Based on the anisotropy induced by the critical stress line, the idea of transformation of stress space is presented. With reconstituted soils taken as an example, the formulas of transformation of stress space and stress increment are provided, and the influence of stress Lode’s angle is considered also. The modified Cam-Clay model is expressed again and improved in the transformed stress space; the stress-stain formulas of the improved model are presented also. Through the comparison of the computed results of four kinds of stress path by the improved model and the modified Cam-Clay model, a lot of merits of the improved model are discovered: the influence of anisotropy can be reflected better; the stress-strain characteristics of triaxial extension can be described more reasonably; the soften phenomenon of some stress path, such as , can be described.

Red clay is of swelling properties in a similar way to expansive soils. Compared with common clayey soils, the strength behavior of red clay and expansive soils are more complicated. Strength of red clay and expansive soils, as the standard of shear resistance, is an important parameter used in evaluating stability of embankment slopes such canal, roadbed and earth dam. Many failure records of earth constructions due to red clay and expansive soil slopes and foundations require a definite understanding of strength of red clay and expansive soils. The strength characteristics of unsaturated red clay and expansive soils have been studied experimentally. The main features and influencing factors of strength behavior of red clay and expansive soils which are different from those of common clayey soils are discussed. The interrelationships between the shear strength parameters and water content of red clay and expansive soils are established on the basis of experimental data.

A series of experimental researches on the deformation character were made of twenty undisturbed saturated samples of silty clay from a deep foundation pit in Wuhan at K0 consolidation and no drained shear test. The aim of the tests is to find the test curve of stress-strain and equation of elastic modulus in unloading of silty clay. The research results have shown that the curve of stress-strain in unloading is a hyperbola and is similar to the curve of triaxial compression test, but there is difference of a constant between them, and the equation of elastic modulus is different each other.

The natural element method(NEM), which can possess the characters and advantages of finite element method and other meshless method, is a perfect meshless method in the numerical analysis of geotechnical engineering. In NEM, the whole interpolations are constructed with respect to the Voronoi tessellation of the given point, the essential boundary conditions can be exactly enforced, and the time cost is little higher than the finite element method. The basic theory and application of NEM are introduced. According to the speciality of geotechnical engineering, the auto-arrangement method of discrete nodes is also given for the analysis of meshless method.

The Beam-on-Dynamic-Winkler-Foundation (BDWF) model was utilized to determine the lateral dynamic response of a pile with finite length in a viscoelastic subgrade. An analytical solution was obtained with the simple form in the time domain for a laterally cyclic force applied at the pile head. Based on the solution, the transient response of the pile loaded by semi-sine force was acquired with superposition principle. At the same time, the dynamic impedance parameters at the head of pile were also obtained through some straightforward algebra. Then by the analysis of the amplitude-frequency and phase-frequency curves for the steady-state motion, the influence of dimensionless stiffness coefficient and damp coefficient on resonance frequency and peak values during the resonance was mvestigated. Finally, the influence of tip conditions of pile on the lateral dynamic response was also discussed. The theory developed herein presents an analytical method for the dynamic analysis of a single pile and may be used as a preliminary reference in engineering design.

The modulus degeneration of sand is thought as one of characters of dynamical nonlinear to analyze the seismic liquefaction of subsoil of building. Based on the total stress method ,a cone model theory by Wolf and Meek, combined with the model of pore water pressure generation presented by Martin ,is introduced to simplify the interaction of soil-structure and calculate the dynamical stress field of subsoil , so that pore water pressure under the building can be evaluated directly, an effective stress method is suggested to evaluate liquefaction potential of building’s subsoil.

In general, when dealing with issues on strength of clay, emphasis should be paid on the stress variation and the relative change in pore pressure. The unsaturated clay due to the existence of the solid, fluid and gas phases is much more complicated to deal with. In this paper applying the elastic deformation theory and theoretical gas law, and assuming the conversation of mass , a general pore pressure formula has been derived; as the result the Skempton formula’s coefficients A and B are obtained. On other hand, applying the mixture theory the Bishop formula’s coefficient X is obtained also. In parallel works, the experimental results have been presented to validate the academic theories. It shows that the capillary action has a little influence on pore coefficient.

The settlement characteristics of the underlying soil layer of composite ground are studied systematically; through comparison of the settlements , by proper numerical modeling tests for composite ground, two-layered soil, artificial ground and natural ground with different improvement parameters, such as replacement ratio and elastic modulus ratio between pile and soil. Finally, a new settlement calculation method for underlying soil layer of composite ground is proposed．

The distribution characteristics of pore water pressure of saturated stratum are analyzed during dynamic compaction firstly. Based on a Theoretical solution of pore water pressure distribution of saturated stratum during dynamic compaction loading, a method for predicting the consolidation deformation of saturated stratum is proposed; and furthermore, the effects of soil parameters on consolidation deformations are analyzed. The calculation results show that there are obviously various magnitudes of consolidation deformation for soils with various permeability under dynamic compaction loading instantaneously; and furthermore, the maximum settlement lags behind the maximum surface contact stress. Besides, the various dynamic compaction loading-time curves have definite effects on the processes of consolidation, and have little effects on the total consolidation deformation during dynamic compaction loading.

Based on the principle of the foundation coefficient “K-K” method，the finite difference method is presented to analyze the internal forces of a whole anchor-stabilizing pile . The calculation and figure treatments are programmed . An example shows that the high precise solution can be obtained if the segments are small enough , though more computing time may be consumed . Obviously , the calculation precision is better than that of traditional method . The results of figure treatments by the program can optimize the construction design of stabilizing piles . Three kinds of supported condition are taken into account. Foundation coefficient “k-k” method applies to the situation that both above and below the slide-surface are terrains.

Pile loading tests of two bored piles of length 47m in soft soil are carried out for 28 days and 1 750 days after they are constructed. In-situ test shows that the ultimate bearing capacity of these two single piles increased about 30 %. The mechanism of time-effect of bearing capacity of pile is analyzed; and method of analyzing the effects of the time-effect of a pile’s bearing capacity on pile-soil interaction of pile-raft foundation is discussed with an engineering example.

Based on the initial stress method for elastoplastic finite element, analysis an iteration procedure for elastoplastic stochastic finite element analysis is proposed, and a method of reliability assessment for stability of surrounding rock is suggested based on the theory of structural reliability. The mean value and standard deviation of shotcrete’s stresses can be obtained. Corresponding computer program for elastoplastic stochastic finite element analysis and for reliability calculation of the safety of tunnel is developed .Two illustrative examples are presented; the first numerical example is examined to show that the proposed method yields accurate results compared with the direct difference results; the second example is for the stability analysis of tunnel; some useful conclusions are also obtained.

The strength, length, location in dike and layers of geotextile etc. have to be taken into accounted during the reinforcement design of dike. A finite element method with strength parameters reduction technique is introduced. By employing the Plaxis code, the geotextile reinforcement analysis for a dike is conducted; and the length of the geotextile reinforcement and the location of the geotextile reinforcement design are discussed. A suggested design method is given.

Based on the static test data of bored piles in Tianjin, a reliability analysis of the bearing capacity of single bored pile is made by utilizing the limit state equation of dimensionless random variables. The index of reliability of the single bored pile is calculated with both JC method and Monte Carlo method. The influence factors on the reliability index are also analyzed. Finally, the resistance partial factor is determined by utilizing optimization method.

A nonlinear elastoplastic constitutive model is proposed, the elastic matrix can be calculated according to Duncen-Chang model and the plastic parts can be determined with the modified Cam-model. A new theory of modified layer-summation based on elastoplastic principle is presented; the theory has the advantage of layer-summation and can consider the character of nonlinearity and plasticity of soil, The effect of 3-D stress on deformation can be determined also. The new theory will provide a more perfect method to predict the settlement of foundation.

By using the testing system MTS815 with hydro-electrical servo controllers, the 18 marble specimens have been tested respectively under six different confining pressures; and the changing condition of dilatancy force and volumetric strain in the whole stress-strain process has been obtained. According to the analysis of results obtained in tests, the changing law of rock strength, dilatancy force and volumetric strain with change of confining pressure has been discovered. The mechanism of surrounding rocks’ large deformation of high-stress roadways and the interactive relation of support and surrounding rocks may be brought to light.

The post-processing of test data is made by using wavelet analysis. The results show that the noise of system can almost be eliminated. Comparing with Fourier transform method and filter method of adopting mean value of ten points, it seems that the wavelet analysis method could better reserve the characters of original test data. A way to filter test noises that can’t be avoided, is provided.

The relationship between coefficient of consolidation and effective stresses of a soft clay is researched. An expression between them is derived. A series of laboratory tests are also conducted to prove its validity. The positive results can increase the accuracy for the numerical analysis of consolidation.

The spectral ratio method’s rationality of horizontal to vertical component (H/V method) for microtremors is discussed by an elastic layer over a half-space and probability model. The H/V expressions of body microtremors for layered media are derived. The feasibility of estimating the horizontal transfer function from H/V of microtremors is discussed. It is shown that the spectral ratio method of horizontal to vertical component can be used to estimate the site predominant frequency for body microtremors when the impedance ratio is more than 3. However the amplification factor of this method is smaller compared with site horizontal transfer function.

Numerical analysis of static piling based on the commonly used software ANSYS is done. The displacement penetration method is presented, which lets the pile move downward by means of the displacement boundary condition so that to simulate the piling process of jacked pile. The method takes some complex problems into account, such as elastoplastic constitutive law, large deformation and the sliding friction between pile and soil, which is more reality and has the effect of animated simulation.

The cylindrical expansion combining with spatial axisymmetrical consolidation finite element method and modified Cam-clay model, is adopted to simulate pile driving. Stresses around a pile at vavious time can be calculated and then the maximum frictional force of pile-soil interface at various time can be obtained. The load transfer method is adopted to compute pile’s bearing capacity. Considering the change of mechanical property and stress state of soil adjacent pile, a method of calculating pile’s bearing capacity considering time-effect is gained and an example shows it is rational.

In present, the relation between foundation settlement and time always is set up by permeability-consolidation theory, but because there have many presumptive conditions and the factors acting on the permeability-consolidation, it is also very complicated, and the calculation result is always inconsistent with the observed value. By analyzing the process of the foundation settlement and characteristics of Verhulst mode, the foundation settlement of various periods after-construction can be predicted according to observed values in construction period by applying the Verhulst mode. The predicted example shows that the Verhulst mode is very effective and can be applied to the practice

The finite-element method with small deformation formulation as well as the large deformation formulation, is used to perform elastoplastic analyses of an underground opening with different embedded depths, and investigate the plastic zones, displacement distributions and secondary stress fields in the surrounding rockmass. It can be seen that when the embedded depth is small the computations obtained from small deformation and large deformation methods are quite close to each other, but when the embedded depth is larger , there exists a distinct difference between the results of the two methods because the double-nonlinearity of surrounding rockmass acts obviously at this time , so for the latter case, the right selection is applying the large deformation theory.

Based on the theory of multivariate linear regression, a module about the relationship between ground settlement and its major factors is developed. This module is realized by using VC programming language. Compared with the data from field observations, the prediction of ground settlement using this module is satisfied.

By use of the non-equilibrium push transmission method, a program for analyzing the stability of rock slope named ZSLP is worked out. The program can consider the functions of matrix suction and temporary additional water load. Based on the model experiment results of atomized rain infiltration and the possible efficacy of protective facing measures of bank slope, 12 kinds of analysis cases are drafted. Under these cases, stability analyses of cushion pool slope of Xiluodu project under the influence of atomized rain infiltration are done by use of the program ZSLP. The results show that atomized rain infiltration will bring harmful influence on the stability of bank slope; and the reduce range of safety factor is sensitive to the efficacy of protective facing measures. Therefore, control of atomized rain infiltration should be paid great attention to.

Taking an actual shift project of Jiaozuo-Mineral Administration-Building for example, the foundation treatment techniques for monolithic shift of buildings are described. Some issues such as transformation of the old foundation, design of the moving basement and the new foundation, and treatment of the new ground have been detailed. Due to the large concentrated force in the columns of the superstructure, the surface between the columns and the concreted moving basement forms a weak punching shear surface; the damage mechanism in this surface has been analyzed and the corresponding method for reducing the damage has been also proposed especially. Through experimental research and the finite element analysis, it is shown that the proposed shift technique for existed building groups is feasible.

Based on existing test information in engineering, statistic mechanical model for deep overlying strata reinforced by rotary-type jet grouting is put forward. In this model, the reinforced deep overlying strata is divided into core-shaped and core-unshaped concretion in order to consider the effects of core recovery rate in drill test on the prediction of the macromechanical properties for the reinforced deep overlying strata . By use of stochastic simulation theory, sampling methods of the spatial location and micromechanical parameters of core-shaped and core-unshaped concretion in the mass covering strata are deduced. And then a computer simulation method of determining the macromechanical properties of jet grouting concretion is developed by combining the elastoplastic FEM with stochastic simulation techniques. Finally the macromechanical parameters of the deep overlying strata reinforced by jet grouting at Xiangjiaba hydropower station are investigated by the method proposed above.

The function of geosynthetics including drainage, separation and filtration etc., are described. And according to the mechanical properties and hydraulic performances of the subsoils and the behaviors of geosynthetics, the varions kinds of geosynthetics such as composite geotechnical membrane, asphaltic glass-woven fabrics, asphaltic cottonglue fabrics etc. are adopted to prevent mud boil at roads so as to make the roads in good conditions. The engineering practice shows that these measures can decrease the frozen phenomena of subsoil and they are effective methods for preventing mud boil at roads.

The system consisted of main roof and hard floor is considered as a load system; the interaction and stability of coal pillar and immediate bottom of extraction opening are analyzed. The condition that immediate bottom produces slump is proposed. It is put forward that the reason of floor heave of extraction opening isn’t slump of immediate bottom but effect of horizontal stress.

There are a 31-story building above the ground and a 3-story basement of Zhenjiang National Trade Mansion built at the soft soil foundation. The deep foundation pit is 13.20 m deep. The upper wall of the deep foundation pit adopts slope soil anchor structure system. This building is close to two neighboring ones. Its south side is close to an old residence only 4 m apart, while the distance from the constructing comprehensive building is only 2 m. Besides the other two sides are very close to the underground pipe lines. For this reason, during the design of soil anchor, the anchor-tension test is carried out, and during construction for each rod, a pre-stressed force is added for examination, to ensure engineering quality, and to let the supporting structure produce only a small amount of lateral displacement, thus the safe and speedy construction is successfully carried out , and this experience can be used elsewhere for similar engineering work.

It’s shown by research that the soil’s small strain feature is very important to predict soil’s deformation, this feature is difficaltly to be described by those traditional constitutive model. The boundary model can describe some real feature that can’t be described by traditional plastic theory. How to make more improvement and use it to research soil’s small strain feature is a problem deserving further research..