Soil in nature is usually anisotropic, but most of the classical failure criteria can only take isotropic behaviors into account. A modified deviatoric stress tensor is defined, combining the stress tensor and the fabric tensor describing the characteristics of anisotropic materials. Based on the invariants of the modified deviatoric stress tensor, a failure criterion for anisotropic soils is proposed. Failure surfaces in the general stress space for the anisotropic and cross-anisotropic materials under coaxial conditions, as described by the criterion, and the relationships between the coefficient of intermediate principal stress b and friction angle in different sectors are presented. Their characteristics are analyzed and compared with those for isotropic materials. By comparing with the experimental data from true triaxial tests, the capability of the criterion in modeling the failure of anisotropic material is demonstrated.

The vertical mechanical behavior of composite shaft lining of high strength concrete and double steel cylinder is researched by model test and theoretical analysis. According to the similarity theory, the model of composite shaft lining of high strength concrete and double steel cylinder is designed and manufactured first. Afterward, through loading test, the vertical stress, strain and strength characteristics of the composite shaft lining of high strength concrete and double steel cylinder are gained. The results indicate that the concrete compressive strength increases 1.73－1.92 times under triaxial compressive stresses state because of inner and outer steel plate cylinder restriction, and the concrete utmost compressive strain reached -3900με. The shaft lining is fairly plastic when it was damaged. By mutual restriction between steel plate and concrete, their mechanical performances are improved; and shaft lining vertical bearing capacity increased evidently, which are far greater than sum of vertical ultimate bearing capacity of steel cylinder and middle concrete. Then a formula for calculating the shaft lining ultimate bearing capacity is given on the basis of the theoretical research and experimental results. Thus, the studied results can provide a reference for the theoretical study and engineering application of this kind of shaft lining structure.

It is difficult to do quantitative analysis of the microstructure of soils with traditional methods. A soil electrical resistivity method is introduced to quantitatively by analyze the loess microstructure in collapsing process. The collapsing tests were performed on the undisturbed loess samples with a modified oedometer consolidation cell. The vertical and horizontal electrical resistivity were measured during collapsing. Soil electrical resistivity parameters, such as the vertical and horizontal formation factor, the average formation factor, the electrical anisotropy index and the average shape factor were then calculated and studied. Experimental results show the effectiveness of soil electrical resistivity method in quantitative assessment on the microstructure change of loess during collapsing.

To investigate the influence factors of the soil dynamic properties under cyclic loading, a series of undrained dynamic triaxial tests are conducted at different cyclic stress levels, cycle numbers and confining pressures. The test results show that while being subjected to cyclic loading, the soil’s stiffness softening occurs more or less when the cycle number increase. There are three types of double amplitude strain of saturated soft clay under cyclic loading with different dynamic stress levels, such as stable type, destructive type and critical type. A new backbone curve model concerning cycle number, confining pressure, and cyclic stress level, is constructed to consider the stiffness softening feature of remoulded soil subjected to cyclic loading. Compared with the traditional backbone curve model, the simulative results computed from the dynamic backbone curve model, which can reflect the phenomenon of stiffness softening feature of soil, agree well with the experimental data.

Due to the existence of the seasonally frozen soil layer, there are significant differences in the horizontal displacement and energy consumption of refrigeration between the conditions with and without it. The refrigeration consumption and deformation performance of the frozen soil wall beneath seasonally frozen soil layer were studied; and the results show that the seasonal frozen soil with temperature -12 ℃ can reduce the frozen wall’s horizontal displacement by 23.8% and reduce the refrigeration consumption by 40.4%. It is very important to consider the effects of the frozen layer, also the reductions in energy consumption and horizontal deformation of the artificial frozen wall should be considered in engineering.

Aiming at the softening of some typical saturated soft rocks widely distributed in South China areas, such as silty mudstone and mud siltstone, self-organization criticality theory is adopted to analyze the critical phenomena in the softening process of soft rocks in the saturation test; and based on the test data, some conclusions are drawn as follows: the time points of three months and six months are two critical points for the interaction between water and rock; and the variation of physico-mechanical properties of soft rocks and concentration of aqueous solution both satisfy the same regularity; all the factors are changing greatly in the first three months, gently in the following three months and keeping stable after six months; while the response variation regularity of microstructures satisfies keeping original appearance during first to three months, self-adjusting to order during three to six months and entirely changing to another structure types after six months. Meanwhile, two key characteristics for self-organization criticality of soft rocks are analyzed; and from the angle of system evolvement, the developing process of a non-equilibrium self-organizing order structure in soft rock system is discussed; and the stable critical time of engineering properties variation of soft rocks is proposed.

Current research indicates that the stress path of rockfill during dam construction can be approximated as that the principal stress ratio keeps constant (q/p =constant); and it will become a complex stress path (dq/dp =constant) upon reservoir filling. Drained tests were conducted in large scale triaxial apparatus under two types of stress path, which were the deviatoric compression tests under the paths of constant stress ratio and the shear tests under complex stress paths. According to the test results, an incrementally nonlinear elastic model of rockfill considering the effect of stress path was proposed, which including three modulus functions could describe not only the stress-strain characteristics of rockfill under constant stress ratio, but also the constitutive relations of transitional stress paths according to the appropriate compliance matrixes based on the transitional path feature. From the simulations of the test curves, it is shown that the model can well predict the stress and deformation behaviors of rockfill under complex stress paths.

Based on the outdoor blasting experiments, mid and far field pressures of explosive stress waves are measured using self-made PVDF pressure sensor under the condition of couple charges and water-decouple charges. Whereafter, the attenuation exponent relationships between explosive stress wave amplitude and distance of the wave front from the blasting source in the case of four different decouple coefficients are fitted according to experimental results. The conclusions are drawn as follows. ①In blasting experiments involved range, the attenuation of explosive stress wave amplitude of decouple charge is less than those of couple charge (namely K =1). According to this result, it is verified that water is suggested as an elastic buffer between detonation products and rock which decreases dissipation of explosive energy caused by crushing the rock surrounding a charge, increases the propagation of explosive energy and enlarges the action region of explosive stress wave. ②The attenuation exponent of explosive stress wave amplitude when decouple coefficient equal to 3.29 is more than those when decouple coefficient equal to 1.79 and 2.57. It is shown that decouple medium (namely water) induces excess dissipation of explosive energy when decouple coefficient is too large, because water is non-perfect elasticity medium under high temperature and high pressure. This weakens the advantage of decouple charge blasting. ③There is an optimal decouple coefficient in the decouple charge blasting. At this moment, in contrast with couple charge and other decouple charge; the explosive stress wave amplitude attenuates most slowly; the explosive energy can be fully utilized; and then the best blasting result will be obtained. The study results have some guiding significance for design of decouple charge blasting and its engineering application.

We discuss the methods usually employed for continuous mechanical modeling of geotechnical materials, of which roughly speaking there are two. The first -- called hydrodynamic because it was originally used for deriving the Navier-Stokes equations -- is mainly adopted by physicists, who applied it to systems such as solids, superfluid, liquid crystals, polymer solutions and granular matter. To set up and close the set of differential equations, it starts from generally valid principles including thermodynamics (especially its second law, or the positivity of entropy production), conservation laws (for mass, energy and momentum), and the concept of spontaneously broken-symmetry (for variables such as elastic strain or quantum phase). The second approach to continuous mechanics is constitutive modeling, usually employed by engineers for the study of systems such as plastic solids, non-Newtonian fluids, geotechnical materials. It aims to directly construct functional relations among stress, strain, their rates, velocity, density and temperature, and use these to close momentum conservation (i.e. the force balance). Since both hydrodynamic and constitutive modeling for geotechnical materials are reported in the literature recently, it is worthwhile -- as we do, concisely, in the present paper – to clarify their respective ideology and range of validity, and discuss their similarities and differences. We point out especially what the complete set of state variables in either theory is, and how the treatment of the yield surface and plastic dissipation differ.

A number of consolidated-drained triaxial tests were carried out on the remolded Shanghai clay with different over consolidation ratios (OCRs) under constant confining pressures and constant mean principal stresses. The stress -strain relations at different OCRs, confining pressures and stress paths are obtained. The effects of OCR, confining pressure and stress path on the mechanical behaviors of the remolded Shanghai clay are clarified; and the critical state stress ratio and internal frictional angle are obtained. A constitutive model proposed by Yao et al. for overconsolidated clays used to simulate the mechanical behavior of the remolded Shanghai clay with different OCRs using the model parameters from isotropic compression and triaxial shear tests. The simulated results show that the constitutive model can predict well the strength and deformation of the remolded Shanghai soft clay with different OCRs and stress paths.

In order to study the dynamic characteristics of warm and ice-rich frozen soil with the instability, a series of dynamic triaxial compressive tests on frozen clay of Qinghai-Tibet Railway, with the corresponding volumetric water content 50%, were conducted. Confining pressures are 0.3, 0.5, 1.0, 3.0, 5.0 MPa and temperatures are -0.5, -1.0, -2.0, -4.0℃. According to the tests results, the general hyperbolic model is proposed to describe the stress-strain relationships; and the prediction relationships of their parameters are provided. Based on the nonlinear relationship between dynamic elastic modulus and axial strain, the critical confining stress is figured out. The dynamic modulus decreases as the dynamic strain increases when the confining pressure is larger than 0.5 MPa. The dynamic modulus increases at first and then decreases as the dynamic strain increases when the confining pressure is below 0.5 MPa. Moreover, the damping ratio increases with increasing of shear strain amplitude or confining pressure; and with the decrease of temperature, the damping ratio becomes small.

Mechanical characteristics and micropore structure of granite under high-temperature (from normal to 1 300 ℃) have been researched with hydraulic servo system MTS 815 and micropore structure analyzer 9310. The results are as follows: ① Mechanical characteristics do not show obvious variations below 800 ℃; strength decreases suddenly above 800 ℃ and bearing capacity is almost lost at 1 200 ℃. ② Rock porosity increases with rising temperatures; the threshold temperature is about 800 ℃; at this temperature its effect is basically uniform with strength decreasing rapidly. ③ The connectivity is good although rock porosity is small. The coexistence of the characteristics of different widths of micro-fissures is displayed in phase pressure-mercury test curves. The accumulated pressure-mercury test curves show a stepwise shape. Ultramicropores gradually convert to micropores and connectivity increases when temperatures are over 800 ℃. ④ Rock fractal dimension of pore distribution decreases with rise of temperature. Thermal damage of rock transforms from irregular crack structure to homogeneous pore structure gradually at high temperature. The weakening of rock heterogeneity is the basic reason for the decrease of fractal dimension of pore distribution.

Taking the loess-like silty clay in Sanmenxia area for the study object, using undrained test method on the improved triaxial test instrument,the unsaturated soils triaxial test were carried out by controlling the different dry densities and moisture contents of the remoded soil preparing to different states of samples. The test results show that the matrix suction of loess-like silty clay has a close relationship with the changes of the soil basic state; particularly, in the same moisture content and the same confining pressure, the matrix suction under the different dry densities conditions will increase firstly and then decrease as the saturation increasing. which can be analyzed by the parameters of the structural body making up with the soil particles in the unit soil.

A model test of single pile static load has been carried out through visualization model box. Considering some influence factors, such as the different diameters of piles and different soil compactnesses, the settlement mode of single pile, the behaviour of skin friction resistance and pile-tip resistance with penetration are researched. Through screen and image-processing technology, the change rule of porosity in pile tip and pile-surrounding soil is researched too, through exploitation the process of planar particle flow code ,simulation the pile-tip resistance and the change rule of porosity in pile tip and pile-surrounding soil. The results show that the simulation using method of particle flow code can preferably simulate the process of static load of single pile and post the mechanisms of macro-scale and meso-scale of static load of single pile.

Through repeated load-unloading triaxial shear tests, characteristics of deformation and damping of EPS beads-mixed lightweight soil under repeated load-unloading were studied. Laws between axial accumulative strain and axial total strain, between modulus of resilience and axial total strain, and between damping ratio and axial total strain were analyzed under different confining pressures, different cement-dry soil ratios and different types of soils. Results show that the axial accumulative strain and the axial total strain is a linear relationship. The modulus of resilience increases as the confining pressure and the cement-dry soil ratio increase. Under a range of the confining pressures and the cement-dry soil ratios, the modulus of resilience of sand type lightweight soil is larger than that of silty clay type lightweight soil when the axial total strain is smaller than 8%. While it changes to the opposite side when the axial total strain is larger than 8%. Curves between the modulus of resilience and the axial total strain can be fitted by diminishing power functions. The damping ratio of the EPS beads-mixed lightweight soil increases as the axial total strain increases, and decreases as the confining pressure and the cement-dry soil ratio increase. The damping ratio of the sand type lightweight soil is smaller than that of the silty clay type lightweight soil, but differences of the damping ratio between the two types of lightweight soil are small and the damping ratio is an approximate constant.

Experiments were carried out to study the strength and deformation properties of anhydrite under conventional triaxial compression by servo-controlling testing machine. The experimental results indicated that failure surface was shear failure under low confining pressure; when the confining pressure up to 10 MPa, anhydrite behaves obvious plastic flow characteristic; under confining pressure of 18 MPa, these was no obvious failure surface , that is shown volume expansion. It is approximately linear relationship between peak strength and confining pressure. The peak strain and elastic modulus varieties under different confining pressures were also analyzed. The results indicate that the peak strain and elastic modulus increase with confining pressure increase. Protracted Mohr circle envelope curve using triaxial compression results. Regression analysis strength criteria and shear strength parameters c、? , the presented results can be expected to provide useful references to the analysis of underground engineering.

Soil deformation monitoring is an important task in geotechnical engineering monitoring, of which characters are large scale, big diversity of engineering environment and high requirements of real-time. Hence the conventional measurement and monitoring methods and techniques are more and more not to meet the monitoring demands.The Brilliouin optical time domain reflectometer (BOTDR) is a newly developed innovative measureing technique，which utilizes Brilliouin spectroscopy and optical time domain reflectometry to measure strain generated in optical fibers as distributed in the longitudinal direction. Based on experiment, the drying shrinkage of soil is monitored by BOTDR. Characteristics are analysed; and finally, the feasibility of the distributed optical fiber sensing technique for soil deformation monitoring is verified.

In the construction of Middle Route of the South-to-North Water Transfer canal project, bearing structure of traffic bridge and connection bridge are mainly on the two side of canal slope. During the operation load expecially horizontal load will be transfered to the pile on the canal slope by the role of pier and cap, which can produce separation of pile and soil and cause uneven settlement in some deep range, on one hand can fracture the combine of foundation and layer structure of canal slope; and on the other hand affect the anti-seepage effect of canal slope. In order to take effective control measures, the deformation mechanism of pile on canal slope should be masterd. In this paper physical model test which is a link of research is designed to study the horizontal bearing mechanism of pile on canal slope; and the result shows that the anti-deformation performance of pile on canal slope is weaker than that of pile on horizontal subgrade; and horizontal bearing capacity of pile on canal slope is lower than that of pile on horizontal subgrade.

In order to consider the slaking deformation of the clayey soil of a freeway subgrade caused by wetting, a lot of laboratory tests of clayey samples were tested. For the purpose of finding out laws of wetting deformation of clayey soil along an approximate actual stress path. A series of tests along different stress paths were carried out in conventional triaxial apparatus, including conventional triaxial test stress path; conventional triaxial test+K0 consolidation stress path; "K0 consolidation + conventional triaxial test stress path". And test samples with the plane strain " K0 consolidation + triaxial shear"stress path and plane strain constant stress ratio stress path were tested in true triaxial apparatus. By analyzing the experimental data, a power function is employed, to describe the relations between additional axial strain and stress level. By analyzing the stress-strain curves along different stress paths, some formulas are deduced.

A nonstandard Proctor test was conducted on the monolayer cohesive soil to study the relationship among the density, compacting work the water content. Shear strengths of the compacted soil samples were further measured. It is shown that under lower compacting work, the compacting density increased with the increase of the water content; following a linear trend and no peak density being found in the tested range of moisture content. The moisture content for the density peak and that for the shear strength peak were separated by a gap, of which magnitude is in the range of 3.4% to 5.7% in this experiment. The rule of the reduced internal friction angle with the increased moisture content was also found to be valid for certain impacting work. Peak value appeared in the curve of the internal friction angle for lower compacting work; but the curve was replaced by linear trend when the compacting work was increased. Another focus of the experiment was on the problems of remolded soil for indoor model test. Based on the experimental data, the optimum parameters for preparing remolded soil was proposed; and an evaluating index ? was given tentatively.

In light of the effect of cushion on the composite foundation，according to the single pile composite foundation load testing of 12 piles， influences of the cushion on the pile-soil stress ratio have been studied; the test result indicates that both the thickness and rigidity of the cushion have effect on the pile-soil stress ratio，either the excessively thinness or over thick load capacity can not function well. To verify the test data，the single pile composite foundation finite element model is established using ANSYS program; the influences of the cushion thickness and deformation modulus on the pile-soil stress ratio have been analysed. Analysis and experimental results show that the value analysis and test result are consistent. Comparing the finite element analysis and test result, the selection principle of the cushion has determined so as to provide the cushion design basis in the process of composite foundation design.

Unsaturated permeability coefficient of compacted loess is studied by the test system of hydraulic conductivity under different dry densities. The relationship between matric suction and permeability coefficient shows that the permeability coefficient decreases with suction increase nonlinearly, and increases with dry density decrease. It is found that dry density has more effect on the permeability coefficient in the low matrix suction than in the high matrix suction.It is indicated that from test results，the relation between permeability coefficient and matrix suction can be fitted with power function model under certain conditions. The relationship between dry densities and parameters is explored for estimating the coefficient of permeability of unsaturated compacted loess.

In order to study on the anchoring mechanism of the recoverable anchors, the p-s curves are obtained based on the pullout tests of the anchors with various lengths. The test results indicate that the recoverable anchor is a compression anchor and has good mechanical properties, high bearing capacity and good anticorrosive properties as well as it has the advantages of easy to be recovered. When the length of the anchor is large than a critical value, the anchor force will not be increased with the increasing of the length. The anchor does not pollute the underground space, especially adapts to be used in temporary strengthening and instantaneous strengthening. The test results verified the rationality and security of the anchor design. The result of this paper is a valuable reference for the future application of recoverable anchors.

In order to reveal the loading temperature distribution law of fabric-frozen soil interface , the generation, development and evolution for temperature fields of model pile-frozen soil interface was investigated with infrared thermal radiation imaging technique. The results show that there exists infrared radiation temperature rising phenomenon in pile-frozen soil interface during loading process. Before the pile slides, the low temperature areas in the thermal maps decrease both in density and dimension; and the temperature rising amplitude ?T as well as influencing width W at different depths D increase along with time; while ?T and W of the same time both decrease as the depth increases. After the pile has slid, the high temperature areas present a zonal distribution and display a trend of transfixion; in addition, the maximum temperature rising ?Tmax and the maximum area width influenced Wmax present a linear decreasing trend as the depth increases. The research results will provide reference for the applying of infrared radiation technique to the interface temperature field’s test of fabric-frozen soil in frozen regions.

FEM with viscoelasitic boundary element was proposed to discuss the depth significantly influenced by vehicle load. This method is proved by Lamb’s analytical solution and the field test of Lian-Yan expressway. Then, using this method, the effect of vehicle speed and resilient modulus of road structures on the variation of subgrade response at different depths was investigated. The results indicate that the dynamic stress is not enough to describe the settlement characteristics, especially in clay roadbed; and vertical dynamic strain is suggested to define the effective depth induced by traffic load. The depth is about 6－10 m in soft soil roadbed. It has important significance in design treatment of subgrade and controlling post-construction settlement.

The critical unloading void ratio of preloading method is obtained base on Bjerrum’s equitime curve and Yin and Graham’s 1-D elastic visco-plastic model. This critical unloading void ratio decided by runtime duration and allowable settlement takes account into both primary consolidation and secondary consolidation for soft clay, so farther do the critical unloading void ratios for surcharge preloading method and undersurcharge preloading method. The critical settlement for unloading time is determined by the critical unloading void ratios. It overcomes the flaws that the classical surcharge preloading method based on primary consolidation theory could not reflect mechanism where surcharge preloading reduce secondary consolidation compression deformation. The minimum preload can also be decided by the formulae of the critical void ratio for undersurcharge preloading method. In the process of deriving the critical void ratio for undersurcharge preloading method, the new modified hypothesis A is suggested The condition is proved that the modified hypothesis A is approximately equal to hypothesis B. The examples show that both the actual total settlements and the actual critical settlement at unloading time are bigger than those calculated by effective stress area method.

By incorporating the logarithm models of e-lgσ and e-lgk of soil, the characteristics of the nonlinear increase in the soil’s compressive modulus and the nonlinear decrease in the soil’s permeability during consolidation were considered. Based on the above characteristics, an analytical solution was developed for the consolidation of stone column reinforced composite ground. The nonlinear consolidation behavior of composite ground was analyzed and the results show: the average degree of consolidation (ADC) in terms of stress is not equal to that in terms of deformation; in addition, the ADC in terms of stress is greater than that in terms of deformation. When the soil’s compressive indices are lower than the permeability indices, ignoring the soil’s nonlinearity will under-estimate the consolidation rate of the composite ground; however, when the soil’s compressive indices is greater than the permeability indices, the reverse is true, i.e. ignoring the nonlinearity will over-estimate the consolidation rate. For the ADC based on stress, when the soil’s compressive indices are lower than the permeability indices, the increase in the stress increment within the ground due to the external loads leads to an acceleration of the consolidation rate; however, when the compressive indices is larger than the permeability indices, the increase in the stress increment causes a reduction in the consolidation rate. For the ADC in terms of deformation, whether the compressive indices are lower or larger than the permeability indices, an increase in the stress increment within the ground always accelerates the consolidation rate of the composite ground.

The K2 Limestone Immediate Roof of 15# coal seam in Jincheng mining area is 8-10 m in thickness. Such roof structure, which is dense and hard, belongs to strong and difficult collapse roof. Aiming at the thick limestone roof being possible to face with the large area roof fracture and collapse accident, and based on some mechanical parameters obtained from the rock mechanical test, the deformation and collapse characteristics of brittle-ductile thick limestone roof were analyzed by using key strata theory and synthetically researched by numerical simulation and similar material simulation, obtaining the first weighting step distance, periodic weighting step distance, and the collapse rules of such roof. The researches had similar results that the first weighting step distance is 20-25m and the periodic weighting step distance is 10-15 m. The actual mining practice indicated that the theoretical results are in good agreement with that of experiment on collapse characteristics and weighting step distance of thick limestone roof. Therefore, the research result has provided effective way and method to the research and control of the deformation and collapse characteristics of brittle-ductile thick limestone roof in Jincheng mining area.

Since the safety of mid partition is an important issue in underground multi-cavern structure, a method is proposed to calculate the safety degree of mid partition quantitatively based on fictitious stress coefficient theory. In the method, a special fictitious stress coefficient K is sought to meet the condition that the equivalent plastic strain runs through the partition exactly under the K times initial geostress, which is the down limit of safety degree. At the same time, the up limit of safety degree is found by analyzing the inflexion point of curve between opposite deformation of typical points at partition and fictitious stress coefficient. So, the safe interval is gained for the stability assessing of mid partition in multi-cavern. Verification of a physical model test and application of multi-cavern indicate that the interval calculation method is reasonable to assess the safety of caverns and tunnels and is useful to optimize the supporting proposal of mid partition.

In order to reflect the law on shear strength with respect to matric suction in unsaturated soil, a modified logarithmic model is presented. Through comparisons between some important test results at home and abroad, it can be found that the modified logarithmic model is identical with others in low suction range while it has obvious advantages than others in high suction range. In this modified logarithmic model, parameters have explicit physical meanings, and intrinsical characteristics of soil-water characteristic curve can be reflected. Various kinds of soils with different residual values can be modeled well by introducing the parameter named b. The modified logarithmic model is used to analyze the bearing capacity of subsoil under drained condition. The bearing capacity is influenced obviously by water saturation degree. Suction can increase the bearing capacity significantly. The rate of increment increases with the reduction of saturation degree.

Pipe roof reinforcement allows safe excavation by creating longitudinal arching parallel to the tunnel axis. The complexity of boundary conditions of this method, however, imposes difficulties to understand the reinforcement mechanism. In this study, considering the delay effect of initial lining and revising the Winkler elastic foundation model, an analytical approach based on Pasternak elastic foundation beam theory for pipe roof reinforcement was put forward. With the example of a certain tunnel excavation, the comparison of the results between field monitoring, Winkler model and Pasternak model was made. The results indicate that the Pasternak model, which considering a more realistic hypothesis in the elastic soil than Winkler model, gives more accurate calculation and agrees better with the result of field monitoring, and is proved to be a better way to understand the reinforcement mechanism and improve design practice. The calculation results also reveal that reinforcing pipes act as levers, which increase longitudinal load transfer to an unexcavated area, and consequently decrease deformation and increases face stability.

The data mining techniques are used to predict loess collapsibility in geotechnical engineering; and the mining model is constructed by using the least squares support vector machines. Using principal component analysis method, data of model is preprocessed to remove the correlation among the indicators and to eliminate the impact of multi-index redundant information on the mining model, and the model inverse analysis is administered by introducing particle swarm optimization algorithm to determine the optimal parameters. The forecast mining for the actual project data shows that loess resistivity and shear wave velocity is closely related to the soil indicators such as the soil structural properties, water content, density etc, they can be more comprehensively reflect the factors of impact of loess collapsibility. Using loess resistivity, shear wave velocity and soil depth as predicting variables of the model can quantitative predict the loess collapsibility; the proposed model is effective.

Considering the effect of the intermediate principal stress rationally, the unified solution of shear strength for unsaturated soils in terms of two state stress variables is presented, which is based on the unified strength theory and shear strength for unsaturated soils in terms of two state stress variables. Good agreements can be found between the results of this study and some results reported in the literatures. The proposed unified solution of shear strength for unsaturated soils in terms of two state stress variables is validated. With different distributions of matric suction, the unified solutions of active and passive earth pressures for unsaturated soils are deduced, which can avoid the shortages of Rankine earth pressures. The effects of the intermediate principal stress and matric suction on earth pressures are discussed. It is shown that the active earth pressure decreases with increasing the unified strength theory parameter or matric suction, whereas the passive earth pressure inverses. The active and passive earth pressures do not change more quickly when matric suction decreases linearly in deepness than that is constant.

A piecewise linear interpolation and Boostrap resample methods are introduced to enrich information of deformation monitoring data in detail and enlarged data capacity. Moreover, the coordination transforms or space reconstruction is also used to change data representation and rewrite indistinct patterns or rules of monitor data in order to enhance the finiteness and incompleteness of sample data in process of prediction modeling for deformation behavior on rock and soil system. The efficiencies of new ideas are tested by the comparative studies of prediction with support vector machine (SVM), RBF and Elman neural network for deformation behavior of 3 typical projects of which the monitor data are deal back and forth with reproduction and space reconstruction. The results show that the approach method can effectively extend data information and highlight essential laws of evolution. Specifically, the SVM prediction model based on data representation is superior to SVM, RBF and Elman model which directly used monitor data. The data reproduction and space reconstruction can thus be utilized to more server deformation prediction of rock and soil.

Field investigation showed that: 21 expressways and 16 national and provincial roads were damaged during 5.12 Wenchuan earthquake. 24 tunnels (20 417 running meters) were damaged in this earthquake. It had seriously affected the disaster relief and post-disaster reconstruction. The traditional aseismic technology can not guarantee the safety of the tunnel structure. Therefore, by analyzing the earthquake disaster character and reason of tunnel, a damping model of setting shock absorption layer in the supporting system of tunnel is established. According to this damping model, shock absorption layer stiffness, the input of frequency of seismic and shock absorption layer damping on damping effect of tunnel are researched. Through three-dimensional numerical simulation and indoor model test, damping effect of this damping model is proved. Research results provide references for aseismic design of tunnel structure in a highly seismic area.

A set of analytical solutions have been reached through Laplace transform and other mathematical methodologies based on the Fredlund's one-dimensional consolidation theory for unsaturated soil, etc. The problem to be solved is about a layer of soil of finite thickness, adding to one dimension a large-area instantaneous load, while the soil top surface is penetrable and the bottom is impenetrable to water and air. A typical example result was given to analyze the changes in the excess pore-air pressure, excess pore-water pressure and sedimentation rate of soil with respect to time under different conditions air-water coefficient rate, and the changes in the pore-air pressure and excess pore-water pressure with depth at different times. The comparison between the analytical solutions reduced to saturated soils and the Terzaghi solution for saturated soils, indicates that the method is correct.

Because of multifactor synthetic effect，accurate classification of surrounding rock mass stability has always been a difficult problem. Five key factors are chosen to construct the model. In addition, because of few standard samples, fifty standard samples are produced by the way of stochastic interpolation on basis of classification standard. Aiming at the above complex optimization, genetic algorithm is used to get the optimal projection direction. On the basis of the direction, projection pursuit interpolation model is given. Subsequently, five unknown samples are classified based on the model. The classification results are consistent with that from other methods. Therefore, it is effective and reliable. Moreover, particular score of each sample could be computed by the model; so it has more precise classification and is a more promising method.

Currently, primary TIN modeling is widely used to build three dimensional structures of stratified geological objects. However, it is deficient in building geological blocks. Considering the complex location relationship among different geological blocks which caused by disappearance, outcrop and other phenomena, according to features of primary TIN modeling, the sub-face type marks can be set up due to the difference of overlapping frequency of the triangulation networks in corresponding areas among different strata levels after strata intersection and elevation adjustment. This is in order to separate different sub-faces in one stratum level which have different sub-face type marks. The corresponding relationship between geological structural blocks and sub-faces referenced could be built instantly through the type marks of sub-faces. Eventually, geological structural blocks can be separated automatically; and it ensures that the adjacent blocks have the only public-face at the adjoiner. From this, the topological spatial relationship among different geological structural blocks could be established easily.

The comprehensive evaluation of rockmass quality was an important prerequisite and basis for the feasibility study and preliminary design of a block caving mining mine. The most usually method was the RMR system, the local RMR value of the borehole and tunnel was used to represent the qualities of all region traditionally. Based on the investigation data of Jinchuan Mine No. 3 with an elevation above 1554 m, the spatial structural quality and variability of the parameters of the RMR system were analyzed firstly. Secondly, the 3D surface model of different engineerings and lithological regions were constructed; furthermore, they were filled by numerous discrete cuboids unit. Thirdly, by using the best unbiased evaluation method for the regionalization variables, the RMR parameters of each cuboids unit were estimated, and resulted in a 3D RMR evaluation model which reflects the global variation of rockmass qualities of the Jinchuan Mine No. 3. Finally, based on the resulted model, the sustained and occurring hydraulic radius of Jinchuan Mine No. 3 above 1554 m was calculated by Laubscher’s caving chart. The result showed that the mean RMR value of the evaluation region was 39.8, the cavability ranks were good to very good; and the estimated mean sustained hydraulic radius of Jinchuan Mine No. 3 is 20.4m.

Acoustic emission in sandstone specimens are tested under loading and breakage, Kaiser point is determined by parameter analysis method. The frequency spectrum characteristics of Kaiser point signal are obtained by using the fast Fourier transform(FFT). The energy spectrum coefficients of Kaiser point signal are calculated by means of wavelet packet analysis method. The Kaiser point signals are studied by applying the chaotic time series analysis method, and correlation integral method is used to gain correlation dimension D; then the maximum Lyapunov exponent is calculated by reconstructing phase space with adaptable parameters m, ? that are obtained through the false nearest neighbors(FNN) method and mutual information method. The results show that the Kaiser point signals have chaotic characteristics.

A new method for complex strata modeling is introduced. This method classifies discrete borehole data points; and then using radial basis functions to fit the discrete points of different kinds; the generated fitting surfaces are cut each other; then the strata space comes into being; at last, strata interface grids are created using discrete points and interpolation points; then 3D graphics of strata model is displayed after computer graphic processing. This method of complex strata modeling is highly automated; and the result is good.

The importance of study on mechanical parameters of rock mass is elaborated, and some methods and their principles that are often used to determine rock mass mechanical parameters at home and obroad are introduced systematically. Then taking the research of rock mass mechanical parameters from Yunxi Datun Tin Mine for example, based on the rock physico-mechanical parameters which were obtained by indoor laboratory test and the rock mass quality evaluating RMR value, the rock mechanical parameters are reduced and attenuated by these methods; and the results of rock mass mechanical parameters are obtained．The comparative analysis of the results and project application results of recommended values show that：the latest Hoek-Brown criterion, laboratory test, M. Georgi method and Г.ΦИCEHKO method are combined to study and analyze, so that the rock mass mechanical parameters obtained are more reasonable, and computational accuracy of the project rock mass mechanical parameters may be improved.

In geotechnical engineering, many types of rock masses behave in a strain-softening way. It is not easy to get the closed form solution when strength parameters change in the strain-softening process. Literature review shows that the strain-softening problem has not been sufficiently analyzed within the framework of the classical theory of elastoplasticity. Based on the characteristics of strain-softening material in which the strength parameters change while the plastic strain increases, a new method for solving strain-softening problems is proposed. In the proposed numerical scheme, stress-strain curve in the strain-softening stage is approximated in a stepwise way; and the processes of the strain-softening is simplified as a series of stress drop and plastic flow during the increase of plastic strain. Therefore, modeling a strain-softening problem becomes a series of brittle-plastic analysis. The approach is employed to examine the circular opening excavation in a homogeneous and isotropic rock mass subjected to a hydrostatic in situ stress. The effect of lining on the plastic region and deformation in the surrounding rock mass is analyzed; and the influence of strain-softening behaviour is also discussed. Numerical results indicate that it is unsafe to ignore the strength decrease when tunnel excavation and liner installation are carried out in the strain-softening rock mass.

Rockburst processes of a tunnel at different lateral pressure coefficients are modeled by use of FLAC. To model excavation, a FISH function is written and used to delete the elements in the tunnel. For rock elements exhibiting linear strain-softening behavior beyond the occurrence of failure and then ideal plastic behavior, the failure criterion obeys composite Mohr-Coulomb criterion with tension cut-off. The present calculation is divided into three steps. Firstly, the pressures in the horizontal and vertical directions are applied to the plane strain model until a static equilibrium state is reached. Secondly, the tunnel is excavated using the written FISH function. Thirdly, the calculation renews to achieve a new equilibrium state or a plastic flow state. Results show that at lower lateral pressure coefficients, dog-ear or V-shaped notches are generated in the surrounding rock that is stable after rockbursts. At moderate lateral pressure coefficients, V-shaped and U-shaped (panlike) notches are observed one after the other and the surrounding rock is still stable after rockbursts. When the lateral pressure coefficients are higher, the V-shaped notches are firstly generated and then the U-shaped notches are formed; afterwards, shear bands intersect and scalelike failed zones are formed above the roof and below the floor, leading to the unstable failure of the surrounding rock. However, no failed zones are formed at the two sides of the tunnel.

Seepage field has notable influence on rheological properties of rocks; but the related experiment is difficult to achieve because of the limit of test equipment or method. Numerical calculation has been an important method in rock mechanics gradually; in this paper, rheological properties of rocks in seepage field are studied by numerical simulation. First of all, a simulation of an available example is carried out to validate this method. Then, several compression rheological experiments of rock in unidirectional and tridirectional seepage fields are simulated. Based on the simulation results, the dynamic hydraulic force which developed in seepage process will increase the strain of rock specimen in seepage direction. Furthermore, the simulation results show that the axial seepage force in tridirectional seepage field is less than that in unidirectional seepage field; but the lateral seepage force in tridirectional seepage field is larger than that in unidirectional seepage field. Accordingly, the axial and lateral strains have similar regularity.

Based on the construction of Shanghai Metro Line No.10, the characteristic, magnitude and range of ground settlement and excess pore water pressure induced by double-o-tube (DOT) shield construction in free field were analyzed by means of tridimensional finite difference numerical simulation. Analysis results were compared with site monitoring results to get the parameters of simulation construction which could reflect actual construction level. The parameters of simulation construction were applied to the analysis of DOT shield driving beneath existing underpass to forecast the influence of shield tunnelling on the bottom slab of the underpass. The studies indicate that the positive excess pore pressure is hard to dissipate to external environment and the negative excess pore pressure is hard to get water replenishment from external environment induced by shield construction beneath adjacent existing underpass; in front of DOT shield’s excavating face, the underpass’s bottom slab is bearing extrusion force mainly composed of excess pore water pressure; the excess pore water pressure acting on the bottom slab is well distributed in transverse direction, however the soil grain’s extrusion force mainly distribute around the centerline of bottom slab; the rigid displacement of the underpass is the main reason of bottom slab’s settlement; and the structural deformation of bottom slab just induces less settlement; the interspaces of shield tail is the main reason for the deformation of soil mass and adjacent structures owing to shield tunnel construction.

Time-dependent deformation behavior of rock has a significant impact on the stability of rock slopes or underground constructions, and more and more attention is paid to the rheology of rock. However, most rock rheological constitutive models supplied by FEM software have specific usage, and the requirement of engineering numerical analysis can not be satisfied. In this paper, the deterioration effect of the rock parameters is considered and an improved Burgers creep damage constitutive model with variable parameters is established. In this model, the creep parameters of the rock deteriorate with time gradually that makes up the defect of rheology models in FLAC3D. Based on the second development program interface of FLAC3D Version 2.1 software, the basic principle of the second development program for the creep damage is analyzed. The program flow diagram on the special execution of this rheological model and several case techniques that should be taken into account in the process of code compiling are given. Several degradation modes of this model are introduced; and visco-elasticity, plasticity and damage mechanical characters are got through a numerical example. The influence of damage parameters on creep curve is analyzed; and the approach to verify the right and credibility of the second development program compiling is proposed. The second development environment is more friendly and effective with the support of object-oriented approach. Therefore, proposed design mode can bring forward references for the second development of other rheological models.

Hydraulic fracturing is not only a natural action but also an artificial method to alter rock structure. Hydraulic fracturing process, fracture propagation pattern, and influencing factors including shape and magnitude of inlet hole, stress conditions, and specimen strength were investigated by software of F-RFPA2D. The water pressure that causes occurrence of AE is named initial pressure Pis，while fracture pressure Pcs is the pressure which leads to dramatic increase of AE, and makes macrofractures propagate in instability till rock specimen failure. In the same rock specimen size, Pis and Pcs of rock specimen with circle-shaped hole are greater than those with square-shaped hole in the same hole area; and they increase when inlet hole area decreases. Pis and Pcs increase with the increase of confining pressure and strength of rock specimen; while their differences increase only with rock strength; theoretical fracture pressure Pct and simulated Pcs have almost the same change trend. Macrofractures are usually borne near angle points in rock specimen with square-shaped hole, while the positions are random in rock specimen with circle-shaped hole. Macrofracture propagating directions are random under no confining pressure, but they are in accordance with main stresses directions when confining pressure is not zero; the macrofracture along maximum principal stress direction extend until split rock specimen, while others do not grow completely. Above results are of some significance to hydraulic fracturing tests and engineering practice.

The vector sum method (VSM) has clear physical and mechanical definition, simple calculation and gives reasonable assessment of whole stability according to slope stress distribution; and the stress distribution are usually obtained by finite element method (FEM). The boundary element method (BEM) has gotten extensive application to engineering because of reduced order, discretization error only on the boundary and low computational complexity. For plane problem, using the source point serving as origin, the tangent and normal direction of integral element to establish local coordinate system, analytical solutions are obtained for all integrals of linear element. Therefore, analytical solutions for the variables in the region calculated can be acquired; and it guarantees the accuracy and continuity of the variables of region near the border. Using the stress distribution of two-dimensional slope obtained by BEM, together with VSM, the slope stability can be analyzed; the results obtained are compared and analyzed with the VSM based on FEM and the limit equilibrium method (LEM). The results of circle and fold line slip surface slopes show that the vector sum safety factor based on BEM is very close to the VSM based on FEM and LEM; the vector sum factor of safety based on BEM is not sensitive to boundary element size.

The horizontal stress in the floor of roadway plays an important role in floor burst. According to the theory and characteristics of floor burst, a mechanical model is set up; and the dangerous coefficient of floor burst is also initially given. The research results show that the dangerous coefficient of floor burst is directly proportional to the depth, the horizontal tectonic stress , the square of width of roadway and the coefficient of hard roof abutment pressure, and inversely proportional to the elastic modulus of rock and the square of the thickness of soft rock of floor when the Poisson’s ratio is invariable. Through numerical simulation, the distribution laws of horizontal stress rising and vertical stress reducing in the floor are found out. When the stress is more than the breaking point of the floor coal seam, floor burst will happen with the influence of blast firing or roof breaking quickly. According to the research, the intensity weakening theory for floor burst is established. The measure of blasting for stress-relief in the floor is applied to the haulage gateway of 25110 coal face in Yuejin Coal Mine, and has gained good effect. The study conclusions provide theoretical foundation and ways for floor burst prevention in similar conditions.

Finite element method is employed to study the influence on silo foundation including different constitutive relations of elastic part of soil and the different ways of applying coal load. Based on this, the variations in following aspects are analyzed: coal pressure, contact pressure of pile-soil, internal force and deformation of pile and settlement of subsoil. According to the analysis, we will get the optimal design of silo foundation on the basis of the fact that the elastic modulus of soil improves with soil compaction, and coal, silo and subsoil interacts with each another to ensure the force status of silo foundation more practical.

The slab underpinning technology is an effective method for developing underground space of existing buildings. Firstly, after partial top slabs have been constructed, the soil under these slabs support the weight of structure while the soil at the rest places can be dug; then the columns or walls in the basement can be lengthened and the base slabs can be constructed. Secondly, these finished slabs can be taken as underpinning components to support the weight of structure; and the rest jobs such as digging soil under the slabs, constructing the top slabs and the base slabs all can be done. The settlement tendency of column-heels can be gotten by setting up the 3D finite element model using ANSYS program,which can analyze the five phases of underpinning construction. Before the phase of digging soil, the settlement values of column-heels in middle part are larger than those in around part; while, after the phase of digging soil, the settlement values of column-heels in middle part are smaller than those in around part because of the decreasing weight of dug soil. The settlement values have relations with the elastic modulus of soil and increasing load of the building. The additional moments caused by differential settlement can be gained by setting up the 2D finite element model.

A nonlinear relation between concrete creep and its thermal stress appears when the thermal stress is more than the half tensile strength of corresponding aged concrete. A nonlinear creep model of concrete is adopted to simulate its thermal stress; and a numerical algorithm is also presented. With the advantage about temperature crack propagation, element-free Galerkin method(EFGM) is adopted to simulate temperature crack propagation. A numerical example shows that EFGM is of good accuracy and reliability; and crack depth and extension speed of concrete after considering nonlinear creep effect are less than those only considering linear creep because of that the rapid increased nonlinear creep at the cracking moment relaxed thermal stress at crack tip.

During the application of fast Lagrandian analysis of continua in 3 dimensions (FLAC3D), even for some simple irregular geologic bodies, the generation of quasi-3D numerical model with FLAC3D is difficult to construct. A new modeling method is put forward and an interface program of IMAGE-FLAC3D is realized by visual basic language in order to build numerical model of FLAC3D based on pairs of pixel units index numbers (i, j) and give the element different properties as well as different function modules(such as excavation, backfill) based on the color attribute of pixels. Through the interface program of IMAGE-FLAC3D, we can easily generate a microscopic and macroscopic irregular quasi-3D model based on the digital image in a short time. Then a finite difference model of soil-rock mixture and a finite difference model of landslide are developed, which show the feasibility of IMAGE-FLAC3D. The case study shows that the intuition, fastness and automation of modeling can be realized. Finally, the stability of landslide is analyzed by strength reduction method, whose results(such as the safety factor and the location of most dangerous slip surface) are in better agreement with those calculated by limit equilibrium method, which shows the computability of the model from IMAGE-FLAC3D. In a word, this paper gives a typical example that the digital image serves geotechnical engineering.

Characters of lateral displacement, vertical settlement and stability of embankment on inclined weak foundation with stage construction have been studied with FEM. It is shown that the lateral displacement of inclined weak foundation distributed inclined and got its maximal value at the lower toe of embankment, which are different from that of horizontal weak foundation distinctly. The stability of embankment on inclined weak foundation is greatly less than that of horizontal weak foundation, which maybe destructed along the inclined surface of inclined weak foundation. The results also show that anti-slide piles is an effective reinforcement of inclined weak foundation, which reduced the value and increment of lateral displacement of embankment, impeded the failure of embankment along the inclined surface of inclined weak foundation, and enhanced the stability of embankment effectively.

The duration of transportation facilities built on soft subsoil mainly depends on its permanent settlement caused by traffic loads. To predict this part of settlement, an empirical model suitable for saturated soft clay was proposed. A parameter was introduced in the description of residual volumetric strain to quantify the effect of different drainage conditions on deformation development. The influence of partial-drained condition in-situ on the development of residual volumetric strain and residual deviatoric strain was considered through taking residual volumetric strain as a hardening factor in the description of the model. A practical numerical approach was proposed to implement the empirical model in FEM, and corresponding codes named as ROAD2D were developed. The effectiveness of the model and corresponding codes were verified by analyzing an actual boundary value problem. It was found that the settlement of road under undrained conditions was larger, and the pattern of settlement was worse for pavement than under partial drained conditions.