Rainfall infiltration is a process of water flow driving air flow through unsaturated soil, which is a difficult to exact simulate numerically in geotechnical engineering and the influence of pore air is ignored. In this paper, a water-air two-phase flow model is proposed based on the water-air mass balance equations, Darcy’s law and multiphase flow theory. The integral finite difference method and Newton-Raphson iterative method are used to solve the water-air two-phase model. By switching primary variables, a set of phase state (single phase and two-phase) are taken into account. The refined treatments of every boundary condition are described in detail. The water-air two-phase flow model is verified by simulating an experiment of water through an earth column. The process of rainfall infiltration is simulated numerically. The variation of pore water pressures, pore air pressure, capillary pressure and saturation of water and air phase in different depth of the soil are described; and it is verified that the water-air two-phase flow model is a better model to perform transient seepage problem; and airflow will obstruct water flow from infiltrating into the soil.

By optimizing the experimental program, the cement sample inner damage by exploding wave in water is realized; and the phenomenon of shear damage and tensile damage by exploding wave are observed. The piezoelectric transducer, which can be used to measure the pressure or velocity of the exploding wave, is designed, manufactured and calibrated. The wave shape gained from self-designed transducer in water is compared with it of commercial transducer, and the result shows that the wave shapes coincide with each other well and the dimensions of the transducer can meet the need of the experiment. The exploding wave pressure in the cement sample is measured and compared with the pressure calculated by the model from the dimensional analysis; and the result shows that the pressure calculated by the model is 5 %—15 % higher than it measured in the experiment.

Simple shear tests for the soil-soil interface are conducted；and numerical simulation is performed to model the testing process. The different interface constitutive models, such as rigid-plastic, elastoplastic and Clough-Duncan nonlinear elastic models, are used in the numerical analysis; and the failure mode of interfaces is investigated. The calculation results agree well with the test results; and it is shown that the rigid-plastic model is suitable to describe the soil-soil interface.

Using the soil static and dynamic universal triaxial and torsional shear apparatus, a series of cyclic triaxial shear tests under different confining pressures are performed for saturated Fujian standard sands with a relative density of 30 % under K0-consolidation condition. And compared with the cyclic triaxial tests under both isotropic and anisotropic consolidation conditions, the procedure of K0 consolidation and the cyclic shear characteristic of sand under different consolidation conditions are discussed. The procedure of K0 consolidation includes two stages: the gradual deformation stage and the steady deformation stage. The measure of the coefficient of earth pressure at rest K0 is affected lightly by different confining pressures. And the development of the pore-water pressure under different consolidation conditions is different. The dynamic strength of sand under K0 consolidation condition is higher than the dynamic strength under anisotropic consolidation conditions (Kc=1.67) and lower than the dynamic strength under anisotropic consolidation condition (Kc =2.94).

Stability analysis method of slope based on minimum potential energy principle is a new kind of method in developing. A new stability analysis method of slope, which concerns reinforcement of slope with anchor bolt or prestressed cable and based on minimum potential energy principle, is established. Furthermore, an approximate model on shear potential energy in the district beneath slipping surface is presented too. Case studies show: (1) No matter that slope has been reinforced with anchor bolt or prestressed cables or not, results from minimum potential energy method have a good coincidence with that from limit equilibrium method, so as to show the new method is applicable. (2) Shear potential energy from the approximate model is considered whether or not, it is nearly no influence on safety factor of slope with just single stratum; but it has clear influence on that of slope with more than one stratum. In general, the concept of minimum potential energy method of slope stability is clear and reasonable; solving process for safety factor is concise; and the expression of safety factor can be expressed as explicit function. Compared with limit equilibrium method and finite element method, and so on, it has clear value for engineering application.

Starting from the unloading and reloading hysteretic curves of the Hardin-Drnevich model, different expressions of dissipation function are formulated in order to reconsider the energy dissipation mechanism of H-D model based on the thermodynamics principle. Two kinds of different translation rules of the back stress are assumed: one is the straight line; the other is the skeleton curve; and then the yield function expressions in the dissipative stress space are obtained by using of Ziegler’s orthogonality condition. Moreover, adding the shift stresses to the dissipative stresses, the form of the yield condition in the true stress space is deduced. The plotting of yield curve in true stress space indicates that the form of the shear yield curve is straight line for the two different shift rules when the shear strain is below the threshold value. However, when the shear strain is above the threshold value, the shear yield curves appear bending.

The in-situ stress is one of the most important factors for the design and construction of large scale underground structure group. Based on the engineering geologic characteristics and the measured data of in-situ stress in the region of Dagangshan Hydropower Station, the lateral earth pressure coefficient model for 3-D in-situ stress inversion is established taking into account the influencing factor of in-situ stress. A methodology of inversion analysis combining the Nelder-Mead algorithm and finite element method is proposed, in which the finite element program is embedded as a module in the Nelder-Mead algorithm. Then, a new exact penalty error model is established between the actually measures and corresponding calculated results of stresses. Through the finite element approximation analysis, the optimum inversion coefficient can be derived. Through the comparison between calculated and measured stresses of measuring points, it is shown that the calculated stresses are similar with the measured stresses, which suggests that the reasonability of in-situ stress field finite element approximation. Therefore, the calculated stress field can be used for the analysis of the excavation simulation and long-term stability of Dagangshan Hydropower Station.

To evaluate interface friction characteristics and tensile force of geosynthetics, the simulation experiments and analysis are conducted. Firstly, the friction angle and adhesion were obtained between non-woven staple geotextile and soil, HDPE geomembrane, TPO(PE) geomembrane by direct shear experiments. Secondly, the tensile forces at the fixed ends are measured by the centrifugal modeled tests due to compaction work of soil. Test results show that the friction angle is large, and adhesion is small between materials; The tensile forces at the fixed ends become larger with the increase of the height of soil. Based on the interface characteristics, the distribution of friction stress on the interface and the tensile forces of non-woven staple geotextile and HDPE geomembrane or TPO(PE) geomembrane are analyzed by FEM. the calculation results of tensile forces are compared with the centrifugal model experiment results; the calculation values are as similar as experimental values; and the friction stress on the interface under bulldozer is large.

In light of the defecty of conventional rheological models in retlecting the influence of load level and describing acceleration creep, a new improved rhelolgical model is developed, in which the conventional rhelological model is improved and a non-ideal viscous element is introduced. According to definition, the expression of dynamic porosity and general effective stress are amended. Rocks are regarded as porous medium for their own porosity and nonuniform; and the effective stress mentioned in theory of porous medium replaces the constant stress in the improved rheological model. Taking temperature and pore pressure into account, a rheological model of porous medium of deep rock (characterized by high temperature, high ground stress and high pore pressure) is established finally.

Through the analytical solutions, the dynamic responses of elastic half-space-sediment-ideal fluid system due to SV wave incidence are investigated. The sediment is modelled respectively as the elastic solid, viscoelastic solid, ideal fluid and vsicous fluid. The results obtained are compared with the case in which sediment is viewed as a two-phase poroelastic medium. It is found that the two-phase poroelastic medium can be simplified approximately as a viscoelastic solid when its permeability is relatively small (k≤10-3 m/s).

Strength reserve coefficient method based on nonlinear FEM is adopted to analyze the failure process of gravity dam along the foundation surface. Meanwhile, the influences of elastic modulus ratio of dam to foundation and stress distribution along foundation surface on the failure process and strength reserve coefficient (SRC) are studied. The results indicate that the failure process can fall into four periods: smooth connectivity period, acceleration period, short smooth transition, sharp accelerating failure period. With a constant elastic modulus ratio of dam to foundation, the more uniform the stress distribution is, the greater SRC is. The greater the ratio of stress at dam’s toe to dam’s heel is, the smaller SRC is. When stress distribution along foundation surface is invariable, the variation of elastic modulus ratio does not affect the overall failure feature of the foundation surface and the SRC is in proportion with the elastic modulus ratio. Finally, the true safety degree at the range of 1.5－2.5 is proposed for the failure evaluation of gravity dam along the foundation surface under normal loads.

Considering the structural characteristics of soil and the chemical reactivity of contaminants, the kinetic model of contaminant transportation in the soil-water system is established, in which the immobile water and equilibrium/non-equilibrium adsorption-desorption are considered. The model is solved using the quasi-ADI method; and the corresponding program is used to simulate a paddy field, which is in the pesticide application period. The law of the contaminant transportation and transformation in soil is studied; and the effect of immobile water and non-equilibrium on concentration distribution is analyzed. The result from numerical simulation shows that the concentration hysteresis exists both in immobile water phase and in non-equilibrium phase; so it retards the pollution in prior period, and increases the pollution in latter period. The existences of the two phases both have important effect on the contaminant transportation. So they must be sufficiently considered in numerical simulation. The results of numerical simulation and analysis can provide quantitative basis for environmental evaluation, and have important theoretical and practical significance for controlling of contamination.

Under the condition of tamping energy 975－1 125 kN•m per blow with four kinds of typic tampers including the shock absorbed and assembled tamper (SAAT) designed by the first author, the tests of vibration acceleration and comparative tamping settlement are carried out in-situ during the improvement of mud ground with high water content and great void ratio by using the static-dynamic drainage consolidation (SDDC); SAAT first contact with ground, rebound, and impact secondary action lasted for 15ms, 80 ms and 35 ms respectively; vertical and horizontal acceleration under the four temper action descend sharp within 10 m and 5m respectively; the synthesized safety distances satisfying the requirement of relevant code (under seismic intensity grade Ⅶ）are obtained as 20－30 m under the condition, and the safety distance for SAAT is least; the result shows that the SAAT enhances the effect of MSDDC in evidence and diminishes vibration influence on surrounding environment obviously. Besides, transmissions of vibration acceleration produced by impacting are analyzed.

A hypothesis that the skeleton deformation of clay is only the deformation of the interfaces of grains, and the deformation characteristics including nonlinearity and plastic deformation are controlled by the sliding of interfaces of grains within skeleton, is presented. Such a sliding can occur whenever the shear stress on interfaces of grains reach a critical value, and the direction range of sliding increases with the shear stress. This paper view that the sliding of interfaces of grains is a sort of damage in the clay skeleton, and there are two sorts of interfaces within the clay skeleton, the one contacts perfectly, and the other one contacts imperfectly. On plane, according to the relative distance from the stress circle to the initial sliding envelope line, the direction-range value of the sliding interfaces can be determined. The damage ratio is defined as the ratio of the previous direction-range values to its maximum value (determined by failure stress circle). The overall shear modulus is the weighting average of the perfect contact shear modulus and sliding contact shear modulus. The proposed model simulates the shear deformation for saturated clay under consolidated undrained condition reasonably well. In addition, the mechanical properties of the model can be conveniently obtained through conventional triaxial compression test; and the model is capable for predicting deformation behavior under various conditions, including varying hydrostatic stress and stress paths.

In the geogrids reinforced soil structure field test, availably convert the measure strain to tensile stress is very important. This can help to analyze the mechanism of action accurately. Through the indoor tests, the tensile properties of three HDPE geogrids with different strain rates are studied in this paper. It is concluded that the tensile strength and tensile modulus will decrease with the decrease of tensile rate; and the peak strain decreases with the decrease of the tensile rate. The strain rate will have smaller influence on the higher strength geogrids. In the specifical tensile rate, The tensile strength corresponding to 2%, 5%, 10% and peak strain increase in turn, the tensile modulus reducing in turn.

Site condition and fault movement are the main reasons of buried pipeline’s damage. It is the main problem of earthquake lifeline engineering to avoid the damage of buried pipelines affected by site condition and faults under earthquake load. By the parasolid modeling in ADINA, through the definition of site body and Boolean operation, the geometry model is established for the analysis of buried pipeline damage, and finite element modeling of soil-fault-pipe is worked out. With model preferences, parameters of the model are defined, such as the characteristics of rock and soil, characteristics of pipeline. Pipe-soil friction and fixity are applied, and loads of earthquake wave and fault displacement are defined. According to the calculating results, influence of some parameters on the damage of buried pipeline under earthquake load are investigated, such as buried depth, parameters of faults, and pipe-soil friction. The deeper of burying and the bigger of fault throw, the easier of pipe deformation and damage. Optimum volume of pipe-soil friction coefficient and cut angle between fault and pipeline are obtained. Finally, some advices are proposed for the protection of buried pipelines in engineering.

Flood discharge atomized rain is the non-neglectable activator for rock mass landslide, which besides the rainfall. At first, through the relation between seepage characters of fracture rock mass and stress, elastic-plastic constitutive equation of fracture rock mass and control equation of seepage field, the equation continue media model of seepage and stress field coupling is established. Secondly, a 3-D finite element program of saturated-unsaturated seepage and stress coupling under atomized rain programmed, the two-field coupling is solved by iteration method. Finally, taking a typical project for example, the geological model is established according to the earth’s surface information, excavation information, terrane borderline information, drainage hole and purdah information; the rock mass deformation, stress and plastic area are analyzed in detail by coupling computation, the analysis shows that the slope stability has closely related with the change of saturated-unsaturated seepage field of rock mass system; the seepage field of rock mass system must be considered when estimating slope stability. The result can provide some scientific foundation for project slope stability estimation.

Surrounding rock of Gonghe Tunnel is lamellar limestone. Its rock specimens have distinct anisotropy from complete stress-strain curve in uniaxial compression test; and yield failure of surrounding rockmass has remarkably directional property from in-situ monitoring results. According to these results and characters, selecting appropriate yield function and suitable strength parameters vary with angle between layered rockmass or maximum principal stress, combining elastic constitutive function of anisotropy; then elastoplastic constitutive function of anisotropy is obtained and implemented with C++ language. Gonghe Tunnel is numerically modeled by utilizing this constitutive function; and numerical simulation results essentially coincide with failure character. It is shown that the elastoplastic constitutive function of anisotropy is correct; and it can be used for analyzing support design and stability of the tunnel.

Model test of slope reinforcement through electro-osmosis is conducted; the electro-kinetic geosynthetics (EKG) was adopted as electrodes in the test. Isolines of water content of the soil after 15.5 days of electro-osmosis were tested. Test result shows that electro-osmotic consolidated zone extended from anode to cathode gradually. Soil around EKG anode near the wire holder of electrode positive had the strongest effect of consolidation; on the contrary, soil around EKG cathode far away from the wire holder of electrode negative had the weakest effect of consolidation. Energy analysis method for electro-osmosis is presented. This method is applicable for both saturated and unsaturated soils during the drainage consolidation process, if only the soil is saturated at the beginning of consolidation process. Numerical simulation method for electro-osmosis based on energy analysis method is presented. Numerical simulation result shows good accordance with the tested result.

Based on discrete Fourier transform theory and the time domain and frequency domain analysis on a great deal of field test data of the bridge(culvert)subgrade transition section on Qin-Shen High-speed Railway, vibrtion acceleration amplitude spectrum and power spectrum and phase spectrum of the top surface layer of the subgrade, and the relationship between vibration first frequency of the top surface layer of the subgrade and vehicle velocity are acquired. The dynamic responses of subgrade-bridge transition section under high-speed train action are tested in Qin-Shen Railway. The longitudinal distributive regularities of dynamic responses of the transition section, relationships between train speed or axes weight and dynamic stress and variation of dynamic stress with depth are analyzed. The test provides important basis for the design and construction of the transition section roadbed of high-speed railways.

Based on analyzing the characteristics of flow through large soil pores and the transport and transformation mechanisms of volatile contamination, a two-region model for volatile contamination transport and transformation in soil is established; and a numerical solution of this model is qiven; and the behaviors of volatile contamination suck as volatility and absorption etc. in soil are described quantitatively. Taking heptachlor for example and simulating its dynamic transport and transformation behavior in soil, it is concluded that the volatility of pesticide and the water content of immobile region are key factors affecting the concentration distribution of pesticide; and that the volatile mathematical model of pesticide used in the two-region numerical model in soil can more reasonably manifest its behavior mechanism. The study is of significance for predicting and restricting pesticide pollution.

Longyou grottoes have characteristics of shallow embedding, large span and lying in soft rock. The one of important reason for that the grottoes have kept stability for thousands years is that some special structural shapes are adopted, except the integrality of rock mass is better and the holding action of the full water in caves. In Longyou Grottoes, fishtail pillar structures, used to increase the longitudinal length of support area and enlarge chapiter structures (named as pillar caps), gradient roof structures in longitudinal direction and arch-type structures in transverse direction are utilized separately. By comparing these structural shapes with modern structural mechanics theory, results revealed that they correspond well. It is embodiment of the ancients? structural mechanics idea, and also revealing the ancients? wisdom and creativity. By digging and studying structural mechanics idea of containing in grottoes, it may be used to steer more and more underground engineering construction of today, and making the past serving the present.

A series of mechanical experiments about the interface with slurry between the gravel and the concrete are conducted through the monotonic shear apparatus developed by the Yangtze River Scientific Research Institute and Geotechnical Research Institute of Sichuan University. It is confirmed that the thickness of the slurry is closely related with the strength of the interface and there are two critical thicknesses(H1, H2 ? H1

The ellipsoidal sliding body is described by using eleven-variable equation, the new version of simplified three-dimensional JANBU method, in which only one variable is used to represent the sliding angles along all the column bases, is presented and is adopted to calculate the safety factor related to given ellipsoidal sliding body; in the case of determining critical sliding body of soil slopes, a new optimization algorithm which takes good advantages of particle swarm optimization and harmony search is presented. Two actual slopes in three dimensions are studied using the proposed method in order to demonstrate the effectiveness and applicability of the proposed method. Comparative studies have shown that the proposed method is applicable to three-dimensional slope stability analysis.

Through ascertaining the rule which is employed to obtain the value limits of clayey surrounding rock classification indices, value limits of liquid index, natural density and plastic index in design phase are made certain based on analyzing existing research results, a long sequence test data of clayey surrounding rock and test data. The research results show that it is reasonable to ascertain the value limits according to the different conditions of classification indices as intensity ratio changing. While the depth of the tunnel is constant, consistent result, which can be received through statistic analysis and testing, is that intensity ratio decreases with liquid index increasing. If the value of liquid index is larger, the influence of natural density increasing on intensity ratio is inapparent. The value limits of liquid indices are 0, 0.25, 0.5; and 1.6g/cm3, 2.0g/cm3 for natural density; 18 for plastic index, respectively.

Since the uncompressible for red-sandstone embankment, the dynamiic compaction method is used and the 3D FEM model about improving red-sandstone embankment by dynamic compaction is established. The numerical simulation of whole dynamic compaction process is carried out; and the coutours of displacement & stress are obtained with explicit dynamic finite element program ANSYS/LS-DYDA. The results show that the orderliness of stress & strain is quite consistant with the experimental results. The mechanism of improving red-sandstone embankment via dynamic compaction as well as how to determine compaction parameters is also analyzed.Meanwhile,the results show that the effective influence depth is about 4~6 m, and the hammer’s contact distance is about 3.5 m, for hammers with tamping-energy is 1 200 kN•m and diameter is 2 m.

Cyclic loading history is an important parameter to the further dynamic characteristics of soils. A series of draining cyclic simple shear tests on an undisturbed silty clay are carried out; and the development of volumetric strains with the change of load cycles and shear strain amplitude is found out, as well as the correlation between the accumulated volumetric strain and the further dynamic characteristics. The test results show that the volumetric strains increase with the development of cyclic load cycles and the improvement of cyclic shear strain amplitude, and further more with the accumulation of volumetric strain, the dynamic characteristics of the clay soil are strengthened, which means that the dynamic shear modulus goes up and the damping ratio degrades. The effects of accumulated volumetric strains on dynamic shear modulus and damping ratio are analyzed; and some relevant correlation equations are proposed. With the adoption of two coefficients, respectively the coefficient of modulus strengthening and the coefficient of damping degrading, a constitutive model which can take the effect of cyclic load history into account is constructed based on a normal nonlinear model.

The construction process has an important effect on the behavior of the soil nailing. Based on the feature that the soil excavation precedes the nail installation and the facing construction in each step, excavation influential surfaces (EIS——the most likely slip surface when the latest excavation surface remains temporarily unsupported and the nails are not yet installed) is defined where the increments of nail tensile forces are the largest. The concept of excavation earth pressure (EEP——the earth pressure is supported by nails and acted by the soil block where the EIS is the edge during the excavation) is presented in the calculation of the unbalanced forces during the construction of soil nailing. Taking EIS and the increments of nail tensile forces as the main research objects, an analytical method is proposed to calculate the soil nail forces along the nails in different excavation phases according to the two functions of nails—to remain the slope balance and stable. By means of this method, the location and magnitude of the maximum tensile forces during the construction are estimated. The calculated nail forces of Experiment 1 of CLOUTERRE Project by this method agree fairly well with the experiment data.

Based on tests and numerical simulation data of overlength cast-in-place piles, the composition coefficient of pile shaft compression is obtained through back analysis; and a study on curve characteristics between composition coefficient and other parameters, the influence factors of composition coefficient, and the forecast of composition coefficient is carried out. The following conclusions can be drawn. Firstly, under ultimate bearing capacity, the change range of composition coefficient of overlength cast-in-place bored piles is 0.278 5－0.988. So, it is not rational to adopt 0.5 or 1.0 for composition coefficient. Secondly, the composition coefficient increases with the increase of load on the pile top, pile shaft compression, total pile shaft displacement and pile shaft rigid body displacement. The shape of composition coefficient versus load on the pile top curve is various. Thirdly, the correlation between composition coefficient and length-diameter ratio is not obvious. But in generally, the composition coefficient decreases with the increase of length-diameter ratio. For overlength rock-socketed piles in different sits, there are good correlation between composition coefficient and length-diameter ratio, while for overlength non-rock-socketed piles in different sits, the correlation is not obvious except for five piles whose correlation coefficient is 0.9901 in a site. Fourthly, the composition coefficient versus load curves whose Edt/ Ect are smaller are larger than the curves whose Edt/ Ect are bigger. Fifthly, the average correlation coefficient between composition coefficient and load on the pile top for many piles in six sites is 0.9776. So, these regression curves can be taken as important reference for the forecast of composition coefficient for these sites and similar sites.

A newly developed numerical method in geotechnical engineering, i.e. element-free Galerkin method (EFGM) or meshless method, as well as the moving least square method characterized by the local technique, is used to simulate the pile-soil interaction under horizontal load. In the present method, the discontinuous problem of material between pile shaft and surrounding soil is considered and resolved; and an EFGM calculation program is also developed by MATLAB. Based on the program, the deformation behavior of pile shaft under various magnitude of horizontal loads, types of surrounding soil and stiffness rations of pile shaft to surrounding soil is discussed in detail; and some qualitative conclusions are drawn. Through the application of the present method to an engineering example, the good agreement between the results by the program and that by the common FEM software (i.e. ANSYS) indicates that the present method has more advantages in such respects as accuracy and post-process convenience compared with those traditional numerical methods such as the finite element method.

Soil-water characteristics curve (SWCC) describes mainly the relationship of suction and volumetric water content of nonsaturated soil; it is very important to research the fundamental properties of SWCC. The relationship between SWCC and nonsaturated seepage curve has been studied based on theory and experiment. the features of SWCC and of nonsaturated seepage curve are studied by natural proportional rule; then the characteristics among SWCC and its differential curve, nonsaturated seepage curve, grain distribution curve are researched in physics and mechanics; the scope of constant index of SWCC and of nonsaturated seepage function is given; and their relationship is described. The experimental results show that the SWCC is influenced by lots of factors, such as: material compositions, plastic index, porous structure and stress state. The study of SWCC is very important to engineering construction.

The stemming length of blasting hole is an important blasting parameter that affects the blasting effect. Based on the practical engineering, the 3D FEM simulation models with different stemming lengths are built; and the fluid-solid coupling theory is introduced. After the ANSYS/LS-DANA simulation calculation and the comparison of the stress of the key parts, the classical blasting theory is verified; and the optimal stemming length is obtained. And it provides references and help to blasting numerical simulation.

Due to errors in handling slurry, concrete, casings, reinforcement cages and other factors, minor or major defects in piles can be introduced during or after pile construction. Therefore this paper aims to propose a procedure to estimate the statistics of multiple defects in bored piles using the Bayesian theory. A Poisson process is adopted to model the occurrence of multiple defects in bored piles. Moreover the formulae of updated mean rate of occurrence are derived with a consideration of detection uncertainties for coring examination. A modified Bayesian sampling method is presented to update the distribution of mean defect size. Then, a method to evaluate the detection probability of coring examination is formulated. Results from numerical example indicate that the detection probability has a significant influence on the Bayesian estimator of mean rate of occurrence. The mean rate of occurrence will be highly underestimated without consideration of detection uncertainties. The updated mean of mean rate of occurrence increases with increasing values of the number of detected defects, while the updated coefficient of variation of mean rate of occurrence decreases. In addition, the uncertainties in mean rate of occurrence and mean defect size can be reduced substantially through the use of prior information

In order to study the strength character of warm and ice-rich frozen soil, a series of uniaxial compressive strength tests of frozen clays with water contents of 20 %, 40 %, 60 %, 90 %, 120 % at temperatures of –0.3 ℃, –0.6 ℃, –0.9 ℃, –1.5 ℃, –5.0 ℃ were conducted respectively. The test results indicate that: 1) the type of stress-strain curves for the warm and ice-rich frozen clays(temperature: –0.3 ℃ to -1.5 ℃, water content: 60 %-120 % ) is strain-hardening, and the form of sample failure is plastic; 2) The compressive strength of warm frozen clay with water contents of 40 % to 90 % increases linearly with the decrease of temperature, the sensitivity of the strength of lower water content saturation frozen clay to temperature is higher than that of higher water content saturation frozen clay; at the water content of 120 %, the amplitude of the increase in compressive strength decreases with decreasing temperature; 3) when the temperature of the warm frozen clay is lower than -0.9 ℃, there is a most disadvantageous water content (at the same temperature, the compressive strength of the frozen soil at this water content is the lowest); when the temperature of the warm frozen clay is higher than -0.6 ℃, the strength increases with water content increasing.

The GIS-based distributed monitoring information management and early warning system for foundation pit has been developed to meet the need for monitoring information management, integration and sharing. The framework of the system is introduced and the main emphasis is placed on key functions of the system. Based on the GIS visualization technique the developed system implements functions as acquisition of multiple foundation pits geologic, design, construction information, monitoring point, monitoring apparatus, monitoring data and information of buildings around, etc. Furthermore the system implements functions as management, process, analysis, query, prediction, early warming of the information and automatic monitoring reports. The C/S ( Client / Server ) structure is employed for information sharing and team cooperation; and the system has great performance under network circumstances. All the features make it as a powerful information platform for foundation pit monitoring.

The influence of pile group loading on existing neighboring tunnels is assessed by using the finite element method with the aim of furthering the understanding of the interaction problems. Firstly, some parametric studies including foundation layout and clear distance between piles and existing tunnels are carried out using the 2-D plane strain approach. Then a case study of Pacific Square Ⅱ of which minimum distance between pile foundations from Metro No.1 in Shanghai is only 15m, is analyzed by using this approach. According to the results, this approach can satisfy the pile rows loading problems. The loading of piles causes global downward movement and squatting of the tunnel lining. And the horizontal displacement of tunnel lining is much smaller than vertical displacement. The tunnel diametrical distortions are occurred in this case. It is very disadvantageous because of the differential movement of the two rails of the subway tunnel. The bending moment distribution behaves clockwise rotation due to pile loading. The crown settlement of tunnel lining and maximum bending moment change reduce with the increasing of pile space and clear space between pile and tunnel.

On the bases of the plastic mechanical mechanism and the large strain, the early phase of fracture grouting is regarded as the question of cavity expansion in infinite soil. The stress distribution due to the cavity expansion in soil is considered as two zones. The deformation following little deformation in elastic zone and large-deformation in plastic zone is taken into consideration. The initial fracturing grouting pressure is the limited expansion pressure and the second fracture grouting take place when the large and small stress of soil is conversion. On the bases of the stress equilibrium equation and continuous boundary condition of stress and deformation, the stress distribution in the elastic-plastic zones, the terminal plastic zone radius and fracturing grouting pressure are obtained. According to the compassion, the result of the present theory is very near to that of the engineering practice.

Tunnel overloading safety can be gained by overloading experiment. In this paper, the overloading stability of forked tunnel is researched using 3-D geomechanical model test. The displacements, stress distribution and failure of surrounding rock are analyzed. And the model test is simulated by 3-D numerical method (FLAC3D) also. Model test result and numerical simulation result analysis shows that the side displacements increase and vault displacement vector changes from downwards to upwards with the side-pressure coefficient K. The stress of key points achieve high-point at K=3.5; the displacement changes suddenly when K≥ 4.0 and the maximum final displacement achieve 100mm. The plastic zone increases suddenly and surrounding rock at vault begin to crack and fall when K≥ 4.0. Test and numerical result shows that vault and side of forked tunnel are easy to fracturing; the overloading safety degree is 3.5.

Subcritical crack growth of double torsion specimens made of granite is studied by using Instron1342 type electro hydraulic servo test machine in air and in saturated water. The relations of mode-I stress intensity factor KI and subcritical crack growth velocity V are tested by double torsion constant displacement load relaxation method, and the subcritical crack growth parameters are obtained. The behavior of subcritical crack growth law is discussed under two conditions, and the subcritical crack growth parameters are compared. The results show that lgKI -lgV relations accord with linear rule under two conditions. The lgKI -lgV curves of saturated water specimens locate top left corner of those of air specimens. The slope of curve is smaller, and the intercept is bigger. The subcritical crack growth velocity of saturated water specimen is speeded at same stress intensity factor of air specimens, which implies that water speeds up the subcritical crack growth. The results correspond to practice.

Based on the framework of continuum damage theory, a damage model combining continuum damage mechanics with mesoscopic damage mechanics is built through defining the damage variable and describing the damage evolvement using the result of mesoscopic damage theory. For the damage of quasi-brittle materials under compression, continuous damage variable and its evolvement equation correlating with the mesoscopic damage mechanism are obtained; it is based on the hypothesis that the effective moduli from the macroscopic and mesoscopic damage analysis are equivalent. Then, the damage model combining continuum damage theory with mesoscopic damage theory can be developed. The analytical method has been proved to be feasible by the uniaxial compression experiment.

Considering the special condition of the six lanes large-span multi-arch tunnel in the Wanping Expressway, and choosing some representative cross-sections of Wujiazhuang Tunnel, their inner middle-wall's internal forces of the three-layer vertical middle-wall are monitored during the construction. Based on the monitoring data, and considering the interactive influences of different construction stages, the internal forces of the inner middle-wall are analyzed; and the mechanical characteristics during the construction are obtained. Then the safety performance of the Wujiazhuang Tunnel's inner middle-wall is evaluated. It is shown that the inner middle-wall's internal forces are affected by the different excavating sequences, especially in the stage of low bench excavations, however, the inner middle wall remains stable during the multi arch-tunnel construction.

Differential settlement of the subgrade is the main problem encoutered in the reconstruction of old road to expressway. Numerical analysis indicates that the treatment to new nature ground is the key to decreasing the differential settlement. Dynamic compaction is an effective method of improving ground. In order to optimize its construction parameters, dynamic pore water pressure and dynamic soil stress rising during the dynamic compaction; and the dissipation of excess pore water pressure are measured and analyzed. For weathered soil subgrade, test results show that the maximum tamping number shouldn’t exceed 4 and ironing tamping can be carried out just two days after the major tamping.

The original in-situ stress is a basic parameter for the stability of surrounding rock support in underground engineering. The measurement and calculation are presented to determine the 3D in-situ stresses for Tangkou Mine. The surveys were carried out at different structural positions and depths and in different rocks using hollow inclusion measuring method in the ventilated and the west assistance conveyance stone door. The measuring depth reaches 1024—1030 m scope. Based on the determined in-situ stresses，their distribution characteristics are obtained by using theoretical analysis. The relationship between in-situ stress and geological tectonics is also studied; and some manful conclusions are obtained. The influence of in-situ stress on the roadways stability is analyzed elementarily so as to provide foundation parameters for supporting structure design.

Speedy development of city buildings and full use of subterranean space have accelerated the development of deep foundation pits; and that have also brought a mass of geotechnical engineering problems, such as soft soil foundation pits. When the anchor piles are adopted for a foundation fit, displacement of the retaining structure and soil can be controlled effectively; and it is propitious to excavation of earth, showing the extrusive active purpose. A kind of calculation models for anchor piles brace structure is described emphatically; and quite satisfied results are obtained via a comparison and analysis of specific monitoring.

The maximum shear modulus is a fundamental parameter related to the mechanical behavior used for analysis of dynamic behavior and aseismatic design of geotechnical structures of soft clays. The previous methods to get the maximum shear modulus in China are generally from the laboratory test which is of time consuming and lower accuracy. This paper performed the measurements of shear wave velocity using the downhole and seismic piezocone tests on the background of expressway engineering of the Quaternary Lixiahe ages-old lagoon facies soft soils in North Jiangsu. Based on the shear wave velocity test data from the downhole and seismic piezocone tests, empirical correlations between the maximum shear modulus Gmax and parameters derived from piezocone measurements are developed. It is shown that the piezocone tip resistance and pore pressure parameter can be used for a preliminary estimate of the maximum shear modulus Gmax of soft soils.

Based on the in-situ test of pile-box foundation for a tall building, variation charateristics of box foundation, including steel stress of base slab, deformation and settlement of foundation, earth pressure under box, and load sharing ratio between pile and box, etc. are described. The results indicate that the steel stress of base slab is only 8% of its design strength; and settlement of foundation is only 20% of the theoretical calculaed value. Overall flexure value of foundation is only 0.319 ‰; so local flexure is main influence factor on base slab. Soil can only share 11% of the load above and the contact pressure is very small comparing with its resistance capacity. In order to improve earth pressure under box and reduce construction cost, enlarging interals of piles is an effective way.

A simple model for evaluating liquefaction probability using standard penetration test (SPT) data is developed based on logistic regression analysis of 200 sets case histories of 23 earthquakes. The proposed model uses corrected blow count (N160cs) and cyclic stress ratio (CSR) as input parameters. When liquefaction probability level is equal to 50 % as a limit state, the formulation of cyclic resistance ratio (CRR) was proposed with an exponent and the proposed model’s reliability for liquefaction and non-liquefaction estimation of saturated sands is 85.71 % and 76.14 %, respectively. Comparisons of the proposed probability model with previously proposed deterministic and probabilistic approaches are performed to demonstrate the slightly conservation, because the new test data and modified coefficients are used in this analysis, so some sources of uncertainty and variance are eliminated. In order to correlate deterministic approach and probability approach, the relationship between the factor of safety against liquefaction and liquefaction probability is proposed. Five case records are further analyzed to demonstrate the feasibility and reliability of the proposed method.

The correlation between blow counts of dynamic penetration tests and shear wave velocities is researched by analyzing abundant numerical statement in cobble soils. The regression equations of quadratic polynomial, exponential function and power function are derived, of which the exponential function regression equation is more suitable for the correlation. The feasibility of the exponential regression model is verified by the results of surface wave testing and dynamic penetration testing in a similar site. It is shown that the surface wave velocity method can be used to not only determine the ground conditions, but also quantitatively evaluate its bearing capacity.

Through the large general nonlinear finite element analysis software ANSYS, the steel fiber reinforced concrete (SFRC)deep beams are analyzed. The constitutive model of concrete and reinforcement, as well as the properties of their elements are discussed in detail. During the simulation process the ANSYS parametric design language (APDL) is used to set up the finite element model; besides, the model of bond stress-slip relationship between steel bar and concrete which based on the Nilson bond stress-slip relationship theory is established, The simulation analysis and test results demonstrate that the good agreement can be found between simulation and test results, if Solid65 and Pipe20 element are used to simulate the SFRC and reinforcement respectively; and the three-dimensional nonlinear spring element Combin39 can simulate the interaction between steel bar and steel fiber reinforced concrete very well.

Numerical modeling was used to analyze the uplift behavior of normal piles with straight shaft and pedestal piles. The contact problem between pile and soil was solved by direct constraint method. In this procedure, the motion of the bodies is tracked, and when contact occurs, direct constraints are placed on the motion using boundary conditions-both kinematic constraints on transformed degrees of freedom and nodal forces. The Coulomb friction model was used to treat skin friction force of pile shaft. Soil were modeled as parabolic Mohr-Coulomb material. Reasonable initial stress was obtained by using subroutines. The dynamic nonlinear modeling of uplift procedure was done by applying displacement boundary condition on pile top. The result of in-situ full-scale pile test was used to verify the parameter for computation. Then the distribution law of axial force, friction force, displacement and plastic zone of soil around enlarged base were studied.

Process of cavity formation and propagation of the stress wave from single helix parallel hole cut blasting are analyzed with ANSYS/LS-DYNA 3D nonlinear dynamic finite element software. The distribution of element Misc. plastic strain, node Misc. velocity, node time-acceleration history curve and the sketch of the blasting cartridge’s volume ratio during the process are simulated. It is concluded that the process of the blasting wave between theory and simulation is similar and the simulated blasting wave radiating in the form of cylinder . Moreover, the final blasting result has related with the distance from the hole to the bomber; therefore the cavity formation and stress propagation can be visualized. It is expected that the result of the study may provide a positive help to blast design optimization of parallel hole cut blasting.

For calculation of soil slope stability, the slice method as a simple and practical method is widely applied to many engineering projects. The traditional slice method usually adopts vertical slice, while the slice method based on gradient slice and equal central angle adopts gradient slice, which makes the hypotheses of forces between the slices become more reasonable. Besides, with the redefined stress level safety factor, equilibrium equations can be solved more simply and quickly, and the differences of slices’ stress state will be reflected in the calculated result.