Different equivalent area Drucker-Prager yield criteria on? plane, such as DP4(meaning projection areas of Drucker-Prager and Mohr-Coulomb yield criteria being equal on ? plane) , DP5(meaning projection areas of Drucker-Prager and Matsuoka-Nakai yield criteria being equal on? plane) and DP6(meaning projection areas of Drucker-Prager and Lade-Duncan yield criteria being equal on ? plane) yield criteria, can give a approximately estimation for soil failure strength under plane strain condition, this is why these equivalent area Drucker-Prager yield criteria are widely used in two-dimensional slope stability analyses. Combined true triaxial strength failure tests of sand, it is demonstrated from quantitative point that DP4 yield criterion is conservative for safety factor prediction of slope stability; whereas DP5 and DP6 yield criteria, which will exert soil shear strength more effectively under plane strain status, both give a better safety factor predictions for slope stability analyses, thus computation precision of slope safety factor is further improved by using DP5 and DP6 yield criteria in the end.

Based on the similarity theory, the numerical analysis model is established to study the mechanism of dynamic compaction of dry sands by means of secondary exploitation using the PFC2D (particle flow code in 2 dimensions). Dynamic response characteristics of dry sands to impacting are simulated in combination with laboratory mesomechanical model test. The availability and rationality of the proposed numerical method is verified by comparing the numerical solutions with the results of real data. The results show that the dynamic stress of tamper bottom can be well simulated with PFC2D as well as dynamic stress among sand grains and displacement field during dynamic compaction. Apart from movement of sand grains, the change of dynamic stress can be real-time traced and recorded. The findings of this study provide a new route to research the macro-meso mechanism of sands dynamic compaction.

Theoretical aspects of the multiscale method of granular materials based on the average-field theory are discussed. It is shown that the use of macroscopic Cosserat continuum model is necessary when taking account of rolling moment resistance between particles in contact in microscopic analysis. The expressions of stress and couple stress tensors are derived in light of the average-field theory. The constraints to the fluctuations of granular microstructure are also presented; and the intrinsic length scale parameter is discussed. It is the theoretical aspect of multiscale computational homogenization of granular materials.

Starting from the endochronic theory, by rebuilding intrinsic time and introducing a damage variable into the Helmholtz free energy, a new set of endochronic damage constitutive equations of coal containing gas are deduced using the basic principles of the irreversible thermodynamics of continuum media; and what’s more the method for getting parameters of the constitutive model is also presented. At the same time, solution analysis and experimental validation of the equations of coal containing gas under triaxial stress condition are performed. The results show that the endochronic damage constitutive equations can describe faithfully the properties of coal containing gas before and after damage and also can reflect effectively the nonlinear and shear expansion mechanical phenomena of coal containing gas.

To evaluate the dynamic responses of rough pavement subjected to traffic loads, research is focused on the geometric roughness of pavement, and by regarding the pavement roughness as sine function and simplifying the quarter vehicle to a two DOF vibration system, the dynamic loads expressions of the system are obtained and used to analyze the steady-state responses of infinite rough pavement on Kelvin foundation. The theoretical solutions of vertical displacement of the pavement are derived using the double Fourier transform, and the solutions can be degenerated to the corresponding classical solution of static problem. By employing fast Fourier transform (FFT), the numerical results are obtained and used to analyze the influence of moving load velocity, rough pavement parameters and foundation parameters on the dynamic displacement responses. Computed results show that the distribution and variation of pavement’s vertical displacement are influenced by load moving velocity. Two peaks of the deflection can be observed with increase of the rough pavement wavelength and the load velocity because of resonance. The lag effect of maximum displacement caused by pavement roughness becomes strong with the decrease of rough pavement wavelength and the increase of rough pavement amplitude.

By using the copper model piles and silicon oil instead of water, the centrifuge modeling dynamic response of soil slope reinforced with one row of piles on saturated foundation during earthquake was conducted. Based on the test results, the characteristics of the seismic response of pore pressure in foundation, acceleration in soil and moment in piles during earthquake were investigated. According to the observation and analysis, it can be concluded that the accumulation of excess pore pressure in saturated sand foundation, especially liquefaction not only makes the bending moment of pile increase as much as 87 % but also weakens the acceleration response in the slope.

The stress and deformation characteristics of soil mass nearby ground fissure were studied by a large-scale model test of ground fissure activity under the environment of Xi’an typical strata. It is shown that in the hanging wall of ground fissure the negative additional stress in soil mass is induced by the ground fissure movement and so stress in soil decreases; but in the foot wall the positive additional stress in soil mass is created and stress in soil increases, and the more far distance from ground fissure, less additional stress caused by ground fissure movement. Meanwhile, the bilateral soil deformations of ground fissure appear step mutation; and the range of soil deformation is larged from deep strata to shallow strata; and deformation zone in hanging wall is larger than that in footwall. Soil stress distrbution nearby ground fissure in space can be divided into 4 zones, i.e. the initial stress zone of footwall, stress increasing zone, stress decreasing zone and initial stress zone of hanging wall; and the range of stress decreasing zone is 1.5 to 2 times that of stress increasing zone. Also the soil settlement deformation neraby ground fissure can be divided into 3 zones, i.e. the stable zone of footwall, differential settlement transitional zone and stable zone of hanging wall; and the range of differential settlement zone in hanging wall is 2 times that of the footwall of ground fissure.

The main dam of the upper reservoir of a pumped storage power plant is an asphalt concrete faced rockfill dam located in strong earthquake region; so it is necessary to investigate the dynamic properties of the rockfill and foundation materials. The dynamic moduli, damping ratios and residual deformations of the main materials have been measured by using the large scale and multi-purpose static-dynamic triaxial test apparatus. The experimental results show that the dynamic moduli of soft rockfill and alluvium are somewhat less than those of ordinary rockfill; however, their dynamic stress-strain relationships and residual deformations may be still described by the modified nonlinear viscoelastic dynamic constitutive models and empirical formulae, respectively.

The anchorage, which is embedded into the non-homogeneous stratum in most cases, is divided into a series of sub-anchorage segments. The closed form solution for every segment is deduced based on Winkler’s assumption which is widely accepted in the analysis of interaction between the inclusive and ground. At the same time, the solution for the whole anchorage is also gained according to the continuum and compatible condition between the conjoint segments; and a general analysis program is developed for the tension anchor and compression anchor. It is indicated that the proposed solution is practicable by analyzing a compression anchor and a tension anchor, which are placed into non-homogeneous stratum and tested elaborately in site by Kim in 2003 under the multiple load-cases. Especially, the results are more reasonable for the tension anchor when the action between the tendon and grout is taken into account properly.

Starting from the basic governing equations of axisymmetric Biot’s consolidation of saturated transversely isotropic soils, and taking Laplace transform with respect to time t and Hankel transform with respect to r, the first order ordinary differential equations in term of z are obtained. Through the technique of linearization to the basic variables in the transform domain, the relationship between the point of the depth z and the ground surface (z = 0) can be established. Then using the transfer matrix method, combining the boundary conditions and continuity of interface of each layer, the solutions for axisymmetric consolidation of multilayered transversely isotropic soils are obtained. The solutions presented can avoid solving the large equation system due to the increase of number of soil layers, and enhance the computing efficiency obviously.

The improved static and dynamic universal triaxial and torsional shear apparatus for unsaturated soil is employed to perform step stress controlled cyclic triaxial tests under consolidated drained condition. Through a series of tests on unsaturated remoulded clay, the effects of initial confining pressure and matric suction (pore air pressure Ua pore water pressure Uw) on stress-strain behavior are examined. The equivalent viscoelastic model of unsaturated clay considering the influence of matric suction is recommended by improving the Hardin-Drnerich equivalent viscoelastic model and Masing loading and unloading criterion of saturated soil. Moreover, it is verified through comparing experimental data and former improved model that the recommended equivalent viscoelastic model of unsaturated clay can be used to predict the stress-strain behavior of unsaturated soil.

With combined conventional piles and ground source heat pump, a new type of pile, heat exchanger pile, is presented. Firstly, the concept and working mechanism of heat exchanger pile are presented; and the relevant method for classification is come up with. Loops of plastic tubes for heat exchanger are inserted into a pile, which are connected with air-conditional pipe system. The heat transfer from heat exchanger pile and the ground system takes place via fluid in heat exchangers, pile, the surrounding soil and ground water. Heat exchanger piles act as double functions, conventional pile and the borehole in ground source heat pump. Finally, the current application state of heat exchanger piles and the key issues for research on this field are described. In a word, this innovative method is significantly more cost-effective, environment-friendly and energy-saving technology, which is worth applying widely.

The cutting tests on various rocks were carried out using PDC cutters with simulating the shape of cutter section, the worn state of cutter and the state of lapping cutting. The factors, which include cutting area, contact arc length, back rake angle, rock strength against drilling and worn height of cutter, on the forces on PDC cutter were analyzed. Under a constant cutting area, the force on cutter changes with radian coefficient by the relationship of linear, rock strength against drilling by the relationship of power function, and worn height coefficient by the relationship of exponential function. It is found that the force on PDC cutter is the minimum when back rake is about 5-10 degrees. The conceptions of radian coefficient and worn height coefficient were introduced. Based on them, the general mechanical model of PDC cutter is built. Using balance equation of force, the integrated mechanical model of PDC bit is built for force calculation, which offers theoretical basis for bit design optimization and reasonable use.

Based on authors’ previous research achievements of structural characteristics of unsaturated loess, the regularity of relation between structural parameter and strength indexes is explored; and the question how to use structural parameter to ascertain the strength indexes of soils under different structural states is discussed too. The research indicates that the structural parameter is a corking criterion to confirm the strength indexes of soils and further expresses the internal contact with both; and there also has a very consanguineous relation between the ratio of structural parameter of unsaturated loess and influence factors of structural characteristics of soils; using the quantitative index which reflects the synthetical effect of different factors on structural characteristics of soils, named value of synthetical structural state, and considering the strength indexes of intact loess under natural water content, the strength indexes of unsaturated loess under discretional structural state can be calculated.

Using transmission caustics system, the crack propagation experiment of media containing prefabricated flaws under explosive stress wave is carried out. The varieties of dynamic stress intensity factor, crack extensions rate, crack extensions acceleration, and dynamic energy release rate in the crack tip of media containing flaw which is collinear with the borehole are studied. The relationship of them is analyzed. Experimental results show that two wing cracks appear at both ends of the flaw in media subjected to blasting loading. The wing crack A length is longer than wing crack B length. Tow wing cracks expand along reverse direction and are co-linear with prefabricated flaw. The cracking velocity and acceleration oscillated with the increase of crack propagating time. The dynamic stress intensity factor value reaches the maximum in a moment and then gradually decreases. The changes of dynamic stress intensity factor also presents oscillation in whole time. At the end, dynamic energy release rate drives crack extension.

Based on dynamic triaxial test at low temperature, deformation behavior of silty clay sampled from Beiluhe section of Qinghai-Tibet Railway under long-term cyclic loading is studied. At different negative temperatures, frequency, confining pressure and water content, relation curves between residual strain and vibration times of frozen soil are investigated; vibration excited subsidence model is built; and its parameters along with influential factors are discussed. The results demonstrate that the parameters are deeply influenced by adopted vibration times, among which, B(viscous, plastic, rheological and creep rate) decreases and C(creep regression coefficient) increases sharply with increasing of vibration times; with the exception of quickly destroyed specimens, both of the two parameters tend to be stable when vibration up to critical times; under the same vibration times, both of the two parameters decrease with rising of temperature, increasing of dynamic stress magnitude or chamber pressure, and are influenced little as vibration frequency higher than 6Hz. The work makes a contribution to properly predicting of settlement induced by residual deformation of frozen soil under long-term dynamic loads and provides experimental data to further research on dynamic characteristics of frozen soil.

The interaction property between geogrids and soil is fundamental and important factor on stability of geogrids-reinforced earth structure. A series of experiments to investigate the friction on the surface of pulled geogrids are conducted in the laboratory under various levels of externally-applied load. By analyzing experimental data, some conclusions were drawn that the friction on the surface of geogrids gradually transfers backwards along it, which rapidly increases in early time of the pull-out test and approaches to some stable value ultimately. The relationship between the strain of the geogrids and pulling time is simulated by the sigmoid curve. Based on the experimental data of the strain of the geogrids at different embedments, a three dimensional strain surface that represents a function of coordinate and time is obtained. The time function for pull-out force of geogrids is deduced through integration of friction along total length of geogrids. The experimental data is of referring value for design of geogrids-reinforced earth structure.

Indexes of interface friction between geogrids and soil are key of design of geosynthetic reinforced soil. The analysis of soil-geogrids interface friction and the direct shear friction tests and pullout friction tests have been carries out for interface friction characteristic of two tests. In the direct shear friction tests and pullout friction tests, shear strength tested interface angle of friction φsq and interface cohesion csq on composite soil of geogrids reinforced soil; the relative displacements of geogrids and soil are not same, their strength mechanism are distinguishable. Direct shear friction test and pullout friction test are to be each applications; shear displacements of shear stress peak value on pullout friction tests are about five to ten times greater than the shear displacements of shear stress peak value on direct friction tests. The relative displacements of geogrids and soil are little, direct shear friction test can be applied; and the relative displacements are large, pullout friction test can be applied. Normal stress is increase, shear stress pear strength and its shear displacements of direct shear friction tests and pullout friction tests are increase. Shear strain rate is little, shear stress peak value is large, and its shear displacement is large too; shear strain rate is increase, shear stress peak value and its shear displacement is lower, the reasons are dissipation of pore water pressure of soil-geogrids interface and stress relaxation of geogrids. To each projection, there are correct choose direct shear friction test and pullout friction test to determine design parameters.

The existence of the seasonal frozen soil layer provides a favorable environment for the formation of the artificially frozen wall; also it changes the wall’s configuration. To investigate the impact of the seasonal frozen soil layer on the formation of the frozen wall, 49 work conditions were simulat. The results show that to form a frozen wall which is 6 m depth and 1.4 m thichness in seasonal frozen area, the construction time can be reduced by 15 days and the consumption of energy can be reduced to 60 %. It has a significant economical predominance to form a frozen wall in frozen area. Seasonal frozen soil layer improved the expanding velocity of the frozen wall; reduced the consumption of energy and improved the wall’s capacity to bear loads. Finally a nonlinear regression model to estimate the thickness and even temperature of the frozen wall is established. The results of present work provide a theoretical support and guide for the application of artificial ground freezing method in cold regions.

The instability of slope which consists of two strain-softening media is analyzed. The sliding surface is assumed to be planar. There are two factors, which are water and strain, for considering damage soften of the media. The shear stress-strain constitutive relation ship is described by the index distribution law. In this way, a cusp catastrophe model of slope system is established. Through the analytical result, it is discovered that the slope stability has close relation with the stiffness ratio k of medium 2 to medium 1, and the water content of sliding surface medium. Under some specific condition, it finds that with the increase of water content, which results in the change of stiffness ratio k, especially under the condition of rainfall, the landslide is easy to lose its stability.

Based on SMP failure criterion and three shear angles theory, two formulas, which express the peak friction angle of sandy soils in general stress condition as that under axisymmetric condition, are deduced. Then, the influence of the intermediate principal stress ratio is studied. These two formulas are modified by taking account of the difference of peak friction angle that exists between axisymmetric compression condition and axisymmetric tension condition. It is shown that the modified formulas can provide reasonable results against experimental results with true triaxial test for sandy soils.

Much attention should be paid to the permeability of broken rocks in goaf for the sake of the gas outburst and disaster prevention. Using a special device together with the MTS815.02 Rock Mechanics Test System, we tested the permeability of broken coal during its compacting process, getting the relations between the axial stress and the differential seepage pressure and between the pressure gradient and the seepage velocity. The effects of axial stress, grain size, and seepage velocities on the permeability coefficient are analyzed. The results show that the permeability of broken coal with different sizes is closely related with its compaction state: (1) the maximum value of seepage pressure will increase 3.28-166.47 times as the axial stress changing from 5 MPa to 15 MPa; the permeability coefficient of broken coal will decrease one magnitude; and (2) for a constant seepage velocity, the differential seepage pressure and the axial stress can be expressed by an exponential function; and (3) for a constant axial stress, the pressure gradient and the seepage velocity can be also expressed by an exponential function; and (4) the permeability coefficient of broken coal will decrease with the increase of axial stress, having a logarithm functional relation between them.

Minimum rock cover thickness is an important parameter in vertical route design of subsea tunnel; and it affects subsea tunnel cost and security. General methods for minimum rock cover thickness of subsea tunnel are summarized; including engineering analogy method and numerical analysis method. Additionally, appropriate conditions are analyzed for all methods. Minimum distance method is presented for minimum rock cover thickness based on a great number of numerical analysis experiences. Weighted function method for minimum rock cover thickness is presented according to expert experience and is applied to Qindao Jiaozhou subsea tunnel. The research results give a reference to subsea tunnel design and construction.

The loss convergence displacement is induced by the constructing procedure of the monitored section and tunnel. And it is of great value to identification of the deformation state and evaluation of stability of surrounding rock mass. Application of experiential analogy method is considered lacking in reliability due to the challenging condition of surrounding rock mass. And the consistency in the evolving rule of convergence displacement obtained by the three-dimensional simulation and field monitoring is not universal. So it should be discussed before application of the mechanical parameters back analysis methods based on convergence curves. But so far the consistency in total convergence displacement can be ensured. Based on this premise, a method of obtaining loss displacement is presented, in which the Hoek experiential formula is applied and some provisions in specification are cited as the support. Finally this method was carried out in the analysis of deformation rule of surrounding rock mass in Auxiliary Tunnel A and B in Jinping II Power Station. The final monitored displacement, loss displacement, total convergence displacement and relative convergence displacement are obtained. And the good agreement of the fitting curves with the monitored ones shows that this method is rational in obtaining the evolving rule of displacement of surrounding rock mass with the space effect. Furthermore, this method is an important foundation for the evaluation of stability of surrounding rock mass and the back analysis of mechanical parameters.

This paper describes a case history of a geogrid-reinforced and pile-supported (GRPS) highway embankment with a low area improvement ratio of 8.7 %. Field monitored data from contact pressures acting on the pile and soil surfaces, pore-water pressures, settlements and lateral displacements are reported and discussed. The case history is back-analysed by carrying out three-dimensional fully coupled finite element analysis. The measured and computed results are compared and discussed. Based on the field observations of contact stresses and pore-water pressures and the numerical simulations of the embankment construction, it is clear that there was a significant load transfer from the soil to the piles due to soil aching. This transfer greatly reduced excess positive pore water pressures induced in the soft silty clay. For embankment higher than 2.5 m, predictions of stress reduction ratio based on the design methods proposed by Russell and Pierpoint and Hewlett and Randolph are consistent with the measured values and the three-dimensional numerical simulations. For lower embankment, on the other hand, only the method proposed by Russell and Pierpoint gives consistent predictions with the field measurements. During the construction of the piled embankment, the measured lateral displacement-settlement ratio was only about 0.2. This suggests that the use of GRPS system can reduce lateral displacements and enhance the stability of an embankment significantly.

The soils in Beijing usually have characteristics of unsaturated soil; pit instability is more related with impact of water. The excavation supports have more different portfolio forms. The new technology developments are in anchoring technology. Calculation of soil nailing is generally for internal stability control. The node structure in the connecting of face and soil nailing is extremely important; the soil nailing combining with prestressed anchors is a reliable and effective form of support. For multi-anchorage system, by the accumulation of measured data, establishing soil pressure correction model of local conditions is meaningful. By load-dispersive anchor, the anchorage efficiency can be increased substantially. The identical load and synchronous tension method should be adopted to tension test of load-dispersive anchor. The removable anchor is a powerful tool to avoid legal disputes.

It puzzles us how to introduce the soil among piles in foundation design for high-rise building. Based on the in-situ measurement on MBA High-Rise Building of Nanjing University, we know some distribution rules of settlement, earth pressure among piles, pressure at pile-top, steel bar’s inner force and the ratio of load bearing by piles and soil among piles; and it is shown that the high-rise building can adopt the sparse pile foundation. These results can be used in foundation design and theoretical research of high-rise building.

At #IV-#VI ridges in the left bank slope of Jingping First Hydropower Station, there are numbers of deep cracks and faults, such as F2, F5 and F9, which result in huge latent instable block in this area. So the stability of huge block becomes an important problem under the conditions of excavation and flood discharge. The cracks’ distribution character and the influence on slope’s stability are summarized; and the deformation model of #IV-#VI ridges under the condition of flood discharge is analyzed based on plentiful geologic investigation data. Additionally, the change of stress, especially the zone of tension stress is analyzed at the course of excavation by means of three-dimensional numerical simulation, in which the influence of excavation on slope stability is studied. It is the conclusion that there is no evidence difference to stress and whole stability of the ridges after excavation. On the other hand, the deformation of #IV-#VI ridges is analyzed and computed under the changed hydrogeological geology condition by FLAC3D. The calculation based on parameter and water table sensitivity indicates that the whole slope’s stability is more sensitive to rock mass parameters than different water table.

Longfengshan Eeath-Rock Dam has running for a long time; the muddy water phenomenon has occurred seriously in the gutter. The muddy water phenomenon changed cyclically during the day. The atomic absorption spectrometry and the X-fluorescence spectrometry has been developed to analyze the chemical composition of water and precipitates in the drainage. The chemical constituents’ evolution law of the dam foundation precipitates is researched. Research results show that the water is results rich in Ca and the precipitates are rich in Fe and Mn. In the period of groundwater seepage in the dam foundation, groundwater has physico chemical reaction with the rock foundation, leading to chemical corrosion. The chemical corrosion of groundwater seepage is closely related to the nature of the foundation rock. Basic rock category, because of the rich in iron, manganese, and other dark elements, was prone to migrate in the acidic environment.Fe2O3 and MnO2 flocculation-like sediment would appear in the gutter,resulting in the muddle waters phenomenon in the gutter.

With the FEM program of transient unsaturated seepage calculation, the seepage field of coal measure soil slope after excavating and weathering affected by the infiltration process of rainfall is simulated and analyzed according to the monitor ed daily rainfall data in July. Then, based on Morgenstern-Price method, the transient safety factor of coal measure soil slope is computed and analyzed by means of unsaturated soil strength theory and calling seepage results at different rainfall times. The results obtained show that the dangerous slip surface of the slope and its relative safety factor is affected and vibrated with water in different parts of the slope, meanwhile; rainfall infiltration and stability analysis considering weathered layer is more reasonable in coal measure soil slope.

Engineering practice shows that it is an objective problem of upward moving of tunnel segments in the construction process, especially in the large-diameter shield tunnel , which is difficult to solve. The factors affecting the upward moving of shield tunnel lining is analyzed by finite element method(FEM), such as the physico-mechanical properties of stratum material , and the properties of grouting material. According to the finite element analysis results and the state of the lining structure in the construction process, the reasons for the upward moving of shield tunnel segments are expounded. Based on the characteristics of large-diameter shield tunnel , the policies and measures are put forward to control the upward moving of shield tunnel segments in the construction process, which can provide some reference to the design and construction of the shield tunnel.

Granite is the major pre-selected rock type for HLW (High Level radioactive Waste) disposal project in China. Joints existed in it are usually the key factors to effect mechanical and hydraulic characteristics of fractured rock-msss; and it will be the major channel for nuclide to escape from the disposal reservoir to the biosphere when these joints connect to a conductive net. So it is an important work to deep understand these joint’s behaviours. When study these joints, their surface configuration characteristics are the most important aspects necessary to be researched, because most behaviors of joints are determined by these surface characteristics. Lots of in-situ studies of joints surface configuration characteristics are carried out in Gansu Beishan area, where is the pre-selected district to dispose HLW in China. Firstly, some in-situ joints surface profile curves with different length at different directions are obtained. Then, Barton’ straight edge method and a kind of statistics method are used to analyse these curves. Through these studies, scale effect is obviously founded and its threshold value is 70 cm, another characteristics such as anisotropy and the distribution rule of statistics parameters are also obtained. These studies are the basic works to carry out further researches on the mechanical and hydraulic characteristics of granite in this area.

Researching on soil-stone embankment of some expressway, the mechanical parameter of filling and corresponding constitutive relationship is obtained by triaxial test. Analyzing the different degrees of road-dike and digging steps with different sections in road-dike, the deformation stress feature is disclosured and the influential factors are analyzed. The research results indicate that the sedimentation is the major deformation, and it causes horizontal heave in middle-under parts and tendency toward sliding between filling and ramp is obtained. Internal stresses are increased towards to the deep part; and it comes to the top nearby the interface. The stress deformations have direct ratios with height of filling and inverse ratios with degree of slope. Along with the increase of degree of slope, deviation of the displacement phasor was aggravated; the tendency toward sliding was strengthened. And setting digging steps can eliminate the relative sliding tendency effectively, so as to improve the stability of roadbed.

Pile-net composite foundation is a new kind of soft soil treatment method developed in recent years. Through the deformation compatibleness, the respective effects of pile, soil and net are initiated to control the residual settlement or differential settlement. According to the kind of pile, two experimental section are designed to make comparison to investigate the working mechanism of pile-net composite foundation under embankment loads, and analyze its settlement, load transfer, pile-soil stress ratio and internal force of net etc. The results show that: the pile-net composite foundation could reduce the settlement effectively; the load transfer ability of geogrid is better than that of soil arch; the maximum strain of geogrid, which occurs at the edge of pile cap, is just 1 %, the minimum strain occurs at the midst of two piles. The results provide the basis for the theoretical research and optimum design of pile-net composite foundation.

The 1 000 kV UHV transmission line of Southeast Shanxi to Nanyang passes through the mined out space and layout area of Shanxi coalfield. For the sake of appraise the influence of mining of coalfield layout area to foundation stability of transmission tower, according to the data that collect in locale, by using FLAC3D numerical method, mining simulation of the coal seam #3 under N165 tower of 1 000 kV UHV transmission line has been done; the result is that to mine coal seam #3 will bring influence on the stability of foundation of transmission tower; the most subsidence of the ground is 3.7 m and the most incline of the transmission tower foundation along the power line is 9.2 ‰. Without taking anti-deformation measures, the incline of tower foundation will endanger the stability of 1 000 kV UHV transmission line.

Inshore saline soil is a special soil which has some bad engineering properties, such as collapse, dilatability and erosion etc. Filling material of highway subgrade with saline soil is one of the important geotechnical engineering challages, which restricts the development of highway in inshore saline area. In order to solve the engineering application of the saline soil in inshore area, large numbers of tests are done. The tests include the liquid and plastic limits test, compaction test, CBR test and unconsolidated-undrained triaxial test. The feasibility of improved saline soil for inshore subgrade filling material is discussed according to the engineering technique, cost and environment protecting. This conclusions give a reference to the construction of inshore area saline soil highway subgrade.

A great amount of monitoring data were obtained during the grouting reinforcement process in vertical shaft; and then several specific non-dimensional impact fatcors were educed from these original test data.Using nonlinear least square approximation method, the relation between the vertical strain change of arbitrary position on the shaft lining and the given grouting phase was reached. The analysis result shows that not only the relative space location between grouting place and monitoring point, but also the grouting pressure and injected amount affects this vertical strain change nonlinearly; and that vertical relative location has the more prominent affection.

：Based on osmotic method and vapor phase technique, the soil-water characteristic curves of unsaturated soils-the sandy powder soil and the silty clay which produced by dewatering construction of Zhongzhou-Kaifeng underpass project were studied. Results show that the air-enter values for the sandy powder soil and the silty clay are about 2 kPa and 250 kPa; the residual saturation degree values are about 15 MPa and 28 MPa and the desorption process of both unsaturated soils shows clearly in step-phase. The step-phase study of characteristic curves of unsaturated soils has very important meaningful for dewatering construction and the excavation face reinforcement of Zhengzhou-Kaifeng project.

Based on the constant volume cyclic biaxial test in particle flow code (PFC), PFC2D, the behavior of sand liquefaction under cyclic loading is simulated by PFC2D . The major advantage of PFC2D is the evolution regularity of microscopic fabric parameters including co-ordination number, contact normal, normal contact force, shear contact force, can be achieved together with the macroscopic liquefaction response. The micromechanism of sand liquefaction is further discussed. The results of numerical simulation indicate that the sand liquefaction is reflected by the accumulation of excess pore water pressure and progressive decrease in mean effective principal stress in macroscopic response; and on the other hand, corresponds to the cumulative loss of co-ordination number and continuous reduction of contact forces in microscopic fabric. The micromechanical research exposes that the loss of co-ordination is related to the lagging of fabric anisotropy behind stress anisotropy.

A three-dimensional finite element method was adopted to investigate the behavior of a concrete faced rockfill dam (CFRD) including the thin vertical joints of face slab on the basis of substructure concept. Using this method, we analyzed the stress-deformation behavior of the Bakun CFRD in Malaysia by different filling materials and widths of vertical joints of face slab. The analysis results show that the filling materials and size of the vertical joints have insignificant effect on the deflection, slope-direction stress, horizontal tension stress and peripheral joints’ deformation of the face slab; but they have a significant effect on the horizontal compression stress of face slab and the compression deformation of vertical joints. By decreasing the modulus of filling material or increasing the width of the vertical joints, the horizontal compression stress can be decreased while the compression deformation of vertical joints can be increased. The horizontal compression stress can be decreased by a half if using softwoods instead oft hardwoods. Such an influence may be significant for the same stage face slab, especially for the neighboring one.

A series of studies of suction bucket foundation in normally consolidated clay are carried out to investigate the bearing capacity of bucket foundation under inclined loads. A finite element method for assessing bearing capacity of offshore foundations or structures under eccentric and inclined loads is numerically implemented in the framework of the general-purpose FEM software package ABAQUS. In the method, a number of three-dimensional elastoplastic FEM computations for bearing capacity and failure mechanisms are conducted. The numerical results computed by the proposed method indicate that the effect of bearing capacity against vertical inclined loads is more significant than that against horizontal inclined loads. Moreover, failure envelopes in V-H loading space are reducing with the increase of eccentric distance and further investigations of a simple unique expression of failure envelopes. Finally, the three-dimensional failure envelope is formatted in different V-H corresponding to varied eccentricity. Those results by computed will provide referential resources for design and construction.

A three-dimensional nonlinear finite element analysis is performed to simulate the observational construction procedure of bias closely spaced tunnels with altitude difference. The main works are focused on the displacement field to investigate the construction mechanics features under alternative construction sequences. The results present more deterioration of adjacent rock for parallel tunnels with small distance than superposition of two independent tunnels because of the interaction; and the interaction effect more on pillar than ground surface and tunnel periphery. Though the construction sequences are different, the basic features of final displacement field are consistent; they are just different in quantity. The preferable construction sequence under the presented condition is given.

A displacement back analysis method is proposed by combining uniform design method, the least squares support vector machine (LSSVM)and particle swarm optimization (PSO). The learning samples are produced by uniform design and FLAC3D. The parameters of LSSVM are determined in global optimal by PSO. Thus, the LSSVM with optimal parameters are used to describe the nonlinear relationship between the back analysis parameters and displacements. The PSO is used again to search for the optimal rock mechanical parameters in global ranges. The displacement back analysis method combines the advantages of three algorithms. The PSO has merits such as easy operation, highly active; the LSSVM has merits such as small sample, good generalization and the uniform design method can produce small sample.The model of PSO-LSSVM is used to make back-analysis of in-situ stress field of the underground powerhouse area of Longtan Hydropower Station. By comparison of measured and calculated displacements and in-situ stresses of rock masses, it is shown that the obtained results are satisfactory. The results also indicate that the model can be well applied to the fast displacement back analysis in geotechnical engineering.

Recent developments in software engineering and in the field of object-oriented C++ programming have made it possible to model physical processes and mechanism more expressively than ever before. And an interest in the use of object-oriented programming methods in finite element computing is growing. Specific ideas are provided for the development of object-oriented programming approach to the finite element analysis of multiphase seepage in an oil reservoir. The basic concepts of objects, classes, methods, and inheritance as well as an expandable application framework are introduced. According to the object-oriented programming methods and the equations of the finite element analysis of the multiphase flow in oil reservoir, the classes and their methods，which describe matrix，element，node, material, shape function etc., have been developed and implemented using the object-oriented programming language C++.NET. The program is implemented and a numerical example is simulated to show the programming of finite element method.

The studying landslide locates in the left bank of the reservoir of a planned large-scale hydropower station in Jinsha River; and it is nearby the dam site. Its total volume is about 256 million m3 and belongs to a giant landslide. So it is stability or not will has a heavy influence on the dam safety and the reservoir normal work. But for its cause of formation is very complex, the rational evaluation and scientific prediction still have difficulty. In order to solve it, combining with the data analysis of detailed investigation and exploration, its qualitative formation mechanism has been analysed. The result thinks that its mechanism is mainly sliding and bending model, and by any possibility some local is sliding and fracturing or creep and fracturing. Based on it, using the numerical analysis method of three-dimensional discrete elements, the evolution process of deformation and destruction has been reappeared; and the genetic formation has been verified further. At the same time, it still has primly explained the reasons of main slip band below the present riverbed and obscure south borderline of main slide body. The simulation results will provide the powerful foundation to evaluation of development and evolution tendency, stability and harmfulness.

Based on principle of initial parameter method, the initial parameter matrix equation of force and displacement of circular beam on elastic foundation if established. Then, the matrix equation and some structure characters, including structure symmetry, force balance and displacement compatibility, are used to achieve initial parameter values for multi-center circular tunnel lining. As a result, force and displacement of every point on circular arc could be obtained. Finally, the result of case calculation indicates that the method proposed is feasible and effective. Meanwhile, the method could be considered as another approach of internal force analysis for tunnel design.

To evaluate the ultimate bearing capacity of inhomogeneous subsoil under combined loading is very valuable in engineering practice and significant in theory. Based on limit equilibrium theory of soil, the ultimate bearing capacity of undrained two-layered subsoil under combined loading is achieved by using the general-purpose finite element analysis package ABAQUS. The critical thickness of upper soil Hcr, the ultimate bearing capacity of vertical loading Pv and the failure envelope under combined loading are presented. It is found that the critical thickness of upper soil mainly depends on the undrained shear strength ration of Su1/Su2; the ultimate bearing capacity of undrained two-layered subsoil and the failure envelope under combined loading mainly depends on the thickness of upper soil H1, undrained shear strength ration of Su1/Su2 and shape of foundations.

Since single row anti-slide piles is not capable of providing efficient bracing structure under larger sliding-force, portal double row anti-slide piles, which have the advantages of less displacement in the top of the piles and large anti-force, can be used to reduce the piles deformation. However, the calculation models of double row piles in prior ignore the interaction features of piles, beams and soils; and the calculation results based on the models are not accurate enough. Taking portal double row anti-slide pile as a single-layer multi-span frame affected by piles, beams and soils, and analyzing spatial coordinative interaction between top ring beam and link beam, as well as the affection of soil arch effect on the frame, a spatial forces model of the portal double row anti-slide piles is presented. A deformation equation is established by using pile lead border condition, continuous deformation of strong point, static force balance and deformation compatibility between top ring beam and pile lead. A program is developed by finite element method and Winkler beam on elastic foundation method. Finally, the model is applied to the test of the Three Gorges reservoir area prevention and curing project; and the result shows it is suitable for similar engineering.

Silt soft clay is widely distributed in littoral expressway foundation. Its consolidation is a popular geotechnical engineering issue. Seaside silt is always under periodical effect of wave and tide. Cofferdams and back berms are often built in the two sides of a roadbed for convenient construction, resulting in obstructing wave but letting tide come into the top of the silt roadbed through drainage layer, which have great influence on the consolidation process. A finite element model of plain strain sand-wall roadbed is established, in which the effect of back berms and tide is considered. The horizontal permeation coefficient of sand-drain roadbed is calculated from the field measurement data; and the corresponding horizontal permeation coefficient of sand-wall roadbed is ascertained. The calculation results show that the effect of tide and back berms on the consolidation process is obvious.

Given water load as a kind of body load, the nonuniformity coefficients of reinforcement strain and concrete strain are introduced to compute the lining’s permeability coefficient. A water-filled joint element is developed to simulate the limited cooperation between reinforced concrete lining and surrounding rock; and an equivalent method is adopted to develop the program, The reinforcement stress and the rock stresses in hydraulic tunnel with inner water exosmosis are calculated. The results show that the reinforcement stress obtained by the new method is smaller than that of the traditional method. The fact that the reinforcement stress in the reinforced concrete tunnel under high inner water load is in a lower level, is verified.

Due to the difference of heat conduction coefficient, specific heat capacity and expansion coefficient between concrete and rock, under cyclic variation of temperature, the junction plane is liable to crack in the slope supported by shotcrete. Using FEM, the coupled action of thermal stress and crustal stress has been taken into account. The regularities of distribution of the horizontal displacement of surface of slope and the shear stress of junction plane between shotcrete and rock are discussed too. According to the analysis, under the combined action of thermal stress and crustal stress, top and foot of slope are liable to be destructed. Ordinary, the destructional form of the top is tensile failure and the bottom is shear failure. There are some time effect of displacement and stress in the surface of slope and distribution of temperature in slope, which agrees with actual measured rules. The results reveal that when temperature fluctuation is large, the effect of thermal stress should be taken into account to prevent the slope.

End friction effect is one of common problems in triaxial test. In the Mogi-type true traxial test, two pairs of loading platem need to beset on four ends of quadrate sample, which means that the end friction effect is more significant than that in conventional triaxial tests. This study aims at revealing the extent to which the end friction influences rock strength and deformation behavior. True triaxial tests are simulated using FLAC3D where Mohr-Coulomb ideal yield criterion is adopted. The simulation results indicate that the end friction can also lead to illusive effect of intermediate principal stress, even though the rock has no intermediate principal stress effect, the intermediate principal stress will still cause the increase of maximum principal stress, and this tendency become more obvious with the increasing of friction coefficient. Then, the reasons of the results and tendency are analyzed; and the importance of reducing end friction effect in the true triaxial test should be pay much more attention to.

The basic principles of the perturbation stochastic finite element method (PSFEM) are introduced. By using the second order PSFEM where the mean value is taking as the center and the local-average space discrete method, the second order statistic mean value, covariance and deviation are analyzed. Considering the failure characteristics of the bedding rock cutting slope slipping along the soft intercalation and based on Mohr-Coulomb criterion, the formulae of the safety factor and reliability of the slope stability have been obtained. Taking a typical engineering example of the bedding rock cutting slope, the slope stability and reliability of the slope are calculated by PSFEM. The results show that PSFEM presented can be used to consider the influence of the multiple stochastic variables. The safety factor and reliability can be taken as the evaluation indexes of the slope stability at the same time. By this way, the evaluation results may be more accurate and overall.

Based on the static limit equilibrium analyses of sliding soil mass on rupture, the range of variable and the model of objective function are built to calculate the Coulomb earth pressure of cohesionless soil and cohesive soil by optimization method, and the genetic evolutionary method is used to carry out an example analytical solution. The results indicate that the genetic algorithm increases the convergence speed, shortens time and has high calculation precision in the process of calculating Coulomb active earth pressure on retaining wall. The numerical results of cohesionless soil active earth pressure on retaining wall about 5 groups from example 1 are very closer to the classical Coulomb solutions; the average error is 1.748 % and the average number of generation is 15. The numerical results of cohesive soil active earth pressure on retaining wall about 8 groups from example 2 also match well with the documents’ solutions; the average error is only 0.017 %; and the average number of generation is 17.125. The genetic algorithm is very suitable for solving optimization problem of geotechnical engineering because of its good adaptability and strong search performance.

The effects of unloading and relaxation during the excavation of Xiaowan arch dam foundation are evaluated by 3-D nonlinear finite element method. Based on the analysis，the relaxed and un-relaxed cases are compared on the basis of stress, deformation, yield zone and the shear safety factor of critical section in shallow dam foundation. It is found that the relaxed foundation mainly affects the deformation and stress distribution in local section at low elevation, but has little effect on the whole dam. Compared with the un-relaxed case, the first principal stress in dam heel on dam foundation surface(EL.953.0 m) have increased to some extend after the foundation relaxation, while the third principal stress in dam toe decreased appreciably. It is also found that the contribution of cantilever beam has been weakened slightly and the shear safety factor of crown cantilever has a little decrease. The shear safety factor of dam foundation surface in the original design with un-relaxed foundation can basically satisfy the request of “Design Specification for Concrete Arch Dams”; but in the relaxed case it reduced obviously. Therefore proper measures should be taken in order for the improvement. This research has provided a reliable basis for the decision-making.

According to penetration mechanism of jacked pile, the expansion of a series of spherical cavities in semi-infinite space is used to simulate the process of pile installation; and soil is assumed as Mohr-Coulomb material. By using the theory of spherical cavity expansion, imaging method and Boussinesq solution, the surface stresses is corrected; then ultimate frictional resistance and end-bearing capacity can be confirmed respectively. The data from field test show that the effect of friction fatigue during installation is obvious; and the relevant formula of friction fatigue is presented; then the computation formula is deduced based on the factors above. It is proved that this method is feasible because the values calculated by the presented formula with software Matlab6.5 are consistent with the field test results in Taiyuan of Shanxi Province under given depth.

A simulation of the joint network in mining area III of a nickel mine in China is made based on the Monte Carlo method and by using joint plane space geometrical data measured in-situ. According to the above theory, a 3D fragmentation size prediction software named MAKEBLOCK is developed and used in the forecast and analysis of ore fragmentation size distribution of the mining area. The result shows that the most of the ore body blocks are discoid and blocky, with block size less than 0.2 m3 and equivalent dimension from 0.2m to 0.5m. The predicting results can be used as the basis for design and practice of block caving.

Since 1990s, the centrifuge modeling technique has increasingly been used in the research and practice of geotechnical engineering. Comparing with the expensive and unknown of field testing, the centrifuge modeling has more advantages and that’s why the researchers prefer them. Then the details and advantages of drum centrifuge at the University of Western Australia (UWA) are described, including modeling of linear features. Finally, a joint research between GeoHohai and UWA on PCC pile modeling in drum centrifuge is introduced.

The intelligent pile ultrasonic computerized tomography (CT) testing system represents a direction of development for ultrasonic testing technology. Its main characteristic is data got by cross-hole fanning testing, and ultrasonography got by CT inversion. The formation, basic theory, key technique and application of the intelligent pile ultrasonic CT testing system are discussed systematically. The simulated annealing algorithm(SA) is used; and the relationship between CT testing system and SA is analyzed. According to project cases, the data of defective like scale、severity, will be got by ultrasonography. In addition, the result will be gain visually.