Considering that total rheological model is independent of stress path and rheological genetic characteristic of rockfill dam is omitted, a seven-parameter incremental rheological model which is more suitable for the rheological analysis of coarse grained material is achieved based on the theory of hereditary creep. The analysis of normal triaxial rheological test data of some rockfill indicates that: the linear function could be adopted to fit the relationship between ultimate volume rheological deformation and corresponding volume stress, and hyperbola function could be adopted to fit the relationship between ultimate shear rheological deformation and corresponding generalized shear stress; so rheological volume modulus and shear modulus of coarse grained materials could be calculated based on the above-mentioned functions. Finally, a verification analysis is done; it could be concluded that the incremental rheological model approximately agrees with the experimental results; and it can be applied to earth dam projects.

Xiamen subsea tunnel is the first undersea road tunnel in China. The investigation, design, engineering experience will be used for reference to other subsea tunnels’ construction. The encountered problems about rock mechanics and tunneling designs for subsea tunnel construction are more complicated than other road tunnels. There are many problems which the present criteria have not be covered yet; and all the questions are urgently needed to be solved. In order to study the mechanical characteristics of the host rock in weathered strata, a strain hardening elastoplastic model and cohesion evolution equation are established to describe the hydro-mechanical coupled behavior of the strongly weathered granite based on laboratory test results; and corresponding parameters have been identified by back analysis. The developed strain-hardening elastoplastic model can well describe the mechanical characteristics of strongly weathered granite. The method suggested in the paper is worthy to be widely used.

Strength property of slip zone soils has important control action for slope stability. It is essential premise that revealing the variation law of strength indices for slope stability analysis. Aiming at an ancient landslide in reservoir area, the experimental study of shear strength of fine-grained soil containing coarse-grains in sliding zone was carried out. Based on large-scale field shear test and laboratory consolidated quick shear test, the shear characters of slip zone soils were compared; and the strength indices were defined by field recycled strength, field reduction strength, and consolidated quick shear strength in laboratory. For the deficiencies of repeated direct shear test in fine-grained soil containing coarse-grains, the improvement of test process and examination apparatus has been carried out; and the reasonability of test result was verified. Basis of the statistic rule of test data, the influence of moisture content, plasticity index, and coarse-grained content on strength indices has been discussed; the shear property distinctness between fine-grained soil containing coarse-grains and clay or sand was summarized.

The stiffness coefficients, cohesion, friction angle are the important parameters in reflecting the mechanical characteristics of the joints. Based on the tri-axial compressive tests for rock mass samples containing different joint angles and analysis to stress and displacement, the analytic solutions of stiffness coefficients in the elastic state can be deduced by establishing the new equations of strain and displacement according to the reciprocal work principle; and the cohesion and the friction angle of joints are obtained by the Mohr-Coulomb strength theory. In order to verify the validity of the presented method, the direct shear tests for the rock mass samples containing the similar natural joints are implemented; and the normal stiffness, the shear stiffness, the cohesion, the friction angle of the joints are obtained. The comparative results show that the parameter values obtained by the given method are close to those by the direct shear tests. Thus, the stiffness coefficients, cohesion, friction angle of the rock joints can be got by the tri-axial compressive test, and the parameters can be concise-fleetly measured

Interface instability between HDPE geomembrane and sand is a main reason for landfill structural failure on lining interface. Though frictional coefficient of textured geomembrane is large, it is easy to be splited by the huge tension force accumulated on the landfill lined slope, or to be weared and teared. A novel concept of reinforced HDPE geomembrane is proposed. A series of direct shear tests were carried out to investigate interfacial characteristics and stress mechanism under different normal stresses and spaces of reinforcement. Comparison was made between stress-strain relationship and strength property of reinforced geomembrane, smooth geomembrane and textured geomembrane. It was shown that cohesion of strip geomembrane was increased, internal frictional angle was reduced, while both of lump geomembrane were increased considerately. Along with decreasement of space, cohesion of reinforced geomembrane added. However there is a gradual reduction of internal frictional angle when it exceeds a specific value. Compared with smooth geomembrane and textured geomembrane, reinforced geomembrane, as is a new kind of geosynthetics, not only has a higher interface shear strength with sand, but also has a better rupture strength.

In order to investigate the homogeneous bank fall of reservoir and the changing features of the phreatic line during uniform rising water level, three homogeneous bank models with different structures are built with the sand containing little clay excavated from the Three Gorges Area; and four tests with different water level rising rates for each model are carried out. The model testing results indicate that the larger the rising water level rate, the more possible the bank fall. During rising water level, some factors advantaging or disadvantaging the bank stability may be induced by the interactions between the model soil mass and the ground water or reservoir water. In these factors, the vanishing of the capillary force induced by the rising water level is very important. The typical phreatic lines in the model slope obtained from the experiment are compared with those obtained from a published analytical solution. The comparison indicates that the published analytical solution may over-valuate the evaluation of the phreatic line.

The classic Burgers creep model could only describe the behavior of rock material before the third creep-phase. The fractional element, defined by using fractional derivative, is an element between spring and dashpot. Through the substitution of a dashpot by a fractional element, a fractional Burgers model is developed. Moreover let the dashpot acted in series be a nonstationary parameter of time for describing the acceleration stage of rock creep. Their constitutive relation and creep compliance are obtained. When the nonstationary dashpot work or does not work, the model could respectively describe two-phase and three-phase creep. It is shown that the creep testing curves under different conditions are coincident well with the theoretical curves. The model can well describe the variation of creep in the period of attenuation, steady period and the period of acceleration. The validity of the model is verified by the experiment data

In the process of soft foundation treatment using dynamic drainage consolidation, the growth and dissipation of pore water pressure play the decisive role. It is not only primary bases to control the construction schedule, but also is an important parameter to ascertain the strengthening depth and evaluate the reinforcement effect. So the model test, it simulated an expressway site conditions, is carried out with test apparatus designed by ourselves. In order to comprehend the variation of pore water pressure under different parameter combination, these parameters include tamping times; tamping energy; hammer weight; hammer bottom’s area and fall distance, the test is divided into several groups. These tests include the pore water pressure of the same or different depths under different or the same tamping times, the pore water pressure of the same depth with different combinations between tamping energy and hammer weight and so on. Research shows that, when keeping tamping energy invariant, increasing tamping times will slower dissipation of pore water pressure. And increasing hammer weight will be more effective than increasing fall distance. The high tamping energy can make pore water pressure has bigger amplitude, and the corresponding reinforcement range will increase. In order to speed up dissipation of pore pressure, construction procedure should adopt the method of “multiple tamping, and successive increase tamping energy”.

A series of stress path tests on typical soft soils (silt and organic silty clay) in the influence range of foundation pit in Fuzhou city were conducted by using triaxial apparatus with stress and strain control in order to research the stress-strain behaviours of unloading and loading caused by excavation and retaining structure of foundation pit. Compared with the results of triaxial tests between normal consolidation and K0 consolidation samples in the same confining pressure, it is indicated that there are large differences in deformation and strength. Based on the results of K0 consolidated triaxial tests, Duncan-Chang parameters were figured out and the methods of certification of each parameter in the model were put forward. At the same time, comparison with model parameters obtained by normal consolidation samples showed that some parameters had significant difference; and they decided the difference of stress-strain relationship. Duncan-Chang model parameters were suggested to obtained through triaxial loading and unloading test by K0 consolidation samples for the sake of satisfying numerical simulation analysis of foundation pit engineering. Duncan-Chang parameters of typical soft soils offered by the tests can be referred to numerical simulation of foundation pit engineering in Fuzhou city or other similar strata sites.

A series of samples with same dry density and different moisture contents for comparative tests were made from Malan loess collected from north of Shaanxi province in China. Soil-water characteristic curve of the sample was tested by volumetric pressure plate instrument. By disintegration tests of samples with different initial matric suctions with self-made disintegration device; relation curve of average disintegrating velocity and initial matric suction was gotten. The results of tests indicate that the water stability of dry loess is worse than wet one. There was a logarithmic relationship between average disintegrating velocity and initial matric suction. Influence of matric suction on disintegration of unsaturated remolded loess can be concluded as following two aspects: 1, infiltration speed of water increase by matric suction. Quick infiltration of water increases the pore water pressure, dissolves cement of particles, and cause the softening of loess; 2, during the quick filling of pores in samples, the air of sample come out in the form of bubbles and cause outward pressure.

Through laboratory model tests, the following discussions are performed based on macrostructure and microstructure: the vertical displacements varying with depth, the distribution of maximum principal strain and maximum shear strain of clay soil slopes, creep properties and crack functionary mechanism of clay soil slopes respectively under loading. The results show that, with the increase in loading, the values of creep increase microstructure of soil slopes. Creep of soil slopes can be considered as the process of damage, and process of energy dissipation of microstructure of soil slopes; and anisotropy of damage is made clear. The longer time of loading is, the larger vertical creep and damage accumulation of soil slopes is. At the top and inclined slope of soil slopes, damage becomes serious; and cracks appeared. The top of soil slopes, the values of vertical displacement are bigger than lateral displacement; on the contrary, at the bottom of soil slopes, the values of lateral displacement are larger than that of vertical displacement.

Accuracy of soil resistivity measuring result in the laboratory will be influenced by electrodes arrangement, types of test signal, etc. Five types of soils with different textures are selected to investigate the influencing factors of soil resistivity measurement. A comparison of resistivity measuring results between four-electrode method and two-electrode method is made firstly; and the influence of potential electrode penetrations in four-electrode method is also studied. A comparison between the resistivity measuring results with DC and AC voltage test signal is made. Moreover, influence of the current density and AC signal frequency on soil resistivity measuring results has also been investigated here. The results have shown that, measuring results by two-electrode method contain the contact resistance between electrodes and the soil, which will increase rapidly when the water content of soils decreases. The soil resistivity test can be performed with little penetration, or little disturbance to the tested soils by the four-electrode method. Alternating current test signal should be used to prevent polarization effect of DC voltage. Due to the fact that thermal capacity of the test soil is limited, current densities should be kept less than 1 mA•cm-2 to test soils with electrical resistivity less than 200 Ω•m. Soil resistivity has been found to be decreased as test signal frequency increases.

The viscosity coefficient is a key parameter which expresses the soil creep and flow characteristics. Electron microscope scanning, particle size analysis, X-ray diffraction and chemical analysis test of Huangshi, Zhangzhou and Qingdao areas soft clays are performed. The test results show that soft clay’s granulometric composition, mineral component, physicochemical properties and structure type influence the viscosity coefficient remarkably. In the soft clay creep process, the structure haploid had the directional arrangement or had the glide, its relative motion caused the bound water viscosity to reflect that then caused the viscosity coefficient change. The direct shear creep test is carried out and using Chen method to process creep test data. The test results show that because the microscopic structure increases along with the shearing stress damages gradually; the viscosity coefficient increased along with the shearing stress achieved the peak value, a consolidation pressure bigger peak value manifests is more obvious; the peak value correspondence's shearing stress is also bigger. A new seeking long-term strength method which the viscosity coefficient peak value correspondence's shearing stress replaced the critical shearing strength with the different consolidation pressure is proposed, and confirmed the accuracy of this method through the tentative data. The test results make contribution to understanding the creep mechanism and that the constitutive model can be set up according to the actual engineering.

Rock and soil material has strong rate dependence; its complete stress-strain relation belongs to the type of hardening-softening, It is important to describe these two characteristics. Based on the analysis of physical deformation mechanism, considering the structure characteristic, the elasto-viscoplastic model is used. To set up the elasto-viscoplastic model which can describe the structure changes, the variable viscosity coefficients and its evolution equation are applied to the elasto-viscoplastic model. The result of basalt normal triaxial constant rate test is used to test the rationality of the model. The result shows that the model can completely and rationally describe the complete stress-strain relation and its rate dependence, and also the peak strength, residual strength characteristic

Three-dimensional surface fracture is set in specimens composed of rock similar material. In order to get the effect of bolts on strength and propagation mode of the pre-existing fracture, uniaxial compression tests are carried out on specimens with different anchorage modes. The results show that, comparing with the specimens without bolts, compressive strength and compression modulus of reinforced specimens increase in different degrees. Compression modulus of reinforced specimen is enhanced more significantly than compressive strength. Residual strengths of four types of reinforced specimens are approaching to each other with the value being about 3 to 3.5 times that of specimen without bolt. The failure process of anchored specimen is divided into four phases: ① initial fracture compression phase; ② micro-fractures developing phase; ③ unsteady failure phase; ④ post-failure phase. And the surface macro-fractures all appear in the post-failure phase. Due to the reinforced and crack arresting effect of bolts the mode of crack propagation changes. Curved fracture plane and low-shear-strength plane are found in the reinforced specimens. Three types of cracks are found in test, namely tensile crack, shear crack and tensile-shear mixed crack.

In order to study the structural characteristics of earth retaining wall reinforced with double twisted hexagonal steel wire mesh, a field experiment is conducted on a composite panel earth retaining wall reinforced with which on the site of K124+340 of Xiangtan-Hengyang West Line Expressway, its vertical earth pressure, horizontal earth pressure, tensile strain distribution of geosynthetics and gabion deformation law are tested. The results show that: along the length of the reinforcement, the distribution of vertical earth pressure is bimodal-shaped distribution in the lower part of the retaining wall while a single peak-shaped distribution in the upper part; the horizontal earth pressure along the wall is nonlinear distribution, the tested maximum occurs at the height about 1.5 m and it is less than active earth pressure; the tensile strain of reinforcement distributed in a nonlinear form along the length; and different layers have a different forms, the deformation of reinforcement takes place in the construction period mainly; the deformation of gabion showed a bulging form.

Rheological property is one of the most important mechanical properties of rock. Great importance shall be attached to long-term strength of the rock among mechanical properties in most geotechnical engineering, while the present study of it is asymmetrical compared with the creep property. Creep test is the most common and practical way to confirm long-term strength of rock. Based on uniaxial compression creep test of red sandstone rock in the CSS-2950 biaxial rheological testing machine; theory accuracy and operability of transition creep and isochronous curve methods are discussed in the research of testing long-term strength of the rock. Meanwhile, a new method to confirm long-term strength of the rock is proposed; and the time for rock to be destroyed under load is predicted by the combination of creep curve and stress-strain curve. The results show that the combination of creep curve and stress-strain curve plays a leading role in the confirmation of long-term strength of the rock in geotechnical engineering field.

Taking a foundation pit in Beijing as the background, the fast Lagrangian analysis of continua in 3 dimensions (FLAC3D) numerical calculation program and Mohr-Coulomb constitutive model are adopted to make analysis of the deformation and force condition of pile-anchor supporting system on the case of deepening excavation of the existing foundation pit. Calculation results show that the deepening excavation will induce poor bending performance of pile, larger horizontal displacement of supporting structure and failure of anchor system based on the existing supporting scheme. In order to ensure stability of the foundation pit, increasing pile fulcrum is necessary. Several reinforcement schemes are compared on the basis of design change and construction condition. The scheme of increasing anchor cable is adopted to reinforce the foundation pit. The mechanical behavior of foundation pit after deepening excavation with above supporting scheme is analyzed by using numerical simulation. The calculated deformation of foundation pit and supporting system is compared with field monitoring data; and the result shows that the scheme is reasonable. So the research results are of significance as a reference for similar engineering.

Upper bound limit analysis method is an effective tool in solving geotechnical engineering problems. Conventional calculations in stability of slopes are formulated assuming the soils obeying a linear Mohr-Coulomb yield criterion. However, experimental evidences show that the failure criteria of almost all geomaterials are nonlinear over a wide range of normal stresses. In this paper, the soil masses of slopes are assumed to follow a nonlinear Mohr-Coulomb failure criterion. Based on the nonlinear failure criterion, the paper studies the problem of slope stability by combining the slice method and limit analysis upper bound method. The nonlinear strength parameters cohesion and internal friction angle are introduced through the tangent method. Joined influence of nonlinearity is established. The equations of equivalent in rates of external work and internal energy dissipation are established based on the joined influence. The equations of factors of safety for slope with different slide surface (straight line, broken-line, and circle) are deduced and the plastic analysis upper limit solutions are calculated well by these equations. A classical slope calculation case shows that the method is of correctness and high precision which consists with previous achievements. The new method can be used to guide the slope stability analysis based on the nonlinear failure criterion on the plastic upper limit theorem.

Based on the successful design experience of Jinmao Building and Shanghai World Financial Center, this paper attempts to analyze and evaluate the behavior of piled raft foundation for Shanghai Center Tower from the design perspective. The weight of the building, buoyancy of the water and load-sharing between pile and soil are analogously analyzed. Capacity of pile, load on pile group, thickness and bending moment of raft, settlement of piled raft are calculated and analyzed especially. The analysis thinking, methods and results can be served as references for design and study of piled raft foundation for super-tall buildings.

How to evaluate the stress state in an engineering rock mass is one of the most fundamental problems that all the underground structure designers have to be faced with. Evaluating the stress state needs considering both sides of this problem, rock mass strength and stresses in the rock mass. The evaluation results reflect the deformation and failure responses of surrounding rock masses under the actions of secondary stresses when they observe a rock mass strength criterion. Most research findings in the past on high stress criterion are summarized to infer a general deformation and failure law for underground structures under the impact of high stresses. By analyzing the relation between the rock mass strength and the rock mass rating parameters and the uniaxial compressive strength (UCS) of rock specimens according to the Hoek-Brown criterion, a conclusion is come to that the ratio of the rock mass strength to the UCS should be less than 0.5 in most situations. With respect to the new high stress criterion put forward by the authors in 2009, basic relationships at different frictional coefficients between the rock mass strength and the maximum principal stresses present in the rock mass are obtained by analyzing the Hoek-Brown strength criterion and rock friction theory comprehensively; based on this relationship and the redistribution law of secondary stress field around an underground opening, the new high stress evaluation criterion is verified from the aspect of rock mechanics. The application of this criterion to some engineering practices all over the world proves that this new high stress evaluation criterion works very well. Finally, the authors put forward the general rules and procedures for how to use this new criterion, and some concerns that should be careful of.

The field measurement had been performed for one and a half years, which was aiming at the impact-cone concrete piles of the bridge abutments on the deep silt foundation. Before constructing the pile cap, during the period of building the abutment, constructing embankment near the transition section, constructing embankment of the transition section and after building the span beam, the abutment pile strain and the pore water pressure on pile side had been tested; and the pile deflection and the abutment inclination had been observed. Based on the measured data，the stress and deformation properties of the abutment pile are analyzed. The results show that: the abutment pile is compressed before constructing the pile cap; due to the interaction of superstructure and earth filling, the compressive strain of the front side of the pile body is remarkably different from that of the back side; after finishing subgrade filling, the maximum negative bending moment of the pile appears in the shallow position of the silt layer; and the maximum positive bending moment appears in the soft-hard soil juncture; the abutment inclination is rectified after constructing the span beam.

A large number of accurate and reliable settlement data were obtained via on-site long-term monitoring test. The basic settlement law of pile foundation and characteristics of settlement curve were studied. Single forecast model was used to fit the monitoring data. The inadequacy that the evaluation of reasonable prediction model was limited to the correlation coefficient index in current guidebook was pointed out. It was proposed that mean-square error, mean absolute percentage error and average absolute error were introduced to comprehensively examine, evaluate the fitting effect and the reference value corresponding to the evaluation index was recommended. Combination forecast model for high-speed railway bridge post-construction settlement prediction was proposed; the characteristics of existing combination prediction models were analyzed and compared; specific steps and basic principles of bridge pile foundation post-construction settlement forecast were brought forward; and corresponding computer program was developed to improve forecast accuracy and efficiency. It was found that, by engineering examples, the optimal combination forecast method based on least-squares criterion could be thought of as the favor model owing to effectively and comprehensively improving the prediction accuracy. The valuable supplement and reference were provided to confirm reasonable time to construct railway and calculate post-construction settlement.

The traditional rigid-body limit equilibrium method and finite-element-based strength reduction method has some problems in stability and reinforcement analysis. Based on deformation reinforcement theory (DRT), a stability analysis method of slope is presented with elastoplastic finite element analysis. Plasticity complementary energy(PCE) is used to evaluate the whole stability of slope; and safety factor of slope can be obtained through the PCE curve with strength reduction factor. Reinforcement location and force can be determined by unbalance force distribution in the slope. Possible sliding surface also can be located on the boundary that direction reverse of unbalance force occurs. Three classical examples of slopes has been modeled and analyzed. The safety factor and reinforcement key location and force have been determined by the PCE curve and unbalance force distribution. The results indicate that the DRT based on nonlinear finite element analysis is effective in analysis of stability and reinforcement for rock and soil slopes. The failure process can be reflected by the development of unbalanced force with the strength reduction.

Scientific and rational prediction of post-construction settlement is a key link of high-speed railway construction. Based on the field observation data of subgrade settlement of Wuhan-Guangzhou high-speed railway, aiming at measured settlement data being characteristic of small in magnitude, but large relative fluctuation, the suitability of exponential curve method for predicting settlements of subgrade under ballastless track has been studied synthetically. it was found that exponential curve method can't be directly used for predicting subgrade settlements in high-speed railway. The basic idea of three-point method is introduced into exponential curve model, a three-point modified exponential curve method for predicting subgrade settlements has been proposed. Combining the measured settlement data of subgrade in Wuhan-Guangzhou high-speed railway, the characteristics of three-point modified exponential curve model have been analyzed. The analysis shows that selecting three points as forecast sample on settlement-time curve of subgrade can commendably evade the influence brought by data fluctuation; and the settlement regularity after inflection point on settlement-time curve of subgrade more tally with exponential curve, therefore, the samples must be selected after inflection point on settlement-time curve of subgrade; and three samples should reflect the settlement development tendency as far as possible. The prediction results of three point modified exponential curve method are stable with high correlation coefficient. The new prediction method has engineering value.

The deformation control criterion in seismic engineering design is a new tendency in recent years; and the reason of the seismic residual deformation of large caisson quays is a complex problem in seaport engineering. The effective stress method is used in the study, in which nonlinear constitutive model of a multiple shear mechanism type is defined in strain space; and the effect of rotation of principal stress axis direction has been considered. By the method, the regularity of the seismic residual deformation of caisson quay wall top is analyzed caused by different influential factors such as the level of seismic wave, blow count of standard penetration test (SPT) and disposal extension of replaced sand under quay wall and backfill sand behind quay wall and width-height ratio, etc. Some conclusions are drawn as follows. The level of seismic wave, blow count of SPT and disposal extension of replaced sand under quay wall and width-height ratio are sensitive factors; and that a rational disposal extension in backfill sand behind quay wall exists. A series of calculation distribution figures in the paper can be applied to initially predict the seismic residual deformation of quay walls for engineering designers.

The law of guided wave propagation in grouted and free rock bolts is studied by theoretic analysis and laboratory testing method. The wave propagation velocity in grouted rock bolt and free bolt within 20 kHz-3 MHz is tested in laboratory respectively. The and research shows that the different frequencies have different sensitivities to grout quality. Low frequency (20 kHz-200 kHz) guided wave changes its velocity greatly with grout quality; and high frequency (1-3 MHz) doesn’t change. So low frequency (20 kHz-200 kHz) which has high sensitivity to grout quality can be used to test grout quality and high frequency (1-3 MHz) whose velocity doesn’t change with grout quality can be used to test integrity of rock bolt. The laboratory test results show that the method has very good accuracy; and a method for testing grouted length of rock bolt is proposed

Mining induced ground surface subsidence could result in pipeline bending in a large scale which has great threatening to pipeline safety. An analytical methodology for evaluating stress and strain distribution of buried pipeline crossing mining subsidence area is developed. Ground surface spatial deformation due to mining is predicted by using Probability function integration method. Deformation compatibility equation between pipeline physical elongation and pipeline geometrical elongation is derived taking care of axial pipe-soil friction and steel pipe material nonlinearity; and pipeline stress and strain are calculated with iterative solving method. With proposed method, stress and strain distribution of pipeline crossing mining subsidence area is investigated. The result shows that tensile and compressive deformations at different pipeline segments due to pipe-soil friction associates with pipeline spacial bending deformation. Results of proposed method are close to that of finite element method and it is approved to be competent for investigating the response of buried pipeline crossing mining subsidence with any angle. Finally, effects of mining, pipeline and backfill on pipeline deformation and stress are analyzed; and two simple equations for evaluating the maximum stress and strain of pipeline are developed.

For the purpose of getting the strength value of Baihetan interlayer shear belt with the characters of dislocation history, large scale spread, assembled multiplex structure, multiplex mineral, etc., six kinds of tests are introduced, including ring shear test, high stress direct shear test and triaxial compression test for soft argillization layer, and straight shear test, triaxial compression test and in-situ shear test for multiplex shear belt. Based on the testing data of above six tests, the relationships between strength of shear belt and loading mode, value of normal stress, character of specimen and moisture content are summed up. The strength properties of shear belt, include assembled structure effect, thin cementation effect, confining pressure effect and water soften effect are found. What’ more, the conceptions of “original strength” and “disturbed strength” of interlayer shear belt are put forward, which have different cohesive strengths and friction angles. These cognitions can provide useful cures for supporting design of Baihetan underground caverns and study of similar argillization layer in deep underground engineering.

Based on the practice of a metro tunnel crossing below ground buildings in Shenzhen soft soils, taking a frame structure residential building for example, a 3D nonlinear constitutive model that consists of the tunnels, surrounding soils, the building and its foundation is established by finite element program MIDAS/GTS. The four conditions of the crossing angle of 90°, 60°, 45° and 30° between tunnel axis and the ground building have been calculated; and the regularities distribution of the building foundation settlements and the structure deformations and stresses due to excavation under different conditions have been analyzed. The results indicate that there are obvious differences in the settlement process and distribution of foundation when the metro tunnel crossing through the building under different crossing angles. With the decrease of crossing angle α, the settlement of foundation rises by 37.3% at most; and the surface settlement of foundation changes from symmetrical distribution to lateral tilt; and the differential settlement of adjacent plinth increases obviously. Tilt displacements and distortion of building increase significantly under different crossing types; and it could rise 10 times at most. Compared with the deformation of the building foundation and the bottom of structure, the influence of changes of crossing angles on internal forces of structure of the building is light.

Based on MapGIS-TDE platform, aimed to the highway slope model building, the “entity-oriented spatial data model based on feature” which has good adaptability and flexibility is applied to achieve the data organization and storage. Using the survey and design data of highway, the 3D model building methods of the slope surface, ground and underground are presented; the sub-model building methods of the unexcavated slope, excavated road and excavated slope are also discussed for building terrain model. In addition, based on the surface displacement and rainfall monitoring data, 3D real-time inquiry and statistics are available to provide real-time analysis for highway landslide monitoring and precaution. The 3D slope model of the Changde－Jishou expressway in Hunan province has been established by this method.

Rock mechanics is based on rock mechanics test, which is one of the most important methods in studying rock mechanics and engineering. But the experimental results of rock mechanics test are always influenced by many factors and the discrete experimental results are ubiquitous. Those bring some inaccurate or even reverse results. Based on the relationship among ultrasonic velocity, rebound value and strength of rock, the ultrasonic-rebound comprehensive method was applied to the rock sample selection which has the advantages of two methods. In order to get the accurate results, the rock specimens which may cause discrete results can be selected out first before the laboratory test. Practice shows that such a comprehensive sampling method has good applicability. It is quite convenient to distinguish the rock specimens with interior defects and has no injury. At the same time, the ultrasonic-rebound method is quite useful to predict the compressive strength. So the application of this method in sampling of rock mechanics test and strength prediction is worth using for reference.

In seasonally frozen soil regions, geogrids used for slope reinforcement always come out of ground because of frost heaving and thus lose effectiveness. In order to study the effectiveness of replacement with non-frozen materials in preventing frost-heaving damage to geogrids, outdoor frost heave test was conducted in the site reinforced with geogrids. The frost heaving soil in one side was replaced with volcanic ash and the other was not. Comparison between the values of frost-heave of geogrids in the two different soils shows that the residual value of frost-heave of the geogrids can be reduced about 50 percent by the method of soil replacement. It is concluded that the method of soil replacement with volcanic ash is effective in preventing frost heave damage of geogrids and is of applied value

Through the discussion and analysis of the two traditional computing method of elastic modulus with the normal compressed deformation curve of in-situ direct shear test, which indicate that the real value is bigger than its directly calculated modulus of confined compression and the modulus calculated by the empirical formula of the in-situ load test. A novel integrated method is proposed to calculate the elastic modulus with the in-situ direct shear compression curve. At the same time, the three methods are used to calculate the elastic modulus of highly weathered hornfels in Lingao Ⅲ. The elastic modulus calculated with integrated method of in-situ direct shear compression curve is the sum of the directly calculated modulus of confined compression and the modulus calculated by the empirical formula of the in-situ load test. The calculating principle of integrated method is consistent with the mechanics and deformation mechanism of direct shear test with normal direction load. The calculated value is more close to the real value with which the problem of calculating elastic modulus is resolved effectively in the stability analysis of slope rock deformation.

The West Route of the South to North Water Transfer Project is taken as the engineering background and the excavation disturbed zone in surrounding rock of tunnel by tunnel boring machine (TBM) driving are studied. Considering the rock post-yield damage, a new constitutive model based on the cohesion weakening and frictional strengthening (CWFS) brittle model is proposed and is implanted to FLAC3D program by debugging dll in VC++. Based on the results of triaxial compression tests, this constitutive model is verified through parameter back analyzing by optimization algorithm such as neural network and genetic algorithm. The results show that the model can reflect the elastic characteristic, post-yield characteristic, brittle failure and post-failure residual strength characteristic of slate. Based on this model, the surrounding rock deformation characteristics, stress evolution law and damage characteristic of TBM driving of the South to North Water Transfer Project are studied and also compared with the results by Mohr-Coulomb constitutive model. Finally, the conclusion is drawn that the constitutive model proposed can better reflect the damage rule of the surrounding rock daring TBM driving, i.e. the damage develops along the weak zone.

The earth pressure theory by Rankine and the formula for calculating subsidiary stress by Boussinesq were employed to study the interaction between earth berm and retaining structure for cantilever retaining structure. On one hand, the earth berm in a pit can strengthen horizontal resisting force of the soil body in the passive zone owing to its gravity. On the other hand, it can reinforce the stability of the retaining structure due to the horizontal resisting force of itself. Considering the two points aforementioned, a method is constructed to determine embedment depth of retaining structures. And more, a pit excavation is computed by the proposed method for further investigations. The study shows that reinforcement of the earth berm on retaining structure is remarkable because of the large moment arm even the magnitude of the horizontal resisting force is not very great. Therefore, the needed embedment length of the retaining structure in the pit excavation having earth berm can be distinctly cut. It can be concluded that the earth berm method should be recommended in suitable situations for its better economy, higher efficiency and lower pollution.

Thawing settlement deformation is one of the main freezing damage for the structure in permafrost region. The actual thawing settlement is the superposition of two parts: thaw settlement and compression settlement. The volume compression coefficient is the key calculation parameter in estimating the compression deformation. Basing on the 286 thawing compression test data of undisturbed frozen soil samples, it has put forward various types of regression equations including linear equation, binomial equation and logarithmic equation and these equations represent the relationship of volume compressibility and dry density of six sorts of soil on the two different pressure sections 0−100 kPa and 0−200 kPa. These soil types are fine gravel, sand, silt, clay, peaty clay and peat. On this basis the empirical volume compression data table of the six sorts of soils is given out; meanwhile, the problems in recommended methods of specifications are pointed out.

The stability of slope is influenced by multiple factors. It is one important subject to evaluate and predict the stability reasonably in the research of slope. Based on the approved grey correlation analysis and analytic hierarchy process (AHP), the comprehensive method is proposed to analyze the slope stability. According to the principle of grey correlation analysis, associate degree of slope stability is estimated and the slope grade is appraised by maximum correlation law. This method avoids the disadvantage that interval of the grade standards is not taken into account in traditional grey correlation analysis. The AHP of scale 3 is used to discuss the index weights; and precision of grey correlation analysis is improved. Case study shows that this method is reasonable and feasible to estimate slope stability.

Under random seismic excitations, the precision of results with the scope of soil region in seismic response of soil layer and soil-structure interaction was analyzed. In this paper, with the bedrock white noise spectrum and Du Xiuli modified bedrock spectrum as excitations, random seismic response of soil layer was analyzed; and the effect of random seismic response of soil layer with three artificial boundaries(free boundary, fixed boundary and viscous-spring boundary), damp coefficient and the ratio of width to depth (L/H) was discussed. Based on the above basis, suggestions of reasonable scope of lateral artificial boundary were given. At the same time, with the bedrock white noise spectrum, Du Xiuli modified bedrock spectrum and the power spectrum of seismic waves records as excitations, the random seismic response of soil-structure interaction was analyzed after the reasonable scope of soil selected and the model of soil-structure interaction established. The results show that the scope of lateral artificial boundary is satisfied for random seismic response of soil-structure interaction analysis

With the vertical fractures filled with sands of grain diameters 0.5-0.63 mm, a fractured rock model is fabricated by using granite rock blocks taken from the Beishan area in Gansu province, which is being investigated as potential site for the high-level radioactive nuclear waste repository in China. Fluid flow and heat transfer experiments and numerical simulations are conducted for the model; and the influences of heat source temperature, the water velocity and aperture of the vertical fractures on the steady-state temperature of the model are also parametrically analyzed. The experiment results reveal that for a 120 ℃ heat source temperature, there is no phase change in the fracture water, and the steady-state temperature field is similar in pattern to that for 95 ℃ heat source temperature; the range of influence of the heat source and the time for asymptotic steady-state temperature field increased with the heat source temperature; sands filled in the fractures enhanced the heat conduction of neighboring rock matrix, making the range of influence of the heat source and the time for asymptotic steady-state both larger than the unfilled fracture model. The temperature field from the experiment is similar in pattern to that from the numerical simulation; however, since some degree of boundary heat loss in the experiment is unavoidable, the measured temperatures are smaller than the numerical simulation results for adiabatic boundary conditions; and the differences increased with the heat source temperature. Numerical parametric sensitivity analyses reveal that the fracture water flow adjacent to the heat source controlled the temperature field of the model, while the vertical fracture water flow further away from the heat source mainly affected the time for the model temperature approaching steady-state and the far side boundary temperature, the retardation of the horizontal heat transfer due to vertical fracture flow is more significant for higher water velocities and larger vertical fracture apertures.

The one-dimensional consolidation problem is studied based on principles of Liebmann’s resistance network method. A Matlab procedure is programmed to analyze pore water pressure in saturated soils. Details about the similarity between voltage in resistance network and excess pore water pressure in consolidation phenomena are presented. A Matlab procedure is used to simulate the single and double-drainage one dimensional consolidation problem respectively. It is shown that the simulation is practically perfect compared with the consolidation solution. The differences between analog results and analytical solutions under effects of variable ?t and the fine level of meshing ?z are analyzed and discussed. It is suggested that the smaller value of ? the more obvious of convergence and accurate of the analog. It is considered that the applications of Liebmann’s resistance network can be extended to more complex situation.

Reduced order bounding surface model was employed to study 3-D seismic ground response of site considering the nonlinearity of soft soils in Shanghai. A nonlinear procedure for response analysis of horizontal layered sites subjected to multidirectional earthquake loading was used to study vertical and horizontal ground responses, respectively, under unidirectional and multidirectional base excitations (Taft). Also, the development of ratio of vertical and horizontal peak acceleration and the effects of the variation of groundwater table on the characteristics of seismic responses were studied. The study results show that the characteristics of vertical seismic ground response are much different from those of horizontal seismic ground response; the amplification effect is greatly increased under multidirectional base excitations compared with that under unidirectional base excitations; greatly difference is induced by the rise of groundwater table between vertical and horizontal seismic response, as result of the rise of groundwater table, seismic amplification effect at ground surface increases in horizontal direction, but decreases in vertical direction，which are important for geotechnical engineering aseismic design in Shanghai region.

Digital image processing method is used as a tool to represent the heterogeneity of rock, which can be introduced into the finite element method; and a numerical model considering the real mesostructure of rock is established. By using this method to represent the heterogeneity of granite, a numerical specimen of granite is built to carry out uniaxial compressive tests. The influence of granite’s mesostructure on its deformation and strength is studied. The results show that the mesostructure of granite has an important effect on stress concentration under loading. The compressive strength of granite is evidently different when loading under different directions, and presents anisotropic behavior. But the influence of mesostructure of granite on its elastic modulus is very small. The digital image-based numerical method proposed provides an effective tool to study the mesomechanical behaviors of rock and rock-like materials.

The improved node virtual flow method is used to solve unconfined seepage field; and the damage vertical flow behavior is simulated by zero thickness crack model; and then the finite element method of crack seepage problem of the concrete faced rockfill dam (CFRD) is obtained. Based on a CFRD, the program composition with Fortran was used to calculate the 3D seepage field under the failure condition of the single or more than one vertical fracture of concrete slab; and the water head distribution, saturation line and leakage are obtained; and then the rules and characteristics of unconfined seepage field are analyzed. The results show that the method can accurately position exit point and saturation line of seepage field of CFRD, and well simulate seepage field in dam area under the failure condition of vertical fracture of concrete slab so as to provide reference for concrete face jointing design of CFRD.

Based on the classical 3D Delaunay tetrahedral mesh generation method, a 3D constrained Delaunay triangulation algorithm is presented. By restoring the constrained boundary and removing the local degeneracies, the consistency of the solid boundary and the uniqueness of the mesh could be guaranteed. In this way, the constrained Delaunay triangulation method could be applied effectively to generate tetrahedral mesh for any complex 3D solids with the constraints. By controlling the ratio value of the circumradius of the tetrahedron to its shortest edge length (denoted as a), and the ratio of the volume of the tetrahedron to the volume of its circumscribing sphere (denoted as n), the low-quality elements are avoided; and also a method to calculate the a and n which simplifying the calculation process is proposed. For the entity with complicated geometry, especially the entity containing the thin layers, adding constraints could improve the mesh quality and shorten the calculation time. So, by using the method, the 3D finite element mesh for complex region under different geological conditions could be automatically generated in the civil engineering; and the high quality of the mesh which could be guaranteed provides sufficient condition for the high-precision finite element calculation. The verified examples show that the high-quality constrained tetrahedral mesh for any complex 3D solids could be generated by the constrained Delaunay triangulation method; and it could be applied effectively to the finite element mesh generation in engineering.

The volume of Zhenggang large landslide accumulation body in Gushui hydropower station is up to more than 47,500,000 m3. There are many ultra-deep landslide places with the thickness over 50 m; its stability is directly related to dam construction and operation. However, Field engineering geological investigation and data of deformation caused by rainfall in 2008 show that the landslide is multi-period and complex, mainly composed of bedrock, slip soil and unconsolidated accumulation. There are so many tensile and shear cracks on the surface that the accumulation body is prone to produce creep deformation under the normal condition and slump under any condition, so the treatment such as excavation and reinforcement is needed. Due to lateral restraint of computation cross-sections and bottom sliding surface curvature effects in space not considered by two dimensional method, 3D limit equilibrium method and large deformable Lagrange finite difference method are applied to build some 3D computational model according to actual geological information. By comparative analysis of changes of stress, deformation, plastic zone and safety factor before and after the treatment, the stability is evaluated qualitatively and quantitatively; and furthermore the stability after the reinforcement is checked by the finite element point and surface safety factor method. The results truly reflect the situations and laws of stability of the landslide, which are consistent with the field exploration results. The local and whole stability obviously increased after excavation and reinforcement; if combined with drainage measures will be more conducive to maintaining. The research results can provide meaningful references to the similar projects.

A finite element solution for multibody contact problems is presented. Contact conditions being exactly introduced, this solution takes nodal contact forces as primary variable and limits contact highly nonlinear problem in potential contact surfaces to iterate, so it is an accurate and high efficient approach. The paper begins with 3D mechanical model for two bodies contact and compatibility equation in incremental form is educed from global finite element equation. On this basis how to obtain compatibility equation on multibody contact problems is discussed in detail. Subsequently, solvable and judged conditions in incremental form of contact problems are presented in which generalized Mohr-Coulomb criterion is used as friction condition. For the characteristics of any slipping direction of contact nodes on the contact interface in 3D case, contact states and friction force components are judged simultaneously in the program by which iteration and convergence are fast and accurate. For the common non-smooth contact namely corner problems in the more contacting bodies, more reasonable techniques are proposed by classification and real contact state of corners. Finally, after being verified by several numerical examples the program is employed to model rock discontinuities; and the results are satisfactory.

Storing oil in large underground caverns by water sealed is an important way of strategic oil reserve in the world. It needs to optimize the layout of caverns for the stability of such a large-scale unlined underground cavern. Based on the analysis of the engineering geological characteristic of an underground project in Shandong province, the numerical model was established. And the mechanical parameters of rock mass were estimated by the generalized Heok-Brown failure criterion with the integration of rock sample triaxial test and rock mass classification of rock mass rating (RMR) system. Choosing the depth, axial direction and space as factors, and calculated the displacement of the caverns by the FLAC3D code in different schemes, determined by the orthogonal design. The visual analysis of the results of the evaluating index, key point displacement and plastic zone area was done. The axial direction is the significant factor, and the influence on the stability was studied separately. The optimized layout of the underground caverns is that the depth is -60.0 m, axial direction is N30°W and space is 25 m. It has some values for the layout of the underground oil storage caverns.

In the analysis of dynamic soil-structure interaction, viscous artificial boundary condition, viscoelastic artificial boundary condition and far-field artificial boundary are often used to simulate the scattered wave propagating in infinite base. Viscous artificial boundary condition and viscoelastic artificial boundary condition have many advantages such as low computing cost and good accuracy; but amount of labor work of applying boundary elements is heavy; although far-field boundary saves the work of applying boundary elements and can provide highly accurate results; it requires expensive computing cost. In order to address the problem of high labor cost in viscous artificial boundary condition and viscoelastic artificial boundary condition and high computing cost in far-field boundary, an equivalent far-field artificial boundary condition is proposed based on the wave propagating theory and the reflection and transmission principle of wave on the interface of medium by setting a fully-transmitting layer and lowering the speed of wave considerably propagating within it. Then numerical simulations and studies of factors affecting accuracy for equivalent far-field artificial boundary condition are conducted with FEM. Researches show that equivalent far-field artificial boundary can be set up only by setting rational mass and Young’s modulus parameters in transmitting boundary layer to simulate reflected wave propagating in infinite base. Equivalent far-field artificial boundary has many advantages such as good accuracy and efficiency and saving the labor work of applying boundary elements; so it can be applied to the analysis of dynamic soil-structure interaction.

An elastoplastic constitutive model based on Zienkiewicz-Pande yield criterion is developed secondarily in FLAC3D and applied to stability analysis of surrounding rock during the process of excavation in a certain underground hydropower station. Zienkiewicz-Pande yield criterion is the one of forms of improved Mohr-Coulomb criterion，which is a smooth curve and has neither the singular vertex in the p-q plane nor the ridge corners in the π-plane. It is easy to handle not only in the numerical iterative calculation process, but also taking into account the relationship between yield curve and the hydrostatic pressure to some extent, as well as the impact role of the intermediate principal stress ? 2 on the yield surface. The criterion has been applied to calculation for excavation and supporting in several large-scale underground caverns of hydropower stations, but has not been adopted by any large numerical software. According to elastoplastic mechanics, incremental iterative calculation format of elastoplastic constitutive model on Zienkiewicz-Pande yield criterion is derived in detail. Based on the program interface of secondary development provided by FLAC3D, VC + + programming language is used to realize the calculation process and compile into dynamic-link library files loaded and invoked. In simulating to an ideal circular tunnel, the self-defined model is consistent with Mohr-Coulomb criterion to verify the correctness of the calculation format. Finally, this constitutive model is applied to stability analysis for excavated surrounding rock in large-scale underground caverns; and the distribution rules of calculated plastic zone, displacement field, stress field are accord with Mohr-Coulomb criterion, which validates the applicability and reliability of the model further.