The characteristics of meso-structure evolution of expansive soil and loess were studied systematically with a CT-triaxial apparatus in various stress paths, wet-dry circle, soaking swelling and inundation-collapse. The expansive soil samples were taken from two sites located in the canal slope of the Middle Route Engineering of South-to-North Water Transfer Project in China. The loess simples include Q3 loess and Q2 loess, and the former was taken from the site of Pumping Station #11 in Ningxia Province, and the later was taken from the site of Pucheng Power Plant in Shaanxi Province. A number of CT images and CT data of meso-structure evolution of the samples were obtained. The research results show that the macro-behaviors of samples are closely related with their meso-structure changes and CT data. The fissures sprout and develop during loading and lateral unloading on undisturbed expansive soil and during wet-dry circles on remolded expansive soil in free state; and their meso-structure are damaged. However, the original fissure in remolded expansive soil is toward close under loading and immersion; and the meso-structure of the soil is repaired. The tendency of meso-structure change of intact loess in loading process is dependent on the stress and suction level. The holes and fissures of intact loess become gradually small even disappear during inundation; and the original structure of intact loess failure and a new homogenous structure would be formed. The macro-void of intact loess cannot be destroyed ether by high stress or by the combination action of low stress and immersion. On the basis of CT test data, the quantitative indexes describing the meso-structure of expansive soil and loess were defined; and the structure evolution equations for the soils under various test conditions were proposed; as well as a method to determine the yield stress in triaxial test was suggested. Thus, CT technology makes the research of meso-structure of soils to reach the quantitative stage; and the technique also provides a practice test foundation to establish the evolution equations of meso-structure of soils and corresponding structural constitutive model.

The opening mode fracture toughness of rock can be tested by five different configurations of disc specimens, which are flattened Brazilian disc, holed-flattened Brazilian disc, cracked chevron notched Brazilian disc, cracked straight-through Brazilian disc, and holed-cracked flattened Brazilian disc. The loading manner is splitting through diametrical compression. The machining method for specimens is introduced; and the formulas for determining the fracture toughness are given. The results of disc splitting test show that the values of fracture toughnesses for marble determined from the discs with notch are between 0.78 MPa•m1/2 and 0.91 MPa•m1/2; and the values determined from the discs without notch are between 1.01 MPa•m1/2 and 1.04 MPa•m1/2. It is found that values determining from the discs with notch are more stable; and more ideal thinner notch width can be achieved for the holed-cracked flattened Brazilian discs.

Based on the theory of continuum damage mechanics, a modified Mohr-Coulomb failure criterion according to plastic damage evolution and the seepage-stress coupling is applied to analyze the excavation damage of Boom clay influenced by the evolution of pore pressure and plastic strain. Considering the actual case of the construction of the connecting gallery of radioactive waste disposal in the deep Boom clay formation in Belgium, a nonlinear finite element damage model for simulating shield tunneling is proposed in order to study the evolution of damage, pore pressure and permeability of the surrounding rock. The variations of damage and permeability around the tunnel with time are analyzed in detail. The presented method can provide the references for the influence of tunnel drainage on geological environment and creep process analysis of surrounding rock.

Virtual element method is put forward for seepage discharge calculation. The equations of finite element method about virtual element are derived; and then the finite element method disposal techniques are discussed; so that the theoretical system and application method can be well established. Based on the analysis of calculation examples of centripetal seepage problem and flat-bottomed dam foundation seepage, it is shown that the discharge calculation with virtual element method will get a high precision. Virtual element method is endowed with unique superiority in the aspects of finite element method application.

Due to the characters of clear physical meaning and simpleness, elastic foundation method is applied to deep foundation pit design widely. The key factor of this method is choosing horizontal coefficients of subgrade reaction reasonably. Based on Melan’s solution and integral boundary confirming, analytical method of horizontal coefficients of subgrade reaction of strip foundation pit is gained. According to the results of stress path test, the stress path modulus and horizontal coefficients of subgrade reaction of sandy silt in Hangzhou are gained. Compared with the measured results of deep foundation pit of Hangzhou Metro Line No1. testing section, the results of this method are validated; and it is shown that this method can be applied to the following deep foundation pit design in Hangzhou. Compared with traditional elastic foundation method, horizontal coefficients of subgrade reaction of this method are more specific. Compared with continuous medium finite element method, this method is simpler, in parameters, convenient in calculation and clear in conception.

Preservation of historical earthen sites against damage is one of the difficult problems. Rock bolt and soil nailing techniques, with its characteristics of in-situ reinforcement, has been frequently applied to strengthen rock-based ruins, yet their applications to earthen ruins are seldom reported. Dougaeri No.2 historical ruin is an underground historical earthen kiln, tensile cracks have been developed at the poorest location while removing the backfilled soil inside of the kiln. Finite difference method code- FLAC has been employed to evaluate the effectiveness of micro-soil nailing technique for reinforcing the tensile cracks. Parameter studies are performed to investigate the effect of nail length, inclination angle, spacing and diameter of drill hole. Considering the field practical condition and the specific requirements for the appearances of the earthen kiln’s preservation, reasonable reinforcement design and practice method have been presented. The successful application of micro-soil nailing for reinforcing tensile cracks of the kiln will be of benefit to the preservation of underground soil-ruins.

An explicit finite element method to analyze the surface motion of layered alluvial valleys with soft interlayer is developed based on the numerical simulation of the continuous conditions on the boundaries between fluid saturated porous medium and elastic single-phase medium. The soft interlayer of layered alluvial valleys is modeled as saturated porous medium. Numerical results are provided to illustrate the effect of the thickness and stiffness of the soft interlayer on seismic dynamic response of layered alluvial valleys with soft interlayer.

Concrete is regarded as a composite consisting of coarse aggregate and mortar matrix. A model of two-dimensional aggregate random distribution is developed with improving judgment of overlap between two aggregates. Based on the model, the concrete carbonization is taken as the example and the obstacle effect of aggregate random distribution in the CO2 diffusion is analyzed. The results show that the diffusion path of CO2 is influenced by the shape, size and position of the single aggregate; and aggregates influence the speed of diffusion by changing the length and the tortuosity of diffusion path. The roundness ?, average diameter d and content of aggregates ra have the fine corresponding relations with the diffusion coefficient of the concrete Da. The equations are established by numerical simulation to describe the relationships Da-?, Da-d, Da-ra in two-dimensional diffusion, which are convenient for future engineering application.

An experiment of pre-existing flaw limestone fracturing process is conduced under uniaxial compression in order to investigate the behavior of rock fracturing under chemical corrosion and water pressure with a new meso-mechanical testing system. Analysis the varieties of limestone’s micro-structure and composition under chemical corrosion by SEM, X-ray diffraction, water quality analysis etc.. The meso-fracturing process of rock is real-time observed and recorded using the microscope. The mechanical behavior of specimens under chemical corrosion and water pressure are studied. The researches indicate that: under chemical corrosion, the micro-structure and mineral composition have changed differently, which increase the nonhomogeneity, and degrade the strength and modulus of elasticity. The degradation of mechanical property is related to the variety of mineral amount. Water pressure changes the loading state of crack and mineral grains, which increase the velocity of crack propagation, and reduce rock strength. So the fracturing behavior under chemical corrosion and water pressure becomes more complicate.

The ground vibration isolation efficiency by wave impeding block (WIB) in a three-dimensional (3D) context is studied. The analysis is accomplished with the aid of a 3D semi-analytical boundary element method (BEM) based on thin-layered method (TLM), on which the Green’s function is regarded as fundamental solution of a stratified half-space. Then the active isolation effectiveness by WIB is studied in detail under horizontal-rocking loading in elastic half-space. Effects of relevant parameters on the isolation effectiveness by WIB are analyzed in detail. The results show that WIB is efficient to isolate the vibration by horizontal-rocking coupled loading. Increasing the thickness and shear modulus of WIB, and decreasing the embedment depth of WIB can substantially increase the screening effectiveness. Moreover, increasing the diameter of WIB can diminish the amplitude of surface displacement in the area of WIB obviously, while the effect of it on outside ones is more complex.

In order to study the mechanical behaviour of frozen soil under the roadbed of the Qinghai-Tibet Railway and explore a new method to estimate the uniaxial compressive strength quickly and correctly, the stress-strain-electrical resistivity experiments for the clay in Beilu River are done under different temperatures during the whole process of uniaxial compression. The complete testing data for the stress -strain curve and the associated electrical resistivity -strain curve are obtained. The experimental results indicate that the uniaxial compressive strength increases with decrement of the temperature T, and they follow the linear relationship. The initial electrical resistivity rises while the temperature decreases; however, initial electrical resistivity increases sharply with increment of T when ℃. The relationship between uniaxial compressive strength and the initial electrical resistivity can be described as linear Semi-logarithmic equation , whose correlation coefficient is very high, so can be quickly and correctly estimated by which can be measured more conveniently. The stress-strain curve can be separated into compression stage, elastic stage, plastic flow stage, break-up stage corresponding to decreasing fast stage, decreasing to minimum stage, steady increasing stage, unsteady increasing stage in resistivity-strain curve. This associated relationship indicates that the strength and displacement problem can be effectively solved by the electrical resistivity method.

Based on the ideal of stochastic medium, the ground ridging induced by frost heave submits to normal distribution. Regarding on research background of the crossing engineering in Shanghai stadium, the express of frost heave for multi-freeze pipes is derived by the basic principle of superposition method. Simplifying the non-uniform distribution load as multi-stepped uniform distribution load, displacements and force of interaction between frost heave and beams on foundation are acquired by solving the equation of beams on elastic foundation on freezing soil with the program of MATLAB. Moreover, it is verified by survey. Finally, the conclusion that the frost heave decreases with the increase of the rigidity of beams on foundation and external load, and increases with the increase of the factor of elastic drag and free frost heave, is drawn by analyzing the influential factors of interaction between frost heave and beams on foundation.

The slope failure is a complicated process with the rock soil body’s slide, translation and rotation, which has uncontinuity in macroscopic view and randomness of a single block movement. It is unnecessary to assume position of slip surface and the shape on using particle flow code(PFC) to simulate the deformation and failure of soil slope; and particles adjust their position according to their contact forces received, and finally slope occur shearing failure from the weakest surface. Therefore, the discrete element method is comparatively ideal approach to simulate the mechanical behavior of side slope deformation and failure. The influences of microscopic parameters on slope failure’s forms of sandy slope and clay slope are analyzed respectively by PFC numerical simulation. The results reveal that the soil property greatly influences the form of soil slope failure; with the increase of the particle viscidity, the types of the slope failure transit from plastic failure to brittle failure.

The more rapidly the national economics develops, the more important the environmental sciences research is; the environmental sciences research must be emphasized. The sanitation landfill of refuse is main content of environmental science study, and is the comprehensive research topic. The height of refuse disposal plant and of refuse dam is estimated based on the stability theories of civil engineering; the seepage subject is of important in refuse sanitation disposal plant and it is resolved based on the seepage properties of geological material and on the technical of anti-seepage by geotechnical material. At the same, the discharge of gas in the refuse disposal plant is disposed by the physico-mechanical behaviors of refuse. The waste water of the sanitation disposal plant must be treated. Some geotechnics are analyzed for the refuse sanitation disposal plant from physico-mechanical behaviors of geomaterials in the site and of refuse itself by an example in a city.

The subsurface rock masses for Jinping Second Stage Hydropower Station caves features with abundant joints. A shear rheological experiment was carried out on the weak rock interlayer masses i.e. slate and marble, with respect to their shearing behaviors. A weak-surface direct shear rheological apparatus was employed to fulfill the experiment. Time domain related shear stress-shear displacement curves of the rock masses were obtained. Long-term shear strength parameters of weak rock interlayer samples were found that decreased compared to those given from rapid shear tests. Rock cohesion is more effective than its internal friction coefficient in affecting shear rheological behaviors. A standard linear viscoelasto-plastic rheological model is proposed by simulating testing results on six general shear rheological models. The proposed model is suitable to describe the shear rheological behaviors of the weak rock interlayer masses. Model parameters are gained through back analysis.

Based on the field tests of the retaining wall with tenon, three-dimensional nonlinear elastic finite element method has been developed to analyze theoretically the field tests of the retaining wall with tenon of 0, 0.7 m and 1.0 m length. The sliding resistance mechanism of the tenon of the retaining structure in the soft ground has been researched. The finite elements theoretical analysis results are consistent with the testing results. The strength reduction finite element method has been applied to the limit design of retaining structure with tenon finally. This theoretical study results provide a theory of sliding resistance of tenon for engineering design.

After mine roadway in deep ground are excavated, they are encircled in scope of surrounding rock, which possesses three properties of cracking, plasticity and elasticity. The mechanical analysis of mechanical properties of the scope of these three kinds of circle level is made, through calculating the surrounding rock in mine roadway; and then the distortion mechanism is expounded. The stress-strain expression within the rock plastic circle is derived, so as to provide a theoretical support to choose the roadway support mechanisms, to control the expansion of the fracture scope economically and effectively, to improve their stress states, to improve their own residual strength and the carrying capacity, and to choose the system of protecting synthetically in deep mines.

Attenuation characters of Rayleigh wave in layered soils are key factors for environmental micro-vibration control and analysis. Transfer-matrix is used to calculate dispersion curve of Rayleigh wave in layered soils. A thorough discussion is done on Rayleigh wave attenuation characters in different kinds of layered soils (upper-soft-and-lower-hard, middle-soft and middle-hard layered soil) under different vibration frequency; and some conclusions are drawn as follows: (1) Attenuation characters of Rayleigh wave in layered soils are influenced by vibration frequency and profile of layered soils; (2) Higher vibration frequency, faster attenuation; (3) The existence of special soils (soft soil or hard soil) can locally change the Rayleigh wave attenuation characters; (4) Location and amplitude of displacement is governed by vibration frequency and profile of layered soils. Finally, this approach is applied for calculating attenuation characters of SSRF site; and results have a good agreement with field test data. It is convinced that, comparing with attenuation curve in elastic half space, attenuation curve in layered soils can more reasonably simulate propagation of Rayleigh wave in layered soils.

The dynamic viscoplastic memorial nested yield surface model of soil has been constituted previously and published on the Vol.28 (No.10) of Chinese Journal of Geotechnical Engineering. In this paper, the model is developed and the model parameter , the point angle of cone-shaped yield surface, doesn’t assumed to change by the supposed rules. According to the reality changes of nested yield surfaces, the incremental expressions of model harden parameters are deduced. These developments on the model perfecte its theoretical foundation and are consistent with the test results. At last, the earthquake responses of a site is analyzed by using the developed model and primary model respectively; and the differences of two models are analyzed.

Two-dimensional elastoplastic dynamic responses of close parallel metro tunnels to vibration loading caused by passing metro trains are studied by using finite element method. The responses of soil-tunnel system such as vibration acceleration, axial load and bending moment etc. are analyzed for one-arrange train loading and two-arrange train loading. Calculation results show that the dynamic responses such as axial load and bending moment are obvious. The responses of the tunnel with passing metro trains are greater than another tunnel without passing metro train. When two-arrange trains are passing simultaneously, the dynamic responses are notably increased than the responses caused by one-arrange passing trains.

In order to study the dynamic response of reinforced pavements on soft clay under traffic loading, cyclic triaxial tests were first conducted to investigate the effect of initial deviator stress, loading frequency, overconsolidation ratio, and cyclic stress ratio on softening behavior of clay. The empirical equation for softening of clay was proposed by regression analysis. The equation was imported into FEM program through compiled subroutine. Dynamic response of unreinforced and geogrid reinforced pavements was studied by FEM in order to investigate mechanisms of reinforcement. FEA results indicated that softening behavior of clay had visible effect on the performance of unreinforced and reinforced pavements. The effect of reinforcement increased with the increase of loading number. Geogrid reinforcement can provide lateral confinement at the bottom of the base layer and reduce surface deformation and nonuniform settlement. The effect of reinforcement was also shown to reduce the influenced depth of clay under traffic loading.

The shortage of the traditional method to evaluate aseismic stability of the rockfill on the dam’s slope by the maximum horizontal acceleration is analyzed. Then the formula of the overflying safety factor Ks of the pavement plate for slope pavement is put forward synthetically considering the factors of both horizontal and vertical responding acceleration and the slope angle. The stability of the pavement plate on the downstream slope of a concrete faced rockfill dam is analyzed by the proposed method.

The equation of exponential curve model, which used to predict single pile limit bearing capacity, is super-set and nonlinear. Traditional optimization methods including the least squares method on the parameters regression of the exponential curve model often make the predicted results with a great deviation because of computational complexity and artificial factors. Therefore, the real coding based accelerating genetic algorithm (RAGA) is used to optimize the parameters and theoretical limit bearing capacity of exponential curve model. The RAGA solution program is compiled in the software MATLAB environment. Then some contrastive model applications to branch-piles is given. The results show that the RAGA based exponential curve model can better fit the measured data and effectively predict the limit bearing capacity, and RAGA is a high effective algorithm with many good properties such as high efficiency, high precision, fast computing speed, small artificial factors, etc.

Tests show adding propriety nanometer silicon to cement-stabilized soils can improve compressive strength of cement-stabilized soils greatly. Based on tests, constitutive model of nanometer silicon and cement-stabilized soils is proposed by using the yield criterion attained by tests, related flow rules and plastic work hardening rules. The authors deduce finite element equations in conditions of spatial axisymmetry applying means of incremental stiffness by use of annulus element of triangular cross-section and principle of virtual work; and give Matlab programs; and the rationality of programs is verified by triaxial tests. Regarded as new kind of geotechnical material, nanometer silicon and cement-stabilized soils are used in ground improvement in airfield project in stead of routine cement-stabilized, and compared its use with routine cement-stabilized soils. The results show that nanometer silicon and cement-stabilized soils can decrease ground settlement and improve ground bearing capacity. Born on the same overlying pressure, the settlement of nanometer silicon and cement-stabilized soils is less than that of routine cement-stabilized soils.

In order to protect and exploit ocean resources and carry out engineering constructions on coral reefs, it is essential to investigate the bearing capacity and deformation characteristic of calcareous sand on coral reefs. The results of plate load test show that bearing capacity and deformation modulus of calcareous sand are much bigger than silica sand, but deformation is much smaller. Bearing capacity increases and deformation decreases when failing down with the relative density increasing. Bearing capacity and deformation modulus of saturated calcareous sand is much smaller than dry calcareous sand. Soil pressure in calcareous sand ground decays rapidly with depth increasing. Load could spread to 2-3 times breadth of load-plate. Soil pressure spread from superficial to deeper layer with increasing load.

Rectangular closed diaphragm wall foundation is a new type of bridge foundation. Wall group efficiency and settlement ratio and influence of wall spacing on wall group effect were studied through a model test. There were two groups of model walls in the test, all of the walls had same thickness and height, but side length of model walls in group A was less than that in group B. It was observed that the load ratio of closed diaphragm wall and single diaphragm wall with the same settlement was always large than 1; further more, the load ratio and wall group efficiency of closed diaphragm wall B was more lager than closed diaphragm wall A. The settlement ratio of closed diaphragm wall and single diaphragm wall with the same head pressure was also large than 1; and the settlement of closed diaphragm wall A was more lager than closed diaphragm wall B. Enlarging the wall spacing was a effective measure to improve the wall group efficiency and load-bearing capacity with the same wall thickness and wall height. Then better economic benefits would be obtained.

In order to generate 3-dimensional digital stratum, a stratum data model of tri-prism is presented based on borehole data, which is applicable to urban geological engineering and geotechnical engineering. Due to the variant distribution and different attributive values among boreholes, the geological properties at unknown locations have to be estimated or interpolated by some special methods. However, common statistical methods could not resolve such problem which includes selection of sample points, spatial estimation and comparison of bilateral data. A distance-weighted interpolation method for scattered borehole data points is proposed, which exploits the Kriging method in geostatistics. On the premise that the distributed statistics characters of the spatial borehole data are obtained at first; according to the distributed statistics characters, the spatial interpolation is presented successively. Case study shows that the generation of 3-dimensional stratum by proposed interpolation methods can gives a good result.

According to the field experimental results of the reaction of rigid piles with cushion and soil among them for composite foundation of high-rise building, the characteristics of surface pressure of pile and soil among piles, load sharing among piles and soil as well as the settlement of foundation varied with change of superstructure loads are analyzed. Results show that load-bearing capacity of soil can be fully utilized due to installation of the cushion; the gross superstructure load is shared by piles and soil among piles; and the results are compared with that of loading test. The conclusions are useful for further theoretical studies and engineering design.

simulation model of hydraulic fracturing propagation is proposed by using the software of ABAQUS. The key factors of geotectology such as in-situ stress distribution, mechanical properties, fracturing fluid properties etc, which affect on the characteristics of fracturing propagation, are studied with the model. Several conclusions are drawn from the simulation results. When injecting pressure is constant, the fracture initiation pressure is proportional to the magnitude of minimal horizontal stress, critical stress and initial pore pressure, elastic modules, and is independent of fracturing fluid viscosity and maximal horizontal stress. The fracture length and maximal fracturing width are inversely proportional to the minimal horizontal stress, initial pore pressure and elastic modules. Further more they are independent of maximal horizontal stress. The process of hydraulic fracturing may be divided into four stages, namely no growth, quick growth, steady growth and slow growth stages. The obtained conclusions are of much significance for the perforation parameter optimization and design of hydraulic fracturing treatments.

Based on the brief discussion of main mechanical properties of geomembrane, the nonlinear finite element method is applied to calculate the deformation and stress of a composite geomembrane rockfill dam on thick alluvium deposit which is under construction, with emphasis on the mechanical behaviors of composite geomembrane and anti-seepage concrete wall. According to the calculation results, several types of composite geomembrane are discussed and the appropriate one is chosen for the dam. Furthermore, the sensitivity analysis of the earth-rockfill material parameters on the mechanical characters of composite geomembrane and concrete wall is done. The analysis results show they can meet the need of the dam’s normal operation.