Systematic experimental studies of granite from Dagangshan Hydropower Station were made and a series of stress-strain curves under different confining pressures were obtained. According to the active state of the microcracks existing in rock samples during the process in which the samples are loaded, four stress thresholds are defined, i.e. closure stress, initiation stress, damage stress and peak stress. These stress thresholds can represent the progressive damage process of granites and reflect the damage extent of rock samples. The pre-peak stress-strain curves can be divided into four stages in terms of character stresses. Deformation modulus and Poisson’s ratio should be calculated for each stage. It should be noted that the deformation modulus is not only related to the confining pressure but also to extent of damage of granites; and the Poisson’s ratio is only related to the rock’s extent of damage. Stress thresholds can be identified by volume strain-axial strain curve and linear regression technique. A constitutive model for granites in consideration of progressive damage is advised. In this model, the deformation parameters (deformation modulus and Poisson’s ratio) is regarded as function of stress and the strength parameters(cohesion and internal friction angle) is function of plastic strain. The model is embedded into general finite element software ABAQUS and a series of triaxial compression tests with different confining pressures are simulated. The results show that the simulated curves are close to the experimental curves; and the model can represent the nonlinear mechanical behavior of granite before its peak strength is reached.

Based on the soft ground improvement project at Jiaxing section of Shen-Jia-Hu-Hang Expressway using Y-shaped vibro-pile, field tests on reinforced embankment with Y-shaped vibro-pile were performed to study stress distribution at road embankment surface, and above and under pile caps under road embankment load; so that the stress distribution and change rules were obtained. A series of stress differences were compared at specific positions, such as different points at soil surface among pile caps, above and under pile caps, soil surface under pile caps and among pile caps, on pile caps and pile heads. The changing tendency and rule of pile-soil stress ratio and load distribution ratio under road embankment load were analyzed. The adjusting process of soil stress and pile-soil stress ratio after filling was analyzed during special time period. The adjusting rule of pile-soil stress ratio and load distribution ratio during preloading period were also analyzed based on the monitoring data during preloading period.

Solidifying inshore saline soil with lime, which causes the microstructure indices of saline soil change obviously because of a lot of chloride. With the help of Leica QWin5000 software it has been proved that microstructure indices, including particle diameter, particle oblate degree, and particle area ratio, increase or decrease at approximately linear relationship with the increase of salt content through analyzing SEM’s photos. With the increase of salt content fractal dimension of particle granularity has been increased; and uniformity degree of particles diameter has been decreased; however fractal dimension of particle orientation rises firstly; secondly decreases, and finally is stable progressively; and orientation of particle is fixed in the some direction. And the conclusion is corresponding with the results of particle size analysis of solidified soil.

A parameter inversion method is presented for fully coupled analysis of steady water flow and stress in fissured rock masses based on forward coupling analysis and new hybrid genetic optimization algorithms, as well as different types in-situ measured data of both water head and displacement. The sensitivity of in-situ water head measured data to seepage parameters is considered in constructing the objective function and the sensitivity of in-situ displacement measured data to mechanical parameters is considered in choosing unknown parameters for inversion based on the concept of relative sensitivity. The validity and rationality of the method are studied for a fissured bank rock slope problem. According to sensitivity analysis of displacement to mechanical parameters, the best optimized location of points for displacement measuring is suggested. The fully coupled inversion of parameters for the slope is carried out as wall as forward analysis results are assumed to be the measured data.

In harsh and/or inaccessible areas, monitoring, measurement and survey using traditional methods are generally time-consuming and laborious, even impossible. Although the techniques of satellite remote sensing and aerial photogrammetry can partially overcome the above restricts, their precisions and resolutions are too low to be used for the purpose of displacement monitoring and geological survey. Moreover, the aerial photogrammetry is subjected to the aviation regulation. It is therefore of great practical interest and prospects to develop effective and cheap displacement monitoring techniques, which are not restricted by field conditions and subjected to few aviation regulation restricts, but still have reasonably high resolution. A new monitoring technique, namely, model airplane-borne photogrammetric system, recently developed by the authors, is described. The system has been successfully used in the topography survey of the Moon Mountain, Yangshuo, and in the site investigation and displacement monitoring of the steep slope slides on the Daye Iron Mine, Huangshi.

Through the analysis of the definite and randomness in choosing the settlement modified coefficients by the traditional calculation methods for foundation deformation, the Bayesian statistics was brought forward which was built on the old information and the sample information. The posterior distribution of settlement modified coefficients had been obtained. Conjoining the road bed engineering structure of one passenger dedicated railway, the value range of settlement modified coefficients had been obtained through its posterior distribution. The case study shows the priori probabilities of modified coefficients were estimated to obey uniform distribution in the certain range based on the old information. The settlement modified coefficients had been obtained through analyzing the observed deformation and calculation deformation. Combining the deformation information from the field tests with the prior information, the posterior probabilities of modified coefficients were calculated to obey normal distribution by Bayesian statistics. In addition, the parameters were investigated by estimation of Bayesian confidence interval. According to this red clay, interval estimation of modified coefficients was optimized at [1.0, 1.7]. And probability distribution models of modified coefficients had been obtained under different load conditions.

Based on the Mohr-Coulomb strength criterion of joint in rock mass and reliability theory, the strength parameters of rock and joint as well as the obliquity of joint are taken as random variables. Some influences caused by these random variables on the failure probability of joint are analyzed. The regularity of failure probability of joint with the change of the obliquity is discussed. A formula for calculating the failure probability of rock and joint is brought forward. Some main factors which influence the failure probability of joint are found out. Results show that the reliability analysis method of joint in rock mass is more reasonable than that of traditional method.

The uplift rock-socketed piles have been widely used in modern civil engineering constructions. However, some mechanism of it such as the load transmission characteristic, the side resistance distribution and its influencing factors has not been studied clearly. The shear lag model is used to analyze the side resistance distribution law and the load-displacement characters of uplift rock-socketed piles. Based on theoretical analyses and checking calculation, it is shown that when the load is lower than the elastic limit, the distribution follows the exponential law; and the load-displacement curve assumes linear changes. On the contrary, when the load exceeds the elastic limit the side resistance distribution will be divided into two parts as decoupling section and coupling section respectively. The side resistance is even in the decoupling section, while it follows exponential law in coupling section. Meanwhile, the load-displacement presents a nonlinearity.

The triaxial compression test of hard brittle limestone soaked in different pH value, 0.1 mol/l, Na2SO4, CaCl2 solution and distilled water is carried out; and the effect of chemical solution on mechanical behavior of limestone is studied. The variety regulation of strength and deformation parameters are investigated. The change regulation of ion concentration of chemical solution is gained; and the mechanism of chemical corrosion on rock mechanical property is analyzed. The experimental results show that: chemical corrosion results in the transformation of brittle failure to ductile failure of rock. The cohesive force c, internal friction angle and modulus of elasticity are reduced; while the Poisson's ratio increased. The degradation of strength and deformation parameters is related to the variety of mineral amount; the great the ion concentration dissolved from the specimens, the great degradation of mechanical parameters.

A new technique for calculating nonlinear settlement of foundations is proposed by using the data of plate loading test (PLT) and standard penetration test (SPT). Firstly, hyperbolic curve fitted out from the data of PLT and the correctional tangent modulus equation of soils is established. Secondly, the correctional tangent modulus equations of different stratified soils at different depths are determined using input soil parameters from SPT in accordance with the linear correlation. Finally, the total nonlinear settlement of a large foundation is calculated by using layerwise summation method with correctional tangent modulus and additional stresses. The results of settlement analysis of a foundation of an oil tank and a raft foundation of a tall structure in Guangdong Province show that this technique is able to calculate the entire nonlinear settlement from initiation to ultimate limit state with its simple principle, reliable parameters and accurate results, so as to achieve the objective of subsidence control for foundation engineering design with this method.

Based on the fundamental theory of upper-bound limit analysis of plasticity, the limit heights and stability coefficients of the reinforced steep slopes with different slope angles, top slope angles, internal friction angles, cohesive, reinforcement tension strengths, reinforced spacing, reinforcement arrangement, unit weights, seismic intensities and additional loads are calculated based on a code written by the authors. The sequence of sensibilities is listed; and the results show that the internal friction angle and earthquake are the key factors that influencing the critical heights of the reinforced steep slope. Whereas, the sensibility of cohesive is descend contrast to the gentle slope. Therefore, the emphasis should be placed on the selection of the internal friction angle for steep slope and the effect of earthquake as well.

A new method for calculating foundation settlement reliability is proposed. The kernel technique is based on modified Cam-Clay model in FLAC and least squares support vector machine (LSSVM) combined with MCS. The sensitivity of parameters involved in modified Cam-Clay model is analyzed; and the sensitive parameters are chosen as random variables. The stochastic variables are sampled according to the probabilistic distribution. A program is programmed to calculate the reliability by Matlab. The results show that the method of MCS combined with LSSVM is worth to study for reliability analysis of soft foundations settlement.

In view of mass monitoring information and monitoring data of hydropower slope projects, in order to reduce the labor intensity of manual information management and data analysis and raise the labor productivity, using Microsoft Visual C++ technology and SQL Server data base, the authors develop the geotechnical engineering remote visual monitoring information management and monitoring data analysis network system which has the advantages of advancement, reliability, generality and extension. The system is applied to Longtan Hydropower slope project. The remote real-time sharing and network management and analysis of monitoring information and monitoring data of the slope have been realized. Monitoring analysis results are fed back to designers timely, which plays an important role in evading design and construction risk and ensuring the construction and operation safety of the slope.

The dynamic displacement response of continuously reinforced concrete pavement (CRCP) resting on viscoelastic Winkler foundation has been investigated when the system is subjected to multiple rectangular moving loads. The pavement is treated as an orthotropic plate and infinite in the moving direction. The theoretical solutions of the vertical displacement of CRCP under single moving load are obtained by using the trigonometric series and Fourier transform, and the superposition method is used to obtain the analytical solutions of CRCP under tandem-axle, dual-wheel and four-wheel loads in the transformed field domains of moving space. By employing fast fourier transform (FFT), the numerical results are derived and used to analyze the influence of the load velocity, frequency, viscous damping, reinforced ratio and the distance and phase between the multiple loads on the maximum deflection and on the deflection distributions.

A method of particle size distribution testing with digital microscope and image analysis software is presented during the research of the stability of filtration system. Microscopic image analysis method is suitable for gradation analysis of small quantity of soil particles which can not be tested through densimeter method. Cost of this testing method is low; but the sampling requirement is high. Good testing result for the silt adopted in the test was achieved by taking isopropyl alcohol as dispersant and 4 g/L as the concentration of the soil. Compared with the testing result of densimeter method, it is shown that the testing result of microscopic image analysis method is credible. Error analysis shows that for the flat and irregular particles, microscopic image analysis method tends to get higher particle size and less fine particles; and densimeter method tends to get the opposite result. Microscopic image analysis is an effective method for the study of the stability of filtration system.

Based on the limit equilibrium theory and by treating the backfill as an ideal elastoplastic material which followed the Mohr-Coulomb yield criterion, some drawbacks of the Coulomb's earth pressure theory are pointed out, and it is explicitly postulated that the limit earth pressure results from the plastic soil body behind the retaining wall. By assuming that a family of slip lines in the plastic zone are straight lines, namely, the plane slip surfaces, a more reasonable slip wedge analysis model for clay is established to solve the active earth pressure on the retaining wall, the reaction force on slip surface and their distributions. The classical Coulomb's and Rankine's active earth pressures could be considered as the special cases of the solutions.

The super-large shallow-buried box culvert with jacking method and pipe-roof crossing Beijing-Zhuhai Expressway in Zhengzhou is the largest in soft soil in Asia. How to control the soil displacement and protect the expressway are the main problems considered in design and construction. With in-situ data, FLAC is employed to study the soil displacement during the construction process. By analyzing the measured results and numerical stimulation results, the soil displacement regulations are given as follows: ① The biggest settlement point of the pavement is not on the axis, and the distance between the point and the axis is about half span of box culvert. ② The biggest horizontal movement is in the soil in front of excavating face with the same elevation of the box culvert axis. The horizontal movements of pipe roof composites are roughly equal to that of the pavement. ③ The pore water pressure is more sensitive to the disturbing of soils in the process of box culvert jacking.

The deformation shapes around a tunnel cavity and the elastic solution for the prediction of the tunneling-induced ground deformations for shallow tunnels in the soft ground, are studied. A general ova deformation of ground is suggested and incorporated as the boundary condition of the displacement around the tunnel section. The difference between oval deformation and vertical translation ground deformation patterns on surface settlements and lateral deformation is investigated. The results indicate that oval deformation has a greater effect on lateral deformation than on surface settlements.

Comfort and safety of moving train is directly determined by dynamic response and stability of railroad subgrade. In order to investigate behaviors of silt subgrade soils subjected to moving train loading, cyclic triaxial tests including conditions of soil compacting factor, water content, deviator stress, and loaded frequency were conducted in laboratory. Based on the test results and field measurements of subgrade stress during train loading, it is found that with train speed increasing, silt railroad subgrade should be stable if its natural moistness is near to optimum water content and compacting factor is not less than 0.9; moreover, if subgrade compacting factor is only 0.85 and deviator stress of subgrade surface is less than 70 kPa, subgrade is also stable; but it would lose stability at higher deviator stress level. With train speed increasing, the elastic deformation of subgrade rises linearly, but resilient modulus changes negligibly. With increase in saturation, the threshold stress and resilient modulus of subgrade decrease significantly, while the elastic strain and cumulative strain increase sharply; and it may result in failure of subgrade, so train speed should be limited in wet season in order to reduce subgrade deviator stress.

Taking the Bijiashan tunnel under construction in Chongqing city as prototype and geometric similarity ratio of 1: 25 is adopted in model test, then selecting cavity of 60? range in arch crown of level Ⅲ surrounding rock as the objects, the research is carried out. During the model test, firstly, applying the load on the structure till it produces the defects, and then applied load again while the structure is destroyed after taking different inner surface reinforcing at the same rock mass and load form in tunnel; the bearing capacity of structure is researched emphatically while it’s failed in different inner surface reinforcing material and range. And the distribution of internal forces and forms of failure for secondary lining in different reinforcing manner are obtained; and finally, the reasonable conclusions are drawn so as to offer instruction opinion for maintaining and reinforcing in future.

In light of the heterogeneity of rock, by introducing the constitutive model based on damage mechanics and statistical theory and using the RFPA2D, the influene of the horizontal in-situ stresses on the distributions of plastic zones is discussed. The deformation and nonlinear gradual failure characteristics of circular roadway in deep rock mass as well as the displacement and the stress variation of the key positions in the periphery of the roadway are analyzed, When ≤1, the plastic area is large-scale, but deflection more little; when , the plastic area is little-scale, but deflection more big. The study indicates that the stress concentration occurs in the periphery of the roadway after evacuation and plastic deformation zone engenders under the persisting stress of the surrounding rock; then the cracks appear and expand continuously; the broken rock zone appears at last and the intensity of the stress concentration decreases as well as the stress field shifts beyond. This study is very useful and significant both on the theoretical and practical aspects.

The computation method of water and earth pressures on retaining wall is closely related with that of earth pressure. Under the precondition of computing water and earth pressures separately, the effect of the computation method of earth pressure on that of water and earth pressures is studied. Results show there exist two kinds of critical states of sliding on a plane and rotation around a log-spiral cylinder surface; and there are two kinds of methods to compute the water and earth pressures. Comparisons with measured data show that the two kinds of attained results can be regarded as an interval estimation of the water and earth pressures on retaining wall.

Initial geostress is one of the key factors influencing stability of slope, underground cavity and foundation; and it is one of the elementary indexes required in engineering design. According to the measured geostress data of Zijinshan gold and copper mine, initial geostress field is derived from back analysis based on the support vector machine and simulated annealing. Firstly the support vector machine is used to substitute the time-consuming finite element analysis; secondly simulated annealing algorithm is used for the optimization of objective function for fear that the search often falls in one of the minimums and cannot go any further when the conventional mathematical optimization methods are employed. Through the comparison between computed and measured geostress values of measuring points, it is shown that the two are similar in values and directions, so that the results by the back analysis results are very close to the real geostress field; and it can satisfy design requirement.

In view of the assessment slope treatment schemes being a problem of group decision making, a two-dimension leg-mark selected location method of group decision making of slope treatment is presented. In this method, the simple two-dimension leg-mark coordinate figure or assessment function is used; and the optimal scheme of the decision of slope treatment can be determined. The method is applied to the decision of Xigoukou landslide treatment; and its application is discussed in detail.

The determination of boundary condition which changing with weather condition is always a challenge problem in geotechnical numerical analysis of unsaturated soil. Some methods used widely in agriculture for soil-atmosphere interaction analysis are introduced. Moreover, the energy balance method and aerodynamics method are used to setting the boundary condition in the analysis of Rouen test embankment in France. Embankment behavior in January 2005 is simulated; and results including energy exchange between the embankment soil and atmosphere, soil temperature, soil volumetric water content and suction are given. It is shown energy analysis methods used widely in agriculture are also effective in geotechnical problem analysis.

At present elastic creep model is often adopted to compute thermal stress of concrete dam. This method is feasible when thermal stress in dam is lower. But the creep deformation of concrete is no longer to be linear relation with thermal stress when thermal stress is larger than the half of concrete tensile strength; and the relation between the creep and the thermal stress shows a strong nonlinearity. Thermal stress is more close to concrete strength, the concrete creep deformation is more larger. A concrete nonlinear creep model is presented based on concrete creep test results and a corresponding algorithm is also presented. The computation results of an example and actual project show that the thermal stresses computed by elastic creep model and nonlinear creep model exist a little difference between them; and the thermal stress of the former is larger.

Based on the indoor test and numerical calculation of movement of ground surface and strata, large-scale bed separation in bending strip upside cranny strip is brought by un-consistency of overlying strata subsidence movement due to underground mining and different characteristics of displacement and deformation of overlying strata and ground include periodic caving of bed separation inter-space along with work face mining. Conglomerate layer movement is the main power fountain of rock burst on the basis of local observation that ground surface subsidence change strenuously with high frequency rock burst and more dangerous as ground surface rebounding. And rock burst moves periodically adapt to movement of deep conglomerate layer.

Since deep penetration large diameter steel pipe piles have been widely used in platform foundation, pile drivability analysis and blow count prediction play an important role in pipe driving. Research results show that during driving pile by a hammer, the continuous impacts will cause reduction of the strength of the soil around the pile and make the pile penetration easier. This phenomenon is called the fatigue effect. The soil strength fatigue leads to the prediction blow counts are always more than the data. However, it is all known that much more blows are needed in the subsequence driving process. The soil consolidation and strength restoration make the subsequence driving difficult. In order to explain the phenomenon, the mechanism of soil fatigue and restoration is analyzed based on the consolidation theory in soil mechanics. A program has been established based on the one dimensional wave equation, pile and soil interaction model and soil consolidation theory, which consider the soil fatigue effect and strength restoration in pile driving analysis. By simulating the practical pile driving records of blow account versus penetration of several cases, the advantages of the model are identified. The calculation results show that the model of quadratic distribution with penetration can better simulate the pile driving records. And the proposal method to estimate the ratio of the excess pore water pressure converting to effective stress is reliable.

Large quantities of similar material experiments are absolutely necessarily parts of landslide model tests in the past. The similar material experiments will cost a great deal of manpower and material resources, while the distortions happen due to the material property hard to control or simulate. The distortions are difficult to be eliminated by traditional ways, but the distortion will reduce the accuracy of the test to a great extent. Taking adjusting the seepage coefficient of the landslide model test for example, a way to eliminate distortions of landslide model test is explored; and a new thought to do landslide model test on the condition that the model materials are the same of the prototype is proposed. The way is feasible and useful to eliminate distortions of landslide model test.

By taking the dilatancy and plastic softening of rock mass into account and introducing the concept of the dilatancy gradient and softening modulus, the new analytic solution of the stress and deformation of the soft rock tunnel are educed. The rationality and feasibility of the presented model are verified with the results from other published theoretical models. The influences of the dilatancy gradient and softening modulus on the deformation and pressure of the surrounding rock are analyzed by a case study. The results show the analysis is more rigorous than before by considering the dilatancy and plastic softening of rock mass.The conclusion obtained has some significance in guiding the supporting design and construction of the soft rock tunnel.

The fault zone rock foundation is common in geologic structure. The 3-D analysis of progressive failure of rock slopes including fault zone is very difficult. An interface element style has been put forward according to distribution of fault zone in rock mass to simulate the rock and fault zone in arch-dam zone. The shape function and elastic matrix have been given. And the entire fault zone in the location, 22-fault zone, has been simulated. The Mohr-Coulomb criterion has been selected as yield criterion in plastic analysis. The stochastic distribution of rock and fault zone has been conceded. Cracking analysis has been used to search for critical slip surface based on gradually cracking theory and credibility theory and elastoplasticity theory. Then the probability of slip has been obtained according to reliability theory. Through three thousand times finite element calculation, the location of slip surface, the form of s slip surface and the sequence of cracking have been obtained; the conclusion of the mode of progressive failure of rock slope including fault zone can be drawn as: the failure began at fault zone. With the fault zone cracking, the stress states of slope deteriorate. Some rock layer began changer to plank with different support, then the rock layer began crack, and then the slope began slip. At last the slopes collapse with one or more failure steps.

The relationship between the compression strength of cemented soil samples and curing period, and the links of compression strengths of cube samples and prism samples are established by using a microcomputer-controlled electronic universal testing machine DWD-100. Furthermore, integrating the data derived from triaxial compression test, bending tests of the reinforced cemented soil beams and the published data of the field static loading test, it is simple and reasonable that using the compression strength of the prism to determine the modulus of deformation of cemented soil; and the formulation is presented.

The load transfer and deformation behavior of the short pile foundation is studied by the experimental and numerical analysis of a case history of six-story building in the lacustrine deposits. The test results show that the real bearing capacity of pile is more than 1.6 times of that calculated by Shanghai codes and the observed settlement of pile foundation is less than the predicted value. The interactive behavior between the piles and subsoil is analyzed by measuring the contact pressure under footing, which shows that the bearing capacity of shallow subsoil is neglected. The stress increase and deformation in the soil are obtained by numerical analysis of the short pile-soil interaction. The results show that the settlement of the short pile foundation is mainly caused by the compressiom of the soil under pile bottom, and reduced by the stress diffusing in the shallow leck which is the bearing layer of pile.

Based on stress and vibration fields resulted from linear charge explosion, according to charge characterizatic used in tunnel blasting, blastholes in tunnel face are considered as linear charges blasted in millisecond blasting methods, shape of stress and vibration fields in radial of blasting zone is shape of pillar; and shape of stress and vibration fields in axis of tunnel is combination of several hemicycles. The intensity of stress field is not very well-proportioned; intensity of stress field in in radial of blasting zone is maximal; intensity of stress field from radial to axial is gradually diminishing; intensity of stress in the port of blasting zone is evidently diminishing; intensity of stress in axis in the port of blasting zone is minimal.

The boundary of unsteady temperature field is always a large grade area where a dense mesh is necessary. But too many nodes will cost much time in the three dimensional thermal stresses computation. An effective way to solve the problem is introducing p-version hierarchical finite element method to temperature field. The temperature boundary condition and initial value in p-version finite element method are researched and corresponding program is compiled. For a same example, several meshes with different density are computed by traditional finite element method and a sparse mesh is computed by p-version finite element method. The results show that the p-version hierarchical finite element method brings better precision with a coarse grid in unsteady temperature field analysis.

From the definition of weight, the weak point of weight calculation by traditional analytic hierarchy process (AHP) is analyzed. It is pointed out that the factor weight is not unchangeable, which can vary with the difference of actual values of factors. Taking this as starting point, the simple dependent degree of extension theory is introduced to improve the traditional AHP. The improved method not only can avoid the disadvantages which are caused by subjectiveness during the weight calculation but also can fully reflect the impact on slope stability when the same factor has different data, which should make the evaluation results more reasonable. Finally, a specific example of slope project is studied. The results show that the factor weight has a dynamic characteristic, that is, even if evaluation factors are same, the values of factor weight will also alter with the different data of factors, then the evaluation results of slope stability must be different.

In view of the influence of dismantling temporary supports of large-span shallow tunnel on the preliminary lining, we have employed two ways, in-situ monitoring and numerical simulation, in the phase of Xiamen East Passageway (Xiang-an tunnel) constructed by CRD method. The results turned out to be perfectly matched by comparison and analysis. The research indicates that when the one-time longitudinal dismantled length is 10 metres, the settlement of vault has a 5 %－10 % drop while the safety factor of preliminary lining is about 5 %－15 % lower. In addition，removing the temporary supports has little impact on the safety of the preliminary lining. As a result, this study provides evidence for information-oriented construction of tunnel as well as experience for the future related projects.

An upper bound solution for active earth pressure based on a nonlinear failure criterion is described mainly. Firstly, the power-law nonlinear failure criterion is proposed. Then the variables and are introduced by tangents method; and a unified acceptable velocity field is established. By upper bound analysis, the expression of the active earth pressure is formulated. Because of too many variables in the expression of the earth active pressure, in order to optimize the upper bound solution, large-scale mathematical programming method is applied, in which the widely used SQP algorithm is adopted. Calculating the active earth pressure using the method presented is found to be more efficient; and had a larger range of application comparing with the classical Rankine’s earth pressure theory.

The traditional compacted clay cover system of landfill is studied for desiccation cracks. A new evapotranspiration (ET) landfill cover system is proposed. The mechanisms of compacted clay and ET cover are analyzed. On the basis of considering precipitation and evaporation, a one-dimensional vertical unsaturated soil moisture movement model is developed. The model is used to predict 576h moisture distribution law under 9 charge periods. Results show that the moisture content near the surface is highly sensitive to climate loading; and the effect is significantly attenuated and time lagged along with increasing depth. The compacted clay layer of the traditional landfill cover has low penetrability; so it can not get effective moisture charge. ET cover acts as a reservoir that stores moisture during precipitation events and subsequently returns it to atmosphere as evapotranspiration. It is reasonable agreement between model simulation and measured data. According to this analysis, these results may be used to assist in making decisions regarding proposed modification to the design of the cover system.

Separated tunnel is a primary job practice in deep and overlength highway tunnel. Taking into account the diversity of construction progress of two tunnels, it is put forward that the study of rockburst prediction of the tunnel excavated slower through the rockburst condition of the tunnel excavated quicker. In order to investigate the rockburst influence of the tunnel excavated quicker to the tunnel excavated slower, a series of calculations and analyses are carried out by using the FEM; and some results are obtained. When horizontal stress is equivalent to vertical stress in initial stress field, the rockburst intensity of arch bottom of the tunnel excavated slower will increase with the increment of lateral pressure coefficient and the decrease of tunnel clear distance; when horizontal stress is dominant in initial stress field, the rockburst intensity of crown of the tunnel excavated slower will decrease with the increment of lateral-stress coefficient and the decrease of tunnel clear distance. Finally, the practical example demonstrates that the rockburst situations of the tunnel accord with the analytical result of the method.

To analyze the action relation of rock mass structure and slope deformation, taking Badong county for example, the rock mass structures evolution under endogenic and exogenic geological process of main strata in the region is discussed. Then, the deformation characteristics of surface slope under the control of rock mass structure is analyzed. It is shown that the structure of rock mass is generated by endogenic geological process but rebuilt by exogenic geological process. Based on the scale of laminations, joints and cleavages generated by sedimentation and tectonic processes, the structures of rock mass are classified as layered structure, blocky structure and cataclastic structure. Rebuilding result of weathering and karst process is controlled by the initial structure of rock mass. The layered structure rock mass of T2b3 usually slides along the weak interlayer. However, the interbeded structure rock mass of T2b2 easily collapses because of the different disintegration of layers. The model and scale of blocks failure are controlled by the combination relations and size of discontinuities. The dense cleavages make rock mass cracked, which may bend when unloading. The obtained results will provide an importance reference to analyze and prevent slope hazards.

The support vector machine (SVM)is applied to reliability analysis of underground engineering. A new method of tunnel reliability analysis is proposed by combining the SVM, numerical simulation, first order second moment (FORM) and Monte Carlo simulation. The learning samples are built by numerical simulation; then the relationship between displacement of tunnel and the random variables is built. The performance function and its derivatives in tunnel reliability analysis were approximated by SVM. The statistical moments calculated from the performance function values and the corresponding gradients using SVM were then used in the calculation of the reliability index in tunnel reliability analysis. An example is given for illustrating the applicability of the proposed approach. The new method is effective in tunnel reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.

Laboratory and field scour testing studies for loess slope indicate that the increasing of slope angle degree causes the maximum rill depth of slope surface firstly decreases and then increases later on; the nearer of the difference between the slope angle degree with the critical angle, the smaller possibility of slope surface erosion. The theoretical formula for calculating critical angle of cutting loess slope is derived based on Gradient current theory. A conclusion drawn from investigation is that the longer of the slope height is, the more erosion of the slope surface is. The optimization design model for cutting loess high slope based on surface stability is built when the relationship among slope angle, slope surface length and the erosion mass quantity is studied. At last, this model is verified by a typical example of cutting loess slope; and the result shows that this model agrees well with the actual situation.

It is a basic problem to solve the space foundation in geotechnical engineering. The problem is always solved with one kind of variables in traditional methodology, which is under Lagrange system. Dual variables were employed into the governing equations of mechanics via variable substitutions. Through this way, the governing equations were transmitted into Hamiltonian system. Therefore, the methods of separation of variables can be applied to solving the problem. In the completed solution space, the eigenfunction expansion of the solutions of the equations was obtained by the use of the properties of symplectic geometry. Discussed the zero and nonzero eigenvalues of the equations and their physical meanings. Different from the traditional methods, the paper gives a direct method to solve the problem of the half space foundation

An elastoplastic critical state-based framework for describing the constitutive behavior of unsaturated soils are presented and briefly discussed. Base on the model, eleven model parameters were ascertained after seven laboratory tests on unsaturated soils. Then a revised elastoplastic incremental stiffness matrix for unsaturated soil is deducted; and it has a same form with that of saturated soils. Finally, a program has been workout which can consider the affection of mean stress and suction on soil hardening laws. As a consequence, a new method is proposed for analyzing the elastoplastic problem of unsaturated soil.

Tunnel construction with underground excavated method in soft soil often induces ground deformation. Due to that the city underground excavation tunnel lies in area with dense and intensive buildings, the damage of soil deformation to adjacent structure is noticeable. 2D FEM is adopted to study and simulate the underground excavated tunnel construction of adjacent structure. The building is with length of 15m. It is indicated as follows. Surface settlement together with force and deformation of the lining are increased by the existence of building; simultaneously, additional stress and deformation of adjacent structure are induced during tunnel excavation construction. L is defined as horizontal distance from tunnel axis to building axis. When 0 m, the building is relative secure. When , the building incline to sides of tunnel. When to 20 m, great surface settlement is produced with more settlement difference between building head and tail; and the building is in danger. When to 40 m, the impact of building on the tunnel construction is small. When 40 m, the influence of building on the tunnel construction is negligible. As a result of the foundation, the maximum of bending moment, the axial force and the shearing force vary little; with extends range is less than 10 %.

By studying the influence of displacement on active earth pressure, the active earth pressure depends mainly on the relationship between relaxed stress and displacement which can be agreed well by the hyperbolic-function through recent studies. Then the approximate mathematic expression of the active earth pressure considering displacement is given; and the expression of the parameter in terms of two centrifugal test results is derived. This method is feasible and reasonable according to model test and numerical calculation results. Finally, Rankine active earth pressure model considering displacement is also derived so as to offer a new way to calculate active earth pressure considering displacement.

Four test bored piles in Daweng bridge & Qinyu bridge projects in Vietnam have been tested with self-balanced method of bearing capacity. The pile tip post-grouting technology was used in two of them. The fundamental principles of this method and the pile tip post-grouting technology are introduced. The experimental data gained are analyzed. The results indicate that the design codes of Vietnam over estimate the tip bearing capacity; and the pile tip post-grouting can boost the bearing capacity of piles.

According to existing analysis methods, the vertical deformation of down tunnel has been predicted and reached different results. But it is proved by in-site measuring that the vertical deformation of down tunnel behaves in different time-space laws because of quick excavation. It is important to take into account time-space effect when the vertical deformation of down shotcrete tunnel happens. Velocity and mode of deep-dip excavation is one of key factors of vertical deformation. Based on analysis and study of in-site measuring data, some useful experience and lesson has been concluded. It may be useful reference to similar engineering in future.

The research based on silt ground disposal project of the first stage of Guangzhou Nanshataishan petrifaction storage area, the construction technology and idea of improving saturated soft clay with dynamic-static drainage consolidation method are described. Real time monitoring and inspecting are conducted during construction; improving effects are detected through pore water pressure, layer settlements and plate load tests etc. The results show that it is obvious to improve the silt with the new construction technology of low-energy and “few times and more cycles” dynamic compaction combined with precompression with soil load and the plastic vertical drain, the mechanical property and anti-deformation characteristics of silt are improved obviously. The whole consolidation effects are remarkable; physico-mechanical properties are better than expected.

The combination of a single row of man-excavation piles and a single-row of anchorage pillars is applied as the support structure for a complicated planar foundation pit. During the construction of the support structure and excavation, horizontal displacements monitoring is carried out for the pit. Monitoring results show that in some parts the tops of support structure, their deformations is larger than the advance warning value and continue to aggravate in the process of the excavation; the support structure is in dangerous state. The construction union don’t take measure against dangerous state and get no effect. The situations of the support structure in design and monitoring condition are described; and the monitoring results of 19 points are analyzed; the mechanism of the dangerous situation is explained; and the reinforcement measures are proposed in light of these existing problems, so as to obtain good effectiveness.