The present studies on stress-strain characteristics of rockfill materials are mainly performed with the conventional triaxial test; and the verification of constitutive model under complex stress path is unsufficient. Using the large scale triaxial test results of Nuozhadu Rockfill materials under complex stress path, the commonly used constitutive models such as Duncan-Chang’s EB model, nonlinear uncoupled Tsinghua KG model and Shen’s double yielding surfaces model are compared and verified. The results show that the Duncan-Chang’s EB model often overestimates the volumetric compression and give incorrect loading-unloading criterion under some complex stress paths. The other two models are more applicable for rockfill materials under complex stress path.

A framework for numerical modelling of miscible contaminant transport contained homogeneous /heterogeneous chemical reactions in porous media is presented. The mathematical model of the chemical-reacting processes integrates the homogeneous fast/slow and heteroneneous fast/slow governing phenomena. The transport behaviors of governing processes mainly include: convection, diffusion and degradation, adsorption etc. A finite element method based on the implicit characteristic Galerkin discretization is used to numerically solve the initial and boundary value problem for the model governing equations. The solving process separates the reactants and products in the homogeneous chemical reactions and the material in liquid and solid phases in heterogeneous reactions. The reactants in homogeneous reactions and chemical cations in liquid phase of heterogeneous reactions are simulated as the basic unknowns. The products in homogeneous reactions and the chemical cations in solid phase of heterogeneous reactions are solved individually. The different governing equations, then, can be classified as its intrinsic nature. The unknowns are also decreased by such treatments. The iterative operation is performed for the reason of the nonlinear right side contained the internal state variables. The numerical results and the stability analysis of the algorithm validate good performance of the present model and efficiency, accuracy and stability of the present numerical method.

Once a soil slope is led to the limit equilibrium state by means of the finite element – strength reduction technique, usually, the critical slip surface goes through the points at which the equivalent plastic strain takes the maximum. First, some vertical lines are arranged along the horizontal direction. Then, along each of the vertical lines the point with the maximum equivalent plastic strain is found out. All such points compose a wave and make up the functional data. Finally, the functional data are smoothed by the least square method and the position of the critical slip surface is determined. The proposed procedure is confirmed through the comparison with other mature methods.

The theory and methods of anisotropic shear yield criterion is studied on the basis of isotropic Mohr-Coulomb yield criterion. The above theory and methods are applied to establish orthotropic shear yield criterion and to analyze the way to introduce it into the numerical analysis. In order to introduce the orthotropic shear yield criterion into FLAC3D, the codes are developed by using the FISH language of FLAC3D. Theoretical analysis and numerical analysis indicate that the orthotropic shear yield criterion is related to 3 principal stresses and the isotropic shear yield criterion is a special case of the orthotropic shear yield criterion. The analysis also shows that the maximum shear stress plane can not be the same of yield plane in orthotropic materials.

Fuzzy character widely exists in elastic media slope. A fuzzy finite element method is proposed to describe the variation of the displacement and stress of slope due to the fuzzy feature of the mechanical parameters. Based on the construction of basic equations for elastic media, fuzzy operations and fuzzy integral and fuzzy differential are employed to deduce fuzzy expression form of geometrical equations and physical equations and equilibrium equations. Governing equations of fuzzy finite element method in which the parameters are considered as fuzzy number are constructed by using minimal fuzzy power principle. Case study illustrates that the numerical results obtained from fuzzy finite element method could objectively describe the effect of fuzzy character of mechanical parameters on calculated stress and displacement.

Based on the theory of fast Lagrangian analysis of continua, the theoretical basis of the stress release method is discussed. Through the analysis of a case in which the excavating and unloading process of a circular tunnel is simulated by using the stress release method and the three-dimensional simulating method respectively; the problems including the differences of stress paths, the accuracy of the calculating results and the applicability of the stress release method are discussed. Firstly, the results indicate that the stress paths are different in these two methods. So, the stress release method can simulate the excavation in tunnel engineering only in some limitation. Secondly, as to the material with the nonlinear mechanical property, the different stress paths induce the different results. But, the results from the two methods are equal approximately if the required conditions are satisfied and the error magnitude will decrease with the increase or decrease of the confining-pressure coefficient from 1.0. Finally, GRC in the convergence- confinement method can be obtained simply through the stress release method; and it indicates the importance of this method in the corresponding application.

It is assumed that voids are uniformly distributed in the substance space occupied by soils and the sorption of soil skeleton onto the contaminants behaves equilibrium and linear feature. Based on the analysis of basic interrelationship between volume and mass, an empirical formula is presented for evaluating the change of the porosity induced by sorption of soil skeleton. Under the condition of variable porosity, the governing equation for describing one-dimensional contaminant migration is established; and the initial conditions and boundary conditions are formulated for actual conditions including landfill profile, waste degradation and compacted clay liner (CCL) of finite depth in practice. The resulting initial boundary-values issue is numerically solved. Through parametric computations and comparative analyses, it is shown that the reduction of soil porosity induced by sorption of soil skeleton will decrease the breakthrough potential of contaminants into compacted clay liners. Compared with the case of constant porosity, the peak of concentration of contaminant transport in CCL will be reduced 10 % when the variable porosity due to sorption is considered. When the variable effect of soil porosity is taken into account, dispersion mechanism play a controlling role in the contaminant transport and the effect of the distribution coefficient in the sorption equation on contaminant migration is appreciable.

Several mechanics problems and related concepts in engineering design of anchored slide-resistant piles were analyzed and discussed. There are two mechanics models and corresponding calculation methods of embedding section of anchored slide-resistant piles, which were classfied into rigid pile model and elastic pile model according to the relative rigidity of pile-soil system. By means of mathematical operation of limit, the mechanics consistency of the two calculation methods was illustrated. That is, calculation results based on rigid pile model is just only a special case of elastic pile model. Comparition results of displacement and bending angle of embedding section between the two mechanics models showed that, by using elastic pile model is more safe for determining tensile loads of anchor cable than by using rigid pile model in design of anchored slide-resistant piles. The criterion of converted length of embedding section is 1.3 (“m method”) or 0.8 (“K method”), for if calculating depth are less than them, the difference between two mechanics models are less than 5 %. Because the dip angle of pile’s anchor cable effect on horizontal restraining force and horizontal restraining rigidity as well, the optimal dip angle can give consideration to both diminish initial prestress loads of cable and decrease horizontal displacement of pile. The principle of bending moment equilibrating in engineering designs was conditional actually, because the target of making approximate equality of peak value of pile’s positive and negative bending moment extremely depends on sufficiently large tensile loads can be supplied by anchor cables and appropriate initial prestress loads were applied.

Based on the theory of field of plastic moduli and the multi-yield-surface constitutive model, and combined with isotropic hardening rule and translating hardening rule, a new multi -surface elastoplastic constitutive model was proposed in a new stress space. And a simple model which was suited to the triaxial tests, was infered. Finally, combined with a residual pore-water pressure model, the new model has been validated by means of a cyclic triaxial test of saturated soft clay. The validation indicates that the multi-yield-surface constitutive model can be used to simulate the cyclic triaxial test, direct shear test and plane strain test.

Based on the theory of particle flow, Particle Flow Code(PFC)model of soil with weak intercalated layer are constituted by adopting the contact-bond model and the slip model. The failure process and strength of sample are studied by PFC numerical simulation to analyze the stress-strain relationship curves of PFC model under different confining pressures and parameters and diagnose the trend of failure via displacement vector fields. The simulation results show that that failure occurs along the weak intercalated layer in the condition of general confining pressures, but in a special confining pressure, failure is not controlled by weak intercalated layer. The peak value of stress-strain relationship curves declines as normal stiffnesses and friction coefficient of weak intercalated layer bring down, the sample will present yielding flow character in the early stage of loading when the friction coefficient approaches 0. The peak value of stress-strain relationship curve declines only when the shear stiffnesses are under a special value. Through analysis, inhesion relations between particle’s micro parameters and macroscopic mechanics actions are gained; and have a further understanding of weak intercalated layer’mechanical properties and progressive failure of soil.

Mutation particle swarm optimization (MPSO) is a kind of improved stochastic global optimization based on swarm intelligence. The advantages of MPSO are that the probability falling into the local extreme values can be reduced; and the global optimal searching capability is improved. A new algorithm which combined MPSO with radial basis function (RBF) is presented. It not only has the advantage of the global optimization of MPSO, but also has local accurate searching of RBF. Numerical example shows that the presented method can solve the problem which includes multi-parameters identification and nonlinear optimization problem. This approach has the characteristics of global convergence. The intelligent algorithm is simple and precise.

The shell model finite element methods are better than the simplified analytical cable model methods in simulating shell deformation properties of pipe for the response analysis of buried pipeline crossing fault; but the cable model methods are still used in the relevant guidelines in China and other countries. The differences of estimated maximum tension strains of pipes and main factors inducing the differences are investigated based on the calculating results by a shell model method and the Newmark’s cable model method; and an improved Newmark’s cable model method is proposed by introducing an empirical relation with the fault displacement and wave velocity of surrounding soil for the case that the crossing angle between pipeline and faults less than 70 degrees. Furthermore, case studies show that the fitting degree between proposed method and the shell model method is not less than 0.87 for cases with different crossing angles between pipeline and fault and material behaviors of pipes.

Characteristics of salinization of saline soil in west coast area of Bohai gulf are closely related to ground elevation of plain, climate conditions, physical and hydrological properties of soil, mineralization of groundwater, and people’s actions. So far as degree of salinization, it has been investigated that salt content of soil in higher elevation position is more than that in lower elevation position; salt content of soil in upper level point is more than that in lower level point; and the effective depth of salinization of soil above groundwater table is about one meter because of evaporation and rainfall. In pace with weather change, saline soil in inshore area shows some characteristics, such as salt accumulation in top soil in spring because of evaporation; and salt moving down in summer because of rainfall. With an increase of depth, salt content of soil decreases slowly in vertical direction, but salt content raise slightly near groundwater table; and the grade of salinization of soil is classified into three kinds of sections of salt content from ground surface to groundwater table; i.e. evaporation and salt accumulation section, changeable salt content section, and salt solution section. In horizontal direction, i.e. toward the coastal line of Bohai gulf, the soil changes gradually from slight salinization to high salinization via moderate salinization, and salt content and degree of salinization of soil is more and more obvious. Degree of salinization of top soil is serious at the condition of a sallow groundwater table and more mineralization of groundwater.

Evolutionary strategies is a new method when it comes to solve the optimal solution of the global optimization issues; at the same time, the study of optimization design in the pit supportings by using the theories and methods of evolutionary strategies is carried out. Considering the optimization design’s disadvantages in convergence and convergence speed when it deals with optimization issues of nonlinear function and high-dimension optimization, a sort of faster evolutionary strategy is presented by combining the tabu search(TB) with the beam search which can effectively overcome the downbacks mentioned upon. Taking the studies and analysis of some cases of construction as background, which indicates that evolutionary strategies are not confined by the differentiability, continuity of design space and so on; but especially fit for calculating the issues of the supporting projects which relating to discrete design variables and uncertain factors. The new improved evolutionary strategy presented has a better convergence as well as the capabilities of the global optimization which avoids local optimum solutions effectively.

A new type of meshfree method is developed by incorporating the generalized node which is originated from manifold method with the conventional meshfree method. The proposed method is termed as the generalized-node-based meshfree method. The fundamental theory together with numerical formulations is presented. When the zero-order displacement interpolation function of the generalized node is chosen, the proposed method will be reduced to the conventional meshfree method. Based on Biot’s consolidation equations, the numerical formulation for analysis of consolidation in soil mechanics are especially established by using the proposed method. The accuracy and rationality of the present analysis are verified by comparing the computational results with the solution obtained by FEM for an example.

Plasticity theory must satisfy the thermodynamic restriction conditions, of which Second Law of Thermodynamics is the most important. Yield /failure function is the original concept of plasticity theory, and it concerns the dissipation process described with Second Law nearly. Entropy or dissipation potential is a key state variable defined from Second Law of Thermodynamics to describe this irreversible process. So yield /failure function must have a close relation with the dissipation potential. In this research, dissipation potential corresponding to class of yield /failure functions in plasticity theory is deduced through solving the dissipation differential equation transformed from the yield /failure functions. Especially, the methodology of getting the dissipation potential is applicable for both the linear and nonlinear yield /failure functions. Thus the thermodynamic consistency of these yield /failure functions can be verified from this dissipation potential expediently. Moreover, the thermodynamic restriction conditions on the yield /failure function are deduced using the dissipation potential corresponding to a class of yield /failure functions and second law.

With the improved triaxial equipment, a series of K0 consolidation and undrained shear tests have been carried out to study the unloading deformation properties of a typical soil in Tianjin urban area. According to the experimental results, the stress-strain curve is a hyperbola and has obvious normalization character. The initial tangent modulus obtained is directly proportional to the initial confining pressure.

A deformation prediction model of surrounding rocks in double-arch tunnel based on BP neural network was established with a practical project. Mechanical parameters of surrounding rocks were obtained by back analysis method based on measured data in left tunnel. Deformation prediction and stability analysis of surrounding rocks in right tunnel were carried out by finite element analysis. The proposed prediction model made feedback design on supporting parameters and construction method more effective. By Comparison, it is shown that the results of prediction are in good agreement with those measured in situ. It can meet the requirement of geotechnical engineering.

Based on the Mohr-Coulomb failure criterion and an associative plastic flow rule in the plane strain regime, an elastoplastic analysis is presented for the deformation in an infinite slope of cohesive soil with the model of translational slide due to the raise of groundwater table. And an attempt is made to establish a relationship between the horizontal displacements developed within a slope before failure and the safety factors. The numerical results illustrate that, as the groundwater table rises, the initial state of stress and the shear strength of soil have an important influence on the thickness of plastic zone, the plastic strains and the horizontal displacements before failure.

The differential settlement induced by discontinuous gradient of bank slope is one of the main reasons for transverse cracking in earth core of high dams. A series of centrifuge model tests were performed to investigate transverse cracking using mixed core soils of the Nuozhadu dam. Transverse cracks leaded by the abrupt change of the gradient of the bank slope are observed in the centrifuge model tests. Then the experimental results were analyzed with three numerical methods commonly used in earth core dam engineering: deformation gradient method, Leonards-method and finite-element method. The results show that the first two methods are applicable only when sufficient measuring data are obtained; the finite-element method is more efficient for transverse cracking analysis in earth core dams.

At the conditions of internal dumping and non-internal dumping, six homogeneous slope models and the slope model of the 1st Yimin open pit are founded, and solved these model’s angle of the end wall by FLAC3D program. The analyzed results demonstrated that the internal dumping can increase the maximum stable angle of the end wall in open pits at the same safety factor. So, using the internal dumping can decrease the waste volume or increase the ore’s production, reduce the stripping ratio, improve the mine’s economic benefit.

It is improved that there is staged characteristics of lateral pressure coefficient K0 of soft clay. When the test load P is less than sample’s remaining structure strength , the value of is small, and when , the value of K0 is increased. It’s the reflection of the staged characteristics of soft clay’s mechanical property. When , the structure of soil sample is undamaged, the sample is similar to a rigid material, the value is small; When , soils microstructure is damaged, the sample is changed to be elastoplastic material, the value is increased. In geotechnical practices, the sample is disturbed during drilling and sampling, the microstructure of under-consolidated or normal-consolidated soft clay is destroyed, the staged characteristics of index is disappear.

By establishing displacement optimization function based on some measured geostresses, a new approach of getting initial geostress field in the whole interested region is represented, which adjusts displacement boundary conditions automatically and make full use of 3-D finite element calculation. Finally, this method is applied to underground power houses of Three Gorges Project. The calculated results are in good agreement with the measured ones; and it is proved that this method is effective.

According to the results of in-situ tests, the failure mechanism of composite foundation is mainly decided by the interaction between soil and cushion in the state of thick cushion or under embankments; and the practical bearing capacity of a pile in composite foundation is not brought into full play. The following rules are got from the calculation results of FEM: (1) the stress ratio of pile to soil (n) decreases with the thickness increasing; as the thickness exceeds 300 mm, the influence of cushion thickness on n reduces sharply; as the thickness exceeds 500 mm, the influence of cushion thickness is small. (2) When the cushion thickness is relatively thin ( 100 mm), the influence of cushion modulus on n is great; as the thickness exceeds 300mm, the influence decreases; as the thickness exceeds 500 mm, the influence is very small. (3) as the rigidity of bearing plate is smaller than 6.25 MN•m2, the stress ratio of pile to soil increases with the rigidity increasing; as the rigidity exceeds 6.25 MN•m2, the influence of rigidity on n is very small.

Based on the test data of fifty nine static loading tests driven into gravel stratum of precast concrete piles and the results of standard penetration test in the layers beside the pile, combining with the results of the in-situ stress tests of seven precast concrete piles, the end resistance, the partake scale of end resistance with total load acting on the pile and the displacement to exerting the end resistance of pile are analyzed. Through the test data of one hundred and twenty one static loading tests and the final pressure acting on the pile, the relationship between the ultimate bearing capacity and the final pressure acting on the pile of precast concrete pile statically pressed into gravel stratum is discussed.

The interface shear strength was studied using direct shear machine with high stress and tilt table device with low stress. Here the interfaces between three different types of HDPE (high density polyethylene) geomembranes and sand, geotextile and geocomposite were considered. Tests were performed with interface scale of 200 mm 200 mm. Through the analyses of test results, some frictional characteristics of HDPE geomembrane interface were provided; and the comparison between direct shear test and tilt table test was made.

At present, the finite element method is adopted to simulate the interaction between retaining structure and soil during the pit excavation. Based on it, the authors put forward a method which couples the temperature field to the stress field to analyze the pit strut temperature effect. Combining case history, it is simulated by adopting modified Cam-clay model and considering different excavation processes. And it analyzes the strut temperature stress effect caused by different construction stages. Then it is pointed out that the strut temperature stress should be designed according to the worst cases caused by all kinds of work conditions. It comes conclusions that the effects of the temperature should be considered as a case when it changes greatly.

In order to keep track even and steady in high speed railway, it is necessary for no embankment settlement after construction; but red beds are easy to collapse and soften, which belongs to stuffing for the third grade. Based on results of long-duration static test of simple compression without confining pressure (the grain size of sample is below 2 mm and compacting degree is above 95 %), the creep characteristics of red beds are analyzed; and at the same time settlement after construction can be predicted by numerical algorithm for engineering applications. So it is proved that red beds can be served as stuffing with a certain construction methods and no settlement after construction is entirely fulfilled.

According to the inner forces distribution of double span tunnel under the surrounding rock loading action during different construction stages, the failure mode of the tunnel lining are made by a series- parallel connection system. Then, the Monte-Carlo random FEM is adopted to calculate the reliability of tunnel lining section, with full consideration of influence of the material characteristics, geometric dimensions, elastic resistance coefficient of surrounding rock, loading, etc.; and by using the breadth border method, a range estimation method, the system reliabilities of tunnel lining during different construction stages are studied. The system reliability index of a typical tunnel case is calculated in the end. The calculated results show that the system reliability index of middle wall is smallest after the single tunnel is excavated; and it can’t be safe when be used in long-term. When the tunnel is in construction, the safety of middle wall must be pay attention; and the double arch should be built as soon as possible.

According to the distribution of horizontal strain in the soil under embankment loads, the characteristic of lateral deformations along the depth is analyzed based on measured data and existing research results. The results show that the typical curve is bow-shaped. On this point, the predicted model is established to forecast the lateral deformation. The three parameters in the model, a, b and c can be easily solved. This model has been applied to study 2 cases. The model can reflect both the distribution of lateral deformation along depth and the location where the maximum deformation occurs. The comparisons demonstrate that the predicted deformations are in good agreements with the measured data.

Illegal mining has a great influence on stability of mines. Based on the prototype of the representative metal mine, two-dimensional physical simulation model test on an underground iron mine is carried out. The regulations of surface deformation and surrounding rock movement with or without illegal mining are obtained respectively. Results obtained indicate that when ore between –270 m and –550 m are excavated, the subsidence of surface and deformation of surrounding rock increase slowly. But when ore below –550 m are excavated, the subsidence of surface and deformation of surrounding rock increase quickly because the obliquity of orebody become smaller. Because of stress redistribution caused by illegal mining, the size of surface subsidence increases near surface gob and horizontal displacement of surface increases greatly; but the range of surface subsidence almost has no change.

Both the bearing capacity and deformation have to be considered when the embankment is constructed on the soft foundation. Based on the main features of the soft ground in mountainous areas, using the soil-cement piles and geogrid to improve the soft foundation is an innovation. It is significant for engineering design and construction that choosing appropriate experimental measure to study this type composite foundation. Centrifugal model test was used to simulate construction course of embankment on soil-cement piles and geogrid composite foundation. Gypsum column and a type of pretensioning grid are used to simulate soil-cement pile and geogrid, respectively. Engineering characteristics of this type composite foundation were presented. The results indicate that soil-cement piles play an important role in strengthening soft foundation; and the effect of the geogrid is mainly to balance loads and constrain lateral deformation. The conclusion can be for reference in design and construction.

Stone columns composite foundation is analyzed by the developed fully coupled three-dimension effective-stress dynamic analysis procedure; the influence of stone columns design parameter on anti-liquefaction nature of composite foundation is discussed. The research shows that the influence of column length is minor in superficial layer and is major in deep level; under other condition fixed, with the diameter of stone columns increasing, the excess pore water pressure decreases; with the spacing of columns increasing, the excess pore water pressure increases. In engineering design, the ratio of the diameter and spacing of columns should be bigger than 0.27, or the spacing of columns is smaller than 3.75D; with the permeability of stone columns increasing, the excess pore water pressure in different depths decreases; and the influence is stronger with the depth increasing.

For investigating the scale effects in strength and deformation, an experimental study of constitution ratio of similar simulation materials of brittle rocks has been carried out; in which a method of generating simulated joints with initial materials has been provided; and a method of producing randomly-distributed-joint specimens has also been developed. We have then completed an experimental study of scale effects in axial compressive strength and deformation using the prepared specimens of fractal-joint rock mass with simulated materials, and have obtained consistent results comparing with the same study with the natural rock masses. We conclude that the scale effect in rock mass deformation is not completely resulting from the joint closure and shear degradation, while the scale effect in rock mass deformation is mainly due to the augment of shear deformation before the shear degradation happens.

As a digital image measurement method, the sub-pixel accurate location of a corner can be found in digital image by sub-pixel accurate corner locator. The purpose of this paper is to introduce digital image measurement method for measuring triaxial specimen deformation based on sub-pixel accurate corner locator. The distortion target of high precision is used to analyze the precision of the method. The results show that both axial and radial measurement precisions achieve 0.02 pixel and the magnitudes of relative measurement precision achieve 10-4. The high precision distance transducer and sub-pixel accurate corner locator method are simultaneity used to measure the small deformation of dry-specimen in triaxial compression test; and the accuracy and reliability of the method are proved.

Aiming at the disadvantages of FLAC3D modeling, such as the modeling process is not intuitionistic and mesh generation has great workload, a new kind of modeling method is proposed based on SURPAC software. On the base of building SURPAC block model of the complex geologic body, the SURPAC block model data in the manner of data file are exported and processing it using the Access database; and then the modeling order flow is generated and to run the order flow in FLAC3D to construct the FLAC3D model automatically and fleetingly. The new FLAC3D modeling method has been used in building the cavity stability analysis model of Tongken Copper mine in Guangxi Autonomous Region; and the result shows that the new modeling method is feasible and effective.

Two point probability function and linear path function depicting the characteristics of core’s pore space are introduced. A new method of constructing digital core named stochastic search algorithm based on majority operator is presented. Its theory of constructing digital core and the stochastic search strategy for both pore voxel and grain voxel based on majority operator are illustrated in detail. Good intervals for majority operators when searching pore voxel and grain voxel are suggested to be [9,12], [4,7] respectively. Study shows that this method, without being constrained to lithology, can construct digital core with good quality. The constructed digital core’s pore space gains good topology and distribution which is similar to the genuine rock pore. Although a number of isolated pore and rock phase units appear in the core, their total fraction is quite small. The core’s pore space connection, isotropy and permeability are all good enough to make it a good tool for study of fluid distribution and flow in porous media. As the core’s connectivity becomes poor with its porosity decreasing, the method presented here can be better used for constructing digital core with large porosity.

Genetic algorithm is used in three-dimensional slope stability analysis. The slip surface of 3D slope is complicated, so it needed to be simplified. The slip surface is assumed to be formed as ellipsoid by seven parameters; and then the most possible slip surface which has the lowest safety factor will be searched out through genetic algorithm. If the slope has the explicit slip surface, the slip surface will be regarded as the whole slip surface; and the whole safety factor will be calculated. And then the local slip surface which has the lowest safety factor will be searched by genetic algorithm.

Slope treatment is the key problem of the study of slope engineering. The selection of slope treatment schemes is a decisive factor of the success of slope treatment. The slope treatment needs rich experience and knowledge; but acquiring knowledge is always the bottleneck problem of slope treatment decision-making. Many engineering bases have been accumulated for a long time in the practice of slope treatment. These bases contain rich experience and knowledge, which needs excavating and applying. For this reason, aiming at the selection of slope treatment schemes, case-based decision support system for the selection of slope treatment schemes is presented, so as to provide an effective decision support for the selection of slope treatment schemes.

According to the features of geologic research for landslide, the NURBS-BRep hybrid data structure was put forward to meet the needs of 3-D landslide geological modeling. Then, the corresponding constructional model of geological structural blocks was established. Based on these techniques, a set of integrated 3-D modeling method was advanced for landslide geologic bodies. It included four sections: the pretreatment for basic geological data of landslide, the 3-D modeling of landslide digital terrain and sliding surface, the system construction of geological structural surfaces, the generation and representation of geological structural bodies. This method was applied to a landslide in reservoir area successfully. Based on the established actual 3-D landslide geological model, a series of practical visual analyses proceeded. They contained arbitrary 3-D section analysis, digital drill, contour lines generation, automatic subdivision of slide blocks, visual dynamic simulation of landslide instability and accurate volume computation of landslide mass. These results can offer powerful supports to exact calculation and objective evaluation of landslide stability.

Considering the support difficulty of the roadways with high stress zone in Jinchuan Mine No.2, a prestressed cable support technique is studied and adopted at 1 178 m sublevel in Mine No.2. The prime support parameters were first given with the help of engineering experiences. Then orthogonal numerical experimentation regression analyses were executed. The results show that pretressed cable with the length of 6.5 m should be used in the Ⅲ or stronger grade (with RMR of 40) surrounding rock or the tunnel affected by the mining lightly, as for the tunnel suffered from the mining seriously, cable supporting with length of 6.5 m can make the safety coefficients reach 1.28, therefore, cable with length of 5.5－6.5 m can meet the stability need of sublevel tunnel.

Wushaoling tunnel is the longest single line railway tunnel in China up to now with the length of 20.50 km, and the F7 fault is the largest active fault, in which the geological conditions is highly complicated; it effects the tunnel construction badly. According to the characteristics of F7 fault and the problems met in tunnel construction, the stress and displacement of rock wall and lining structures were long term monitored after excavating in F7 fault section of Wushaoling tunnel. The trend of stress and displacement changing are analyzed based on the site monitoring results; and the mechanism of the extrusion large-deformation are explored so as to understand the regulation of stress releasing of rock wall and rock pressure. Furthermore, based on the site monitoring results, the optimized dynamic design and improved construction measure are proposed and adopted for the section at which the tunnel crosses the F7 fault. It not only avoided the large deformation occurrence, but also guaranteed tunnel drilling through the F7 fault section safely and quickly.

The generator sockets construction and the closely-related stability problem of lower side wall of Shuibuya Underground Powerhouse are key problems to solve in the powerhouse construction. Synthetically utilizing orthogonal design, three dimensional numerical simulation, genetic algorithm and support vector machine, the back analysis process for Shuibuya Underground Powerhouse is proposed. According to the process, using the monitoring data of upper sixth construction step, the mechanical parameters of surrounding rocks are back analyzed. Based on the mechanical parameters, the subsequent sockets construction schemes are numerically simulated and the optimal one is selected, so as to keep the stability of high side wall and generator sockets surrounding rocks. The optimizing result has guide meaning to the construction.

The wet sprayed concrete technique has good virtue of improving the working condition within the tunnel. Compared with the common sprayed concrete technique, the wet sprayed concrete technique has fewer reflective concrete loss and higher sprayed concrete quality. It is worth of being spread in the tunnel lining structure construction process. The wet sprayed polypropylene fiber reinforced concrete was first introduced in the Dongjusigou railway tunnel lining structure in China Baoji-Lanzhou resuming line. The nonlinear least square method is used to regress the tunnel horizontal convergence curve at two transverse sections. The tunnel stability fuzzy probability analysis theory is applied to calculate the probability of the railway rock mass stability at different section locations. The analytical result shows that the railway rock mass using the wet-sprayed fiber reinforced concrete lining structure is in stable state and the tunnel rock mass has higher reliability index. The wet-sprayed fiber reinforced concrete lining structure has good lining effect.

Guomao station of Metro No.10 line of Beijing city is designed to cross the pile-group foundation of Guomao ground overpass. In order to evaluate the effect of creep deformation of soil around the metro on long term safety of tunnel, bridge foundation and its upper structure, some drained triaxial creep tests of soil of this site had been carried out; and then the parameters of Mesri creep model, which was found to describe the creep character of the soil samples perfectly, had been given. The study indicates that soil around the tunnel has a small quantity creep deformation; and the speed of steady creep is slow. When soil is under low diviatoric stress, the calculated creep deformations with Mesri model consist with test results well; while under high deviatoic stress, the calculated results have a little difference with test results. However, Mesri creep model can describe the creep character of Guomao station soil perfectly.

Influence on the neighboring viaduct pier’s extending footings was numerically studied by using MSC.Marc 3-D software, which induced by the tunnel staged construction and the traffic loading during the working period. The incremental developments of these extending footings’ stresses, settlements and inclinations were analysised, as well as the retaining structure’s lateral displacements. And the obtained results indicate that: (1) These extending footing’s unloading during the construction is due to that the tunnel bottom level is higher than these extending footing’s. (2) The No. 6 extending footing’s inclination and settlement is mainly induced by the planning traffic loading which directly acting on its one top side. (3) The extending footing’s maximum inclination is 0.000 6. (4) The extending footing’s maximum settlement induced by the tunnel traffic loading is 3.7 mm. Combined with the obtained results of the groundwater seepage, it deems that the tunnel construction and working period does not endanger the viaduct’s safety theoretically.

Construction scheme design of diaphragm wall deep foundation pit constructed by “top-down” method based on 3D FEM is researched; and design method according to deformation control is put forward. The oversized deep foundation pit of Hutchison Whampoa Ltd. project in China’s Tianjin is calculated and designed as an example. Firstly, structure design of the slabs under vertical load is done. Secondly, three design schemes are put forward based on the structure design and 3-D FEM models of which are established; and every state of each scheme is calculated respectively. The stress and deformation of the diaphragm and slab under different states are obtained. The key state of construction and the weak parts of the whole structure are found out. At last, with consideration of the practical situation, advantages and deficiencies of the schemes are analyzed. Optimal scheme is selected by synthetical consideration.

It has been founded that the analysis model of semi-infinite three-dimensional spatial finite elements for the slab track-roadbed systems with soft rock as embankment filling, firstly, based on weak variational form of the equilibrium equations for the system in D’Alembert method; and the dynamic characteristics of the slab tracks in high-speed railways are investigated. Various state dynamic response values of the blanket top surface and soft rock filling embankment top surface are acquired, which is important for design and construction of engineering. Secondly, the engineering physico-mechanical characteristics of roadbed filling with soft rock as embankment material have been traversed by indoor test; intensity and deformation characteristics were mastered, It was demonstrated that the fillings can satisfy the requirements provision of ballastless track and embankment for high-speed railway and standards of high-speed railway roadbed design in the aspects of strength and stiffness properties.

By in-situ dynamic test on expansive soil section in high and low embankments of He-Ning High-speed Railway, their engineering characters under simulative dynamic loads are analyzed. It is verified that the principle of dynamic stress attenuation coefficient of both depth is alike; the elastic deformations of both depth’s embankments are 0.39 mm and 0.48 mm separately, which is allowable; the plastic deformations of both depth’s embankments are 0.7 mm and 1.5 mm separately; on the dry condition, combined dynamic rigidity coefficient of high embankment is about 317 MPa and 220 MPa after storm rainfall, while low embankment is 365 MPa nearly all the time, different modified soil thickness causes different dynamic rigidity coefficients.

Based on the in-situ monitoring data of the post-load settlement of a deep-water port, the consolidation coefficient of soils is back analyzed; and the post-load short term settlement is calculated. The result shows the great accuracy and good agreement with monitoring data. Long term post-load settlement is calculated and predicted with the proved consolidation coefficient of soils. By contrast with traditional methods predicting post-load settlement, this method is good at reflecting mechanism of consolidation of soils; and the result is much more reliable.

Based on controlling principle of metro construction and dynamic forecasting method of group pile-approached by shield tunneling, numerical simulation is adopted to simulate ground and structure group piles approached by shield tunneling of Hankou Railway Station according to design of Wuhan metro and two different displacement cases between no-loading ground and structure group piles approached by shield tunneling are analyzed. Finally, the impact of shield tunnel on city floor and construction could be derived to evaluate; and some helpful suggestions on construction safety control of shield tunneling approaching are offered.

The fractal theory is used to study characteristics of settlement curves of building basements. Box dimensions of accumulate settlement curves from various measured positions of two buildings are calculated; and relationships between changes of dimensions at the measured positions and changes of final settlements are analyzed. From the calculation and analysis, it is shown that the settlement curves of the building basements have fractal characteristics. The magnitude of the dimensions of the measured position reflects the complex degrees of the settlement processes of the building basements; the changes of the dimension of the measured position and the settlement have the corresponding relation. With this method, the settlements of the building basements are analyzed from a new viewpoint.

Data about 400 landslides in Three-George reservoir area were collected and summarized in recent years. It is concluded that there are five types of sliding-prone strata in reservoir area on the basis of geologic analysis and engineering geology analogy analysis. Through K-S finite contrast method, test of goodness of fit was respectively carried out on 3 308 groups of shear strength parameters; and the results showed that distribution forms of parameters c and ? are normal distribution and logarithmic normal distribution. The optimum fits of probabilistic models of c are mainly logarithmic normal distribution. As there are gravels in soil in landslide zone, linear regression analysis was carried out between the gravel content and the parameter ? of soil in landslide zone and the results indicated a well positive correlation relationship.

Based on investigation on spot and geological analysis, an unstable rock masses of Xiloudu Hydropower Station may to be failure through two modes: shear-falling and rip-topple is proposed; and a mechanical model for calculation of stability by limit equilibrium theory is established; and the unstable rock masses deformation and failure characteristics are analyzed by numerical simulation. The results show: stability of the unstable rock masses is relatively bad if the failure mode is rip- topple , but is good if shear-falling. Based on stability analysis, the anchor reinforcement force is calculated as 12 306 kN when safety factor is 1.5 and the failure is rip-topple; and some reinforcement measures of the unstable rock masses are put for ward follows: fill hollow of rock and fill in cracks and prestressed anchor cables and anchor bolts combination reinforcement. The results of numerical simulation show that: effect of the reinforcement measures is better.

By the physics-mechanics property examination of rock speimens which are on dry state, natural state and saturation state, Softening property of typical rocks are experimented in Danjiangkou Reservoir area; which can provide basic data for the study on reservoir-induced seismicity mechanism of the subsequent object of Danjiangkou Reservoir. The result shows that values of physical mechanics parameters reduce with the decrease of water ratio in rock, including uniaxial compressive strength, elastic modulus and Poisson's ratio. So the softening coefficients of rocks are directly related to void ratios.