The investigation report about the application of numerical analysis of geotechnical engineering in China was introduced firstly. Then the key of analyzing geotechnical problems with continuum mechanics and the current situation of geotechnical constitutive theory were discussed; the developing directions of geotechnical constitutive theory was put forward. Finally, the status of numerical simulation in the geotechnical engineering was evaluated. Through above discussions it can be concluded that, the result of numerical analysis is one of the most important back ground for the engineering judgment of geotechnical engineers in the geotechnical engineering analysis; the key of analyzing geotechnical problems with continuum mechanics is to establish simple and practical engineering constitutive model. Establishing many simple and practical engineering constitutive models and accumulating a lot of engineering experience, numerical analysis can be used in geotechnical engineering from qualitative to quantitative.

To analyze the stability of ore chute, the regular pattern of the ore movement in the ore chute and the deformation law of ore chute should be researched. This article is based on the kinematics theory to discuss the regular pattern of the ore movement in the ore chute and a similar material simulation is made to test its results. The study shows that in the beginning the normal impact is larger than others and with the increase of shock times, the normal impact becomes weaker and the tangential impact grows. The main damage to the shaft changes from normal breakage to tangential breakage. The interval between two impact spots is getting bigger; and bigger and the angle of impact reduces gradually. After two or three times struck, ores fall into chute vertically. Through the theoretical derivation calculation, there would be two impact zones under the well head: one is from 2.0-5.6 m and the other is from 26.4-40.2 m. The impact range obtained from the experiment is from 1.95-10.2 m and 19.4-40.2 m; and that is a bit larger than the result from the calculation. The data of the pressure box changes difference: the max change from the impact areas, less change from the ore attrition areas.

For performance assessment of nuclear waste repositories in fractured rocks, a simplified conceptual model and mathematical formulation is proposed; and a Laplace transform and Green function semi-analytical method is developed for calculation of flow and heat transfer in single-fracture rock with distributed heat source. Taking into account of distributed heat source and 2D thermal conduction in single-fracture rock of infinite extent, the mathematical model is formulated and solved by using a Green function approach, in which a fundamental solution of the governing differential equations after Laplace transform is employed. The singularities in the integral equation are handled through analytical integration; and a numerical procedure is developed to solve the transient temperature distributions in fracture water and rock matrix. Numerical examples are provided for illustration of the proposed method with comparison of an analytical solution based on 1D rock thermal conduction, as well as for features of flow and heat transfer in single-fracture rock and the sensitivities to fracture aperture, rock thermal conductivity and heat source intensity. The calculations indicate: (1) The temperature of water in the fracture calculated from using the semi-analytical method is lower than that calculated the analytical solution, due to the fact that the former method takes account 2D thermal conduction in the rock matrix, whereas the latter assumes 1D conduction. (2) Temperatures in fracture water and the rock matrix are more sensitive, in a relative sense, to the fracture aperture and the heat source intensity than to the thermal conductivity of the rock matrix. The proposed model and solution method may serve, among other possible applications, as a foundation for semi-analytical calculation of flow and heat transfer in multiple fracture rocks with distributed heat sources.

Setting up the mathematical mechanical model of rheological deformation mechanism under the interaction between surrounding rock and support is an efficient way to solve the support problem in the underground rock engineering. How support affects it is the key problem in the process of rheological behavior of surrounding rock. According to the ideal elastoplastic solution of axisymmetric round well based on Levy-Mises model and D-P yield criterion, the assumption that all the tautochrones of one-dimensional creep curves are similar, and the results of three-dimensional rheological test, the creep equation of that primary rock stress and passive supporting force are constant; in the same time, surrounding rock is under 3D stresses is derived; and the formula for rheological deformation of nonlinear viscoelastic plasticity in axisymmetric round well is also proposed. Comparing to the works made by previous researchers, there are two parameters in the formula derived, initial rock stress and the uniaxial plastic yield stress of rock, which play decisive roles in the process of rheological deformation, for this reason, the theoretical foundation of the formula derived is more complete and credible.

Abstract: Cyclic wetting-drying were conducted on the undisturbed and remolded specimens from Jiaohe cultural heritage, Xinjiang, China to understand the durability of earthen architecture to wind erosion and the strength attenuation. Test result shows, under the circumstance of the low original water content, the specimens weight is increased during the beginning three wetting-drying cycles, and then proceeds to a relatively steady state. With the change of moisture content during the condensation-evaporation process, specimen weight expressed a decreasing tendency. With the increase in wetting-drying cycles, undisturbed specimens shows a decrease in compressive strength and an increase in wind erosion quantity, reflecting a weakening effect of durability. Comparatively, remolded specimen shows an increase in strength and a decrease in wind erosion quantity, or an inhencing effect of durability at the early wetting-drying cycles; but during the later cycles, a decrease in strength and an increase in wind erosion quantity, or weakening durability is found. It is considered the healing of destroyed microstructure during remolding and the aging of chemical cohesive agents are responsible for the strengthening of remolded specimen at the earlier wetting-drying cycles.

Bottom-hole differential pressure is one of the important factors which affect the drilling penetration rate; and it is proved that underbalanced drilling is usually more efficient than conventional drilling. The purpose of the article is to study the effect of bottom-hole differential pressure on the vertical bottom-hole stress field. Based on the of mechanical analysis of the bottom-hole rock, the fluid-solid coupling model with the bottom-hole differential pressure is established under axisymmetric condition and the numerical simulation calculation of the bottom-hole stress field under different differential pressures is calculated with the finite element method. The comparison between the numerical and theoretical solutions and analysis of the stress state of bottom-hole rock to break are carried out. The results show that the numerical solution is consistent with the theoretical solution and the fluid-solid coupling model is reasonable. The bottom-hole rock is divided into three regions: triaxial tension region, biaxial compression region and triaxial compression region. Study of the bottom hole rock stress field under different drilling methods is the theoretical basis for faster and more efficient drilling.

Mechanical model is the basis for analysis of energy deposit engineering stability in salt seam; and the coupled damage and plasticity mechanism is the basic mechanical behavior of rock salt. Using rock salt from Yun-Ying, triaxial compression tests are performed under different confining pressures; and the deformation characteristics of salt rock are analyzed. Based on a brief account of experimental investigation, a coupled elastoplastic-damage model for salt rock is proposed. The model can describe the coupled relations between plastic deformation and damage evolution; and also a non-associated rule is preferred in order to describe a transition of plastic volumetric strain from compressibility to dilatancy. A simulation case is conducted to investigate the deformation processes of salt rock under triaxial compression; and the results show that the numerical simulations perfectly agree with the experimental data; so it is shown that the proposed coupled elastoplastic damage model is able to describe the main mechanical and deformation properties of salt rock.

To make the construction safe and implement the informative construction, it is important to analyze and predict the practical monitoring data during pit excavation. Time series analysis of existing trends is very difficult to meet the actual construction of highly nonlinear problems of fitting; and forecasting error is big. Based on this consideration, taking the practical monitoring data of the surface settlement from a pit construction in Tianjing for example, the time series-projection pursuit regression model is presented. After analyzing the raw data, the model can be considered both time series and the highly nonlinear fitting performance. First, comparative analysis of the approximation error and the forecast error of several time series methods, we find an approximation of good time series forecasting methods. The predicted and observed time series data combined with projection pursuit regression fitting. Application results show that the approximation performance of proposed model is good; and its prediction error is small. The methods presented herein are important reference to the dynamic design and informative construction for pit engineering.

A series of triaxial tests of saturated remolded loess under dynamic loading in isotropic and anisotropic consolidation stress states on condition of drain and undrain are performed to analyse its dynamic characteristics and backbone curves. Based on the dynamic triaxial test results, the effect of accumulated plastic strain is considered; and then the applicability of modified model of Hardin-Drnevich to saturated remolded loess is discussed. The results show that the modified model of Hardin-Drnevich could simulate the backbone curve of saturated remolded loess well. After that, the influences of isotropic and anisotropic consolidation stress states, confining pressure of consolidation, wave form and drain or undrain on the backbone curve for saturated remolded loess are also discussed. The backbone curves are all upper shift under anisotropic consolidation with the increasing confining pressure of consolidation; and it is shown that the strength of samples is increased; the impact of wave form on backbone curve is little; the effect of drain condition on it is upper shift comparing with undrained condition and this indicates that the strength of samples is enhanced. The conclusions can be for referenced by engineering designers.

Shear strength tests of sandstone under different hydrochemical environments were carried out. The effect of hydrochemical action on sandstone structure was analyzed from the viewpoint of meso-mechanism; and the mechanism of hydrochemical damage of sandstone was discussed. On this basis, the effect of hydrochemical action on shear strength of sandstone was analyzed; and a variable was introduced to quantitatively express the hydrochemical damage evolution of shear strength parameters. Moreover, the evolution of hydrochemical damage degree of Chongqing sandstone under certain environment was simulated by chemical kinetics method. Based on the simulation, the shear strength parameters can be predicted. The study results can be used as a valuable reference to quantitatively evaluate the hydrochemical corrosion of rock; so as to offer an effective method to estimate the safety and stability of rock engineering under water-rock interaction effects.

There are many limitations for important hydraulic project’s rock site at present, such as envelopment effects of probability-consistent response spectrum, and frequency stationarity in acceleration time history, etc.. In order to overcome those shortcomings, a new method of determination of ground motion input parameters for important hydraulic project’s rock site has been put forward in this study. The effective peak acceleration with different exceeding probability, as well as the dominant potential seismic source which had the largest contribution to the site, have been determined by using probabilistic seismic hazard analysis, which based on effective peak acceleration. The magnitude of scenario earthquake within the dominant potential earthquake sources is determined by the largest probability of magnitude-spatial joint distribution,and the corresponding design response spectra is determined by the attenuation relationship of acceleration response spectra. Then evolutionary power spectrum is gained according to scenario earthquake and the attenuation relationships of evolutionary power spectrum model parameters, and the amplitude and frequency non-stationary acceleration time history at dam site are synthesized by using trigonometric series superposition method, which based on evolutionary power spectra and minimum phase spectrum. In a case study of Shapai dam site, based on the evaluation of regional seismic activities and seismotectonic environment, ground motion input parameters at dam rock site with different exceeding probability, including the effective peak acceleration, design response spectra, amplitude and frequency non-stationarity acceleration time history, are determined.

Loess collapsibility test and compaction test have been carried out. The concept of compaction rate is suggusted. The classification and regression trees (CART) algorithm is improved; and is used for analyzing the correlative (data) mining. The correlative mining has been performed to undisturbed loess collapsibility and index of compaction test. The results of correlative mining indicates that coefficient of collapsibility is closely correlated to the compaction rate, but significantly in negative correlation with the collapsibility coefficients. In the compaction process, the closer the soil water content is to the optimal water content, the stronger this correlation is. Finally, this paper presents a viewpoint that undisturbed loess collapsibility is correlated with the engineering property of the compaction loess, and undisturbed loess collapsibility can be evaluated with deformation property of disturbed loess samples. This is a new method of evaluating loess collapsibility.

A series of centrifuge model tests for deformation mechanism of soil slopes under rainfall were conducted using the rainfall simulation system in centrifuge. The models were loaded to 50g; and then the rainfall was generated. The displacements of slopes during the rainfall were measured by the image-analysis-based system; and the suctions of typical positions were measured by the tensiometers T5. The results show that the displacements of slopes increased as the rainfall proceeded and the deformation area centralized on the face of the slope and gradually enlarged as the water penetrated into the soil. The strain changing of soil elements has a close relationship with the suction variations. The strain of a typical soil element started to increase quickly just as the water content increased of the element. The strain of the soil element increased as the rainfall proceeded. The strain-rainfall curve has two inflexions; and based on which two fronts are defined. The slope is divided into three parts by the two fronts; and the deformation process of the slope can be described by the fronts’ movement.

The Newmark accumulated displacement evaluation model was built based on the ground motion data obtained from the Wenchuan main shock distributed along the Longmenshan area. The fuzzy membership functions were used to calculate the degree of memberships when an accumulated displacement was obtained from the evaluation model; and the grade of landslide risks can be decided with the help of the degree of memberships. To quantify the evaluation results, the fuzzy conversion approach was used to convert the degree of memberships into a probabilistic number; and by this way, more depth calculation can be carried out. As an example, the landslides distribution induced by the Wenchuan earthquake was given to compare with the evaluation results, which show the evaluation model and the quantified probabilistic numbers calculated for each region are fit well with the real case. Analysis shows it is more accurate to describe the regional landslides hazards distribution in probabilistic way, which can be achieved by the fuzzy mathematical method.

The soil properties under small strain are tested through advanced stress path triaxial test system (STDTTS+UNSAT) equipped with high precision local displacement tensor. Using three dimensional numerical simulations, the influence of tunneling on traverse settler was studied by the models of small strain and Mohr-Coulomb separately. Some conclusions are drawn. Firstly, there is high modulus of soil under small strain and modulus degrades with the increase of strain. When logarithm coordinates are applied to describe shear strain, the rule of shear modulus decaying with shear strain can be expressed by reversed S-shaped curve with two inflexion points; and the function of the curve is deduced. Secondly, rules of the results by both models are similar. Finally, both the maximum subsidence displacement and the width of traverse settler by using small strain model are accorded with practical project. While there is an incompatible problem by using the common models, that is, only the maximum subsidence displacement or the width of traverse settler is reasonable. The comparative analysis is made to validate the indispensability of small strain consideration, as well as the reasonability and feasibility of the second development model.

The swelling properties of limestone and sandstone at 300 ℃ to 700 ℃ were investigated by the experiment system used to measure the swelling properties of rocks at high temperature and designed by ourselves. The experimental results show that the swelling stresses of limestone and sandstone increase with temperature increasing during raising temperature; and the swelling velocity of sandstone is more quickly than the limestone. The swelling stress of sandstone is 2.45 times as that of limestone when just reaching to 700 ℃. The fitted functions of curves about swelling stress and temperature are second-degree parabolaes during raising temperature; and the related coefficients are all above 0.94. The swelling stresses of two kinds of rocks increase slowly during constant temperature with time prolonging and tended to steady values at last. Two kinds of rocks’ swelling stresses reach to the limit values at 600 ℃; but the specific processes are different. The swelling stress of sandstone is 3.14 times as that of limestone when constant temperature process finished at 700 ℃. The swelling stress of rock is obviously related to lithological characters, mineral resolving, porosity and sound velocity.

The complicated mechanism of interaction between soils and reinforcement is the key problem in the application of geosynthetic reinforced soil engineering. Through laboratory pull-out tests, the mechanism of interaction between sand and geogrid and the factors of grid metric features influencing the pull-out resistance have been explored. This research work tentatively reveals the action mechanism of transverse ribs and longitude ribs and the influence of grid rigidity on the pull-out resistance. The results indicate that the interface friction of longitude ribs and the passive resistance of transverse ribs develop basically simultaneously when the pull-out displacement is small; while the displacement becomes larger, the longitude ribs’ fricton reaches gradually the peak value, the increaseing of pull-out resistance is mostly attributed to the development of transverse ribs’ resistance. The tensile modulus and the structure stiffness of geogrids are the important factors affecting the mechanical charateristics of interface between soils and reinforcement.

Using ?2.5 mm×5 m pothole, the experimental study of the interaction between blast wave and structure in highly saturated soils is accomplished systematically. According to recorded waveforms of stress, strain and momentum, the experimental results are interpreted. The experimental results indicate that blast loads on structure are not much more than value of pressure in free field; loads on roof of structure are more uniform than expected value; the overall deformation of structure is generated under blast loads, central loads are used to take place the entire loads; whether or not there is the shock wave, the law of reflection is the same; blast wave velocity and the reflection coefficient of structure increase with saturation degree.

The variation principle of deformation and stress triggered by excavation of slope often provide the scientific basis for safety monitoring of slope. Model experiment is an important way of displaying evolution of displacement and stress of high-cutting slope along highway. Taking K88+725 High-cuting Slope that locates in second-grade highway from Chongqing Wushan County to Wuxi County as the prototype, this paper approaches evolution of displacement and stress of slope excavation from similarity model experiment, and obtains Similarity material proportion is that borax: water: sand: cement: plaster is 0.01:1:7.705:0.384:0.900. Using physical model of 1:30 geometry, is divided the excavation of the model into 3 stages according to the actual construction process. The results indicate that the displacement peak is rising suddenly and it will remains steady after 4 days; but stress displays weakening fluctuatly; it will sustain weakening after 10 days. Based on difference of evolution of displacement and stress and continue of stress of slope excavation, the proposal that 3D stresses is principal monitoring and displacement monitoring is minor, is put forward.

Whole analysis model about the bank slope (above water and underwater) and the riverbed was established to study directly the influence of river scour effect on seepage flow and deformation of embankments by using theoretical analysis and finite element technique. Tractive force of river, gravity stress and seepage force is considered comprehensively in the model. Moreover, the influence of river scour on the whole stability of embankment slope is also analyzed by strength reduction FEM. The results indicate that the maximum value of seepage velocity occurs at the toe of embankment slope; and the river scour increases seepage velocity in slope to some extent. Horizontal displacement of the slope increases greatly considering effect of river scour. The closer it is to the toe of slope, the bigger the increase of displacement becomes. What’s more, the toe of embankment slope suffers from the influence of seepage flow and river scour most easily for different water levels. Plastic-strain range expands further in embankment and riverbed, and the safety factor of embankment reduces when the effect of river scour is considered. In addition, influence of river scour on seepage flow and deformation and stability of embankment increases with the rising of river water level.

In order to increase the strength and anti-deformation of inshore saline soil, reinforced saline soil with wheat straw can be used for overcoming some problems from salt expansion and dissolution. Saline soil and anti-corrosive wheat straw is mixed in a certain of length and mass ratio, and is compacted in the condition of some compaction way, water content of soil and mass ratio and length of wheat straw is selected as effect factors for compaction effectiveness in heavy compaction test. The results indicate that: (1) Maximum dry density of reinforced soil is smaller than that of saline soil, and these optimum water contents are approximate. (2) Dry densities of saline soil and reinforced soils increase first, then decrease. (3) With the increase of mass ratio and length of wheat straw, optimum water contents of reinforced soils are hardly changed, but these dry densities decrease continuously at a low speed. (4) Dry density with mass ratio of 0.2% is the most one, and that with 0.3% is the least one. (5) Dry density with length of 30 mm is the most one, and that with 70 mm is the least one. It should be proposed that samples of reinforced soil is made in the condition of mass ratio of 0.2% and length of 30 mm for studying the strength and stress-strain by means of triaxial shear test.

Combining with theories of hydraulics and river dynamics, numerical expressions of head loss resulting from different types of 3D geomat with roughness and local head loss of runoff resulting from grass are given respectively; and then formula calculating runoff velocity of slope surface for grass jetting on 3D geomat and toggling velocity of soil aggregate based on the theory of river dynamics are established. Furthermore, on the basis of calculation results, comparative analyses are made to examine effects of slope angles, types of 3D geomat, types of grass, and density of grass on runoff velocity of slope toe. The results show that the runoff velocity of slope toe increases with increase of slope angle; and types of 3D geomat do not affect significantly on runoff velocity, but can lower remarkably runoff velocity compared with non-slope protection; runoff velocity of slope toe decreases with increase of inclination angle for base and leaf of grass. In addition, the minimum density value of grass can be achieved by supposed to be equal of toggling velocity for soil and runoff velocity of slope toe. The results about mechanism of grass jetting on 3D geomat could be used to guide project practices.

In order to explain the frequent phenomenon that tall chimneys with a height more than 150m always fracture during falling process during demolition blasting, a mechanical model of tall reinforced concrete chimneys is set up in the directional falling process through the appropriate structural design parameters selected in accordance with the design standard of chimneys. The inner force distribution and limit bearing capacity expressions of chimney section at any time are derived; and the failure mechanism is analyzed. And then the evaluation is carried out if chimneys will fracture or not during demolition blasting according to its load and section strength. Results show that tall chimneys with a height more than 150 m will fracture at the section to the top 1/3 height when the tilting angle reaches to 40°-60°during demolition blasting.

In order to investigate the effect of intermediate principal stress on strength of sands, a series of true triaxial compression tests of Shanghai silty sand under different intermediate principal stress coefficients are performed on flexible true triaxial apparatus. Then the Lode angle dependent shape function of Mohr-Coulomb's strength criterion is modified based on true triaxial tests results; and the true triaxial test results of Shanghai silty sands are simulated. The results show that the strength criterion based on true triaxial tests can describe the strength characteristics of sand in true 3D state preferably.

When the soil specimens are ruptured the rupture angle , which is obtained from the calculation using the total stress intensity index is not the real rupture angle. It is only a hypothetical rupture angle. Corresponding to the hypothetical rupture angle is the hypothetical shear rupture surface. According to the results of the tests, it is concluded that the real rupture angle is obtained from the calculation using the effective stress intensity index when the soil specimens are ruptured. It is analyzed and demonstrated that, in the shear strength calculation formula of the soil related, the effective stress intensity index and the total stress intensity index can not be confused. And in the formula, the effective stress intensity index should correspond to the effective stress; the total stress intensity index should correspond with the total stress.

Field test of vibration velocity was carried out during the excavation of cable shaft in Xiluodu Hydropower Station. The attenuation formulas of seismic wave propagation were obtained through regression analysis of the test data with Sadaovsky empirical formula. Vibration velocity of measuring points in range of 18.2-24.5 meters away from the bottom of shaft in height were predicted with the attenuation formula. Comparison between the data of in-situ test and prediction showed an elevation amplification effect in the propagation of seismic wave and the magnification coefficient of horizontal velocity was about 1.49-2.24 while the vertical was about 1.78-2.73. Sadaovsky empirical formulas were corrected by taking the amplification effect into account and corresponding attenuation formulas were obtained. The corrected formulas presented significant linear relationship and to be references to similar projects. Dynamic finite element method was used to simulate the responses of the shaft under the load of blasting. It is indicated that the trend of the numerical simulation results is fit with that of the field testing data when the height from the bottom of the shaft to the measuring points were not so large. The vibration velocity attenuated rapidly when the distance from the measuring points to the bottom of the shaft were within 0-15 meters and more than 60% of overall vibration velocity attenuated in this range. Less than 10% of the overall vibration velocity attenuated when the distance was over 30 meters. Strength failure criterion of rock-concrete was adopted to check the stability of the shaft under blasting load and references for the safety of the following construction were provided.

Double-row of piles is a new support structure of the deep foundation pit. But its design method is not simple and effective. By means of basic thought of the beam of Winkler foundation, and on the premise of neglecting the friction effect in vertical and space effect between pile and soil, this paper analyzes the mechanical mechanism of support structure of double-row of piles and builds plane bar finite element model based on the effect of pile-soil effect for double-row of piles firstly, and then study the distribution of soil pressure and elastic resistance coefficient around the key parameters of plane bar finite element model of double-row of piles. Considering the critical distance of traditional slip plane of soil behind pit increased by the tension of coupling beam, the distribution law of soil pressure by slip proportional coefficient is obtained. In view of the uncertainty of positive analytical value for elastic resistance coefficient, the value of elastic resistance parameter is proposed by using the optimization method of displacement back analysis. Finally, on the basis of solving steps of optimal criterion function for displacement in bar finite element and back analysis, the doublerowpile and doublerowpileparameter calculation program are compiled respectively; and corresponding engineering calculations are performed. The results show that the calculated displacements are consistent with monitoring displacements, internal forces accord with code requirements and elastic resistance coefficient is accurate comparatively.

It is a new idea to adopt pile-net composite foundation for circular coal yard in fossil power plants, while not only certain soil strength is required to bear the upper load, but also the influence of soil deformation in load area on ring foundation shall be taken into account. Through prototype test and study on pile-net composite foundation of circular coal yard, this paper gives an introduction to that how to test stress and strain of pile, soil and cushion under large-area load. During the process, two loading and testing schemes were designed, while two layers of geogrids were arranged in test zone 1 and no geogrids in test zone 2. Based on the test results of two test zones, the paper investigates the depth and range of influence of large-area load on soil deformation inside and outside the load area, and analyzes the variation principle of vertical and lateral stress of cushion and soil in different elevations. Then combining with the change of pile axial force of middle pile and boarder pile in load area, the negative friction of upper soil is calculated. According to the stress of cushion and soil near the cap table, the pile-soil load sharing ratio and stress ratio are computed. Therefore the effects of geogrids on stress and strain of soil inside and outside the load area are deduced to provide objective technical parameters and suggestions on the design and construction of pile-net composite foundation of circular coal yard.

The calculation model of soil pressure displacement is established based on Mindlin strain solution, that the difference of soil pressure between the calculated state and the static state is considered as the calculated distributed stress. The limited displacement of soil under active state of plastic equilibrium and that of soil under passive state of plastic equilibrium are both obtained with th model. The calculation program is programmed according to the calculation model to analyze the regulation of both the limited displacement of soil under active state and that of soil under passive state from some key parameters, including inner friction, cohesive force, calculated depth and calculated width. The measured data from a mdel test is used to illustrate the validity and rationality of the proposed model. The model can be used for calculating of soil pressure with different limited values of soil displacements, so as to provide a theorical basis.

Based on conventional belled pile and wedge pile, a new type pile, belled wedge pile, which can improve pile shaft friction, tip resistance and reduce the influence of negative skin friction is developed. The stress mechanism and construction method of belled wedge pile is briefly introduced. Based on FLAC3D, The results are verified by engineering examples analysis; the mechanical properties on compression capacity and negative skin friction of belled wedge pile is preliminary studied. Conventional belled pile, wedge pile and equal section pile which are in the same concrete volume are comparatively analyzed. The mechanical properties of belled wedge pile which influenced by modulus ratio of pile end soil and pile surrounding soil, wedge angles, the diameter of enlarged pile head and the modulus of pile are discussed. It is shown that, when in the same surface load grade, the downdrag of belled wedge pile is minimum; the dragload of belled wedge pile is between the values of conventional belled pile and wedge pile.

Aiming to the problem about expensive cost and low efficiency of stochastic global optimization technology for displacement back analysis in geotechnical engineering, a novel cooperative optimization algorithm based on particle swarm optimization (PSO) algorithm and Gaussian process (GP) machine learning for back analysis is proposed. In order to reduce the cost of numerical calculation during displacement back analysis, the new method not only takes advantage of the global optimization performance of particle swarm optimization with quick convergence, but also uses GP model to summarize the historic experience during searching optimum solution and predicting the most perspective zone for guiding the flying of particle swarm. The results of performance analysis for different benchmark functions and application to a tunnel engineering show that the method is feasible to reduce remarkably computational time-consuming for solving problem of displacement back analysis based on numerical calculation.

Abstract: Urban rail transit in Xi’an is the first metro tunnel constructed in loess region in China. In order to meet the functional requirements of double line normal running and enlarged inner section of the right stabling yard in line 1 between North Zaoyuan Road and Hancheng Road(K12+792.744-K12+889.899), construction scheme with the combination of shield method and cross diaphragm (CRD) method is chosen, in which the left tunnel with small inner section is excavated by shield method and the right one with large inner section is constructed by CRD method. 3D-FEM model is established to analyze the construction process and mechanical behaviors. According to the results of the finite element analysis, the settlements of the ground, the stress distribution in the middle soil pillar and the development of plastic zones in the surrounding rocks are discussed. Based on the discussions, the reciprocal influences of construction sequences on the two neighboring tunnels excavated by shield method and CRD method respectively are demonstrated. It is shown that the excavation of anteceding tunnel with large cross-section by CRD method has greater influences on the ground settlement above the subsequent tunnel with small cross-section. In addition, the transfixion of the subsequent tunnel results in the ground settlement axis formed during the excavation of the anteceding tunnel offsetting a distance about a half of the net spacing toward the subsequent tunnel; and the ground settlement caused by the anteceding tunnel excavated increases near the side of the subsequent tunnel. Furthermore, the stress of middle soil pillar is influenced more significantly by the excavation of the anteceding tunnel with large cross-section than that of the subsequent tunnel with small cross-section; and the greater interactive influence caused by parallel tunnels exists near the same excavating face. The research results based on the metro project in Xi’an city will provide valuable practice experiences and worthful research achievements for future construction of other metro tunnels in loess region.

As we know, the soil has viscoelastic characteristic, the control equations of saturated soil described by fractional derivative model are established based on the theories of porous media and theories of fractional derivatives, in which the soil is regarded as porous medium filled with water; and the stress-strain relationship is described by fractional derivative viscoelastic model for considering the viscoelastic properties of soil skeleton. The vertical coupled vibration of a pile in a saturated soil described by fractional derivative model is investigated by introducing the potential functions and separation of variables method under the three-dimensional axisymmetric condition; and the influences of the model parameters on the vertical vibration of a pile in saturated soil is analyzed. The results indicate that the control equations of the saturated soil described by fractional derivative model has a wider application; and the model parameters has great influences on the vertical vibration of a pile in saturated soil.

Based on elastic thin plate theory and key strata theory, the stratum subsidence was described quantitatively. The characterization of fissures distribution in overlying strata under the influence of mining is studied. Then, an approximate formula of porosity in the regular movement zone of overlying strata along strikes is achieved. The results show that the amount of the fissures on both sides of fissure field is more than that in central area, while the bigger separation appears below the key strata. The porosity is lessening along with the decreasing of depth. Generally, the curve of porosity of bottom area in mining overburden takes on a saddle shape; and the change is located around the key strata or hard rocks. The porosity curve of top area along the strikes is symmetric arched. The conclusions can be applied to the research of rock mass seepage and the comprehensive gas control.

Based on the engineering that Nanshanxia Tunnel down-traversing Qiancangshan Tunnel of Wen-Fu Passenger Dedicated Line, the vibration effects on the existing tunnel caused by blasting of an adjacent cross tunnel have been monitored. The results of the tests show that: the position of blasting surface affects velocity distribution of the cross-section of existing tunnel; when the distance between vibration source and measuring points is more than 30 m, the main influence factor of vibration is distance; while it is less than 30 m, the main factors are the amount of dynamite and distance; the harder and more complete the rock is, the slower the attenuation of the propagation of blasting vibration wave is. Measures such as pilot tunnel blasting in advance of smooth blasting; pilot tunnel blasting that the initiation of cutting holes, periphery holes and bottom holes are separated; and controlling maximum explosive volume for single segment can weaken the impact of blasting vibration effectively and control the vibration effects on Qiancangshan Tunnel; it can be a reference for similar projects.

Based on the research of predecessors, investigated slope gradients of 221 redbed rock in Sichuan, Chongqing and Yunnan, etc. Southwest China, and through the statistical analysis of investigating data, Several design formulas for soft rock’s slope gradients are established based on the rock quality evaluation method; the differences of different soft rock’s grade designing formulas. Through applying the design formula of slope gradients to actual projects, the results show that the formula of slope gradients is reasonable and feasible.

In light of the uncertainty of concrete dam and rock foundation parameters, a rough neural network (RNN) model is constructed and applied to interval parameters inversion of dam body and rock foundation. The RNN model is a combination of rough sets and BP-NN, which has the interval input and output just as rough sets and has a similar network structure to BP-NN. The steps of this method are as follows. Firstly, the structure is analyzed with interval finite element method. Secondly, the corresponding interval samples are chosen from interval FEM results according to special requirements for interval parameters inversion. Thirdly, the interval samples are trained continuously by RNN model until the error is less than a given threshold. Lastly, the interval parameters of dam body and rock foundation are calculated by means of network recollection and back normalization. It is shown that this method can be used to interval mechanical parameters inversion of dam body and rock foundation and the result is reasonable. Moreover, this interval analysis method based on RNN model theoretically can also be used to other interval parameters inversion after some expansion and improvement.

The differential equation governing one-dimensional consolidation was modified to consider exponential flow law and time-depending load. Finite difference solution was acquired by Crank-Nicolson difference scheme which was relatively stability. The reliability of difference programming was verified by comparing the results with analytic solutions. The results show that, if the exponent is greater than 1, the rate of consolidation is faster than the case of Darcy’s flow at short time factor, slower than the case of Darcy’s flow at long time factor. On the contrary, if the exponent is less than 1, the rate of consolidation is slower than the case of Darcy’s flow at short time factor, faster than the case of Darcy’s flow at long time factor. If the exponent is greater than 1, the less the load, the slower the consolidation rate for the same soil layer. At the case of exponential flow law, the classical similitude between consolidation of laboratory samples and that of field layers is not satisfied. The faster the loading rate, the faster the consolidation rate.

On the basis of global analysis procedure and PAN Jia-zheng’s maximum principle for the stability analysis of slopes, a nonlinear optimum model is set up for calculating the factor of safety, which takes as independent variables the factor of safety as well as the normal stress on the slip surface. The objective function is just the factor of safety. The constraint conditions include that (1) the equilibrium equations are satisfied; (2) the normal stress and the interslice thrust are not negative; and (3) the thrust line is within the slip body. Since the objective function is linear and the constraint functions are polynomials of at most degree two, the model has weaker nonlinearity, enjoys a large scope of convergence, and can be solved by means of the conventional optimization algorithms.

How to consider the relevance of mechanical parameters of heterogeneous coal is a key issue to simulate coal bed. The 102 sets of experimental data including elastic modulus, uniaxial compressive strength and tension strength are derived from Wulong Mine of Fuxin city. Five dimensionless physical parameters including index of elastic modulus, index of uniaixal compressive strength, index of tension strength, index ratio of tension vs. elastic modulus (IRTE) and index ratio uniaixal of compressive strength vs. elastic modulus (IRUCE) are defined. Statistical analysis of the data shows that (1) Elastic modulus, uniaxial compressive strength and tension strength all follow statistical distribution, and may be fitted by Weibull distribution. (2) Indices of elastic modulus, uniaxial compressive strength and tension strength are correlative. (3) IRTE and IRUCE follow Weibull distribution. Then the probability model of heterogeneous coal with the correlation of the mechanical parameters is presented. The corresponding virtual generating system is developed. Two numerical cases are studied. In case 1 the virtual coal samples and the mechanical parameters are generated with the correlation and without the correlation of mechanical parameters, respectively; and the verifications are performed. The results show that the data from the former method are nearer to the experimental data. In case 2, the macroscopical stress-strain curve and the failure process of the numerical coal sample from the both methods under the conditions of plane strain and unaxial compression are studied. The simulating results from the former method are much better. Therefore the model proposed is a better way to simulate the mechanical heterogeneity of coal.

A new global optimization reliability method, knowledge-based clustered partitioning (KCP) method, is proposed. The proposed method includes five steps, namely, partitioning, random sampling, calculation of the polar radius, backtracking, and calculations of reliability index and design points. A flowchart for the proposed method is presented. Moreover, a C-language based computer program is developed to carry out the reliability computations. Two examples of reliability analysis for rock slope stability with plane failure are presented to demonstrate the validity and capability of the proposed method. The results indicate that the proposed method can obtain the reliability index and the design points simultaneously. Furthermore, the global optimization solutions can be obtained. The proposed method can ensure sufficient accuracy for reliability computations; and its efficiency is significantly higher than the traditional Monte Carlo simulations, which can be considered as a potential method for reliability analysis of slope stability, especially for slope stability involving implicit and nonlinear performance function. The proposed KCP method with equal-step-length can search the angles systematically, which results in the accurate design points. It is recommended that angle below ten degree should be adopted to ensure sufficient accuracy and reduce the computational effort as low as possible.

Considering the means of fuzzy random variables are fuzzy numbers, the relationship between the variation ranges of the means of fuzzy random variables and sample size is obtained based on the theory of fuzzy random variables and the theory of small sample size. Through the fuzzy random finite element reliability analysis of slope stability using the cutting method of sensitivity, the fuzzy random reliability indices and the fuzzy slip surfaces of slopes can be calculated; and the relationship between sample size and fuzzy random reliability indices can be obtained. It is demonstrated that the method of fuzzy random reliability analysis based on the theory of fuzzy random variables are the natural extension of the normally used method of stochastic reliability analysis. The normal value of fuzzy reliability indices is not a constant for it will change a little with the changing of sample size. Under the same confidence level, the variation ranges of the reliability indices will decrease with the increasing of sample size. Then, we can decrease the fuzziness of fuzzy random reliability indices by increasing the number of sample size.

The initial fabric of sample grain is a hard artificial controlling factor in the laboratory triaxial tests of coarse-grained soil. Based on cellular automata method, combining the laboratory triaxial tests of coarse-grained soil developed the HHC-CA model which generated the coarse-grained soil samples of different initial fabrics of grain to characterize the heterogeneous and random distribution of coarse-grained soil grain group. Then by means of the fast lagrangian analysis of continua in three dimensions (FLAC3D), conducting triaxial numerical simulation tests of coarse-grained soil and discussing the relationship between the gravel contents of sample shear band and samples and internal friction angle. Numerical simulation results indicate that the relationship between internal friction angle of coarse-grained soil and gravel contents of samples shear band were increasing function in the same size grading. According to the increasing of samples gravel contents, the internal friction angle might reduce, but the mean internal friction angle significantly increases with the increment of samples gravel contents.

A numerical calculation model of the ultimate bearing capacity of soft rock foundation based on the fast lagrangian analysis of continua (FLAC) is presented. The soft rock foundation is assumed as homogeneous, isotropic and continuous material which exhibits perfect linear elatoplasticity. According to the failure feature of rock, the Hoek-Brown nonlinear failure criterion and non-associated flow rule that can consider dilation angle of soft rock is used in analysis. To simulate easily, the Hoek-Brown nonlinear failure criterion is transformed to Mohr-Coulomb linear failure criterion by tangent method. The formula of instantaneous internal friction angle and instantaneous cohesion are derived from principle of equivalency; and then subprogram is compiled based on FISH language in FLAC. So the ultimate bearing capacity of circular footing on weight or weightless rock foundation is gained through adding vertical velocity vector. By comparing to theoretical values and in-situ values, the result is obtained of which the value from Hoek-Brown solution is more close to in-situ value than that from Bell solution; but all of them are too conservative. However, the numerical results are in better agreement with the in situ results. Especially there is only two percent deviation in the condition of considering gravity. It is shown that the numerical simulation by FLAC based on Hoek-Brown nonlinear failure criterion is appropriate to calculate ultimate bearing capacity of soft rock foundation.

As a powerful universal finite element analysis program, ABAQUS possesses immense ability for nonlinear computing, pre-and-post-processing. But the constitutive model of soil adopted in standard ABAQUS is inadequate in terms of the inability of reflecting militancy of cohesive soil, strain-softening and hardening of sand as well as the impact of stress path on deformation, etc. So it became an emergency for new constitutive model library which is more suitable for soil to be added into ABAQUS. In order to enlarge the computing ability of ABAQUS in the area of geotechnical engineering, new constitutive model library such as Duncan-Chang model, NHRI model and Sand model which are more adaptive for engineering application were developed with the help of secondary development toolkit UMAT as well as data interface. In this way, the convenient pre-and-post-processing and powerful nonlinear solving platform were made full use of in the study, and that more pertinent and more realistic finite element calculation for the stress and strain in soil can be accomplished, which is able to provide technique support for engineering practice. A numerical example is given; and the results verity that the second development of constitutive model library is valid.

A calculation model of dynamic response of transversely isotropic saturated soil under train load is proposed. Rail, rail pad, sleeper, ballast and elastic layer were added into the model. Based on Biot's dynamic poroelastic theory, the dynamic responses of elastic layer on transversely isotropic saturated soils generated by the train load is presented by using the Fourier transform. Numerical results are obtained by using the inverse fast Fourier transform(IFFT); and then, they are used to analyze the influence of the moving load velocity, anisotropic parameter and stiffness coefficient of elastic layer on soil displacemen and pore pressure. The results show that the displacement amplitude increases with the increasing of the load velocity; and the elastic layer has great influence on ground vibration and pore pressure.

Strength anisotropy and non-homogeneity are common phenomenon in clays. It is obvious that the anisotropy and non-homogeneity characteristics influence the bearing capacity of the foundations. To study this influence, the multi-block upper bound method is employed to calculate the bearing capacity of smooth strip foundations resting on the clay with anisotropic and non-homogeneous strength. The failure mechanism adopted by the upper bound method has already been verified by other scholars to be the best mechanism to calculate the bearing capacity of the smooth strip foundations on isotropic and homogeneous soils. The implementation of the multi-block upper bound method to calculate the bearing capacities in the anisotropy and non-homogeneity clays is presented. And the calculation program is compiled in the Fortran 90 language. To examine the calculation results by the multi-block upper bound method, comparisons are made with the results given by the characteristic method and other solutions by the upper bound method. It can be found that the method in this paper always gives the best results in all of the other upper bound solutions mentioned. With the multi-block upper bound method in this paper, the values are given in figures for different anisotropic and non-homogeneous coefficients. The effect of non-homogeneity on the failure envelops is also discussed to disclose the inner reasons for the influence law of non-homogeneity on the bearing capacity.

Based on the deep excavation of Shanghai 2010 Exposition 500 kV substation, the plane strain and axisymmetric elastic foundation FEM are used to simplify the space effect of the enclosure structure. The space effect of the annular enclosure structure, the inner liner and the different water and soil pressure distribution model are considered for the mechanical and deformation characteristics of enclosure structure. Through comparision between the calculated and measured results, several results are obtained: the space effect of the annular enclosure structure has a great influence on the mechanical and deformation characteristics of it; the ring stiffness of the enclosure structure must be considered during calculation; the inner liner is beneficial to the mechanical and deformation of the diaphragm wall, like a ring supporting; the measured horizontal displacement of the diaphragm wall is close to the result of axisymmetric finite element analysis when lateral pressure coefficient is 1.0; the measured hoop stress and bending moment of diaphragm wall are between the result of estimating water and earth pressure separately and lateral pressure coefficient is 1.0.

Geomechanical model tests play important roles in stability analyses of large-scale underground cavern groups. However, the application of this type of test was restricted by a number of factors, in particular the measurement of physical quantities during the test. A large-scale geomechanical model test was conducted under three-dimensional stress state. To measure small displacements in the surrounding rock masses, a mini multipoint extensometer measurement system was developed. The variation process and regular curves of the displacements of surrounding rock masses during excavation can be obtained. In addition, 3D numerical simulation was performed to simulate the whole process of the physical model tests. The comparison between experimental and numerical results leads to conclusions on the stability of the underground cavern group. The study shows that design and application of the mini multipoint extensometer measurement system have achieved satisfactory results.

Because of the characteristic of concrete quality detection, it’s necessary to adopt the bending ray in the technique of ultrasonic tomography. A grid model of wave speed distribution is built at first. Then the ultrasonic ray is traced with the shortest path method and the simultaneous iterative reconstruction technique(SIRT) is adopted to image. In order to adjust the algorithm to bending ray, the calculation procedure of SIRT is revised. The iteration in the outer layer is enhanced to do the next inversion of the modified path. To improve the inversion precision, the signal reliability coefficient is established and revised according to the informations such as: ray propagation distance, amplitude attenuation and frequency break, etc. According to this coefficient, the weighted average is calculated when solving the modified value of grid slowness. In order to improve the calculation speed, the grid number is dynamically adjusted; and the shortest path is searched in bi-direction. Through the numerical simulation and field measurement of concrete piles, it is proved that there is an obvious improvement on the calculation accuracy; and its calculation speed can be accepted in the engineering application.

The building blocks were drilled by the triangle-shaped probe unit with different rotational speed and penetration speed on the rotary penetration apparatus in the laboratory in order to study the influence of cutting action and penetration mode on penetration resistance. The data of axial pressure and torque as well as depth of penetration were collected during the test. The typical S-shaped result curve between axial pressure, torque and the depth of penetration is composed of three parts, which are starting, climbing and steady part. The conclusion was reached by analyzing the laboratory test data that the different penetration methods from CPT enables the probe unit to be pressed in soft rock or hard soil with available mechanical equipment. Theoretical analysis and laboratory tests indicate that the way of probe unit with cutting edge is rotated during being pushing in is an efficient measure for probe unit to go smoothly through the harder strata such as hard loess, soft rock and frozen soil.