A slope stability analysis method based on finite element analysis is developed. The slip surface is still assumed to be circular arc. The mesh of finite element consists of a family of circular arc lines and a family of vertical lines. The slip force and the resistance are analyzed for the arc belt which is between two neighbouring arc lines, and the equilibrium equation is set up. Then the factor of safety is determined. The arc belt corresponding to the smallest factor of safety is the possible slip belt. The position of circle center is changed and the circle center of real slip surface is seeked by the optimum seek method. For the real slip surface, the factor of safety is minimum. The computation examples show that the calculated factor of safety is quite close to that of Bishop’s method. And this shows that the proposed method is reasonable. The outstanding merit of the proposed method is that the stress state on slip surface can be obtained directly from finite element computation, and is more accurate. The method can reflect nonlinear deformation behavior of soil and is more close to the real situation. Besides, as one of the methods of slope stability analysis by finite element, the displacements are calculated. This offers the possibility to estimate the slope stability during construction by displacement monitor in situ. And it can also be used to analyze the slope of expansive soil in considering the influence of expansive deformation.

Formulas of infinite element with 6 nodes are presented; and an object-oriented geotechnical infinite element(IE)-finite element(FE) coupling software based on Windows is designed by combining VC++ with Matlab. As its application, the stability of underground excavation of a hydropower project in Yunnan Province is calculated by FEM and IE coupled with FE method; so that the accuracy of formulas is proved. The analysis of the example shows that, when infinite or semi-infinite calculating zone is involved in, the application of IE coupled with FE may eliminate “boundary effects” and raise the efficiency of calculation.

On the basis of probability and statistics theory, a systematic study is carried out on the probability design of consolidation of sand-drained ground, which overcomes the shortage of the current determination method of design. The probability design method——the design coefficient method, is proposed, that is correlated with the conventional design by the mean of design coefficient. The design value of horizontal coefficient of consolidation can be made by multiplying its standard value and design coefficient or by multiplying its mean and central design coefficient. Under the conditions of the horizontal coefficient of consolidation being either a log normal distribution or a gamma distribution, the formulas for computing design coefficient are derived. According to these formulas, the variation of design coefficient is studied. The central design coefficient is decreasing function of coefficient of variation of horizontal coefficient of consolidation, and increasing function of probability of failure. The method of calculation on standard value of horizontal coefficient of consolidation is discussed. The tables and diagrams are given, which can be used to look up the coefficient of consolidation. A probability design procedure for consolidation of sand-drained ground is established; and its practical application is illustrated by example.

The vertical chaotic motion of the nonlinear viscoelastic pile embedded in rock with a vertical displacement, is investigated. Supposing that the pile satisfied the constitutive relations of nonlinear elasticity and linear viscoelasticity, and the reacting force of soil to the pile is in direct proportion to displacement and speed rate as well as the damp. The nonlinear partial differential equation of the pile motion is obtained. Based on the Galerkin method, the equation is simplified. Moreover the numerical simulations are carried out, from which the time-path curves, phase-trajectory diagrams, power spectrums, and Poincare section and bifurcation diagrams for the motion of piles are obtained with different parameters under the following conditions, such as the reacting force and the damp of the soil, the damp of the pile comparatively big, small and very small etc.. The results show that the vertical motion of the nonlinear viscoelastic pile could present periodic, quasi-periodic, bifurcation and chaotic motion.

Based on the theory of continuous medium, a saturated-unsaturated seepage mathematical model is presented. The method of calculating unsaturated seepage field by FEM and the mechanism of rainfall infiltration and the rainfall simulation are proposed. Unsaturated seepage program SUSC is compiled based on above theory. Through the analysis of seepage field in a slope under rainfall infiltration, results show that the deeper as well as surface of slope are saturated rapidly due to rainfall, and surface water infiltrated to the deeper under slope. Pressure water head changes from high (zero) to low, then to high again through top to deep. The area of negative pressure water head decreased gradually due to rainfall and the absolute value of negative pressure water head reduces at the same time. The pressure water head keeps on increasing for 1 to 2 days owing to groundwater infiltration when the end of rainfall in some areas of slope. According to calculation results, maximal pressure water head in some areas of slope appears after two days when rainfall finished. Simulation results show that the model and program are reasonable; and it is of great importance in application to analyzing stability, designing drainage and reinforcing slope engineering.

The model of aquifer’s horizontal elastic displacement caused by water injection is difficult to solve because adequate description of its boundary conditions is unavailable. According to the anti-symmetric characteristics of constant-rate pumping and injection flow in Theis confined systems, it is assumed that their infinite boundaries of bulk flux should be also anti-symmetric and then the solution of aquifer’s horizontal elastic displacement with constant-rate water injection is derived. The results show that the skeletal solids movement velocity and its accumulated displacement, radial strain and tangential strain are expressed in constant-rate injection process as negative ones as they are expressed in constant-rate pumping process. In the injection process, there are two types of radial deformation areas: extension one is near to the well and compressive one is far from the well. The maximum displacement exists along the line dividing the two areas. If the confining beds of the aquifer are relatively stable, the relative displacement of the aquifer caused by water injection is enough to make well casings of water and oil wells deformed or even damaged. The aquifer keeps extension in tangential direction and the maximum tangential strain locates in the borehole wall, which can lead to radial tensile fractures of well adjacent rock.

Based on 3D viscoelastic dynamic equations for transversely isotropic fluid-saturated soil, the Fourier expansion approach and Laplace-Hankel transformation are used to solve the viscoelastic dynamic response of the transversely isotropic fluid-saturated soil. Through strictly theoretical deduction, the closed-form solutions are derived in terms of solid matrix displacements and fluid displacements relative to the soil matrix. According to initial condition and boundary condition, the boundary-value problems of transversely isotropic saturated viscoelastic half-space under the action of vertical and horizontal dynamic loads are solved. The solutions in time domain can be obtained by using Laplace-Hankel inverse transforms. The computer programs are developed for calculating the stress and diaplacement of transversely isotropic fluid-saturated soil. Selected numerical results are presented. The results show that it is necessary to take into account viscoelasticity of saturated soil.

To analyze the stability of a laneway’s surrounding rock with single crack, the multi-domain boundary element method is used. The sub-regions are obtained by dividing the whole region along the crack. The boundary integral equation is established in each sub-region. The traction singular quarter-point elements are collocated at the tip of the crack. For the opened or closed crack, not only the characteristic of in displacement but also the characteristic of 1/ in stress near the crack tip are represented. Qua the target, the stress intensity factor is calculated. According to the theory of rock fracture mechanics, the influences of the following factors on the stability of the cracked surrounding rock are analyzed systematically: geometric position of the crack, the ration of dual-pressure, the friction factor of the crack surfaces, the length of the crack. Some valuable conclusions are obtained. This numerical method is suitable for the stability analysis of laneways with complex geometric shape and laneways in layered medium.

The fractal characterization in the evolving damages of concrete structures is studied based on physical model experiments. It is revealed that the surface-crack distribution of the damaged concrete structures takes on fractal behavior. This shows that fractal dimension is able to characterize the surface-crack distribution quantitatively. Then fractal geometry is employed to investigate the crack evolving process of concrete structures; and the relationships between the fractal dimension of surface-crack distribution and the mechanical properties of the damaged structures are discussed in detail. It is found that there exists a good linear correlation between the fractal dimension and the natural frequency, which shows that the fractal dimension of surface-crack distribution is able to act as a damage feature index to reflect the damage degree of concrete structures effectively. Compared with the conventional damage feature indices generated from vibration testing; this novel damage feature index is of some advantages and distinguishing features. It provides a promising approach to develop new technologies for structural health monitoring and safety evaluation.

From many influence factors which affected the deformation of foundation pit’s surrounding soils, three main effective factors such as Young’s modulus, dewatering depth and the permeability coefficient had been chosen as the significantly important factors for input in the 2-D FEA model and the behaviors of settlement were then analyzed. Furthermore, by the 2-D FEA model, the effect of the reduction of the surface settlement due to different distances of recharge or the depth of water-sealing was studied. The obtained results verified that the surface settlement and surface differential settlement of the ground surface could be largely reduced by recharging or water-sealing.

The land subsidence and the construction’s foundation subsidence caused by groundwater withdrawal from deep foundations are the environmental disaster problems in city construction. When groundwater is pumped from a confined aquifer, groundwater level decline will lead to increase effect stress and motion of solid grain in soil layer. Accordingly, it takes place land subsidence. According to this mechanism analysis of land subsidence, a groundwater movement equation considering water expansion, aquifer compressibility and solid grain movement due to groundwater pressure decline is established. It also can be found that Biot’s and Helm’s formula are the special case or the simple mode of the groundwater movement equation. The proposed equation is applied to analyze and calculate land subsidence in foundation engineering. The result indicates the presented groundwater movement equation can efficiently explain the mechanism of land subsidence. Through analysis of alternatives, several control measures are proposed such as waterproof wall, local pumping well, unsymmetrical well group, and small pumping rate.

Pre-consolidation pressure is one important index of soils. The shortcomings of existing mathematic models are discussed based on the practical shape of e-logp curve, and the thought of using famous Harris model to fit e-logp curve is put forward. By comparisons and analyses, this new model’s superiorities to the traditional cubic and quartic polynomial models are revealed. Besides, one calculating program is written by using the 0.618 method and the least-square fitting method. The inputted data is very simple and the results are of high accuracy according to the calculation results of an engineering example. It shows that this new model has definite reference value for engineers.

Pitch concrete is often used as seepage prevention of the bottom of pumped storage reservoir. Crack may be found in it if the filling rate is too larger or the filling water head is too high. In this study, based on an example of the upper reservoir of a pumped storage power station, the influences of the filling rate and filling water head on the settlement, settlement rate of the reservoir foundation, and the strain rate of the pitch concrete are analyzed. Before analyzing, the model parameters of some materials are obtained based on observed settlement data and initial model parameters using an optimum method. The 2D FEM and Biot consolidation theory are used in this study. The results of analysis indicated that the filling rate has little effect on the ultimate settlement of the foundation, but has larger influence on the settlement increment during filling, the maximum settlement rate of the foundation and the maximum strain rate of the pitch concrete; and the filing water head has little effect on the maximum strain rate of the pitch concrete, but has larger influence on the settlement increment during filling, the maximum settlement rate of foundation. The relationships between the settlement increment during filling and the filling rate and filling water head, between the maximum settlement rate and the filling rate and filling water head, and between the strain rate of pitch concrete and the filling rate are also given.

Interactions between sands to liquefaction and piles were studied using shake table model tests. The relationships between pile bending moments and cyclic cumulative pore water pressure ratio were obtained for different relative densities sands to liquefaction. Degradation p-y curves of soil-pile interaction were determined during the sand to liquefaction using pseudo-static method. Bending moments along the pile are further calculated using the nonlinear Winkler foundation beam and degradation p-y curves. Calculating and test bending moments were compared. Results show that the lateral resistance of the pile does not reduce if the cyclic cumulating pore water pressure ratio ru≤0.2, it degrades 90 % if the relative density of sands Dr≤40 % and the cyclic cumulating pore water pressure ratio ru≥0.8 and it degrades 75 % if the relative density of sands Dr≥50 % and the cyclic cumulating pore water pressure ratio≥0.8.

Based on a loading model for shield tunneling and the concept of gap parameter, the mechanism and a prediction method of shield tunneling-induced ground movements are introduced. The offsets of a tunnel shield from its design axis are the main cause for ground movements. Identification of the gap parameter is one of the most important steps when using an analytical method. A semi-empirical and semi-analytical approach is proposed; and as a case study of shield tunneling, the field-observed and the theoretically predicted ground movements are comparatively analyzed.

One hybrid method of finite element analysis of rod structure coupling with load transfer approach for pile group settlement was established. The nonlinear behavior of shear-displacement on the boundary between pile and ground was determined by the Randolph and Wroth’ Model in the approached closed form solution, coupling with the hyperbolic model. The action of pile groups was evaluated from the Mindlin equation solution, and adjusted by the “reinforcement and curtain” action approximately. The nonhomogeneous behaviours of ground between piles is characterized with an exponential function. The influences of number of piles, the pile length, the space between piles, and the pile-soil relative stiffness factor on the characteristic of pile groups were analyzed in a systematic way. The interaction of pile group affected by the settlement of piles with rigid cap was discussed emphatically; and the results may be used for reference in the construction in which the settlement of pile group foundation is limited strictly, e.g. splicing of bridge structure.

The ground settlements and the disturbance of soil around tunnel by shield driven are summarized by means of measurement of Tianjin No.1 subway line project. According to the actual engineering, a 3D FEM model is proposed to simulate the excavating of shield tunnel by means of general FEM program ABAQUS; the model change method is put forward to imitate moving-forward shield process. And the results of simulation are compared with the results of measurement.

Based on Mohr-Coulomb strength theory, the effect of intermediate principal stress is ignored by the critical pressure and the formula of ultimate bearing capacity of shallow foundation, so its results are usually smaller than real values and that the potential of soil’s strength is not fully utilized. From unified strength theory that considers the effect of intermediate principal stress, the common formula of ultimate bearing capacity of foundation was deduced and the unified solutions was obtained. The formula of Terzaghi ultimate bearing capacity of foundation is the specific case of the unified formula. Through changing parameter of unified strength theory, a series of solutions can be obtained. The results indicate that bearing capacity of foundation is greater than Terzaghi ultimate bearing capacity of foundation because of the effect of intermediate principal stress.

High and low confining pressures have different effects on the deformational properties and mechanical index of frozen soil. Triaxial compression tests were carried out for frozen silty clay under three different temperatures and four confining pressures at different strain rates. The test results indicate that the stress-strain curves behave in the same form under different confining pressures and different strain rates at the same temperature of frozen soil; the triaxial shear strength has a linear relationship with confining pressure and temperature, and an exponential relationship with strain rate; the deformation modulus, independent of confining pressure, has a linear relationship with temperature, and an exponential relationship with strain rates. And then the deformational property is explained from the viewpoint of structural changes of frozen soil.

In order to study the dynamic characteristics of sands in Xiamen city, a series of dynamic triaxial tests were conducted for the medium-coarse sand and the thin-fine sand at Jinqiuhaoyuan site, and 4 resonant column tests were performed for the medium sand with slurry inclusion. According to the research results, the liquefaction curve and the constitutive relationship for the medium-coarse sand and the thin-fine sand were established; and a model of pore water pressure for the two kinds of sands was proposed. The change regularities of dynamic shear modulus and damping ratio for the medium sand with slurry inclusion were obtained.

After reviewing the research results and application of the flat dilatometer test (DMT) in the evaluation of soft soil parameters at home and aboard, authors introduced the application of DMT and other testing techniques to analyze the soil engineering properties of soft foundations for expressways synthetically. The calculated undrained shear strength based on DMT results is in accordance with that of field vane shear test (VST) basically; and the undrained shear strength from DMT also reflects the law of soil strength increasing with depth. Besides, the influential factors causing the difference between DMT and laboratory test results were analyzed. The results would provide reference for the application of DMT to domestic geotechnical engineering field.

Fissured clay is one kind of special clay. The failure of fissured clay slope is progressive. Traditional limit equilibrium method can not be used to simulate and analyze the process and mechanism of the slope progressive failure; and the judgment for long-term stability of slope is also not accurate. In this paper, the progressive failure process of fissured clay slope is simulated and the stability of slope is analyzed with FLAC code. The numerical analysis of an example shows that the simulation of the progressive failure of slope and the judgment for slope stability by FLAC code are feasible.

The determination of mechanical parameters of jointed rock mass is a difficult and key problem in evaluating stability of rock engineering. In 1980, E.Hoek brought forward and advanced a method to solve this problem, which includes the characteristic of the jointed rock mass especially. The principle of E.Hoek method is introduced systematically; and the key issues in operating by this method are discussed. Then a case study of jointed rock mass of Baiyian landslide in the Three Gorges area is expounded. It is shown that the E.Hoek method, which is effective and feasible, may precisely reflect the mechanical behavior of the jointed rock mass. As a result, the E.Hoek method is suggested to apply to similar rock engineering.

The geological investigations during construction of Neixiang-Zhenping section of Nanjing-Xi’an railway revealed that Nanyang expansive soils origins not only from Quaternary alluvial, diluvial clays but also Neozoic lacustrine clays. Expansive clays with different origins differ in terms of space distribution and engineering characteristics. X-ray diffraction tests indicated main expansile clay mineral of Nanyang Expansive soils is mixed-layer illite/montmorillonite. Change of water content will result in significant difference in swelling force and dilatancy for the compacted soil sample because of the variation in material composition and physicochemical properties. To compacted samples prepared by same expansive soil material, the smaller the prepared moisture content the higher the expansive force. Even if the moisture content only reduced 1 %-2 %, the corresponding expansive force would upper to 200 %. The direct shear strength is affected by calcareous cement degree and nodes content. As high or very high expansive clays, if nodes content were less than 15 %, the reduced value of direct shear strength after dried and saturated cycle would be 40 %- 60 %; Whereas direct shear strength would reduced no more than 40 % if nodes content were 25 %-30 %. The geological properties, engineering characteristics, expansibility of compacted samples and direct shear test date of swelling soils are analysed, suitability for embankment is discussed, and suitability grades is presented in this paper. Applications of the subgrade-construction techniques developed based on the research work have achieved good effect.

Based on CPT(qc, Rf ) tests in eleven representative engineerings, liquefaction estimation of sandy soils with thin clay interlayer in Shanghai area is studied. It is revealed that there are significant relationship between specific penetration resistance, friction-resistance ratio and soil clay content through statistical analysis of tested data. The liquefaction estimation method based on CPT(qc, Rf) is given. And its application shows that the method is effective.

Based on 726 cases of mountain floods and geological disasters from 1950 to 2003 in Hubei Province, their temporal and spatial distribution properties are analyzed first; then two abrupt increasing points(1974,1988) of the annual numbers of cases are checked out by moving t-test method (the mountain floods and slope-slip most remarkably) ,and annual rainfall also suddenly increased at these two years, and their correlative coefficient is 0.3, which means rainfall is the main natural forcing factors to mountain floods and geological disasters; further analysis shows that severe rainfall above rainstorm is the main leading factors to mountain floods, slope-slip, debris flows, landslide; and lasting rain is the main leading factors to subsiding and also has important impact on slope-slip, debris flows, landslide, but the least impact to mountain floods.

Soil liquefaction is a major cause of site damage during earthquakes. Since Casagrande’s works, significant progress has occurred. But, most of these are applicable for sandy soils. So, based on the former research and the dynamic triaxial test, some questions are analyzed, including the mechanism of silty soil liquefaction and some factors, such as the clay particle content, the relative density and the structure of the soil, which impact on the liquefaction strength of the silty soils. The pore water pressure is also studied. Considering that the number of cyclic loading is non-continuous, a new applied model is proposed to evaluate the pore water pressure, which is expediently applied into the finite element method programs.

The model test of a new type of retaining and protecting structure called squeezed branch pile has been carried out to survey the compaction efficiency, loading transfer behaviors, rational structure style and characteristics of the squeezed branch pile. Compared with the cantilever reinforced concrete retaining piles, the major characteristics of squeezed branch piles contain: (1) The embedded depth can be shortened 15 %-30 %; (2) The bending moments are distributed evenly, the maximum one is decreased 40 %- 60 %; (3) The total displacement in top can be reduced 30 %-60 % approximately; and (4) The retaining height can be increased 20 %- 30 %. It is concluded that the squeezed branch piles have many significant advantages, including advanced technology, great economic situation and little risk. It will provide a reliable and economic method of retaining and protecting for foundation excavation.

Rigid pile composite foundation is an effective ground treatment method in the construction of highway. And one of this kind of composite foundation, the PCC composite foundation, is more and more frequently used in highway ground treatment. But the correlative research is less. Combined with its use in Wei-Wu highway ,the design, construction and quality test of this method are introduced. Test results show that the pile quality is good and its bearing capacity is high. This kind of method is also economical.

How much of hydraulic pressure value upon lining may be intituled high hydraulic pressure? Now, there isn’t clear boundary value in the field of tunnel engineering. The boundary value of high hydraulic pressure was researched by calculating and analyzing the safety factor of lining whether achieving the railway tunnel design code requirement or not, using plane FEM based on standard design drawings of single-track railway tunnel, needn’t change the shape of standard design cross-section as principle. The results show that in single-track railway tunnel, the first boundary value of high hydraulic pressure upon upright wall lining is 0.05－0.10 MPa and the second boundary value is 0.18 MPa; The first boundary value of high hydraulic pressure upon curved wall lining is 0.20 MPa and the second boundary value is 0.40 MPa. Hydraulic pressure is the main load upon lining when its value is higher. The boundary value of high hydraulic pressure is rarely related to the surrounding rock classification but is closely related to the shape of lining section. Curved wall lining’s capacity hydraulic pressure bearing is far higher than upright one. The capacity hydraulic pressure bearing of standard design section in single-track railway tunnel is limited. Other optimized sections should be used when static head is higher than 40m.

The Nanjing subway section between Zhujiang Road station and Gulou station passes through many ground buildings and dense underground pipes in soft-flowing mucky silty clay ground. The stratum is of high compressibility, low intensity, easy creeping, and no self-stability. The synthetical measure is adopted in this project, such as large pipe shed and small tremie as advance support and deep hole grouting at the work face, bench excavation and steel surpport, steel mesh and shotcrete support. In order to realize scientific decision and safety construction, calculation simulation is carried out according to the actual working condition to predict the surface subsidence. At the same time, subsidence monitoring is done during construction. The safety and smoothness of the tunnel construction is assured and the buildings are sound without any destruction.

Two technologies of vibroflotation compaction without additional stone aggregates for improving silty and fine sands as well as well dewatering combining with low energy dynamic consolidation for strengthening the disturbed soft soils underlying the hydraulic silty and fine sands is introduced. The treated ground meets quality requirements. The effectiveness is also discussed. All the results given are of great practical value for similar soils improvement in the future.

The basic working principle of ground penetrating radar and its application effect in some fields are introduced; and the conception that the ground penetrating radar technology is used to choose sites for municipal solid waste landfills, inspect leakage and measure thickness of cladding after landfills are closed is taken forward. The feasibility and technological advantages of ground penetrating radar technology are also discussed. The application of ground penetrating radar technology to choose sites for municipal solid waste landfills, to inspect leakage and measure thickness of cladding after landfills are closed, is regarded as an effective new method based on summarizing some relevant documents and combined with in situ investigation.

Generally, conventional water-pressure test is always carried out with five phases and three pressure stages, 0.3, 6 MPa and 1 MPa. But for some Engineerings with high water pressure such as the dam and deep covered underground ones, the results of the conventional water-pressure test can’t reflect the true permeability characteristic of the rock mass. The experiment is carried out in a 500m borehole of a granite region, and the pressure stages are designed as 2, 4 MPa and 6 MPa. 21 typical segments are selected to carry out high water-pressure test and the length of each segment is 6.5 m.The seepage law of this area is obtained through high water-pressure test. The permeability is relatively low. The grouting pressure should be larger than 5MPa when treat with fracture rockmass.