In order to reveal the influences of stress path on the deformation behavior and strength characteristic of unsaturated sand, the four kinds of stress path experimental study of conventional triaxial compression (CTC), reduced triaxial compression (RTC), conventional triaxial extension (CTE) and reduced triaxial extension (RTE) on shallow gassy sand from the Hangzhou Bay is carried out by GDS unsaturated triaxial system. The results show that the stress-strain relationship of unsaturated sand in unloading stress paths of RTC and RTE appears strain softening, and the light strain softening and significant strain hardening deformation behaviors for loading stress paths of CTC and CTE relatively. The shear strength parameters of unsaturated sand are also different under the condition of unloading and loading stress paths, the effective cohesion value of the former is higher than the latter; and the internal friction angle is the opposite. However, the relationships between the apparent cohesion and the matric suction in various stress paths of unsaturated sand are effectively described by the power function , and the test parameters of a and b are different. Therefore, the shear strength formula can be used to express the strength characteristic of unsaturated sand reasonably.

In order to investigate the behaviors of cemented soil meso-cracking under environmental erosion, a series of environmental erosion tests are carried out on the basis of the rock meso-mechanics device provided by Key Laboratory of Rock and Soil Mechanics, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. The meso-fracturing process of cemented soil is real-time observed using the microscope and the digital color camera. The stress-strain curves and the corresponding micro-images of specimens are obtained. The results show that there are two types of fracturing behaviors of cemented soil under environmental erosion. That is elastoplastic failure and brittleness failure. Meanwhile, the meso- cracking tests are effective method of cemented soil in erosion environment.

The settlement after construction is the major research project for subgrade of dedicated passenger railway line, in which it is indispensable to keep the accumulated settlement under long-term train load repeatedly with a reasonable range. To discover the rule of loess foundation accumulated settlement under long-term train load repeatedly, a series of cyclic traxial texts were carried out for undisturbed loess; through anisotropic and long duration loading simulating the condition of constant loading of train load, the loess behavior of dynamic strength and cyclic stress-accumulated strain relationship under different confining pressures were obtained; and the cyclic stress-accumulated strain relationship at small cyclic stress were normalized. Results show that (1) The loess accumulated strain increases as time, and it can reach a relative stability value when the cyclic stress is less than critical stress, whereas it can't do. (2) The loess accumulated strains under different confining pressures increase with the increase of the cyclic stress; and the critical stress increases with the increase of confining pressure. (3) Under the same confining pressure and strain failure criterion, the dynamic strength decreases with the increase of cyclic number. (4) Under different confining pressures and the same cyclic number, when reach the same strain value, the cyclic stress increases with the increase of confining pressure. (5) When the cyclic stress is small, the loess accumulated strains under different confining pressures increase linearly with the cyclic stress.

The interfacial interaction between the fiber and soil matrix is a key parameter in controlling the strength behavior, physico-mechanical properties of fiber reinforced soil (FRS). Therefore characterization and analysis of the micromechanical behavior such as the interfacial shear strength ?f is significant for investigating the mechanism of FRS and particular application to engineering. In order to assess and investigate the ?f and interfacial residual shear strength ?r of PP-fiber (polypropylene fiber) reinforced soil, the single fiber pull-out tests are carried out on the soil samples with different water contents and soil dry densities by using the tester designed by ourselves. The influence of water content and dry density on the ?f and ?r is analyzed. This investigation proves that the designed tester can be applied to single fiber pull-out test effectively; and the test results are exact. It is found that the ?f and τr of samples are decreased with the increase of water content, while increased with an increase in soil dry density. The behavior of the force-displacement curves in the pull-out test depends ultimately on the intrinsic characteristics of the interface; and the shape is not significantly influenced by the water content and dry density. Finally, the critical fiber length is assessed by the obtained interfacial shear strength of fiber/soil.

A method is presented to analyze the nonlinear behavior of pile groups under torsion. In this method, the lateral and torsional responses of individual piles in a pile group are modeled by load transfer curves; the far-field interactions among the individual piles in the groups are predicted using classical elastic solutions; and the coupling effect of lateral resistance on torsional resistance of the individual piles is quantified using an empirical factor. The proposed approach is capable of capturing major pile-soil-pile interactions and the coupling effect in pile groups subjected to torsion. It is verified using results of centrifuge model tests.

Based on a large reinforced soil project in Shanghai, a series of pull-out tests and direct shear tests were carried out to study the interface characteristics between uniaxial/biaxial plastic geogrids and different soils. The effects of reinforcement and the mechanism for the developing of interface shear stress were comprehensively compared between uniaxial and biaxial plastic geogrids. The influences of soil density, vertical stress level and displacement rate on the interaction characteristics were also discussed. It is found that the force-displacement curves of pull-out and direct shear tests for uniaxial geogrid reinforcement generally exhibit strain soften characteristics; but those for biaxial geogrid reinforcement often demonstrate strain harden characteristics. The effects of biaxial geogrid reinforcement are better than uniaxial geogrid reinforcement because of distinct enchasing force between soil and biaxial geogrid. Soil density, vertical stress level and displacement rate will all influence the interface characteristics; but the extent and mechanism of those influences are different for different soils.

Creep properties of rock salt under the coupled thermo-mechanical effect are studied using the statistical mechanics and fractal rock mechanics. A damage variant is proposed under the confining stress, and the damage equation under the coupled thermo-mechanical effect is deduced based on previous studies. Based on the test data under the coupled thermo-mechanical effect, main creep features are analyzed on the transient creep stage, steady creep stage and accelerating creep stage. And then a new creep model with thermal damage considered is set up by introducing a nonlinear function to Bingham’s creep model for the transient and steady creep stages and introducing damage for the accelerating creep stage. Finally, the new model is used to analyzed the triaxial creep stages of rock salt; and the results are of good accordance with the test data.

Large filtration erosion tests of many soil samples are performed to study the filtration erosion property of the gap-graded coarse-grained soils. The test results illustrate that piping will occur for the gap-graded coarse-grained soils if the fine-grained component less than 30%. This result accords with the criteria of boiling and piping proposed by previous researchers. The piping type can be divided into continuous and discontinuous piping. The criteria of continuous and discontinuous piping proposed by Liu Jie and Кондратьев are used to distinguish the two types of piping, but the test results disagree with their criteria. Based on the criteria of continuous and discontinuous piping proposed by Кондратьев, the criteria of continuous and discontinuous piping are proposed considering the filling degree of fine particles to the void of coarse-grained components and the influence of percentage of gapped particles. This criterion provides new idea and method to distinguish the two types of piping for the gap-graded coarse-grained soils.

To control the rock mass damage under blasting and to minimize the range of blasting cracks in tunnel excavation are of great significance for project safety. Based on the study of the forming mechanism of blasting cracks under blasting stress wave, using Mohr-Coulomb criterion and maximum tensile stress criterion, the proportional radius of blasting-induced cracking zone (PRBICZ) affected by in-situ stress under blasting stress wave is studied. The study results indicate the PRBICZ is mainly influenced by in-situ stress. In compression and shear failure mode, the PRBICZ decreases with the increase of in-situ stress; the distribution of PRBICZ on tunnel wall is affected by side pressure coefficient of in-situ stress. If the unloading of surrounding rock stress is considered, the PRBICZ along radial direction of the tunnel wall is shorter than that without considering nature stress unloading. The PRBICZ in tensile failure mode is relatively shorter than that under compression and shear failure mode; compression and shear failure of the rock mass is more likely to occur along structure weak plane under blasting stress wave.

The interaction mechanism between anti-sliding piles and landslide mass is complex. In this paper, this interaction mechanism was investigated through physical model tests of anti-sliding piles and landslide mass, in which FBG sensors and common electric sensors were installed as measurement devices. Main parameters such as pile sizes, pile spaces and angle of sliding surface were investigated. Their relationship with the resistance force function was correlated. Some special landslide phenomena and pile bearing status were observed, and the interaction mechanism was understood.

Based on Biot’s consolidation theory, a semi-analytical solution to axisymmetric consolidation of a semi-infinite isotropic saturated soil subjected to time-dependent loadings is presented. By introducing state variable, using the method of Laplace-Hankel transform, the government can be solved. Through some numerical analytical example analysis, some consolidation behaviors in the time domain such as the fluid pressure and discharge are investigated. For the ramp loading case, the Mandel-Cryer effect can be seen when the construction time is little and under the deep of the foundation. For the cyclic loading, there is a negative pore pressure.

Supposing that the failure mode of borrowed soil with surface seepage parallel to horizontal surface is a translational sliding surface parallel to the original sloped surface along the upper surface of plane nets. Based on this failure model，the stability analysis of the soil is carried out; and then a general equation on stability thickness of the soil under earthquake and surface seepage parallel to horizontal surface is given. Stability charts for the soil are obtained after discussion on parameters of the equation. Using the charts with surface seepage parallel to horizontal surface and with surface seepage parallel to sloped surface, the stability of the soil is compared. The result shows the stability of the soil with surface seepage parallel to horizontal surface is remarkably reduced than that with surface seepage parallel to sloped surface, and reduced degree is inversely proportional to instability thickness of the soil.

Under the impact of frost heave, thaw settlement and salt heave on the embankment and pavement of the highways in the zones of seasonally frozen ground in Gansu province, Northwestern China, many road damages, which has serious influence on road stability and security, occurred such as pavement cracks and road boiling etc. In this paper, repeated freeze-thaw experiments of saline soils taken from where some damages always occurred in the subgrade and pavement were conducted to investigate the characteristics of frost heave, thaw settlement and salt heave of these saline soils under the periodically fluctuating temperature, and to study the mechanisms of the road damages. The experimental results show that salinity has significant impact on the deformation process; and that the deformation mechanisms are different for the saline soils with different salinity. When salinity is very high, the deformation is mainly caused by salt heave. When salinity is low, the deformation mainly results from frost heave and thaw settlement with possible frost heave. For the non-salt and frost susceptible soil, it is caused by frost heave and thaw settlement. Meanwhile, some suggestions have been proposed to prevent the embankment and pavement of highways from damages and instability in saline soil regions.

The pore water pressure will be altered with the changes of groundwater characteristic and seepage condition. It will be also a crucial factor to the bank slope instability. Based on the model experiment and the numerical simulation (EMU), they the influence of drainage velocity on the bank slope stability is verified. This test also validates that the siphon drainage technology can reduce the water head between the reservoir and groundwater in the bank slope and make seepage path better. The results will be useful in engineering practice.

The chemical improving expansive soil of Anyang in Henan province by experiment with ionic soil stabilizer is studied. Through free swelling ratio test results combined with construction cost, the optimal ratio of ISS solution is identified as 1:350. The soil test was carried out after the soil is chemical treated in optimal ratio of ISS solution. The soil tests include the shrinkage test, swelling index tests, consolidated quick shear test, high-pressure consolidation test and water immersion test. The soil test results show that the linear shrinkage ratio and swelling index decrease, shear strength Increase; and the improved soil has been changed from hydrophilicity to hydrophobicity and has good water stability; videlicet, the expansive soil become non-expansive after chemical treatment. It appears that the mechanism of action of ionic soil stabilizer on expansive clay can be explained through cation exchange with the surface and interlayer cations. This reduces the density of the electrical charge around the clay particles which leads to them being attracted closer to each other to form flocs; it is an irreversible process which leads to reduction of expansion and modification of the engineering properties of the expansive soil.

Coal-bearing soil is weakened when encountering water and its strength is sharply dropped down with increasing water content. Taking coal-bearing soil which ranges along with Guang-Wu Expressway for example, and based on analyzing the physical properties of coal-bearing soil, its shear strength is measured through direct shear test; influence of water contents on shear strength of coal-bearing soil is analyzed; and some suggestions are put forward to treat coil-bearing soil. The results indicate that the shear strength and initial water content of coal-bearing soil have marked correlationship; and the bigger initial water content of coal-bearing soil is, the smaller its shear strength is. With water content increasing, cohesion of coal-bearing soil decreases overall; but its changing trend is of marked characteristic of stage. When water content of coal-bearing soil is under some value, its cohesion changes in small ranges; after water content of coal-bearing soil is over the value, its cohesion decreases with water content increasing; and the interrelationship between the logarithm of its cohesion and water content is linear. Water content of coal-bearing soil has no marked effect on its internal friction angle; but its internal friction angle firstly increases and then decreases, so it has marked peak value.

Two typical swamp soils in Sanjiang Plain and another wetland soil in Cuihu, Beijing are tested in aspects of micromorphic, microstructure characteristic, mode arrangement of soil particles, pore-size distribution, organic content and mineral composition etc. Test results show that moisture content, liquidity index, void ratio, void number, void size, void volume and organic content of the black swamp soil are far more than that of the white swamp soil; and the wetland soil, which indicated that the properties of the swamp soil are obviously different. Study results can provide references for understanding properties of swamp soil, sinking salvage, protection, rational exploitation and engineering construction in swamp regions.

The generalized Kelvin-Voigt creep model under sinusoidal load is established from a macro perspective of the rheological characteristics of materials; and the model characters are also analyzed in the suppositional condition that the fatigue failure of material under low frequency harmonic loading is neglected and the cyclic stress range is constant. The results indicate that change law of dynamic creep model is the same as that of statistic creep model, of which the loading is as much as the maximum of dynamic loading; and dynamic creep strain is smaller than that of statistic creep during the initial stage and stable stage; which are similar to the test results in references. In addition, the longer the cycle of dynamic load is, the longer the time of initial creep stage is and the larger the long-term strain is.

Creep tests under different levels of loads have been performed on briquette under confining pressure of Datong #7 mine belongs to Songzao coal-electricity group. Through changing the level of creep loads, integrate three-stage curves and characteristics of each of creep steps are obtained. According to the analysis of the experimental results, laws and parameters of each of creep steps under confining pressure are obtained, both initial amount of creep and creep acceleration of acceleration creep phase showed an increasing trend as the addition of creep loadings, but the relationship between lasting time of transfer and stable creep steps with creep loadings showed non-regularity; and constitutive relation of briquette can be reflected by cohesive-elastic-plastic model. Based on calculation, parameters of cohesive-elastic-plastic model are obtained.

In order to meet heavy demand of uranium resources due to rapid development of nuclear power in China and solve the problem of low permeability of the ores in in-situ leach uranium mining from low-permeability sandstone-type uranium deposits, this paper borrows ideas from successful experience of enhanced rock mass permeability methods that have been successful applied to oil, gas, CBM exploration and coal gas control, and analyzes the deficiencies of these methods in case that they were used in in-situ leach uranium mining, and then proposes the method of blasting enhanced permeability of no free surface deep rock mass(abbreviated to BEPDR) to increase the permeability of the ores with low permeability. The implementation of preliminary model tests of BEPDR verifies the feasibility of this method.

Based on three unsaturated soil shear strength tests, it is found that the Mohr-Coulomb failure surface is a ruled surface. The improved Mohr-Coulomb failure theory is suggested to describe the failure surface. And then, to get the index of the Mohr-Coulomb failure theory, equal cohesion-suction curve and the equal fraction angle-suction curve are suggested. Finally, several shear strength theories are evaluated by drying soils and saturated soils. Improved Mohr-Coulomb failure theory can describe the failure of unsaturated soils.

In light of the drawbacks met in the double-layer lining，the permanent tunnel lining of single-layer steel fiber shotcrete and wet-mix method is studied systematically. The different percentages of steel fiber and other additives were subjected to laboratory tests including compression test, tensile test, impermeability and bending strength test. The results of experiment show that the tensile, flexural and anti-penetration of steel fiber shotcrete are improved for 65.6 %, 94.7 % and 98.1 %. It is indicated by the test results that the presence of steel fiber gave great rises to the strength and plasticity of shotcrete. Then, the economical and reasonable mixture ratio that meets the requirement of design is provided through field spraying text; the inclined shaft of Motianling tunnel is chosen as an engineering example. The results show that the early intension of steel fiber shotcrete can meet the requirement of design; and the shotcrete of resilience loss is reduced for 7 %-15 %. The results can offer references for steel fiber shotcrete of single-layer tunnel lining.

All kinds of accident examples and their potential reasons are analyzed and summarized for cutter head failure of composite earth pressure balance (EPB) shield. In order to research the mechanism of the failure mode on cutter disc, cutters and other different cutting components in composite EPB shield machine, fault tree analysis (FTA) is applied to establishing an analytical model on cutter head failure. Firstly, potential failure modes and effect factors of different failures are all analyzed and calculated by set theory in qualitative and quantitative methods. Then, relevant control measures are proposed to reduce the cutter head failure of composite EPB shield. The results will be useful for cutter head design and construction by composite EPB shield in China.

It is necessary to inject grout in shield back in construction process of tunnel by shield driving method. The grouting material is from liquid to solid on stepped unloading pressure. The characteristics of grouting material is different from that on constant load. On basis injection material in tunnel of Nanjing subway No 1 with shield driving method, creep tests of injection material under constant loading and unloading condition have been taken, the rheological equation and nonlinear experiment curves have been shown. Based on analytical solution of spherical expansion in semi-space and rheological test of injection material the displacement solution of soil surrounding tunnel has been presented; influence area from deformation is discussed; the feasibility of calculation is analyzed. The determination method of protection from tunnel construction is suggested.

The definition of vector sum factor of safety (VFOS) is clear in physics and mechanics. Generally VFOS is solved through the stress field computed by finite element method. A simple method for solving VFOS is proposed. Based on the general limit equilibrium method (GLE), the total force and moments equilibrium is satisfied. The VFOS formulation is deduced on the basis of method of slices. Nonlinear programming technique general reduced gradient method (GRG) is employed to search for the critical slip surface. Then the VFOS is solved on the slope of total shear strength of the slip surface. The computation is implemented in the spreadsheet software Excel, which makes the proposed method be easily spread in practice. The results of circle slip surface slopes show that: First, VFOS and the traditional FOS match well and their critical slip surfaces are close too. Second, the slope of shear strength resultant is less the slope angle and quite close to the slope of interslice force when interslice function is constant, thus under equilibrium framework the proposed method can be further simplified: assumes interslice forces is parallel and computes VFOS on the slope of interslice force. Third, The VFOS does not appear to be very sensitive to the interslice force functions (constant and half-sine function). The results of noncircular slip surface slopes show that: First, VFOS and the traditional FOS match well and their critical slip surfaces are close for homogeneous slopes, but there are some differences for slope with weak layers. Second, The VFOS does not appear to be very sensitive to the interslice force functions.

In soft soil engineering, loads are not applied instantaneously but generally multistep. With the consolidation of the foundation to a certain intensity value and then the next level of load is imposed to ensure the stability of the foundation. Based on Xie Kang-he’s solution for one-dimensional finite strain consolidation of saturated soft soil, by means of mathematical induction, the analytical solution under any form of multistep linear loading is deduced; and corresponding general purpose program is also developed for computational efficiency. Then the results are compared with the solutions under linear small strain assumption, and show that the analysis based on nonlinear finite strain assumption is more reasonable in actual engineering.

Traditionally, it is usually depended on engineers’ personal experience and habits to establish the strata layers on the basis of the original data when they doing the desk studies of a site investigation work. The concept of fuzzy cluster is introduced to propose a more reasonable way to merge and classify the soil based on the physico-mechanical indexes of the soil. It can be seen that this method is more simple and universal. In addition, a method used to check the results of fuzzy cluster based on the variation coefficients study of the soil parameters is proposed. The results of fuzzy cluster are corresponding with the statistical parameters; meanwhile, the method also can be used to guarantee the results to meet the standard requirements; and the rationality of the way about merging of soil is proved subsequently.

Negative exponenial form of frequency vs spacing value curve was confirmed by many field discontinuity spacing surveys of rock mass. This article derived the max-value function of the negative exponential form, and argued that the limitation of negative exponential form is really presence. While using the two-parameter negative exponential form by way of regression analysis 'pattern function instead of negative exponential form, the limitation will disappear. The two-parameter negative exponential form could bump regression analysis 'degree of fitting up。Least square curvilinear regression method was considered as the most conformable regression-type analysis. The two parameter negative exponential form have been used on the statistics of dam foundation rock mass discontinuity spacings of Yunnan Xiaowan Hydropower Station successfully.

To define the in-situ stress regime accurately is one very important basis for stability design and evaluation of underground project. By analyzing how to evaluate the in-situ stress state in the past, it is found that many used methods have totally different standards and criterions in China, and one new high stress criterion and analysis method is established by reference to the past findings. Here the internationally-widely-accepted Shoerey’s model is introduced into the modified high stress criterion; but this model does not take the difference between deformation modulus of rock mass and Young’s modulus of intact rock sample into consideration. For this reason, the authors introduce the deformation modulus from Hoek-Brown criterion into this model to better the Shoerey’s theory, and form the modified Shoerey’s model. A tunnel in Lufeng County, Yunnan Province, has burial depth up to 525m, the lithology of surrounding rock mass is sandy slate. Two boreholes, ZK5 & ZK9 for hydro-fracturing in-situ stress measurement, are arranged along the tunnel line, but the measurement results are rather scattered. The in-situ stress magnitude at the tunnel section, estimated with the methods suggested by this paper, is up to 19.29 MPa; but the global strength of rock mass is only about 5.243 MPa. According to the strength-to-stress ratio method and the criterion from modified Shoerey’s model, the tunnel section at the largest burial depth is under the high in-situ stress; and the project construction and design department should pay more attention to such a condition. Finally, the general method and procedures to evaluate the in-situ stress state are summarized to offer some references for other projects.

Fuzzy analytic hierarchy process (FAHP) of risk assessment has been used in tunnel collapse; through collecting and collating information of the tunnel collapse, the major factors are summed up and selected as the impact factor of FAHP. Through analyzing the statistical materials, the membership function is proposed between the factors and the probability of occurrence of collapse and collapse volume. And a comprehensive assigning method is adopted to determine the weight of evaluation indices. Then the model of FAHP has been established and applied to Qingshangang Tunnel. The results are credible.

The landslide is a certain-uncertain dynamic system. As a explicit behaviors of this complicated nonlinear dynamic system，the deformation of landslide is characterized with many uncertain factors. In order to reduce the limitation of traditional methods, the set pair analysis (SPA) theory was introduced to describe the landslide dynamic system. Based on SPA theory combined with analytic hierarchy process (AHP), a new displacement prediction model is suggested. The existence of limit value of maximum same degree for SPA theory in equal potential condition are also suggested and demonstrated. Based on this demonstration, the new SPA model and probability analysis, some new concepts, such as optimum displacement prediction and potential displacement, are suggested. Furthermore, the potential displacement is also used to set up the quadratic correlation SPA model to describe the dynamic correlation between landslide deformation and reservoir accumulation process. As a test, all these models are used to analyze the newly-happened Liujiatuo landslide in Qingjiang Shuibuya Reservoir. The results indicate following three main conclusions. First, the optimum displacement prediction is reliable and has high precision in short-term prediction ability. Second, the potential displacement is the maximal potential for landslide deformation, which can be regarded as an upper limit of displacement prediction in current status. Furthermore, the variation of it can describe the evolution track for landslide dynamic system in macro level. So, it has guiding significance in early warning for landslide deformation acceleration. Third, the dynamic correlation SPA model is the new way to quantitatively study the relationship between landslide response and reservoir accumulation process. It can be used for quantitative inverse the hysteresis effect on landslide deformation responded to the reservoir accumulation process. The lag time deduced by this back analysis model matches the observed information well. It was proved that these set of models are simple, efficient, and can be promoted in practical engineering.

Based on the two hypotheses: (1) the force on shield working force is round and well-distribution; (2) the frictional force between the out surface of shield and surrounding soil is also well-distribution; the mechanical calculation model of shield is established by using the classical elastic theory of Mindlin. In this model, the changeable location of shield is considered when shield is working. Then the stratum deformation calculating formulas around tunnel caused by the additional force on the shield working force and the frictional force between the out surface of shield and surrounding soil are deduced. According to the stochastic medium theory, the stratum deformation caused by the loss of stratum which resulted from shield tunnel construction is deduced, in which the time-space effect of stratum deformation caused by tunnel construction is considered. A case of history is calculated and the time-space change rules of stratum deformation are studied finally.

On the basis of boundary representation, the notion of sealed engineering geological model is proposed; and an approach for building a seamless engineering geological model based on wire frame is presented. And a sealed modeling software system, ROCKModel, is developed. This system includes three main components: original data transforming tools, solid modeling tools and auxiliary tools. And it includes eight basic functional modules, such as: mesh generation for surface and solid, surface interpolation, surface intersection searching, etc. Based on these basic modules, five key algorithms, creating complex surfaces, creating wire frame, interfaces modification and reconstruction, blocks searching, and 3D rock quality classification are proposed and realized. This system can build and visualized seamless models for complex geological and engineering objects, and provide geometrical models for numerical simulation software directly.

A highly effective iterative procedure is developed to examine the load-displacement behaviour of a single tension pile by load transfer theory. Moreover an approximation method that can for predicting deformations of tension pile groups is given. The method assumes pile groups as an equivalent pier so that the analysis method of single pile can be used for pile groups. Compared with field experiment, the equivalent pier method not only can save a large amount of computing time but also give reasonable results.

An in-depth study of displacement of working well and soil counterforce under the jacking force is indispensable to ensuring safe and economical construction. Two practical pipe jacking project were employed to represent respectively the deep-buried or shallow-buried circular open caisson which was used as working well of jacking project. Firstly, a fitting equation of soil counterforce distributing around the circumference was obtained by the 3D finite element method (FEM). Then the comparative analysis of displacement and soil counterforce around the working well under the jacking force for both deep-buried and shallow-buried circular open caisson was performed by different method, namely, FEM analysis, specification[1] method and manual[2] method. The results indicate that: only the soil counterforce that acting at the semicircular was taken into account in specification[1]method and manual method; as a result, the calculated soil counterforce are larger than that from FEM analysis. For deep-buried working well, the distribution and quantity of well displacement and soil counterforce are affected evidently by the acting position of jacking force. The methods proposed by specification and manual are applicable only to shallow-buried working well that jacking force acting near its bottom.

The simulated material models are employed to simulate the spatial distribution of mined crack network in overburden rock stratum under the condition of deep mining. By using the fractal geometry, the evolutional law that the fractal dimension of mined crack network varied with mining width, underground pressure, rock stratum sedimentation is studied. The effect of fault on the evolutional law and the distribution characters for the crack network of rockmass in triple-zone are analyzed. It is shown that the fractal dimension of crack network increases with increasing of mining width in general, decreases under the effect of fault, and has nonlinear relation with advance supporting pressure, rock stratum sedimentation. The crack network of rocks in triple-zone expresses self-similarity, the fractal dimension ratio of crack network of rocks in caving zone, fractured zone and bent zone is 1.0823:1.139 4:1.

The upper bound method of limit analysis can be used for the stability analysis of reinforced earth; the internal works on the slip plane is the crux of the stability analysis. Firstly, the methods of calculating internal works on the slip plane based on the classical plasticity theory of upper bound method are summed up. Then the upper bound method based on the generalized plasticity theory is used to Yang junjie’s method about calculating the internal works on the slip plane. Comparing the upper bound method both based on the classical and generalized plasticity theory and the centrifuge test results, it is shown that the upper bound method based on the classical plasticity theory is simple and clear; the computed result is reliable, although the upper-bound method based on the generalized plasticity theory is more perfect; it is difficult to use when that the slip surface to be an curve plane.

To compute the weight factors that influence slope stability accurately, rough sets theory is used to analysis the raw data. Based on discretization of the measured data, the significance of attributes among rough sets is estimated instead of weight determination, and a relation data model about slope stability assessment is established. A knowledge system is built through making attribute value into eigenvalue. During data analysis, the weight of a slope stability assessment model is computed by analyzing the support and significance of forecasting method for the predicted object. The proposed approach overcomes the subjectivity of traditional weight determination method, improving the precision of risk assessment for slope stability. At last, an example is given to show the effectivity and rationality of this new method.

Based on the principle of Mahalanobis distance discriminant analysis, the characteristics of design system for deep foundation pit are analyzed; the distance discriminant analysis theory is applied to optimizing the supporting plan for deep foundation pit. Considering from three aspects: safety, economy and feasibility, 10 factors influencing the optimization of supporting plan are taken into account; and a distance discriminant analysis model has been built by learning from a great deal of deep foundation pit cases. The re-substitution method is introduced to verify the stability of distance discriminant analysis model and the ratio of mis-discrimination is lower. A set of data in some deep foundation pit engineering and an engineering case in Shenzhen city are used to test the discriminant ability of this model. The results show that this method is an efficient one in solving the optimizing problem of supporting plan for deep foundation pits and can be applied to actual engineering.

Taking the spillway tunnels for Jiangping River Hydropower Station as engineering background, their stabilities in the construction period are analyzed by using large-scale finite element analysis software ANSYS and according to actual geological and topographical characteristics, including different rock strata and faults conditions, Drucker-Prager criteria, nonlinear numerical simulation calculation. The principal stress and displacement distribution law of different rock strata are obtained. Through the analyses of displacements and stress field, expecially the synthetic analysis of tension stress zone, plastic area and point safety factor distribution, the stabilities of spillway tunnels entrance before and after supporting are evaluated. The displacement in the top of tunnel is large; moreover, there are big plastic area and zone that exceed tensile strength of rock body; the stability is poor. After supporting timely, plastic area and zone that exceed tensile strength of rock body become smaller; its stability is improved obviously; but the point safety factor of strongly weathered layer CK2 is just slightly larger than 1.0; and there is still zone inside of which the point safety factor is less than 1.0. Therefore, for the strongly weathered layer CK2, it is best to take measures of strong supporting with steel arch frame. The results provide an important reference for engineering design and construction.

A mechanical model of bottom hole was set up, considering affecting factors such as subsurface pressure, joints, hole depth, geostress, material behavior, diameter of borehole and so on. The effects on stress field in bottom hole of those factors on the stress ficrd of bottom bole are discussed; and the effects on borehole deviation of stress field in bottom hole while gas drilling are also expounded. The Pressure in downhole is far less than ambient pressure while gas drilling. There will be large tensile stress at bottomhole; and the rock is easy to destroy, so, drilling speed of gas drilling is far more than that of fluid drilling; but while tensile stress is larger, the stress concentration at interface between downhole and joint plane is larger. The rock at stress concentration is easy to be destroyed and deviated. The stress status of gas drilling is more sensitive to the change of dip angle, material property, diameter, depth and original stress than that of fluid drilling.

Based on the research of the parameter ? getting, the calculation formulas of primary parameters applicable to various strata are put forward. The elliptical and non-uniform soil displacement pattern, which is more appropriate for the actual cases, is adopted. With the calculation formulas of ? and the elliptical displacement pattern, the revised stochastic medium theory, applicable to the calculation of surface and subsurface soil displacement is put forward. Finally, comparing the calculated results with the measured field data, the method of Shi and the method of Loganathan, it is proved that the calculated results can be fitted well with the measured field data.

In order to build an assessment standard for surrounding rock mass with the Hoek-Brown criterion, firstly, the relationship between Hoek-Brown criterion and Mohr-Coulomb criterion is theoretically analyzed; the yielding approach index (YAI) described by Hoek-Brown criterion parameters is obtained; secondly, the three dimensional calculation for tunnel is founded by FLAC3D, the program of yielding approach index for Hoek-Brown criterion (YAIhb) is compiled; the impacts of material parameters and stress variation to the YAIhb are analyzed, which show that: (1) the areas of YAIhb=1 calculated by the self-compiled program are the same with the plastic areas calculated by FLAC3D, which validates the correction of the self-compile program, and moreover the YAIhb can reflect the yield degree of each element which is superior to the plastic zone distribution standard; (2) with the increase of geological strength index GSI, YAIhb reduces gradually, and the relationship between GSI and YAIhb can be described precisely by the cubic-polynomial equation; with the increase of rock uniaxial strength σci, YAIhb increases gradually in the exponential form; with the damage of element increase, the YAIhb increases gradually, which shows the failure degree of element increases, the relationship between YAIhb and damage index D is in accordance with the hyperbola principle; (3) the increase of maximum principal stress σ1 will lead to the decrease of YAIhb, and their relationship is in accordance with the linear principle; the increase of intermediate principal stress σ2 will lead to the variation of YAIhb in the form of first increase then decrease; and their relationship in accordance with the cubic-polynomial principle; YAIhb increases linearly with the increase of minimum principal stress σ3.

Split-grouting has great effect on stress，strain and stability on earth-rock dam. By using Duncan-Chang E-B model, the grouting period-stopping period of a earth rock dam, and the finite element analysis of stress and strain. Split-grouting can increase the maximum and minor principal stresses at the same time. In the neighborhood area of grouting axes, the minor principal stress increased more extent than the maximum one. The stress level was reduced and lower than before; and the stability of the earth dam increased. Comparing with the observation data, the result is in accordance with the measurment.

Land subsidence induced by groundwater extraction is one of the most serious geo-hazards to be investigated when evaluating a construction site. Because the geological and hydrological situations are usually quite different from site to site, there has been no a generalized method to qualify the estimation of land subsidence for all kinds of sites. A method using the least square method and the measured data set of groundwater decline and the corresponding subsidence to determine the storage coefficients of elastic and non-elastic aquifers of a site is introduced. With the method and data from the construction site of Yizhuang light railway in Beijing, the optimum values of the storage coefficients of elastic and non-elastic aquifers of the site are determined as Sske=(7.0±2.0)×10-7 and Sskv=(6.93±0.5)×10-5, respectively. Further, with the storage coefficients and an effective stress analysis method, the land subsidence tendency of the construction site of Yizhuang light railway is evaluated. The results show that the southeastern part of the construction site will subside as large as 70－126 mm in the next 10 years (2006 to 2015) if the situation of groundwater extraction is not improved.

Accuracy of the slope stability analysis is the key to ensure the stability of deep foundation pit. At present, the common calculation methods used to assume the shape of the sliding surface, and the calculation process is so complex that accuracy of results is decrease. Without any similar assumptions on shape of sliding surface, a minimal potential energy method is used to analyze the stability of deep foundation pit slope. Based on the theoretical analysis of simple homogeneous arbitrary sliding surface slope, it turns out that calculation results attained through the verification of calculation example are relatively close to results from other common methods; and effectiveness of the method is validated. What is more, calculation is simple without iterative process.

In view of the incompatibility and grayness of indices in optimization of supporting scheme for deep foundation pit, an optimization model based on grey matter element analysis is presented. The model takes the scheme to be selected, optimization indices and its grey characteristic value as grey matter elements, and relative optimum supporting schemes for deep foundation pit is obtained by calculating the comprehensive relational degree. The practical example, with 4 supporting schemes for deep foundation pit, is introduced by using such indices as reliability, cost of construction, difficulty of construction, time limit for a project, and environment influence. Compared it with fuzzy optimization theory model, the result obtained is coincident. Considering both the incompatibility and grayness of indices in scheme optimization, the optimization model of grey matter element analysis is clear in concept and reasonable in method，the result is in accord with the practice.

Initial geostress is one of main factors used for analyzing stability of surrounding rock and design of support structures in underground caverns, and whether the company is dependable will directly affect the reliability and safety during engineering design and construction. Based on engineering geological conditions and measured geostress data in region of underground powerhouse of a certain hydropower project, grey control system theory is introduced, and finite element method as well as static three-factor grey calculation model, GM(0,3), are applied to analyze the initial geostress in region of underground caverns. Computing results show that the horizontal geologic structure action is preferably dominant in region of underground powerhouse; and geostress is composed of gravitational stress and tectonic stress. Through comparison between computed and measured geostress values of measuring points, it is shown that the two are similar in values and directions; so that the accuracy and reasonability of the geostress field regression are validated. Thereby, the distribution tendency of initial geostress field of underground powerhouse region can be obtained, so as to provide a rational 3D initial geostress field for excavating simulation and stability analysis of underground powerhouse at a certain hydropower station.

This computing method addresses safety factor with respect to unsaturated slope of downstream homogeneous earth dam. Method to calculate safety factor of unsaturated slope is highly connected with shear strength criteria of unsaturated soil and seepage analysis of unsaturated slope. There is a potential risk for the soil slope of a downstream earth dam to burst along the sliding surface. Most slopes in earth dams are in unsaturated state. This computing method is intended to provide safety factor of a soil slope in saturated-unsaturated seepage. Determining the safety factor of a slope provides information to facilitate the safety assessment of a homogeneous earth dam. This computing method covers a procedure for determining safety factor of unsaturated slope of a downstream earth dam with limit equilibrium method, lower-bound and upper-bound method. This computing method is suitable for unsaturated slope. It is revised on the method to evaluate the safety factor of a saturated soil slope. The contribution of suction to the shear strength of unsaturated soil has been considered. In an example, safety factor of a soil slope is calculated in saturated seepage theory or saturated-unsaturated seepage theory. It is found that the safety factor of a slope considered the saturated-unsaturated seepage in a slope and the suction contribution to shear strength is larger than the one only considers the saturated seepage of a slope.

The safety of underground caverns is a key problem of large substructure work for designer. A new method to calculate the general safety factor of underground multi-cavern is put forward, which is based on the strength reduction technique. The method adopts the Mohr-Coulomb rule as the strength yield criterion and takes the transfixion of equivalent plastic strain in wall rock between caverns as the critical failure criterion of caverns. By reducing rock material strength parameters (cohesion c and friction angle φ) step by step, the general safety of caverns is obtained when the result of simulated excavation shows that the equivalent plastic strain of wall rock becomes transfixion, which is the critical state of caverns destabilization. In the course, the calculation program trends to emanate and the deformation of wall rock also tends to rise suddenly and sharply also. The Laxiwa underground hydropower plant, a large cavern group in the northwest China, consists of main powerhouse, auxiliary powerhouse, main transformer chamber, caudal shiplock chamber, tailrace tunnels, and so on. The high geostress and interaction of caverns lead to very serious stability problem. Using the underground caverns strength reduction technique, the general safety factor of Laxiwa underground caverns is gained, which is 1.45. The assistant tunnels of Jinping II hydropower plant are important tunnels also. The general safety factor, calculated by the method, is 1.73. Both of them prove that the method of underground caverns strength reduction technique is very useful for analyzing the general stability of caverns and design of substructure quantitatively.

Natural frequency is one of the most important dynamic characteristics of field soil layers. In order to avoid the resonance between structure and ground, the natural frequency of engineering establishments should be different from that of ground. On the basis of traditional shear particle system method based on lumped mass matrix (lumped mass method), a new shear particle system method based on consistent mass matrix (consistent mass method) is developed. Then, influencing factors on computing precision of shear particle system method are analyzed. The three aspects of soil delamination, mass matrix form and material damping are mainly considered. The analysis indicates: the more layer numbers we divide, the more precise the results will be and from the standpoint of practice engineering, when layer number is more than three, a subdivision is needless; layer thickness has very small effect on computing results; the result of consistent mass method is superior to that of lumped mass method and has the property of upper bound solution; in small damping circumstance, the material damping has small influence on natural frequency.

The numerical manifold method is the numerical method system including manifold element and the discontinuous deformation analysis(DDA) and FEM, the analysis of interaction between continuous medium and discrete block system is realized in the system of manifold method by establishing the contact equation of manifold element and DDA block. Programmed large-scale numerical analysis program for project of rockfill embankment, in the program, the DDA model of embankment is built with random generation and diameter control and natural stacking of block; it is simulated that extending and rolling embankment layer by layer and the deformation of embankment after construction. The computation example shows, that it is feasible that apply interaction method of manifold element and DDA to simulate the interaction of discrete block system and continuous medium; its analysis of this kind of problem is in accord with actual condition of research object. For the discrete block system, the coupling computation method is helpful to disclose microcosmic mechanism and rule of deformation of engineering object, and investigate the influence of more factors for engineering problem.

The mechanical response of deep rock pillar, which is under complicated stress condition and then subjected to dynamic disturbance, is numerically simulated. Under different lateral pressure coefficients, the dynamic response characteristics of the pillar are characterized; and the effect of the duration of dynamic disturbance on the pillar stability is studied. Through the numerical analysis of the pillar in deep rock, it is found that the triggering action of dynamic disturbances is closely pertinent to the static in-situ stress condition and the action time of the dynamic disturbance. In general, it brings about greater influences on the stability of underground tunnels with the decreasing lateral pressure coefficient and with the prolonged duration of dynamic disturbance.

Adopting reasonable shear strength parameters, calculation results obtained from conventional limit equilibrium method and limit analysis method can not explain the reason why some expansive soil slopes failure under a fairly small dip angle. In fact, there has obvious swelling deformation when water infiltrating into the soil, so as to induce large shear stress near the border between the saturated and unsaturated regions. This effect should be considered in the stability analysis of expansive soil slope. Based on the upper bound theorem in plasticity, a new energy-work balance equation has been strictly derived including the work rate done by expansive stress. Factor of safety defined by strength reduction explicitly exists in such equation can be solved by iteration; and minimized by optimizing the slip surface. The upper bound limit analysis of the slope is numerically performed by element integration method (EIM). By means of EIM, the calculation result obtained from stress analysis can be conveniently utilized. Applying the presented method to an expansive soil slope with a gradient of 1:4, it is demonstrated that the expansive deformation brings obvious decrease to the safety factor of the slope. When considering expansive of the soil, the critical failure pattern obtained from optimization is a small range of shallow slide, which will induce the upside soil mass into another small range of shallow slide. This agrees well with the common traction characters in the failure of expansive soil slope.

Based on theory of viscoelasticity and dynamics, the performance of dynamic stress intensity factor (KI) is discussed under vertical load with different vehicle velocity, rebound modulus and damping ratio by FEM simulation. The influence of KI with both horizontal and vertical loads is analyzed. The numerical results show that the value of KI decreased with increase of the vehicle velocity and the damping ratios. The value of KI increased rapidly with increasing of the base modulus. The peak point of the KI increased with both horizontal and vertical loads, which would influence the shear stress and tensile stress of the road.

The dynamic deformation and stress characteristics of subgrade under two impact loading routes with different compact times are analyzed based on three dimensional elastoplastic dynamic FEM. The results indicate that the three dimensional compressive stresses exist in the affected scope of subgrade underneath the slab. Vertical deformation of subgrade under slab corner is maximum; and vertical deformation of subgrade under slab corner is minimum. By comparison vertical deformation of subgrade, vertical deformation of subgrade is generally lower. Vertical deformation of subgrade increases with distance far away from impact point. And vertical deformation of subgrade exists obviously residual deformation, wave and hysteresis phenomenon. Vertical deformation of subgrade increases with increasing of compact times; and there exists plastic zone after the third compact time. Soil pressure increases with increasing of compact times; but increasing tendency tends to be stable. The range of increasing soil pressure is limited to certain depth of subgrade.

A three-dimensional calculation model of metro station structure and tunnels in soft soil is established; and their three-dimensional seismic responses are studied; and the unsubstantial parts of structures are determined; and the amplitude of inner forces caused by seismic waves are obtained; and the influence of tunnel on station structures is analyzed. Conclusions drawn from calculation results are as follows: (1) the section whose position is 1.5 times of width of station structure away from the end walls can be analyzed by the assumption of plane strain; (2) the disadvantageous parts of station structures include the above end of upper column, the conjoint part of sidewall and backplane, the mid-span of backplane and their conjuntion of front wall of station structure and tunnel; (3) seismic load has maximum effect on the moment of column; (4) the global aseismatic ability of front and behind walls of station structure will be weakened because of the existence of tunnel. The research results can provide references for seismic design of metro station structure and interzone tunnel.

Considering the mechanics status of the excavated surrounding rock and the uncertainty essence of many problems in rock mechanics, the Kalman filtering & FEM coupling back analysis method considering broken rock zone is established and programmed in Fortran. Using the interactive communication technology between Fortran and VC++ based on the operating files, the back analysis module is added into the Tunnel Construction Monitoring Management and Surrounding Rock Stability Intelligent Analysis Software System for one hand; and the back analysis and surrounding rock stability analysis is realized conveniently and visually based on the graphics module of the system developed by ourselves for the other hand. After the initial parameters have been worked out based on the Kalman filtering & FEM coupling back analysis method considering broken rock zone, the maximum shear strains of the global calculating field are obtained based on FEM. And then, by comparing with the critical shear strain obtained by experiment and theoretical deduction, the stability of the surrounding rock could be judged. Because the method mentioned above discards the unreasonable hypothesis of the initial stress field, the results are more practicable and reasonable. The method has been successful applied to the Baiyun tunnel YK48+737; and the changing plastic zone distribution figures through time are obtained. The on site designers and builders would be able to know the stability situation of the surrounding rock in time, and improve their design and construction.

Fractures in rock masses are randomly distributed; and the seepage in the rock masses mainly happens in these fractures. The Monte Carlo method is adopted to generate the stochastic fracture network firstly. Then, on the base of the theory of directed body, the automatic identification method for three dimensional network with random fractures is realized, including the concave and multi-connected blocks. Next, based on the assumption that the intact rock is impervious and the water flows only along the fractures, the block element method for seepage analysis of three dimensional network with random fractures is established. Finally, two examples are studied to prove the precision and validity of this method.

In the modern war or terrorism, nuclear power station may greatly have been attacked by pinpoint general bomb. Using finite element software LS-DYNA3D, taking 5000kg munitions equivalent to TNT bombing 100m away from the nuclear power station as an example, while munitions explosion、propagation among soil together with structure constitution are regarded as a finite element analysis system, the vibration response of the containment foundation is analyzed. The result indicate that the pressure of foundation and containment is dispersed as ring, and the joint show stress focus. The time-history curve for Von-Mises stress and the time-history curve for radial stress show that the mix Von-Mises stress of the containment is 35 Kpa and the mix radial stress of the containment is 32 Kpa. Under the given condition, the response value of the foundation and containment is far smaller than the design value, the nuclear power station is safe and reliable。