Soil-water characteristic curve for unsaturated loess considering temperature and density effect is studied by test. The test data show that the variation of soil density, compared with variation of soil temperature, can result in great change of soil-water characteristic curve. For loess sample in certain water content, the change of matrix suction resulting from variation of soil temperature is less in bigger water content, and is more in lower water content. The more is the variation of soil temperature, the more is the change of matrix suction. After analyzing the test data, taking the soil density and temperature into account, the formula is obtained to determine the matrix suction of unsaturated loess. The test and calculated data verify the reliability of the formula.

Creep behavior of soft clayey soils under consolidation by vacuum, surcharge, combined vacuum-surcharge preloading is investigated by using a new improved triaxial apparatus. Influence of the duration of loading and the rate of loading, as well as loading magnitude etc on compressibility of soft clay are demonstrated; meanwhile, relationship between axial strain (rate), volumetric strain (rate), deviatoric strain (rate), stress ratio amd time are analyzed; Results show: The relationships of lg and lg versus lgt are nonlinear, but part of the relationships may be approximately considered linear; A hyperbolic equation can be used to express the changes of the deviatoric strain with time for different stress ratios; The two hyperbolic equations for deviatoric strain and deviatoric strain rate with time have interesting features. The validation of it has been examined using results of creep tests of soft clayey soil samples of Wenzhou.

Firstly, aiming at the deficiency and limitation of traditional damage theory and starting with the discussion on rational definition of damage geomaterials, a new damage model suiting for saturated soils is established by discussing the microcosmic mechanical mechanism of damage of saturated soils. Secondly, a statistical damage constitutive model which can simulate the full process of deformation of saturated soils under special confining pressure has been erected by introducing statistical damage theory; and then the method for determining the model’s parameters is also developed based on experimental curves of triaxial compressive test of saturated soils. Finally, a rational revised technique for the model has been developed through investigating the relations between the model’s parameters and the confining pressure. Finally, a unified statistical damage constitutive model for saturated soils has been obtained which can be applied to different confining pressures. It is indicated by comparison between theoretical and experimental results that the model is reasonable which can not only reflect the full process of deformation of saturated soils but the effect of water in soils on the deformation of saturated soils.

Laboratory tests of direct tension and compression were conducted for three rock types with a testing unit that can perform both compression and direct tension on a same rock sample. The results showed that for most rock samples, the obtained Young’s moduli in compression EC were greater than those in tension ET. For Gaofeng limestone, the EC/ET ratio was 1.1; for Gaofeng pyrite, the ratio was 1.4; and for Songshujiao marble, the ratio was 2.5. The average values of Poisson’s ratios in compression were also greater than the values in tension. It was also found that the tangent Poisson’s ratios in tension decreased with the increasing applied loading, which was opposite to the behavior in compression.

In project it is thought that the soil with saturation over 80% is called saturated soil. But the saturation of the sample produced in the indoor experiment reached over 95 %. In fact the dynamic parameter of the latter attained through the test is different from that of the former. In this paper, the cyclic simple shear tests of the saturated soil of saturation 95 %, 92 %, 88 % and 83 % were carried out under the consolidation pressure of 50 kPa, 100 kPa and 200 kPa respectively. Of four different sorts of soil sample under three different consolidation pressures, the maximum dynamic shear modulus Gdmax, the maximum damping ratio Dmax and the dynamic modulus ratio G/Gdmax-?, the damping ratio D/Dmax-? generalized curve were attained and analyzed comparatively. The results show that under the same consolidation pressure, the value of the Gdmax, Dmax, G/Gdmax shrink according to the growth of saturation; but the damping ratio D/Dmax, quite on the contrary, becomes larger with the raise of saturation, with the increasing of the consolidation pressure, the differences among the Gdmax, Dmax and G/Gdmax-? decrease gradually. Finally, this kind of phenomenon and its causes are discussed and analyzed.

The infiltration, transportation and transformation of a main contaminant (ammonia nitrogen) in the Taihu Lake sediment through a clayey soil layer are studied experimentally. The permeability coefficient and diffusion coefficient under different pressures are determined through the laboratory tests of stimulation test of infiltration and dynamic soil column test. The adsorption coefficient of ammonia nitrogen to clay soil is also obtained through the static adsorption test. The test results show that the ammonia nitrogen is mainly adsorbed and obstructed by the clayey soil layer in a facility for the dredged sediments from Taihu Lake.

Organic matter often influences the effect of cement solidified soil, humic acid as the main composition of organic was chosen to study the effect on solidification. Test results show that humic acid hamper the hydration of cement, there exists a critical humic acid content of 3.62 %, when the humic acid content is higher than the critical value, continue increasing of organic matter content has little effect on unconfined compressive strength and failure strain, while the plasticity of solidified soil enhances with the humic acid content increases.

Nowadays, vibroflotation without additional backfill treatment method has been widely used in the treatment of foundations at home and abroad. Because of its merits such as the simpleness of construction technology, the applicability and without ‘three materials’ (wood, reinforcing steel bar and cement), it has become one of the most common ways for weak foundations, especially for sands. By giving a review of the reinforcement mechanism, applicability and construction technology of vibroflotation without additional backfill treatment method, the research situation of three key factors in vibroflotation without additional backfill treatment method has been summarized. What's more, the latest technical progress about the technology----the application in the treatment of fine sands and reclaimed silty sands has been discussed emphatically. Finally, the existing questions and developing direction in study are pointed out.

On the basis of simulated draining condition of filter pressing on soda residue soil, the draining consolidation experiment is carried out under vibration by using the dynamic triaxial tester. Making a comparison between the results of hydrostatic pressure consolidation experiment and that of experiments under different confining pressure, amplitude and frequency, the vibration effect on consolidation behavior and drainage is analysed; and the draining mechanism under vibration is drawn. It is indicated by the experiments that the rate and amount of drainage can be obviously improve by vibration; and that the draining effect of soda residue soil is evidently affected by confining pressure, amplitude and frequency. Thereof, the cause that draining effect of existing filter-press technique is dissatisfactory on soda residue soil is analysed. The results of experiments and mechanism analysis are of guiding singificance and practical value for improving existing filter-press technique.

Most of debris-flows are triggered by landslide in Jiangjia Ravine, widespread shear failure of slope is the first step in the three processes of debris-flows triggered by landslide. There is widely distributed gravelly soil in the triggering and sedimentary area. The strength behaviour of the gravelly soil is important for mechanism of debris-flows triggering in Jiangjia Ravine. Because the large grain size, coarse-grained content and specimen size have much effect on the gravelly soil strength behaviour, the large scale direct shear apparatus is used to test direct shear strength behaviour of the gravelly soil with different coarse-grained contents. As a result ,it is found that there is no peak in the curve of relationship between shear stress and horizontal displacement at dried density equal 2.0 g/cm3 and water content equal 7 %, except for the specimen of coarse-grained contents equal 74.31 % under lower upright stress(50 kPa, 100 kPa). The shear modulus when horizontal shear strain is 0.02 increase with increment of upright stress at the same coarse-grained contents. And increase with increment of coarse-grained contents at the same upright stress, which is larger at lower upright stress than higher stress. Friction angle increase with increment of coarse-grained contents. Cohesion drop to the minimum at coarse-grained contents equal 48.7 %, and decreases with increment of coarse-grained contents as coarse-grained contents litter than 48.7 %, however cohesion increases obviously with increment of coarse-grained contents when coarse-grained contents larger than 48.7 %.

Combined the integral representations for displacements of semi-infinite elastic foundation subjected to arbitrary vertical dead load with the bending analytic solution of an elastic rectangle plate with four free edges rested on semi-infinite elastic foundation to develop an efficient calculating technique used to resolve the foundation displacements. Based on carrying on a great quantity of numerical calculation analysis of some instances, the displacement distributed regularities are given for the foundation beneath the plate with four free edges rested on semi-infinite elastic foundation along the foundation depth. Based on the distributed disciplinarians of foundations’ horizontal displacement and vertical displacement, proposed the assumptions that the foundations’ displacements change according to the specified functional relation along the depth. Considered horizontal displacement of the foundation beneath the plate, utilized the plate and foundation system’s principle of minimum potential energy, operated by means of the variational principles, and gave out the refined model for plates on elastic foundations. This model is reduced to double-parameter model under not considering the foundations’ horizontal displacement beneath the plate. The approximate boundary conditions of plates on this refined model of foundations are given.

Creep curves of different shear forces have been obtained from creep tests with consolidation pressures of 300, 500, 625, 800 and 1000 kPa separately for the slip band soil of Dayantang landslide. Burger’s model is employed to simulate the viscoelastic procedure. The method gotten the parameters of Burger model has been introduced and used. The long term strength has gotten from the isochronal curves. The visco characteristics have been analyzed from the results of the creep tests. The relationships between the parameters of Burger’s model and the shear stresses and consolidation pressures have been discussed. A conclusion has been drawn that the long term strength is 0.76-0.77 times the slow shear test.

The two main factors which influence structure of soil are the way of uniting and arranging among soil particles. Furthermore, water and load can change the way of uniting and arranging among soil particles to destroy the structure soil. In this paper, the different tests are done to analyze the mechanic characteristics of K0-consolidation structural loess under critical state, which will be a base to propose a reasonable model to explain the structural characteristics.

The contact relations between rockfill and concrete can be simulated truly by Clough hyperbola constitutive model, and the contact state can also be simulated by augmented Lagrangian multiplier algorithm accurately. Clough hyperbola constitutive model has been applied on jointed element with no thickness and Desai interface element with thickness successfully. Those merits and success experiences are absorbed and combined to be applied on solution of contact friction problem. Sequential quadratic programming method (SQP) is introduced based on augmented Lagrangian multiplier contact algorithm in the same time. Numerical algorithm and implementing steps that Clough hyperbola constitutive model is inducted into augmented Lagrangian multiplier contact algorithm are derived in detail. The computation results of numerical example and the project example show that the stress and deformation state between contact surfaces can be simulated truly with the method.

To cut down the serious environmental problems caused by tunnel drainage with no control as possible, the waterproof criteria of “block off ground water and limiting discharge” that is controlled drainage should be adopted in mountain tunnels with high water level. But how is the mechanical character of the surrounding rock with controlled drainage? It is a key and urgent problem in tunnel design now. An analytical model is established for the first time to analyze the mechanical character of the surrounding rock with controlled drainage; and a series of equations are deduced. The variation of the mechanical character of the surrounding rock with controlled drainage is analyzed; and the corresponding ground reaction curves are drawn; this is a theory base for tunnel design with controlled drainage.

Based on researching the load test of the cement flyash gravel(CFG) pile composite foundation, the bearing capacity and deformation characteristics of CFG piles are analyzed. And through the medium of the earth stress cells buried above the cushion and below the cushion, tested stress characteristic of CFG piles and the soil stress between piles are obtained. According to these measurements, the vertical stress of the CFG pile is about 16 times bigger than the earth stress between pile when the working load is 210 kPa. Along with the increment of working load, the sharing load of the pile increases fast, but the sharing load of the soil between piles increases slowly.

The Rayleigh waves on layered systems are of multimode. The transient responses of the surface are comprised of ones of multimodes. In the near field where propagating distance is small relative to the wavelength, the propagating velocities of modal responses vary with the distance from the loading center, and approach to the phase velocities of modes in the far field. Affected by higher Rayleigh wave modes in the surface wave field, the effective phase velocity obtained by spectral analysis of surface waves (SASW) is not corresponding to the phase velocity of the fundamental mode. The effective phase velocity varies with the propagating distance. In the near field, the body waves have great influences on the effective phase velocity. The theoretical effective phase velocities can be got by spectral analysis of the discrete solution of surface displacement; the layer parameters can be evaluated by matching the measured phase velocity data with the theoretical ones. Influences of the near field as well as higher modes on the effective phase velocity are taken into consideration in this method.

The conception and method of multi-grid is brought forward; the mesh of finite element analysis and the sliding surface’s mesh are deal with as two unattached mesh, and the sliding surface’s mesh can go across any finite elements. In this way, discretionary sliding blocks’ analysis can be done with a set of finite element mesh and a set of stress results. The calculation efficiency of multi-grid method is emphatically analyzed. The 3D multi-grid method is applied to a typical 3-D quadrangular and Jinping Project high slope. Numerical results show that the properly adjusting the mesh of the finite element models and sliding surfaces can effectively improve the precision and calculation efficiency of this method; especially for the large scale structure. Finally, the stability of Jinping Project high slope is analyzed using the second way of multi-grid method.

Strength reduction technique (SRT) is applicable in evaluating the stability of slope in most cases, because it doesn’t need to assume the location and shape of failure surface. But SRT considers only the elastoplastic properties of rock and soil media, neglecting the rheological property. Rheology is basic mechanical property of rock and soil medium. Having some relations to rheology, many slopes occur large deformation or even lose stability in fact. Based on SRT, the effect of rheology on slope deformation and stability is analyzed. The final research shows that the rheological properties of rock and soil media make deformation of every point more large; furthermore it makes slope more dangerous.

In order to reveal the mechanism of disintegration deformation and failure of debris landslide under rainfall, connected with the engineering concrete example of medium and deep debris landslide, through the collection, arrangement and analysis of related data, the site investigation and exploration of engineering geology, indoor and outdoor physico-mechanical test, adopting the analytic means of mathematic statistics, unbalanced-thrust method and three-dimensional contact elastoplastic FEM together, and the theory of groundwater pipe network drainage system(GPNDS), its stability and process of the deformation, disintegration and failure under rainfall were analyzed, which the main disintegration deformation and failure mechanism and general mechanics mechanism of medium and deep debris landslide under rainfall are revealed. The research result shows as follows: First, long time proper strength steady rain or intensive rainfall is the main factor of its instability and failure. Second, adopting contact elastoplastic FEM thinking over the action of rainfall may better reflect the actual locating state and sliding process of debris landslide under rainfall; and it may afford one method that can be used as a reference of stability analysis, accurate evaluation and forecast of the debris landslide.

The elastic wave equations of fluid-saturated porous media are solved by the time-domain explicit finite element method that consists of explicit step-by-step integral format and local transmitting artificial boundary. Then, the elastic dynamic response of fluid-saturated porous media under input earthquake wave is calculated and analyzed with the method mentioned above. At last, the calculating results of elastic dynamic response of fluid-saturated porous media are compared when the seepage of fluid in the cavity is taken account of or not in order to find out the effect of seepage of fluid in the cavity on the dynamic response property of porous media. Calculatiing results show that the figures of elastic dynamic response time history of porous media are same as the figures of input earthquake wave; and the time when the peak value of elastic dynamic response appears corresponds to the time when the peak value of input earthquake wave appears. The seepage of fluid in the cavity has a remarkable effect on the elastic dynamic response property of porous media. In the meanwhile, numerical calculations indicate that the time-domain explicit finite element method is effective for the calculation and analysis of the elastic dynamic response of fluid-saturated porous media.

Traditionally discontinuous deformation analysis(DDA) method adopts linear displacement mode, which has many efects. To get exact stress field of the block, some improvements are developed including: directly using higher order polynomial as displacement function, sub-block division, and adopting the block-finite-element displacement mode, etc.; but these are not efficient in practice. It is suggested here to introduce meshfree interpolation mode, namely natural neighbor interpolation of natural element method, which has interpolation property, very easy to impose exactly essential boundary condition or material continuity condition; moreover it depends on no meshes and has good calculation precision as well as efficiency. Based on this mode, further analysis can be done on larger block bending or crack exploration etc to overcome defects of the linear mode as well as other modes.

The squeezing effect can be caused by the construction of jacked piles. The behavior of soils surrounding a jacked pile is changed; and it has an influence on the load bearing capacity of the pile. The jacked-in process of a single pile is simulated by FEM. The displacement and stress of the soils surrounding the pile are calculated. In addition, stress path controlled triaxial tests were carried out to simulate the stress state of the soils after the construction of a jacked pile; and the mechanical characteristics of standard sand under subsequent loading were studied. Furthermore load transfer method based on finite difference calculation is used to predict the load-settlement curve of single pile with and without consideration of the squeezing effect. It is shown that the axial and radial stresses both are affected significantly; and the radial effect is more obvious than the axial effect. The shear modulus and strength of the soil surrounding the pile increase; and the influence zone is essentially the same. The load bearing capacity of a single jacked pile increases in consideration of lateral squeezing effect. The design method of jacked piles is conservative.

During construction for tunnel, the tunnel is zoned along its axial direction. With experts’ experiences to assigning the geological condition of surrounding rock and the scale of excavation, and taking the convergence measured in all zones as the impersonal standards in different times, the dynamic degree of reinforcement demand is calculated. Using the degrees of reinforcement demand, the first supports in different zones and in different times are assessed. For application to Qiuwoliang tunnel, the stabilities of supports in different zones and in different times are evaluated from the degrees of reinforcement demand, and the criterion for safe is provided in construction.

Permeability heterogeneity in plane is an important characteristic of fluvial facies formation. If it is developed using conventional five-spot well arrangement with equal-well-space, the injection water often fingers along high permeability strip quickly, which results in early water-breakthrough and quick water-cut increase for parts of the wells, while wells in relatively low permeability strips can not be flooded effectively; water does not break through as total water-cut for a well group reaches 98 %. That is, the reservoir can not be flooded in equilibrium, and the developing result is not good. The design formula for well space of vectorial well arrangement for permeability heterogeneity in plane is derived based on porous flow theory. According to the well space formula of vectorial well arrangement, the physical models are made to carry out the contrastive water flooding experiments which are used to check the validity of vectorial well arrangement. The results indicate that the vectorial well arrangement can improve the plane sweep factor for reservoirs with permeability heterogeneity, and raise the efficiency of injection water; moreover, it could improve the developing effect greatly.

The final settlement of such projects as highway, railway etc. is often predicted by way of the result of settlement monitoring. Hyperbolic method is adopted in settlement prediction most often. It is proven by many projects that the predicted settlement using normal hyperbolic method that is incremental hyperbolic method is often less than real final settlement. Result of long time settlement monitoring is needed by incremental hyperbolic method. Based on many projects of settlement monitoring and deep study of incremental hyperbolic method, total hyperbolic method and TS hyperbolic method are proposed. It is proven that the predicted settlement by the two new methods is almost same as that by incremental hyperbolic method and the two new methods can be used for projects whose time of preloading is short.

Slope hazard is a serious natural hazard next only to earthquake and floodwater. It has brought about great losses to the economic and social development worldwide. Each year it causes a loss up to billions of dollars in the whole world. A striking amount of money has been spent on the prevention and redress of the hazard; and much more losses have been incurred indirectly in addition. Many slope treatment cases have been already accumulated for over a long time of slope treatment, but much data information of these slope cases are not completely used and developed, which results in huge resources waste. For this reason, applying the methods of the data mining, knowledge discovery in databases and recurrent self-organizing neural fuzzy inference network, an intelligent evaluation system of slope stability based on case mining is presented. Meanwhile, practical applications illustrate validity and feasibility of the system.

A specified problem is adopted here to study wave propagation properties in a solid of different states i.e., elastic, elastoplatic and strain localization. When the strain localization occurs, or solution of governing equation is in bifurcation, the classical constitutive model can not be used to analyze further material failure. Gradient dependent constitutive model, contrarily, can improve the capability someway, but characteristic dimension employed in material sacrifices high frequencies. And the capability of viscosity dependent constitutive model relies on what viscosity compose, if density and modulus, it can improve; if density only, it cannot.

Defects present in a pile may not always be detected by integrity tests, which will adversely affect safety of the pile. This paper aims to propose a methodology to quantitatively evaluate the reliability of pile foundations considering the possibility of pile defects presence. Taking the toe debris present in a single pile for example, the probability of failure of the pile considering the possibility of toe debris presence is formulated by integrating the probabilities of failure for an intact pile and a pile with toe debris systematically within the framework of the total probability theory. The pile capacity reduction factor is presented to account for the effect of toe debris on the pile capacity. Moreover formulae for calculating the bias factor and coefficient of variation of the pile with toe debris are derived. The results indicate that the impact of the possibility of toe debris presence on the reliability of piles can be quantitatively evaluated using the proposed method in a rational way. The reliability of the pile is adversely affected by the presence of toe debris. The reliability index of the pile with toe debris decreases with the thickness of toe debris and the pile diameter; and it increases with the pile length. When the possibility of toe debris presence is not taken into account, the safety of the pile is highly overestimated. The reliability of piles can be highly improved with the implementation of pile integrity tests.

The design of segments is still one of biggest problems in the design of metro which are required to be solved. For building calculating model of segments, the effects of joint and ground reaction on the structure are considered mainly. We improve simplification of joint in the calculating model of segments, and deduce the formulae for solving inner forces and displacement problems in the improved model with routine method. Taking Beijing Metro Line No.10 for example, the routine method model is analyzed and compared with its improved model; and the results of numerical solution method are analyzed by comprehensiveness and verification. The study results show that the formulae derived are reliable, which are significant to the design and construction of tunnel segments in theory and practice.

Surrounding rock system is of high nonlinear and complexity, and there is no unified cognition for its stability criteria. catastrophe theory is used in the study on outside control condition when catastrophe happens to system state, and mainly expatiate on how nonlinear system tend towards system character catastrophe from continuous gradual change state. Catastrophe theory is used in surrounding rock instability criteria to illustrate its catastrophe condition theoretically. Energy catastrophe criterion and entropy catastrophe criterion are applied to analyze system instability based on physics; displacement module catastrophe criterion and yield zone area around cavern catastrophe criterion and generalized viscoplastic shearing strain catastrophe criterion are applied to analyze system instability based on intuitionistic judge condition (key place displacement, yield zone area around cavern and generalized viscoplastic shearing strain). Above five criteria are respectively applied to analyze surrounding rock stability of a underground cavern section, according to the condition of system catastrophe; system instability is judged from different aspects; and it may provide reference for engineering design and construction.

The transmission tower is located in Xiamen City, China, which is founded on weak, uneven highly compressible soils and its inclination has been increasing after construction. The technologies carried out to explore the applicability of the procedure for the stabilization of the leaning transmission tower are described. Firstly the causes of the inclination and the impact of the inclination on the tower are analyzed; the economic and effective stabilization scheme is brought forward base on it. Secondly the key technologies are discussed; and the future research direction about this issue is pointed out.

A scientific and reasonable design of safety thickness of roof is the basis for stoping the orebody No.92 which under the overlap zones in Tongkeng Mine. Based on analyzing the stability factors influencing the roof of orebody No.92, the finite element model is set up; and the simulation is conducted repeatedly. Then value of safety thickness of the roof in conformity to various groups of affecting elements is worked out. According to the simulated results, the curves between every factor and safety thickness of roof are drawn. A mathematical forecasting model of safety thickness of roof under the complicated backfilling, which considers effect among most of the factors, is obtained by stepwise regression multianalysis. The results which combine engineering practice with numerical simulation validate the feasibility of the forecasting model.

In accordance with the interval shield tunnel of Nanjing Metro, the longitudinal ground settlement is theoretically analyzed. The area of longitudinal ground settlement by shield driven in Nanjing Metro is firstly presented; and the percentages of different course are summed up. In view of the complexity and instability of the information of ground settlement, the longitudinal ground settlement is considered as a stochastic process. Based on the delayed difference equation, the model for dynamic prediction is proposed. The predicting results, compared with the monitoring data, indicate that the model has high accuracy.

The bamboo-truncating tunnel portal’s structure is at complicated 3D stress condition, so 3D numerical calculation method is necessary to used for correct result relatively. For the simplifying calculation model, the trial was carried out for up bamboo-truncating tunnel portal which with the slope 1: 1.5 in Class Ⅴ surrounding rock. Firstly, the model test result was used to proof the arch crown surrounding rock stress which gained by 3D numerical analysis, both have good compatibility. Secondly proceed from the structural stress character and the distribution of surrounding rock stress, the inner force controlling cross-section of structural transverse and longitudinal direction were gained. Through the research, the relationship between q and of arch crown load in each pressure distribution figure was also obtained. Furthermore, the pressure distribution graphics in transverse direction was plotted; and load value calculation methods in longitudinal direction was provided. Therefore, the calculation model was simplified from 3D numerical structural calculation to load-structure model with transverse and longitudinal direction to calculate its inner force separately.

According to new explanation about the m-method in Code for Pile Foundation of Harbour Engineering Supplement and the test pile data of two large diameter rock-socketed steel pipe piles in a wharf, the power function relationship between the constant m value and pile head deflection is concluded; and even the behavior of pile reaction under the influence of m value is obtained too. These can reach a conclusion that the m values suggested in the code can not be used in the case of large deflection. Therefore, by collecting lots of test pile data, it is necessary to establish the corresponding relationship between the m value and large deflection under different soil conditions based on that relationship described in this paper. These results can help to provide reference for lateral loaded pile design.

A series of numerical tests for soil-nailing structure in the sandy, silty and soft soil media are performed. Test results show that, in soft soil medium, the pit displacement is much larger than sandy medium, and the failure mode will change from overturning mode of sandy soil to flowing mode of soft clay; and the structure can not meet the demand of bearing capacity. Among soil parameters, c & ? values are the main factors causing above-mentioned change of failure mode; otherwise K0 value mainly change the magnitude of displacement. Among supporting parameters, nail-density evidently controls the displacement of soil between two rows nails. Nail-length remarkably controls the displacement of upside soil in sandy medium and of underside soil in soft soil medium respectively. The influence of nail-rigidity is embodied as that of rigidity ratio of nail to soil, which is not basically controlled by soil type, but reinforcing bars. Also, the critical supporting parameters are achieved.

State equation method for calculation of seepage-stress coupling field is developed. First the Biot equation is meshed by finite element method in the spatial domain; and the state equation is used to describe the control equation in terms of a plane strain problem. Then the iterative formula for calculating the displacement at the node is deduced by using the fine integral method. Example shows that the results are good in harmony with the exact results; and that the method could save lots of time as compared with the traditional method.

The mechanism of deformation and failure of the nearly horizontal strata landslide is studied from lithologic characters and inducing factors, and the start-up of these landslides is mainly due to sustained rainfall or intense rainfall. From the point of view of mechanics, the start-up criterion of the landslide is discussed; also critical depth of fracture water is deduced. Studies indicate that the effect of the fracture water is conditional; if the thickness of sliding mass is a constant, when the length of sliding surface exceeds a fixed value (safe length), the depth of fracture water has little effect on the stability of the slope. For different length of sliding surface, the critical depth of fracture water is calculated for shallow, medium-bedded and thick-bedded landslides respectively.

The density of groundwater in the surrounding rockmass of a geological disposal repository of high-level radioactive nuclear waste varies with the solute concentration, which will influence the thermo-hydro-mechanical processes in near field and far field of the saturated-unsaturated porous media. At the same time the temperature field and the stress field will also exert actions on the migratory of nuclides and solutes in groundwater. Considering these two factors the relevant momentum equilibrium equation, the continuity equation for water, the energy balance equation and the percolation and migration equation are established and introduced; and a 2D code of finite element method is developed for analyzing coupled thermo-hydro-mechanical-migratory phenomena in porous media. Through a numerical computation for the multi-field coupling progress after nuclide leakage in an assumed nuclear waste repository, the distribution and change of the temperature, stresses, pore pressures and nuclide concentrations in the near field are investigated. The results show that the established model and FEM code can be used to simulate coupled thermo-hydro- mechanical-migratory phenomena, so as to have certain practicality.

The virtual multi-dimensional internal bonds(VMIB) is a multiscale mechanics model developed from the virtual internal bond(VIB). VIB considers solid material to consist of randomized ‘material particles’ in microscopic. The material particles are connected with virtual internal bond. The macro constitutive relation is derived from a given cohesive law between material particles. Different from VIB, a shear effect is introduced into the interaction between material particles in VMIB and the macro constitutive relation is derived in terms of bond stiffness. Owing to accounting for the shear effect, VMIB can present the diversity of Poisson ratio. According to VMIB, the macro response of material results from the micro bond evolution. The mechanical resistance of rock material subjected to confining pressure is considerably strengthened and the failure under such conditions is usually of the shear kind. The underlying micro mechanism of these macro presentation is that the evolution of bond stiffness is governed by the normal and shear deformation of bond itself while the evolution velocity is subjected to the stress state of the microelement at the continuous level. To describe this micro evolution mechanism of bond, a phenomenological evolution function of bond is proposed. By this evolution function, the fractures of brittle materials subjected to confining pressure can be simulated. However, as a tentative application, the presented method couldn’t represent the plastic flow phase in the complete stress-strain relationship since the plastic deformation is not accounted.

It is well known that study on stress and abutment stability of high arch dam under complex environment plays an important role in dam construction and operation successfully. High arch dam studied in the paper will be constructed in a complex geological site, where a large number of faults, altered rock, mantle rock existing in the dam foundation and abutment, which will yield asymmetrical displacement in both abutments, increasing compression deformation and bearing capacity limit of abutment so as to influence normal operation state and decrease stability of dam abutment. Then 3-D finile element analysis is applied to the arch dam and abutment under different operation modes, studying stress and displacement of dam and dam abutment corresponding to their distributing features, and analyzing possible failure pattern, process and mechanism. The results illuminate the arch dam is instable when unreinforced; so reasonable reinforcement measures are adopted in the arch dam including six actuating holes in the right dam abutment and anchor holes in the left dam abutment. And then 3-D finile element analysis is applied to the arch dam and abutment after reinforcement, of which results show that the reinforcement is effective for the arch dam stability, which improves stress and displacement distribution conditions in connection with stability of abutment rock; but the left dam abutment is still instable so as to add anchor holes area to ensure the arch dam stability.

Engineers and technicians are concerned with the dynamic fracture behaviors of brittle rock under blast loading. It is of very importance for construction safety to predict the fragmentation scope and damage value by use of numerical approach. However, a reasonable damage constitutive model is the key thereinto. By assuming rock observes the Mises yield criterion and considering the strain-hardening behavior of rock, the tension damage evolution equation of Taylor-Chen-Kuszmaul model is coupled with the bilinear elastoplastic constitutive model. Subsequently, the developed constitutive model is concisely implemented into the FEM software, LS-DYNA. The rationality and accuracy are tested via a practical example of cylindrical charge explosion in a semi-infinite rock mass. At last, one spherical explosion is numerically analyzed. This damage model and related numerical simulations can be of certain value in a practical rock blasting.

During the construction of large scale geotechnical projects, tunnels and cavern groups are of the common underground structures. In recent years, the technologies of GIS and virtual reality have become very attractive in this research field. However, due to the effect of complex in situ geological condition and spatial modelling algorithms, it is still a difficult and important subject for three-dimensional synthetic model building and visualization analysis toward strata and cavern. A new technique to build stratigraphic model is discussed based on three-dimensional grid data, it results in an adaptive algorithm to build strata model by multi-DEM(digital elevation models). Furthermore, the main subject of this paper related to simulation of three cavern excavated based on three-dimensional strata modeling is systematically discussed; through a series of complex algorithms such as three-dimensional entity model of cavern, subtraction of cavern and stratigraphic skirt, intersection between cavern and strata, the three-dimensional model of cavern including strata information is built finally. A typical case in relevant to a hydropower station is given at the end of this paper.

To satisfy the rapid development of economy and traffic, super cross-section highway tunnel with lower flat-ratio such as four-lane tunnel seems very necessary; and its lower flat-ratio makes that the traditional tunnel support system is difficult to support it. New support system has to be researched to enhance present status. The effects of an innovative “pre-built and prestressed” support system that come of “pre-built” ideology in enhancing the stability of super cross-section highway tunnel with lower flat-ratio have been studied by numerical modeling with FLAC, which are significant for the practice of “pre-built” ideology in super cross-section highway tunnel with lower flat-ratio.

In Kobe earthquake, the metro stations are damaged severely. Most columns of Dakai metro station collapsed and the settlement of ground surface reached to 2.5 meters. The earthquake damages of Dakai metro station are analyzed in detail. Based on the finite element software ABAQUS, a dynamic nonlinear viscoelastic model implemented in ABAQUS is used to model the characteristics of soils under cyclic loadings. The dynamic viscoplastic damaged model is used to model the characteristics of concrete under cyclic loadings. Numerical simulation and analysis of the earthquake damages of Dakai metro station caused by the Kobe earthquake are implemented by ABAQUS software. The damage evolutive process of Dakai metro station is modeled in detail. The results calculated by finite element method are consistent with the earthquake damage of Dakai metro station well. It is proved that the method proposed can be used to analyze the nonlinear earthquake response of underground structures.

Analyzing the image of SEM of clay soil is a very important method to study the soil microstructure. But most of the traditional method is just qualitative. In fact, there are much information in the image of SEM, for example, the distance from the grain surface to the photographic plate. The authors apply GIS to recreate the three-dimension model of the clay through the SEM image. Also, the method of computing the porosity by GIS technique is introduced, including the two-dimension method and three-dimension method. At last, the analysis and comparison of these two methods are carried out. The result shows that the porosity obtained from two-dimension image (binary image) is affected by the threshold in binarization process, the lower the threshold, the more the volume of the grains, and the lower the porosity. Because the porosity obtained from three-dimension image is gotten directly from the grey-scale image and is not affected by the binarization process, it is more reasonable.

The seepage analysis is important to many engineerings including seepage failure of the rockmass, petrolic seepage in the rockmass and waterproof design of the underground rock engineering. The analytical method will be restricted by some practical factors such as the non-homogenous and anisotropy of the seepage medium for the rockmass, uncertain initial conditions, the boundary condition and the complex geometrical shape etc. The meshless method for the seepage of the rockmass is developed. The seepage problems of the rockmass are mainly solved by the meshless method. The discrete equations and relational computation formula of the method are derived by the variational principle. The boundary conditions are considered by the finite element method. At last, the validity and accuracy of the present coupling method solution are illustrated by two numerical examples.

According to the theories of fracture mechanics and damage mechanics, the deformation characteristics of bolted joint face and the bolt near the joint face are systematically studied. By using the method of equivalent strain energy, the constitutive relation of anchored discontinuous jointed rockmass is derived under the state of compression-shearing stress. The constitutive relation under the state of tension-shearing stress is developed according to the theory of self-consistence. Through 3-D FEM programming, the above constitutive models are applied to a certain actual project. The fracture-damage model of the anchored brittle discontinuous jointed rockmass is applied to simulating the reinforcing effect of the bolts. Through the united actions with the adjacent rock, the bolts restrict the deformation of the adjacent rock, improve the stress state of the adjacent rock, and prevent the evolution of damage zones, and so enhance the stability of the underground structures effectively. Synthesizing the facture-damage computation results and the FLAC3D results, we can conclude that the facture-damage computation values exceed the FLAC3D values owing to the appearance of joint in the rock mass. Taking the reinforcing action of the bolt on the joint face into account, the facture-damage computation model brought forward in the paper adapts better to the deformation and damage characteristics of the anchored discontinuous jointed rockmass. So the computation model is proved to be valid and advantageous.

The subroutine UMAT special for user-defined material model in the commercial FEM software ABAQUS is utilized and the implicit integration algorithm for the modified Cam-clay model is numerically implemented in ABAQUS. Combined with automatic time increment method for solving incremental finite element equation, the triaxial drained and undrained shear tests of normally consolidated soil and heavily overconsolidated soil are simulated using ABAQUS with the proposed implicit integration algorithm. The robustness and accuracy of the numerical analyses are illustrated. It is shown that the computational results are valid and can well agree with other solutions available.

The simulation and expression of geological faults is an essential technique of the modeling approaches for the complex geologic bodies. The research domains of this paper are the basic theories and essential techniques of the structural modeling techniques of complex geological entities contained faults. The structural modeling techniques of complex geological entities contained reverse faults are discussed; and a series of approaches are proposed. Based on the practical geological exploration, data types that expressed geological faults in 3D are analyzed and a normative database format for geological faults is designed. Two kinds of modeling approaches for faults, such as modeling technique of fault based on stratum recover and based on interpolation in subareas, are compared. The Unified Modeling Technique for stratum and fault, a novel approach, is presented to solve the puzzled problems of reverse faults with multivalued surfaces, syn-sedimentary faults and faults terminated within geological models. In order to confirm the practical result of this method, a case study of fault model of bed rock in the Beijing Olympic Green District is presented.

When diaphragm is used in the deep excavation with complicated plan as retaining wall, three dimensional behaviors instead of two dimensional behaviors, which is often considered in empirical simplified methods, has two be considered to account for the interaction of neighbor diaphragm wall panels. By using 3D FEM to consider the interaction of neighbor diaphragm wall along with the interaction between wall and soil, the influences of different types of connection between neighbor walls including hinged joints and free end on both sides of the diaphragm wall to the bending moment and displacement of the wall with invariable and changed stiffness is studied. The analyzed results using the method presented in this paper agree well with the experimental test results. The shortages of the empirical methods using 2D FEM are pointed out by comparing the numerical analysis results with model test results. The transverse moment of the wall with hinged joints is analyzed emphatically and calculated results show that significant transverse moment can be generated under such situation and can’t be ignored.

A technique for simulating the process of structures collapse under demolition blast was developed in the frame of ABAQUS finite element software. The choice methods of the height of cut, the mechanical criterion and the discretization of structures were put forward for demolition blast. The instability and collapse of structures were simulated using the nonlinear transient explicit dynamics module of ABAQUS. The technique described in this paper has been used to simulate the process of a practical demolition blast. The results of simulation show that the process of structure collapse and the shape of muck pile from simulation are similar to the practical one.