonstrated when describing the characteristics of stress-strain of clay in the condition of different stress paths.
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Experimental study on coefficient of thermal conductivity and specific volume heat of loess
WANG Tie-hang, LIU Zi-cheng, LU Jing
. 2007, 28 (4):  655-658. 
Abstract ( 1912 )   PDF (560KB) ( 3071 )  
Experimentation for coefficient of thermal conductivity and specific volume heat of loess is explored first; and the experimental installation is installed. Then taking loess samples with different densities and moisture contents, the coefficient of thermal conductivity and specific volume heat of loess are tested. The test data show that for loess with constant water content, if the density is increased, the coefficient of thermal conductivity and specific volume heat both are increased. And for loess with constant density, if the water content is increased, the coefficient of thermal conductivity and specific volume heat both are increased too. Based on research on the test data, two formulas are obtained to determine the coefficient of thermal conductivity and specific volume heat of loess. After that it is pointed out that compared with soil density changes, water content change can result in more variations of coefficient of thermal conductivity and specific volume heat of loess.
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Study on evolvement law of background stress field of multi-step excavation of roadway
ZHAO Xing-dong,TANG Chun-an,TIAN Jun
. 2007, 28 (4):  659-662. 
Abstract ( 1328 )   PDF (849KB) ( 1345 )  
Because of the deep embedding, high underground pressure and fragmentation of ore and rockmass, the Xiaoguanzhuang Iron Mine is one of the most difficult excavation iron mine in China. The study results in recent years indicate that the rockmass of Xiaoguanzhuang Iron Mine has the creep characteristic. After the roadway was excavated, the destruction of supporting roadway is very severe. The deformation of roadway is no convergence deformation; and the iron mine is difficult support mine. According to the field condition, in order to know the distribution law of underground pressure, we used the rock failure process analysis (RFPA), in which the creep evolvement model is drawn into the numerical model, to model the excavation process of roadway by adopting the non-pillar sublevel caving; and numerically analyze the stress distribution of surrounding rock. We found that the surrounding rock occur the creep deformation along with time when the roadway is caving. Because of the creep deformation of roadway, the destruction of roadway is mainly rib spalling, floor heave and roof falling etc.. At the same time, the high stress concentration leads to the severe destruction of pillar between two roadways. Along with the caving of roadway, the stress diverts into surrounding roadway of the newly caved roadway. Because of the multi-step caving, the high stress convergence occurs in the boundary ores, which leads to the difficult excavation of boundary ore. The numerical result is in accordance with the result of field investigation. From the numerical result we concluded that the creep characteristic of rockmass and the multi-step excavation mainly lead to the destruction of roadway.
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Analysis and calculation of energy release and deviatoric stress energy generation of surrounding rock in tunnel excavation process
PAN Yue, WANG Zhi-qiang, WU Min-ying
. 2007, 28 (4):  663-669. 
Abstract ( 1596 )   PDF (8050KB) ( 753 )  
Surrounding rock energy is released in company with tunnel excavation; and in the meantime deviatoric stress is brought in surrounding rock. Surrounding rock stress is the superposition of stress in virgin rock mass and deviatoric stress. The deviatoric stress or its strain energy dominates the breakage of rock mass. On condition that the hydrostatic pressure and the volumetric strain of rock mass is equal to zero, by using the stress distribution expressions of surrounding rock which are educed on base of the constitutive model that its elastic and nonlinear softening segment linked glossily in paper [1], and using multiple integral, the strain energy of deviatoric stress, , is calculated in the elastic and softened zones of surrounding rock. It is proved that can be deduced concisely by way of integrating the ground stress with respect to the displacement of tunnel wall , and multiplying by perimeter of tunnel wall, and the principle of the calculation approach of is expatiated. The energy released by surrounding rock in the process of tunnel excavation is equal to the product of perimeter of tunnel wall and the integral of the surrounding rock pressure with respect to . Thereby, the circumstances of deviatoric stress energy and the released elastic energy in surrounding rock in response to can be expressed by the geometrical form that the area enclosed by the curves - and - . The acquired findings can deepen the understanding of mechanical response of surrounding rock owing to tunnel excavation and operating condition of surrounding rock after tunnel excavation.
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Analysis of single piles under eccentric and inclined loads in layered soils
ZHAO Ming-hua,LI Wei-zhe,YANG Ming-hui,SHAN Yuan-ming
. 2007, 28 (4):  670-674. 
Abstract ( 1905 )   PDF (540KB) ( 1330 )  
It is assumed that bedding value has a longitudinal relationship with depth in single layer of soil with well consideration to the inhomogeneous soils in the engineering practice. And power series solutions, with well consideration to P-Δ effect, are derived respectively for displacement and stress calculation of the pile section above the ground and that of pile section in a homogeneous layer of soil. And matrix methods are incorporated in the derivation of such solutions. Procedures of how to calculate the horizontal placement and stress of piles in layered soils under eccentric and inclined loads, moment of force, gravity of pile, pile-soil friction and distributed load, are presented. Finally, case analysis is done and power series solutions is proved good and practical.
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Analysis of model parameters sensitivity in settlement calculation of construction waste landfill
LEI Hua-yang ,LI Hong-qi ,WAN Zi-rui ,LIU Hong-jun ,YING Yao-ming ,MA Feng
. 2007, 28 (4):  675-678. 
Abstract ( 1580 )   PDF (456KB) ( 1627 )  
The deformation mechanism of construction waste is complicated and is differ from the traditional soil. By a lot of nonlinear finite element method calculation, the main parameters, which have much larger influence on the calculated accuracy of construction waste landfill settlement, are found out; and then the qualitative relations between every parameter and settlement are also given; and the results can be the basis of settlement calculation and parameters sensitivity analysis of construction waste landfill.
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Experimental study on mechanical properties of artificially structured soils
LIU En-long, SHEN Zhu-jiang
. 2007, 28 (4):  679-683. 
Abstract ( 1477 )   PDF (712KB) ( 1550 )  
The deformation and breakage processes of natural soil under loading can be obtained by study on structured soils, on which the design of construction and soil improvement can be based when the structural influence is considered. By adding kaolin soil, cement and salt particles with different contents into the original soil samples, a new and simple artificial preparation method is presented to prepare the structured soil samples, whose natural structures , bonding and fabric between soil particles are formed. Then the compression tests and triaxial compression tests on artificial structured soils with different bonding strengths under drained and undrained conditions are conducted to study the mechanical characteristics, the breakage processes and the deformation mechanism of structured soils.
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Parallel computation of finite element model with millions of DOF in geotechnical engineering
ZHANG You-liang,FENG Xia-ting
. 2007, 28 (4):  684-688. 
Abstract ( 1613 )   PDF (575KB) ( 1576 )  
The parallel strategies of finite element method, the distributed storage of abundant data, the convergence speed of iterative solution of large scale linear equations and the implementation of parallel finite element method are discussed. We use domain decomposition method (“divide and conquer” strategy) to achieve the parallization of FEM. In combination of domain decomposition strategy, we store the data linking with each subdomain in each processor. So the data locality not only can reduce the communication, but also increase the scale of the computation. We adopt Schur complement and preconditioning conjugated gradient (PCG) method to fulfill parallel solution of linear equations with bad condition number. We utilize object-oriented programming method to develop our parallel FEM software. Two examples are given to discuss the efficiency of the parallel software. The results show that the software has high performance.
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Experimeatal study on quantitative relationship between shear wave velocity and cyclic liquefaction resistance of saturated sand
CHENG Guo-yong , WANG Jian-hua , ZHENG Xian-min
. 2007, 28 (4):  689-693. 
Abstract ( 1628 )   PDF (411KB) ( 1558 )  
According to the dependence between Shear wave velocity and cyclic liquefaction resistance of saturated sand, combined tests were carried out for remoldeld saturated sands, during which the shear wave velocity of saturated sand sample was fistly tested in the cyclic triaxial cell and then the normal cyclic liquefaction test performed. Then, by analysing the test results, the quantative relatiobship between shear wave velocity and the cyclic liquefaction resistance of saturated sand was obtained. At last, 174 earthquake sites data was utilized to verify the reliability of the relational expression. The results show among the 66 non liquefied sites the correct rate of the expression is 81.2 % and among the 108 liquefied sites the correct rate is 62.8 % in general, the average correct rate of the relational expression is 69.5 %.
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Effect of faults structure on surface gas leakage in Beipiao mining area
TANG Ju-peng , PAN Yi-shan , LIANG Zheng-guo
. 2007, 28 (4):  694-698. 
Abstract ( 1240 )   PDF (516KB) ( 1338 )  
Based on the special faults structure condition of Beipiao mining area and the gas leakage situation after mines were closed, the three-dimensional finite element model was established using ANSYS software. The variation of stress field and displacement field were simulated under the condition of considering the effect of faults structure or not before and after mining. The contour charts of stress field in fault section and vertical displacements of special horizontal section etc. were presented. Some novel valuable conclusions were drawn based on the analysis and summary about rules of stress field and displacement field before and after mining. Those are that faults structure affects the laws of stress field and displacement field before and after mining; the gob is the original gas source concentration region; the maximal stress values exist in the top and lower ends of the adjacent between faults and gob. This leads to the gob gas diffusing to the adjacent region. Then gas leaks to the ground surface through the continuous fractures. So the faults are the important pathway of gas transport; caving region, fractures region and bending region are regarded as the secondary gas source concentration region. The numerical simulation supplies the scientific reference for faults structure effect on gas leakage, the region determination of the original and secondary gas source. The results have instruction rule for the utilization and usage of gas.
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Three-dimensional damage model for failure process of rocks and associated numerical simulation of geometry effect
LIANG Zheng-zhao ,TANG Chun-an ,ZHANG Juan-xia ,ZHANG Rui ,MA Tian-hui
. 2007, 28 (4):  699-704. 
Abstract ( 1442 )   PDF (9911KB) ( 1143 )  
A three-dimensional soften model is established combined with statistical mechanics to take the heterogeneities on mesoscopic scale into consideration. Two sets of numerical tests are undertaken by using a numerical code RFPA3D to analyze the failure process of rocks subjected to uniaxial compression. Numerical specimens are prepared to investigate the influence of the geometry effects on the macro response of the rocks. One set of numerical tests are conducted without constraint and there are no friction between the loading plates and the specimens. Another set of numerical tests compared with laboratory experiments are conducted to simulate the geometry effect by taking end constraint effect into consideration. Numerical results show that the geometry of specimen influences both the peak strength and failure mode. The peak strength decreases as the ratio of length to width of the specimen increases; and it inclines to a certain value when the ratio exceeds 3.0. When the ratio is small, the failure of the specimens are caused by tensile fracture propagating the top and the bottom of specimens; while the ratio is larger enough, specimens tend to be in shear failure mode. End constraint effect is one of the key factors that lead to geometry effects. The plate restricts the lateral deformation and results in lateral stress in the middle of the specimen, which leads to tensile failure. However, geometry effects still exist even with smooth plates. The transition of the ductile failure mode to brittle mode can be found as the ratio of the length to the width of the specimens increase.
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Post-earthquake response of underground structures in saturated liquefiable soils
LIU Hua-bei, SONG Er-xiang
. 2007, 28 (4):  705-710. 
Abstract ( 1793 )   PDF (680KB) ( 1477 )  
The underground structures in saturated liquefiable soils may be subjected to floatation due to earthquake induced liquefaction. After earthquake, the excess pore pressure shall dissipate and the liquefied soil will experience the process of consolidation. The post-earthquake behavior of underground structures in liquefiable soils is not clear and deserves investigation. Nonlinear coupled dynamic finite element method was used to investigate the response of the liquefiable soil-underground structure system, focusing on the vertical displacement of the underground structure. It was found that the uplift behavior of the underground structure did not cease to develop when the earthquake stopped; instead, it terminated after the excess pore pressure was dissipated to some extent and the underground structure started to settle afterwards, but with a magnitude much smaller than the amount of uplift. Residual deformation existed in the underground structure after earthquake. The stress path, the process of excess pore pressure dissipation, and the effects of cutoff walls and coefficients of permeability were also discussed, in an effort to tackle the mechanism of the post-earthquake response of underground structures in saturated liquefiable soils.
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Research on influence of underground sidewall on internal force of raft
SHEN Jian-hua ,CAI Jian ,LI Guang-le ,HE Chun-bao
. 2007, 28 (4):  711-722. 
Abstract ( 1599 )   PDF (690KB) ( 1591 )  
Based on the theory of elastic thin plate, semi-analytic method is applied to study the interaction among raft, up-structure and ground by considering the horizontal outer flexure and longitudinal plane total bend of underground construction sidewall. Comparing with the computational and field measured results without taking the effect of the sidewall, shows it is more practical for considering the horizontal outer flexure and longitudinal plane total bend. Based on the above study, the effect of sidewall stiffness on the forces acted on raft is analyzed; and the situation by changing the raft size is also discussed.
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Small-strain behaviour of standard sand by stress path controlled triaxial tests
SHI Jian-yong,LAI Yong,LEI Guo-hui,AI Ying-bo
. 2007, 28 (4):  717-722. 
Abstract ( 1801 )   PDF (647KB) ( 1344 )  
By stress path controlled triaxial tests, the stress-strain curves of 16 standard sand specimens, which were tested along directions 0o, 45o, 90o, 135o, 180o, 225o, 270o, 315o in p-q plane after isotropic and K0 consolidation to a same mean effective stress 150kPa, are presented. The shear and volumetric strains less than 1 % are compared by considering effects of recent stress path, historic stress path and stress path rotation. The change laws of shear and volumetric moduli of standard sand tests with the direction of stress path are found to be similar with the reported test results of Bothkennar clay.
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Research on optimized construction procedure for double-arched tunnel in unsymmetrical pressure
ZHANG Zhi-qiang, HE Chuan
. 2007, 28 (4):  723-727. 
Abstract ( 1453 )   PDF (1276KB) ( 1319 )  
Based on mechanical analysis of construction progress of double-arched tunnel under unsymmetrical pressure, the two kinds of partial pressures effects are put forward, which influence together the loaded state of double-arched tunnel. One of them is result from shallow depth ground partial pressure, named ‘terrain partial pressure’, the other is caused by construction order of the two bore of double-arched tunnel, named ‘construction progress partial pressure’. The result demonstrates that the direction of oblique load in ‘terrain partial pressure’ is definite and unchangeable, i.e. the direction of oblique load is from the inside of hill to the outside of hill-slope; the direction of oblique load caused by ‘construction progress’ depends on the early and late construction order of the two bore of double-arched tunnel; the study shows that the direction of oblique load is from the early excavated bore side to the late bore side. As a result, the procedure of the early excavation of external bore closed to the hill-slope is considered as the optimized construction procedure for double-arched tunnel under unsymmetrical pressure, since the oblique load caused by construction progress can be applied to balance out partial load in ‘terrain partial pressure’. The above conclusion is made use of the modification design and construction of double-arched tunnels under unsymmetrical pressure of Jinhua to Lishui highway in Zhe jiang province.
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Numerical analysis of means for reducing differential settlements of primary subway’s modification work in Tianjin
ZHENG Gang, PEI Ying-jie
. 2007, 28 (4):  728-732. 
Abstract ( 2408 )   PDF (722KB) ( 1388 )  
The modification work of the subway #1 in Tianjin is the project reconstructed the stations and some tubes on the base of primary subway. The differential settlement at the juncture of new and old tubes must be controlled strictly for the sake of safety. The technique of high-pressure chemical churning piles is employed to consolidate the foundation. The consolidating means and thickness are determined by the result of FEM; by contrast to the measured data in-situ, the result of numerical calculation is testified to be proper and the design proposal is rational accordingly.
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Torsional vibrations of a rigid cylindrical foundation partially embedded in transversely isotropic saturated soil
WU Da-zhi ,DONG Tian-le ,CAI Yuan-qiang ,LIU Fei-yu
. 2007, 28 (4):  733-737. 
Abstract ( 1755 )   PDF (741KB) ( 1216 )  
Considering the interactions between the embedded foundation and the soil, the torsional vibrations of a rigid cylindrical foundation partially embedded in transversely isotropic saturated soil are analysed. Assuming both the side face and bottom surface of the foundation are perfectly bonded to the soil, the reaction torques that the side soil and bottom soil acted on the foundation are gotten from basic dynamic equations of the poroelastic medium. According to the dynamic equilibrium equations of a foundation subjected to harmonic torque, the torsional vibrations of an embedded cylindrical foundation are presented. Subsequently, the angular amplitude of the foundation, the equivalent stiffness and damping coefficients of the soil are expressed explicitly. Selected examples are presented to investigate the influence of relevant parameters on the results.
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Assessment of effect of ground improvement for hydraulic structure using combined vacuum and surcharge preloading
WU Yue-dong ,YIN Zong-ze ,GUO Ji-zhong
. 2007, 28 (4):  738-742. 
Abstract ( 1562 )   PDF (539KB) ( 1408 )  
The special feature including the mechanism of combined vacuum and surcharge preloading method for soft ground improvement is described. The soft ground improvement work in Huaihe River Zhangma Watergate project is investigated. Based on the field monitoring data (including surface settlement, settlement at different strata, horizontal displacement, pore-water pressure and degree of vacuum), in-situ tests(including CPT, STP,vane shear tests and static load tests) and laboratory tests, the effect of ground improvement is analyzed and assessed. The results satisfy the design requirements. The study provides a reference for similar ground improvement projects using the proposed method.
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Analysis of one-dimensional consolidation of double-layered viscoelastic ground
LIU Jia-cai , ZHAO Wei-bing , ZAI Jin-min , WANG Xu-dong
. 2007, 28 (4):  743-746. 
Abstract ( 1731 )   PDF (493KB) ( 1209 )  
Soft clay has viscoelastic characteristics, which affects the consolidation and deformation of the soil. Based on the existing one-dimensional consolidation theory of saturated clays with generalized Voigt model, the generalized solution expressions of the two layers are obtained. According to the pore pressure and water flow continuity conditions at the conjunction plane of two layers and the boundary conditions at the top and bottom surfaces, the orthogonal relation of the system is presented. The unknown value in the generalized solution expressions can be determined by using continuity conditions, boundary conditions and the orthogonal relation. Generalized Voigt model can reflect the stress-strain relation of the soil at different phases; so the solutions can be applied extensively. A case of double-layered viscoelastic ground is analyzed where Merchant rheological model is applied. It is shown that the viscoelastity decreases the consolidation velocity of the soil. The more deep the soil element locate, the more its consolidation velocity is affected.
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Study on deformation character of Three Gorges Project’s 2nd phase cofferdam during its operation period
JIANG Zhong-ming , GU Zheng-hua , ZHANG Xin-min , SUN Zhi-yu
. 2007, 28 (4):  747-752. 
Abstract ( 1660 )   PDF (750KB) ( 1118 )  
Based on the Duncan E-? constitutive model used for analyzing soil-rock dams, 3 parameters creep model used for studying creep deformation of soil-rock dams is developed and programmed. According to the measured deformation data of Three Gorges Project’s 2nd phase cofferdam of early operation period, calculation parameters used for creep analysis are inverse-analyzed using artificial neural networks. The calculated results indicate that the vertical deformation rule of cofferdam versus time and horizontal deformation rule of cofferdam versus time is different from each other. It is also indicated that the stable time needed for vertical creep displacement is about 6 months after the cofferdam is constructed and the stable time needed for horizontal creep displacement is only 3 months. It also shows that the average creep displacement value of the cofferdam structure is 2-3 times of the initial displacement.
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A semi-analytical method for dynamical analysis of slab and composite foundation
LIU Li-ping , HUANG Yi , LI Xiang-yang
. 2007, 28 (4):  753-757. 
Abstract ( 1973 )   PDF (2096KB) ( 1081 )  
Composite ground can be regarded as transversely isotropic material. Semi-analytical element method is used to study the dynamic interaction of slab and composite foundation. It can avoid introducing redundant boundary condition compared with FEM, and improve computation accuracy. Furthermore it can simplify 3-dimensional computation to one dimension, saving computation time dramatically for its quick convergence. The dynamic property of slab and composite ground is investigated by means of changing substitution ratio, reinforced depth and modulus ratio of pile to soil. The results indicate that the increment of these factors can affect the amplitude of vibration and increase the system's frequency. So when designing the foundation of power machine, some attention should be paid to the impaction of composite ground on the alteration of dynamic property of ground.
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Study on ground data model of drill hole information and database
SHI Qiu-jing ,HU Wu-sheng ,LIU Dan-ping
. 2007, 28 (4):  758-762. 
Abstract ( 1211 )   PDF (396KB) ( 1330 )  
In order to build a well-organized engineering geological information database, the exchange between users’ database and system database is put forward, by which the users’ operation and the procedure of computer are separated. The users’ database is users oriented, while the system database is for the management in the system. A new ground data model is proposed in the system database. This data model is about soil mass and a segment based on “the optimized stratigraphic sequence” of a region. By using it, complicated geological information can be expressed clearly; and drill holes of different stratigraphic sequences are united to a same structure. It can deal with some problems such as faults in the geological body, and make the subsequent management easy.
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Experimental study of piles-cushion-soil interaction of rammed soil-cement pile composite foundation
GUO Zhong-xian ,WANG Zhan-lei ,YANG Zhi-hong
. 2007, 28 (4):  763-768. 
Abstract ( 1491 )   PDF (453KB) ( 1548 )  
In order to study the behavior and working properties of piles-cushion-soil interaction of rammed soil-cement pile composite foundation, field loading tests of single pile and composite foundation with single pile, four piles, nine piles in different lengths and area displacement ratio have been carried out. Distribution of the soil contact pressure, the shaft resistance of pile have been measured by installing special measuring gauges. Based on the test results, the failure pattern, the behavior of piles-cushion-soil interaction were analyzed. Distribution of the soil contact pressure, the stress ratio and the load ratio of pile to soil, distribution of the shaft resistance in single pile and pile of composite foundation have been analyzed.
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Study on calculating methods of earth counterforce in rectangular working shaft by SMW methods
CHEN Chun-lai , WEI Gang , CHEN Hua-hui
. 2007, 28 (4):  769-773. 
Abstract ( 1451 )   PDF (526KB) ( 1275 )  
The loading mechanism under the action of jacking counterforce of rectangular working shaft by soil mixing wall (SMW) methods is investigated. Assuming the horizontal earth counterforce distributed equably, vertical earth counterforce at the back of loaded wall is considered as quasi-normal distribution, a formula for calculating maximal earth counterforce at the back of loaded wall is obtained. Assuming the soil at the front of loaded wall is at active state, formulas for the maximal earth counterforce and permitted jacking force of working shaft are obtained. The analytical calculation results of an example show that the maximal earth counterforce at the back of loaded wall by trapezoidal distributing method is some greater than one with the method presented in text. The permitted jacking force calculated by estimating water and earth pressure together in cohesive soil is highly close to the maximal jacking force measured in field.
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Evolution numerical simulation method for optimizing boundary roof pillar in transition from open-pit mining to underground mining
JIANG An-nan ,CHEN Yong
. 2007, 28 (4):  774-778. 
Abstract ( 1698 )   PDF (486KB) ( 1190 )  
Optimizing the boundary roof pillar in the transition from open-pit mining to underground mining is an important subject; this task including many decision variables and appraise indexes, so the methods given before can’t get the good result. This paper combining the genetic and 3D numerical simulation, the evolution numerical simulation method to globally optimize the boundary roof pillar is researched. The optimizing indexes and processes are given; the method has been used to optimize the boundary roof pillar in the transition from open-pit mining to underground mining of Daxingshan Iron Ore. And it is shown that the method is feasible. The scheme resulted by the method can guide the mining design for Daxingshan Iron Ore.
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Experimental study on ultrasonic properties of sandstone before and after high temperature
HE Guo-liang,WU Gang,HUANG Xing-chun,ZHANG Lei,QIU Yi-ping
. 2007, 28 (4):  779-784. 
Abstract ( 1576 )   PDF (619KB) ( 1665 )  
Ultrasonic velocities and dimensions of sandstone specimens from Jiaozuo that experience different temperature(100 ℃-1 200 ℃) are measured; and their uniaxial strength are tested. P-wave attenuation coefficients of rock specimens are calculated. Crack densities are calculated using relations between ultrasonic velocity and elastic moduli. The volumes, ultrasonic velocities and attenuation coefficients of sandstone specimens before and after high temperature are compared. Results show that the cracks of sandstone specimens develop so that the compactness and ultrasonic velocities of specimens decline. For sandstone specimens that experience different temperature the changes of ultrasonic velocity and uniaxial strength are obviously discrepant. But changes of attenuation coefficients are similar to uniaxial strength. It can be taken as reference to evaluate uniaxial strength at a certain extent.
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Deformation monitoring of bifurcation tunnel and countermeasures of construction technologies
WANG Zhe-chao , LI Shu-cai , CHEN Wei-zhong
. 2007, 28 (4):  785-789. 
Abstract ( 1710 )   PDF (622KB) ( 1438 )  
Bifurcation tunnel is one of the new types tunnels. With less unitary cost for joint bridge-tunnel projects, it is promising in communications construction in West China. A case study of Baziling diverging tunnel is given. The deformation monitoring system is described. The deformation characteristics under the given lining system and construction technology are analyzed. They are longitudinal deformation of the tunnel, construction response of single-arched segment and the influence of the interaction between the two working face. Finally, based on the deformation characteristics, the countermeasures of construction technologies are given. The study provides indispensable evidence for the design and construction of the bifurcation tunnel.
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Finite element analysis of rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt
ZENG Xiang-yong, DENG An-fu
. 2007, 28 (4):  790-794. 
Abstract ( 1953 )   PDF (1008KB) ( 1184 )  
Pointed to a seven-grade 74 meters high rock cutting slope in an expressway of Guangdong Province in China, three-dimensional elastoplastic finite element method is applied to analyze the rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt in mountainous area. Anchorless scheme and three anchoring schemes of the cutting slope are analyzed respectively. Analysis of anchorless scheme identifies the slide face of the cutting slope and furnishes reasons to the anchoring schemes. In three anchoring schemes, prestressed anchor cable and anchor bolt are distributed by three different regulations in the cutting slope. The three-dimensional finite element analysis model of anchored slope simplifies the real anchored slope reasonably and thus the efficiency of computation is improved. In the finite element computation, the prestress of anchor cable is implemented by applying initial strain on the anchor cable elements as the loads. Computation results show that the combined action of prestressed anchor cable and anchor bolt can decrease the plastic zone of the slope effectively. Analyses show that the scheme with interlaced disposal of prestressed anchor cable and anchor bolt in each slope grade is the best scheme in three anchoring schemes for both safe and economical; and this scheme is applied to the practice of reinforcement for the above slope. Comparisons with the monitored displacements of the reinforced slope confirm the behavior predicted by the finite element analysis.
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Observation study of fissure rock damage range under blasting load
XIA Hong-bing , XU Ying , ZONG Qi , FU Ju-gen
. 2007, 28 (4):  795-798. 
Abstract ( 1501 )   PDF (970KB) ( 1066 )  
Detecing the changes of resistivity in deep holes of fissure rock before and after micro explosive blasting to the limestone in Luyuan Mountain Villa with electrical CT image, a certain range,number and width fissures could develop in deep blasting holes after micro explosive blasting,and areas which were caused by fissures mainly located at about 2/3 depth of the bottom of the blasting holes.when the depth of blasting hole is 3 m, and the explosive weighted 330g ,fissures developed easily at the depth of 1.5-2.5 m of the blasting hole.when the distance between the blasting holes is 1.2-1.5 m, penetration fissures could form in the internal rock, providing scientific basis for blasting engineering design and construction.
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Field study of tensile force character of double-layered geogrid in reinforced gravel cushion
HU Qi-jun ,XIE Qiang ,QING San-hui
. 2007, 28 (4):  799-802. 
Abstract ( 1628 )   PDF (558KB) ( 1105 )  
According to field study, it is shown that the tensile force of geogrid in the crosswise direction is largest in the road center; the upper layer reduce 29.5 percent compared with the lower layer in double-layer grid; geogrid of the upper layer in the longitudinal direction works earlier than the lower layer. Track laying can enlarge the value of the tensile force of geogrid in the longitudinal and crosswise directions; but without influence on the roadbed deformation. The reinforced cushion can increase the value of stress ratio of pile to soil inside composite foundation .
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Study on prediction model of soft foundation settlement based on Weibull curve
WANG Wei ,LU Tinghao
. 2007, 28 (4):  803-806. 
Abstract ( 1351 )   PDF (397KB) ( 1570 )  
Based on mechanism of soft foundation settlement, a method with Weibull model to predict the settlement is presented. Parameters of this method have explicit physical meanings. Because of considering loading velocity and construction art, the presented method overcomes deficiency of traditional methods that the ratio of settlement at inflection point to ultimate settlement is relative constant. While making using of other prediction methods, deciding inflection point of observed settlement samples is a necessity to scientifically choose settlement prediction model and relevant observed data. The Weibull model can make good use of observed settlement sample; and exponential model is one of its degradation types; so it is available to both linear and transient loading conditions. Finally, good agreements are obtained between calculating results and field measuring data.
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Research of back analysis of geological examination based on ANN
CHENG Tao ,YAN Ke-qin ,DONG Bi-chang
. 2007, 28 (4):  807-811. 
Abstract ( 1459 )   PDF (5398KB) ( 1026 )  
Mechanical parameters estimation and classification of soils are very important in geologic examination. On the basis of inverse problem theory, a new intelligent method combining RBF neural network and regression analysis is proposed. Then an intellectualized simulation system of soil is established, consisting of two neural networks for mechanical parameter estimation and model recognition. In the system, considering variability of physical parameters is much smaller than mechanical parameters of soils, an artificial neural network model is established to approach the function relationship of the two kinds of parameters. It is effective to reflect mechanical parameters according physical parameters. The mechanical parameters will be input vectors applied to the other network. Then, the new neural network is established; it can offer a good approach to soil classification. This intellectualized simulation system is applied to analyzing geologic examination data in Huangshi; and the results show that the method is simple and effective.
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Analysis of sensitivity factors to stability of bedding rock cutting slope
GONG Wen-hui , WANG Ping , CHEN Feng
. 2007, 28 (4):  812-816. 
Abstract ( 2298 )   PDF (579KB) ( 1249 )  
Based on the elastoplastic theory and FEM, the simulation model for analyzing the stability of bedding rock cutting slopes is established. According to the engineering condition of high bedding rock cutting slopes in Yichang-Enshi Expressway in the Hu-Rong national main trunk, the stability sensibility of the bedding rock cutting slope to the influence factors, such as strength of the structural surface, thickness and inclination of rock stratum, is analyzed. The stability regularities of bedding rock cutting slopes are researched. The results show that the strength parameters of the structural surface play a main control role to the stability of bedding rock cutting slopes; and the rock stratum inclination has obvious influence on the stability of cutting rock slopes. In the engineering geological condition, the stability of the bedding rock cutting slope is in the poorest state when the rock stratum inclination is about 38°.
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Preliminary research on 3-D hierarchical composite element method for jointed rock masses
PENG Cheng-jia, CHEN Sheng-hong
. 2007, 28 (4):  817-822. 
Abstract ( 1559 )   PDF (662KB) ( 1005 )  
This paper explains the basic principle of composite element method and introduces the concept of virtual node and generalized node used in the hierarchical finite element method. Then the concept of covered virtual edge (face) and generalized edge (face) is put forward; and the further classification of virtual node and generalized node is presented. Based on it, displacement function with different orders on the 3-D composite element for jointed rock masses is constructed and the element stiffness matrix is derived. Numerical examples show the rationality and efficiency of the theory. The concept presented is helpful to understand and realize the hierarchy of composite element method and traditional finite element method as a whole, and establish the foundation of p-version adaptivity of 3-D hierarchical composite element method for jointed rock masses.
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Preliminary theoretical study on impact on coal caused by interactions between CO2 and coal
BAI Bing,LI Xiao-chun,LIU Yan-feng,Fang Zhiming, WANG Wei
. 2007, 28 (4):  823-826. 
Abstract ( 1380 )   PDF (386KB) ( 1391 )  
Regarding the solid surface energy decrease as a result of adsorption of gas as the reason why the solid skeleton swells. A theoretical formula is given to estimate the swelling stress without displacement constraint, which is an appropriate assumption as the initial underground stress is so large. The swelling stresses caused by CO2 and CH4 respectively are compared. This is helpful in evaluating the mechanical stability in CO2-ECBM. Then another formula is given to evaluate the coal strength decrease caused by the CH4 or CO2 adsorption; the formula is helpful in evaluating the mechanical properties change and the mechanical stability after the adsorption of gases in CO2-ECBM
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Extended Davidon-Fletcher-Powell(DFP) optimization method and its application to displacement back analysis
Lü Ying-hui,WANG Shui-lin,LI Chun-Guang,GE Xiu-run
. 2007, 28 (4):  827-830. 
Abstract ( 1433 )   PDF (476KB) ( 2467 )  
An extended DFP method, in which the modified Newton decent method is used to obtain good variables and Richard extrapolation is used to compute the gradient in each iteration. The single variable search, which the ordinary DFP arithmetic often has to do, is not required in the extended DFP method; but the optimized results can be reached step by step. Numerical test is carried out by both the extended DFP method and the ordinary DFP method; and comparisons of the results demonstrate that the extended DFP method is better than the ordinary DFP method in numerical stability, convergence and reliability.
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Test of ions diffusion in bentonite
HE Jun,SHI Jian-yong,LIAO Zhi-qiang,ZHU Ning
. 2007, 28 (4):  831-835. 
Abstract ( 1656 )   PDF (544KB) ( 1210 )  
Bentonite is widely used in landfills. When bentonite is used as a material of liner, diffusion through bentonite is a very important transport mechanism. To understand the ability of retard migration of contaminant in different stress states, the diffusion coefficients of Ca2+,Cl- and Zn2+ diffusing in bentonite of different dry densities were measured. The diffusion coefficients of this study are well in the range of previously published results. With the increasing of porosity, the diffusion coefficients of Ca2+ and Cl- increase in exponential form. The estimating method of diffusion coefficient in a given range of porosity is proposed. The estimation is approximate to the measured values.
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Back analysis and multiple-factor influencing mechanism of high geostress field for river valley region of Laxiwa Hydropower Engineering
YUAN Feng-bo , LIU Jian , LI Pu-jian , QIAO Li-ping ,LI Peng
. 2007, 28 (4):  836-842. 
Abstract ( 1690 )   PDF (1298KB) ( 1333 )  
The Laxiwa Hydropower Engineering is located at high mountains and valley regions, existing high geostress in the rock masses due to the multiple-factor influences such as tectonic stress, gravity, river and weathering erosion, etc. In the river valley region, discal phenomena of drilling cores and laminated exfoliation of surrounding rock in the exploration tunnels are obvious. The determination of the 3-D geostress field in the valley region is difficult and complicated, which are tightly related to the tectonic movements in different geological period and the evolution history of river valley. In this study, detailed back analysis of the 3-D ground stress field for the engineering region is finished. Based on the results derived from the back analysis, the spatial distributing characteristics and magnitudes of the 3-D geostress field are studied. Furthermore, focused on the formation mechanisms of the geostress field, the multiple-factor influencing effects are analyzed. The paper provides a valuable reference and engineering case for the study of high geostress field and the establishments of hydropower projects located at Western China, especially for those with strong geological actions.
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Application of digital borehole camera to quality test boreholes for grout curtain in Xiaolangdi Water Control Project
WEI Li-wei , QIN Ying-yi , TANG Xin-jian , WANG Chuan-ying
. 2007, 28 (4):  843-850. 
Abstract ( 1319 )   PDF (1012KB) ( 1292 )  
In order to appraise the quality testing of grout curtain, digital borehole camera technology is applied to three boreholes of the grouting gallery No.3 in Xiaolangdi Water Control Project. This paper introduces the basic theory and analytical method of digital borehole camera technology, presents some typical borehole-wall images of joints, cracks, fracture zones and crack filler of mortar in the three boreholes and further analyzing. It is concluded that: ?The grout is impelled by grout pressure and seeped towards the rockmass around the boreholes mainly along fractures and cracks which have good connectivity and extension in the fracture network. The fractures are filled who open to the main seepage path cracks and those are neglected who not open to main seepage path or partly filled after flerried under grout pressure. As a result of our exploration, three different filling situations of all-filled, partly-filled and run-out mortar are observed in borehole wall. ? The filling of fractured zones depend on the size, property and connectivity with grout holes. These findings of the application have led the author to the conclusion that: the enhancement in rockmass integrity by grout curtain project in the grouting gallery No.3 of Xiaolangdi Water Control Project is obvious. The application of the digital borehole camera technology to quality test of grout curtain by boreholes exploration is feasible.
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