According to the landslide dynamics, a systematic study on the stability prediction of reservoir landslide of Lijiaxia Hydropower Station is conducted based on the results of in situ monitoring, numerical analysis, laboratory and in-situ tests. The creep characteristics of the soil in the sliding zone and the creep-sliding mechanism of the reservoir landslide are obtained. It is shown that the varieties of both the shear stress ratio on the sliding plane and the viscosity coefficient of the soil in the sliding zone play an important role in transforming the landslide behavior from creep sliding to sudden sliding. Moreover, a typical sliding block of the landslide is chosen to carry out in-situ sliding test; the test is implemented under the simulated environment of reservoir; and the variation of the reservoir water level is taken into account. The study shows that in situ sliding tests can be not only a rational approach of verifying creep-sliding mechanism of reservoir landslide but also an effective measure to enhance the stability of landslide.

The thermomechanical approach to establishing elastoplastic constitutive model for geomaterials is introduced briefly. The major attraction of this approach is that it not only provides a tight mathematical structure, but also satisfies the laws of thermodynamics automatically. The whole of the constitutive structure (yield condition, flow rule, hardening laws and elasticity law) is determined just from two thermodynamic potentials (the free energy and the increment of dissipation function). It is demonstrated that, whenever the dissipation potential depends on the current stress; the flow rule is necessarily non-associated; and the concepts of friction and of non-associated flow rule are intimately linked. Then, some research advances, including three-dimensional problems, characteristic of geomaterials on micro and meso level, homogenization of stress-strain relation, dilation and anisotropy, are given. Several important concepts, such as “stored plastic work or frozen elastic energy” and “Reynolds-Taylor State”, are explained and analyzed. Finally, some proposals for further research are made.

Through the RMT-150C testing system, artificial concrete joint samples are employed to study the shearing stiffness and failure mode for rock joint under different shearing deformation velocities, undulation angles and normal stresses. It is suggested that the failure modes of joint samples are dominated by the undulation angles. Under small undulation angle, the joint samples are in abrasion failure mode, while under high undulation angles, the joint samples are in snip failure mode. The failure modes of joint sample are also influenced by the normal stress and shearing deformation velocity. It is also reported that the shearing stiffnesses of joint samples increase with the increasing shearing deformation velocities and undulation angles; and the rising rates tend to decrease with the increment of shearing deformation velocities. As well, the shearing stiffnesses of joint samples linearly increase with the increasing normal stresses. The shear stiffness formula is further presented to consider the effect of shearing deformation velocity and undulation angle. Based on the experimental results, the regression results for the formula are also conducted.

It is necessary to establish the energy conservation equation to research the thermodynamical properties of unsaturated soil; the determination of two representative parameters (volumetric specific parameter and thermal conductive parameter) of fundamental physico-mechanical parameters is a key factor to obtain the results of the energy conservation equation. The effective thermal conductive coefficients of dry soil grain are analyzed for different composition geomaterials; and the thermodynamical properties of porous media with water and gas are researched; the comparative analyses of different calculation methods of thermal conductive coefficient have been conducted; an available calculating method is proposed to determine the thermodynamical parameters; the comparisons among the results of the proposed method, the volumetric average method, the self consist method, the Hashin-Strikman method have been made; the proposed method is of the good agreement with the testing result; and it fits to describe the main properties of thermal mechanical conductivity.

Firstly, according to practical features of nonlinear displacement back analysis for underground structure，the model of back analysis which is based on convergent measuring data of displacements in underground tunnel, is established. Secondly, aiming at low calculating efficiency of general annealing algorithm, a new way or theory of nonlinear displacement back analysis in underground engineering which is based on adaptive hybrid genetic-simulated annealing algorithm, has been set up by combination of genetic algorithm with annealing algorithm together with finite element method and by introducing the idea of adaptation. And then, the relevant analytic software is developed based on studying both application and execution of this method. Finally, simulation analysis is carried out; and it is indicated that the theoretical results tally well with practical ones; and this method can meet the requirements for practical engineering.

Based on the sample-made technology of the liquid nitrogen freeze-dry, samples of saturation soft soil have been prepared. With the help of scanning electron microscope (SEM) technology, the microstructure images of the soft clay before and after its laboratory improvement with dynamic consolidation by drainage are obtained. The change of its microstructure parameters is studied by a developed computer program. Through comparing the results in terms of the number of pore, total area, total perimeter, the classification of area, the average diameter, and the shape coefficient, the roundness, the anisotropy, fractal dimension , the change of the soil microstructure after the improvement with dynamic consolidation by drainage has been studied preliminarily.

The stability of expansive soil slope is always an important research object in researching expansive soil. Taking the expansive soil in Nanyang Prefecture of Henan Province as study case, the improved formulas of calculating shear strength of expansive soil are suggested based on the in-situ shear test; and it is employed to determine the stability of expansive soil slope. The results of landslides stability indicate that the method suggested is rationale.

With the increasing of salt content of saline soil in inshore, salt crystals particles are formed in soil, which causing the microstructure and strength of solidified soil change obviously. According to results of unconfined compression test and triaxial shear test, unconfined compression strength and shear strength of the solidified lime-soil decreases with more salt content and increases with more curing period. Meanwhile, the difference of unconfined compression strength of solidified lime-soil in water and in air decreases gradually with more salt content. Therefore salt content of soil shall be limited in the stage of engineering construction.

A cyclic flow device is developed to study the effect mechanism of sine flow with different frequency on filtration system. A differential equation of pore water pressure accordant with the test model is built; and its analytic solution is achieved. Theoretical analyses show that the smaller ratio between the consolidation coefficient of soil and the frequency of cyclic flow leads to the higher hydraulic gradient on the border of soil and the lower hydraulic gradient inside the soil. Test results show that when the period of the cyclic flow is 0.5min, the amplitude of hydraulic gradient near to the border of the soil is nearly double of the average amplitude of the filtration system. When the period of the cyclic flow is 62.5 min, the phenomenon of hydraulic gradient focusing is neglectable. Test results show good accordance with the analytical results. The phenomenon of hydraulic gradient focusing will lead to more filtration border erosion and it will diminish the stability of the filtration system. Proper attention shall be paid to this phenomenon in the filtration engineering.

The double pilot tunnel method is one of important excavation means for the super big cross-section and large-span road tunnel. It will reduce the excavation area of tunnel face, decrease the construction difficulty and increase the integral stability of tunnel. However, none unified design criterion of the double pilot tunnel method is available. Especially, it will bring out distinct subjectivity to devise the curvature radius of core-soil temporary support. Furthermore, from practice of tunnel construction, it is found that the curvature radius of core-soil temporary support influences stability of tunnel significantly. Therefore, bases on Longtoushan road tunnel with four traveled lanes in each separated hole, the rational curvature form of core-soil temporary support is discussed and studied mainly with numerical analysis, measured data and illustrations in same boundary condition. The purpose of the article is to provide reference for design and optimization of the super big cross-section and large-span road tunnels.

Several formulas for predicting the shear strength of unsaturated soils by the soil-water characteristic curve (SWCC) are summarized and discussed. The SWCC and unsaturated shear strength parameters of intact weak expansive soil from Jingmen City, Hubei Province are measured by the pressure plate and unsaturated triaxial apparatus; based on the comparison of the test results with the predictive values of the several shear strength formulas, the limitations of the formulas are analyzed. The results show that the friction angle of the net normal stress varies with the change of matrix suction for the unsaturated intact expansive soil. According to the double stress variables theory, the contribution of matrix suction to the shear strength of unsaturated expansive soil is associated with cell pressure and different in different cell pressure levels; it is suitable that the variable characteristic of the apparent cohesion with suction is described by power function.

The parameters of Duncan Et-?t, Et-Bt and constant ?t models for the normal consolidated Wuhan clay are obtained by a series of drained conventional triaxial compression tests; the rationality and validity of parameters are confirmed by the finite element analysis; and it provides a reference for the application of Duncan models in Wuhan area. In view of a hyperbolic approximation has been suggested to describe the axial strain-radial strain relationship in Duncan Et-?t model, but the points of test results of real soils are frequently found to deviate from the ideal relationship, indicating that the axial strain-radial strain curves of real soils are not precisely hyperbolic in shape; and it results in some difficulties in parameter fitting. For best agreement of the theoretical and test results, a modified method is proposed that the straight line of ?3 /?1-?3 relationship be fitted to test data at the two points corresponding to stress difference equal to 70 % and 95 % of the peak strength. The validity and superiority of the modified method are attested by the contrastive analysis of prediction of the volumetric deformation of soil samples which adopt Et-Bt model, constant ?t model and the modified method. In addition, the method is simple in form and convenient to use.

The relationship between shear strength and water content of Song-Nen Plain soda-saline soil is studied with two different experimental methods. A shear strength formula is brought out based on tests; and the strength parameters are given accordingly. At the same time, the yield surface and the critical water content of Song-Nen Plain soda-saline soil are proposed; and the mechanism of strength variation is analyzed. The study is valuable to the engineering design and construction in Song-Nen plain soda-saline soil.

A modified calculation method based on Zhang Zhenying’s method has been presented to evaluate the settlement of landfills, considering the effect of degradation of organic content in solid waste and change of gravity density. The degradation law of organic content in solid waste is studied by degradation test and analysis. The modified method is verified by test of solid waste column and calculation parameters. The results show that the more complex effect can be considered in the modified method and the law of Richards growth function can be used as degradation law of organic content in solid waste; and the settlement of landfills in test can be calculated by the modified method reasonably.

Bases on theory of plasticity and the large strain, the early phase of fracture grouting is regarded as the question of cavity expansion in infinite soil. The stress distribution due to the cavity expansion in soil is considered as two zones. The deformation following little deformation in elastic zone and large-deformation in plastic zone is taken into consideration. By using the theory of cavity expansion, hydro-fracture and pore water pressure theory, on the assumption that the sum of initialization stress of soil and increment due to cavity expansion is equal to the pull strength of soil, the soil is fractured by grouting. If the large and small stress of soil is conversion, the second fracture grouting takes place. Based on the above theory, the fracture grouting pressure in saturated soil is given. According to the comparison, the result of the present theory is very near to the those of the engineering practice.

Seepage of bank slope due to water level drawdown is a process of water-air two-phase seepage; in which the saturated soil transforms unsaturated soil. At present, in the relevant studies the air phase is considered as a passive phase, the influence of pore air is ignored. In this paper, a water-air two-phase flow model is proposed based on the water, air mass balance equations, Darcy’s law and multiphase flow theory. Using the efficient integrated finite difference method, a fully implicit simultaneous computation code is developed. By switching primary variables according to different phase states, a set of phase states (single phase and two-phase) which is variable with space and time are taken into account. The water-air two-phase flow model is verified by simulating water through an earth dam with vertical faces known as Muskat problem. The unsteady seepage problem of bank slope due to water level drawdown is simulated numerically. The results indicate that above the free table the value of capillary pressure is much smaller than the value of pore water pressure; there is a saturated capillary water belt with relative large area, in which the pore of soil is filled with water and the matric suction is zero. So the saturated capillary water belt may endanger slope stability; and in refined analysis of slope stability, the influence of pore air pressure should be taken into account.

Seepage field force is calculated to reflect the force effect of seepage flow field. Relationship equation of stress-damage-seepage is built to consider the effect of stress and damage on seepage flow field. Combined with 3-dimension elastoplastic-damage finite element analysis of rock mass, stress-damage-seepage coupling analysis model of large-scale underground surrounding rock is established. The difficulties of solving the model mainly lay on elastoplasticity of rock material, damage, free surface boundary of seepage flow, escaping surface boundary of seepage flow, interaction of stress-damage-seepage, etc. Considering the difficulties, the sequential iteration method is proposed to solve the difficulties by several sequential iterations; and nice calculation result is obtained. The method is used to analyze the large-scale underground caverns of a hydropower station, and a series of useful conclusion is made.

Seepage problem, especially involves free surface or saturation line, is a major and difficult problem in rock and soil engineering. Borrowing ideas of seepage analysis methods from sandy soil dam, and using classical subsection-combination method, simplified model I is obtained for analyzing seepage of foundation pit. Considering the effect of soil strata and using seepage refraction at the interface between two different soils, model II is obtained on the basis of model I. Seepage discharge is calculated respectively by solving the two models under the condition of normal and maximum water levels. Then comparing it with actual seepage discharge, discovered that the result of model II is better than that of model I in the condition of normal water level; and the seepage discharges of two models are less than that in engineering in the condition of maximum water level because of ignoring the impediment effect of cofferdam on groundwater.

By establishing a normal deformation model for rock joints subjected to normal and shear loading with consideration of post-peak dilatancy and shear softening, a generalized cubic law is proposed on the basis of the equivalence principle of seepage flow dissipation energy for better describing the irreducible seepage flow behavior for the joints subjected to large normal closure and the post-peak seepage flow behavior at the presence of dilatancy and shear softening. The proposed theory has been validated by an existing coupled shear-flow test, showing that the seepage flow behavioral trend of rock joints in post-peak stage can be enough accurately predicted by the traditional cubic law penalized with a small constant.

Adopting new developed epoxy series-colophony series material as the model simulation material, through solving a series of technological matters in execution and installation and testing, comparing bolt-reinforced tunnel model with unreinfoeced tunnel model and with various length bolt models by forming same boundary condition in large-scale real triaxial test machine, some rules about how bolt affects the surrounding rock in final are obtained. The stress rises in reinforced area than that in unreinforced model while the stress out of the reinforced area tendences to same standard in both models; the peak stress in reinforced area becomes or approaches the maximum stress value among the surrounding rock; the tensile stress status in unreinforced model alters to compressive stress in reinforced model by bolt effect. The compressive stress in radial and tangential direction enhances with the length of bolt adding and sequentially the stability of surrounding rock enlarged. In addition, the fact that the distribution trend of stress becomes same in various loading rank indicates that the affection by bolt supporting goes in the same way in different deep tunnel within a certain depth. Finally, the gap value of radial strain approaches curvilinear distribution in top of tunnel while that in hance of tunnel approaches linear approximately; and it provides practical base for researching shear stress distribution along bolt in bolt mechanism.

The influential factors and classification method for risk in Beijing metro engineering are discussed in detail. Firstly, the adjacent grade of the adjacent piles must be determined. Two factors such as the spatial relationship between bridge piles and the fracture face induced by metro construction and the distance between piles and metro engineering are advised as evaluation indices. Secondly, the residual bearing capacity for adjacent bidge must be evaluated. The risk grade for adjacent bridge piles can be determined based on the adjacent grade being classified and the residual bearing capacity being certain. The different reinforcement measures must be adopted in term of the adjacent bridge piles risk grade. Consequently, the disposal procedure is formed to ensure the safety of adjacent bridge piles. Finally, a construction example for the adjacent bridge piles disposal procedure is described in detail.

The general structure of real time decision-making system for ground deformation due to shield tunneling is described. The functions of different modules are analyzed. As an example, the gray model for the safety monitoring model of ground deformation is established. The safety rules are concluded to judge whether the ground deformation data are abnormal. The causes of the abnormal data are analyzed. Safety degree is introduced to synthetically evaluate the deformation. The project example shows that the monitoring data can be stored and inquired; and the monitoring data, monitoring models, synthetic evaluation are visualized in this system. With the synthetic evaluation, the system is available to shield tunneling.

Based on the analyzing the research status of the initial ground stresses at home and abroad, the initial ground stresses back analysis method with usable program based on the 3D-FSM IBEM considering the influence of terrain and tectonic stress has been studied. And the corresponding numerical analysis subsystem has also been developed. The analysis procedure is expatiated by using an actual project example; meanwhile, it verifies the applicability and calculating precision of the method.

In recent years, some gravel soil tunnels avalanche along with the continual increase of base-building investment by the government. The stabilities of surrounding rocks of gravel soil tunnels which appearanced on the stocks of railway and highway were computed by using improved discrete element method software. Firstly, the self-stability of surrounding rock was analysed. Secondly, the relations between tunnel-stability and gravel diameter were discussed; and the limited-dig-span of tunnel of gravel diameters of 0.1 m, 0.2 m, 0.35 m, 0.5 m, 1 m, 2 m were studied respectively. Finally, the relation between tunnel span and collapse quantity was computed.The method and result can give reference to the similar engineering.

With rapid developments of metro construction in China, the safety evaluation of pipelines near tunneling is one of the key technical problems urgent to solve. On the basis of understanding basic laws of ground movements, an empirical or semi-empirical method to evaluate the safeties of flexible pipelines is put forward; and it takes the deformation as the control index. Generally the details of pipelines are not necessary to know, and only a few parameters are involved; so the method is more easy to use in engineering; and it can be used to evaluate the latent damages of flexible pipelines rapidly. The method is particularly fit for the case of no sufficient data or especially sensitive pipelines, where the joints must be treated separately and the conservative estimations are needed.

Creep behavior of weak structural plane plays an important role in the creep deformation of rock mass. Water content of the fillings is a significant factor influencing the creep properties of the weak structural plane. A series of shear creep tests on the weak structural plane of sandstone with different water contents are conducted. The curves of the shear creep deformation vs. time under different water contents of the fillings are derived. The effects of water content on the shear creep behavior of weak structural plane of sandstone are analyzed. Based on the test results, the creep model of the weak structural plane is identified; and Burgers model is derived to describe the creep behavior of the weak structural plane. Moreover, the influences of water contents on the parameters of the creep model are further studied; and the creep mechanism of the weak structural plane of sandstone under different water contents of the fillings is presented.

As a boundary-type meshless method, the hybrid boundary node method (HBNM) is based on a modified variational principle and moving least squares (MLS) approximation; so it has the advantages of both BEM and meshless methods. The dual reciprocity method (DRM) is combined with HBNM, in which the solution is divided into particular solution and general solution. The general solution is solved by means of HBNM; and the particular solution is approximated by using radial basis functions. Only randomly distributed nodal points on the bounding surface of the domain are required and it doesn’t need extra equations to compute internal parameters in the domain. The post-processing is very simple. The numerical examples show that this method has high precision and is more suitable for computation in geotechnical engineering.

Through collecting a vast amount of the measured geostress data in Chinese mainland as so far and selecting the data which has less local impact, the geostress trend pictures with depth of magmatic rocks, sedimentary rocks and metamorphic rocks are established and the corresponding regression analysis is conducted according to the respective distribution laws. The research results show that the distribution characteristics of three kinds of rocks are different, which mainly result from the different formed mechanisms. The vertical stress is linearly increased with depth for the three kinds of rocks. The vertical stresses of all rocks nearly equal to the weight of respective overburned rocks. The maximum horizontal principal stress is also linearly increased with depth for the three kinds of rocks. Under the same depth, the maximum horizontal principal stress of magmatic rocks is maximum; sedimentary rocks middle and sedimentary rocks minimum. At the shallow depth, the ratio of the average horizontal stresses and the vertical stresses of magmatic rocks are maximum, and the ratio of metamorphic rocks is minimum. The statistic analysis results above can be useful references for the study of the macro stress field distribution and related professions.

Dichotomy for stress-strain curves of sandstone is proposed to study staged features qualitatively with Lyapunov theory of chaotic dynamics. As former parts of all stress-strain curves of jointed sandstones are in chaotic state, the complicated system evolves only in nonlinear state. After ultimate limit, eighty-five percent of joint systems are in orderly state, which states that transfixed jointed sandstone has destroyed in macro state. Term of joints’ transfixion may be longer as the minimum initial stress increases. Then destructive state of sandstone after ultimate strength may be stepped decrease. If strain after ultimate strength is two-third of the complete strain, system state in the stage may dominate whole evolving state of joint system.

A new method based on the rough set theory and the fuzzy C-means algorithm is proposed to analyze the sensitivity of the influencing factors for slope stability. According to this method, the problem of the sensitivity analysis of the influencing factors for slope stability is translated into the problem of evaluating significance of attributes among the rough set theory. The fuzzy algorithm is then introduced to discretize continuous attributes; and the assessment model is set up to achieve the sensitivity analysis. Taking the circular slip slope for example, the sensitivity analysis of the influencing single factor and multiple factors for slope stability is performed; and it is shown that the proposed method is feasible and effective.

A slope has complex failure mechanism, and its stability is affected by many factors such as geological and engineering factors. Therefore, more attentions are paid to study of slope stability. A catastrophe model basing on the catastrophe theory and fuzzy mathematics is used to analyze and evaluate the slope stability; and a new comprehensive evaluation index of slope stability is proposed: catastrophe progression. This index considers synthetically effect of many factors on slope stability and reflects actually state of slope system. The study results of engineering cases show that this comprehensive evaluation method of slope stability based on catastrophe progression method has higher accuracy and good application to slope stability analysis.

In millisecond blasting, the delay error of detonators can result in possible superposition of vibration induced by separate blasting; and causing transnormal particle velocity. Especially in large scale millisecond blasting, the superposition of blasting vibration can not be ignored. By using genetic algorithm, this problem is studied; and the maximal possible magnification factor of blasting vibration after superposition induced by the delay error of detonators can be obtained. The index of magnification factor can be used to evaluate the hazard of detonators’ delay error so as to offer a reference for the blasting network design and vibration control in engineering blasting.

Strength margin safety factor varies when different yield criteria are used, and some works about relationship between Druker-Prager yield criteria and strength margin safety factor have been studied with numerical method. However, theoretical relationship between them has not been deduced. Functional relationship between Druker-Prager yield criteria and strength margin safety factor, including point and global strength margin safety factor, has been put forward; and the result is that both point and global strength margin safety factor reach minimum when the inscribed cone yield criterion is used; while reach maximum when the expansive cone yield criterion is used. Meanwhile, the gravity dam’s stability of Xiangjiaba Hydropower Project has been investigated by strength margin FEM; and its result further supports the above conclusion.

Planar and three-dimensional viscoelastic artificial boundary conditions in simulation of nonlinear wave motion in soils are proposed. The mode of dynamic modulus vibration in commonly used equivalent linearity model is chosen to consider the nonlinearity of soil; then the planar tangential, planar normal and out-of-plane tangential viscoelastic artificial boundary equations are derived; and three-dimensional normal, three-dimensional tangential viscoelastic artificial boundary equations are generalized too. These new viscoelastic artificial boundaries are applied by means of equivalent linearization method; and numerical examples prove better accuracy of these new viscoelastic artificial boundary conditions, which can be used to study problems of nonlinear wave motion in soils.

Foundation settlement is a kind of severe environmental hazard. The monitoring data of foundation settlement are usually disturbed by rainfall and engineering construction. As a result, there are a lot of data breakpoints in the settlement curve. Therefore, based on wavelet analysis and RBF neural network theory, a new method for foundation settlement is proposed. Firstly, based on the de-noising process of monitoring data by wavelet analysis, the foundation settlement curve that is close to the practical situation can be obtained. Afterwards, the prediction is carried on by radial basic function (RBF) neural network method. The wavelet analysis and RBF neural network method can provide engineering design with scientific basis. Finally, based on the engineering instance analysis and the contrast study between different kinds of wavelets, the results show that the de-noising and prediction effect of triple B-spline wavelet is the best among the chosen wavelets, and it has a good future in the field of engineering application.

When analyzing the deformation problem of rebars embedded in reinforced concrete and anchors embedded in the rockmass of chambers, the coupling deformation between a line element and a solid element has to be dealt with. The general approach is to simplify the anchors and rebars into embedded truss or beam elements, and the rigidity matrix of the embedded elements will be incorporated into one of the solid elements. The two methods cannot reflect the deformation nonuniformity of reinforcing parts under complex stress conditions. On the basis of other scholars’ researches, the reinforced solid element method is proposed to solve such problems, and its relevant analytical model is put forth. In this model, based on foundamental theories of continuum mechanics, a new nonlinear element equilibrium equation is deduced by using minimum potential energy principle, in which the axial deformation energy, torsional energy, bending deformation energy of the reinforcing parts are taken into account. Finally, a computational program based on the model is compiled; and its results are compared with the results from the commercial software Abaqus.

A method for treating soft clay by sand wick and explosive vibration is introduced. And a numerical modelling method is proposed for transforming the three-dimensional soft clay treatment by drainage consolidation with explosive vibrations into a two-dimensional plane strain problems. In this method, the sand drains is transformed into equivalent sand walls; and the explosive pressure on porthole is transformed into equivalent pressure walls, which is based on the mechanism of equivalent impulse. The deformation of soil skeleton and the non-Darcy seepage of pore water is coupled in the numerical modelling. A comparison between numerical results and in-situ experimental results shows that both results are comparable. The numerical method is capable of modelling the dynamic process of the occurrence and dissipation of excess pore pressure and the soil settelment in the course of dynamic consolidation.

According to the mechanical characteristics of rock-socketed anchoring rods under pile toe in the system of vertical load-bearing capacity test of pile foundation by the self-anchored technique, a new load transferring function suitable for anchoring rods under pile toe is set up based on the dilatancy effect between anchorage-body and surrounding rock; and an analytical solution of the critical anchorage length is obtained as well. Then, the distribution of frictional resistance along the anchorage length and the influencing factors are discussed in detail based on the obtained analytical solution; and a parameter ? is introduced to consider the comprehensive influencing effect of various factors approximatively. Comparative analysis result of an engineering example shows that the calculated values by the present method agree well with the measured data.

Through the experiment, the mixture ratio of Yellow River alleviation (silting) soil stabilized by lime-fly ash is studied. The standard age of strength of Yellow River alleviation (silting) soil stabilized by lime-fly ash is analyzed. The influence law of soil and lime-fly ash ratio and content to the strength of lime-fly ash soil is studied; and the new idea about mix design of Yellow River alleviation (silting) soil stabilized by lime-fly ash is put forward. Research thought that the mix design should be based on the 21 d unconfined compression test of Yellow River alleviation (silting) soil stabilized by lime-fly ash, is put forward. The most suitable lime-fly ash ratio of Yellow River alluvial plain soil is 1: 3, and the most suitable lime-fly ash content is between 30 % and 40 %. The grain content of <0.005 mm and organic matter content and thickness ratio can influence the strength of Yellow River alleviation (silting) soil stabilized by lime-fly ash obviously; and the interrelation among them is regular. When the grain content of <0.005 mm is between 17 % and 27 %, the Yellow River alleviation (silting) soil stabilized by lime-fly ash can obtain higher strength.

In light of geo-hazard control in the reservoir area of Three Gorges Project in China, the calculation of critical height of rock-soil elastoplastic area before anti-slide pile on declining sliding surface is carried out with limit equilibrium theory of space wedge block. Firstly, the usual methods of calculating rock-socketed length of anti-slide pile are described, such as engineering geological method and strength controlling method. Secondly, two theories, elastic and elastoplastic theories used to calculating rock-socketed length are compared. Thirdly, the critical height of elastoplastic area of mass before piles is put forword when the slipping surface is declining; meanwhile, the relationships among critical height and angle of sliding surface, resist force of rock and strength parameters of rock are discussed. Finally, taking a project in Wanzhou city of Three Gorges Resevior area for example, the critical elastoplastic height of rock-soil before anti-slide is given; and rules have been found that the critical height h shows a exponential distribution along sliding surface angleθ and cohesion c of rock, and linearly distribution along the resist forceσand friction angleφof rock .According to these rules, we can give proper correction to anti-slide pile’s rock-socketed length and critical height of elastoplastic area of rock-soil before anti-slide pile.

The working behavior of rigid pile composite ground with mat is analyzed. With considering the negative skin friction of the pile, the distribution of side skin friction resistance is discussed. A simplified linear model of this side skin friction resistance is then proposed. Moreover, the interaction between the pile and the mat is analyzed and the penetration magnitude of the pile into the mat is calculated. A theoretical differential equation of pile displacement is then derived. According to this equation and the definition of the neutral plane, a new method is proposed to calculate the depth ratio of the neutral plane. The influencing factors and their value ranges are also discussed. Finally, a case study shows that the calculation results agree well with practical experiences.

CRG piles (concrete reinforced grouting pile) are obtained an invention patent. The construction technological process and the construction are introduced; the difficulty and problems about clearing clay and rock sediment in drill hole, floating concrete reinforced pile and grouting during construction in granite bearing layer are discussed. The grouting materials of CRG piles are bored for samples; it is found that the grouting materials are weak bonding, the bonding strength is low, which resists advancing the strength of CRG piles. The static loading tests are analyzed in-situ; the lateral resistance of piles and bottom rock resistance are fully played; and the bearing capacity of single CRG pile is much higher than that of bored pile. A wealth of experience is accumulated for testing and application of CRG piles to granite bearing layer.

Due to unloading of deep foundation pit excavation, piles of underground structure will be applied skin friction in advance. This friction will endanger the underground structure and pile foundation if not be managed properly, and it will be more difficult to calculate the capacity and rigidity of pile due to this friction. According to the effect of stress path and stress level to the rigidity of soil, a new interface model considering the influence of deep foundation pit excavation is established. The friction parameters of interface model is confirmed by stress path test. Compared the results of different excavation depths, the influence of excavation on the skin friction, capacity and rigidity of pile is gained. The results show that it is unsafe to use the capacity and rigidity of pile under the conditions of earth covering.

The issue to which should be play attention is the detrimental effect of excavation-induced soil movement on adjacent piles. The additional deflections and bending moments of the pile shaft are generated due to soil lateral movement. This may lead to their superstructures distress or failure. The geotechnical finite element numerical analysis software Plaxis 8.2 is used to simulate the process of excavation; and the effects of many factors on the behaviors of adjacent piles are investigated, including excavation depth, stiffness of diaphragm wall, stiffness of pile, net distance between excavation and pile, constraint conditions of pile head, length of pile. The behaviors of lateral displacements and bending moments of piles are studied in detail.

In foundation excavating, upright post piles and engineering piles form a long -short pile composite foundation. According to the variation of shaft resistance around piles simulated by software ANSYS, we regard that short piles(engineering piles) will affect shaft resistance distribution around long piles(upright post piles). Based on shear displacement method，calculation formula for short piles’ influence is obtained. The affected shaft resistance distribution around a long pile is simplified at equal value, thus it can suit Geddes-stress theory. A new settlement calculation method of the long- short pile composite foundation is advanced; and a program PLS for settlement calculation of the upright piles is written. The calculation results accord with the engineering practice basically.

When a new railway line will be constructed along the existing one, in order to control settlements of construction period and post-construction period, and to ensure stability of existing line and the new one, comparative analysis is performed in seven projects with six methods in in-situ test. The results of settlement analysis, stability analysis and consequence analysis of existing line show that dry jet mixing piles are superior to sand well, prefabrication drains and geotextiles in consolidating foundation. Relatively, dry jet mixing pile with short length and small interval has better consolidation effect than the longer length and larger interval one.

A new technique is proposed to calculate final settlement for non-isotropic, nonlinear elastic subsoils by using the data of in-situ tests. Firstly, hyperbolic curves are fitted out from the data of load tests or screw plate tests on stratified, undisturbed soils. Secondly, the relationships between additional stresses and tangent modulus of the soils are established; and additional stress factor is added to consider the influences of foundation depth, non-isotropic and nonlinear elastic character. Finally, the total final settlement is calculated by using hyperbolic curve tangent modulus equation and additional stresses. After fitting hyperbolic curves from the data of load tests, different equations of hyperbolic curve tangent modulus for soils are obtained to find the settlements under different loads. The calculated results show that, the predicted settlements are well in agreement with those from load tests. This technique may be potential to calculate settlements with its simple principle, reliable parameters and accurate results.

Considering the fuzzy uncertainties of the parameters of stochastic variables, a fuzzy stochastic reliability analysis model is derived based on first-order second-moment method (FOSM). By introducing ? cut set, fuzzy numbers are converted into a series of interval numbers; by use of which, fuzzy stochastic reliability is calculated. The proposed method is employed to the reliability analysis of pile foundation. Case study shows that this method is theoretically innovative and practically useful.

A new simplified computing formula of uplift capacity of enlarged base pile in layered soils is deduced according to power law slip surface premises and based on limit equilibrium method. The comparison between theoretical predictions which is in accordance with the simplified formula and other theoretical methods and centrifuge tests and in situ test for enlarged base pile is illustrated in detail. According to the comparative analysis, the following conclusions are gained: the deduced theoretical formula is an integrated simplified method of several failure surface premises and corresponding formulas. The theoretical prediction by simplified method while power N=10 in dense sand and N→∞ in loose sand is consistent with centrifuge tests results. Short pile(L/d<20) and long pile(L/d>20) should be distinguished because in situ test has obvious measurement effect in layered soils. The simplified method is accurate for short pile while power N→∞; on the other hand, this formula needs to be revised using layered discount coefficient for long pile. It is reasonable that layered discount coefficient equals to 0.5 in sand and 0.6 in clay.

Piled-raft foundations can be employed to transfer loads induced by embankments or surcharges to stiffer stratum through soft soil strata and thus to mitigate negative skin friction and lateral push on adjacent pile foundations such as bridge abutments. Using a simplified method based on Mindlin stress solutions as well as 3-dimensional numerical analyses with elastic and elastoplastic constitutive models, the negative skin friction and lateral push on the piles for the Great Trans-oceanic Hangzhou Bay Bridge due to intersecting Jiaxing Port embankment are evaluated. The results indicate that the simplified method based on Mindlin stress solutions can be adopted roughly to assess the negative skin friction and lateral push on piles due to adjacent pile foundations as it compares well with numerical analyses.