With the development of society and economy, the range of the engineering problems that soil mechanics has to deal with is increasing; and these problems also become more and more complicated due to the interaction between soils and environments. In order to deal with these problems, the classical soil mechanics is required to be generalized and developed in depth and scope to incorporate the effects of new phenomena and new variables on soil behaviours. Based on a historical review of the development of soil mechanics, it is suggested that the classical soil mechanics faces three challenges: (1) lack of a unified, rational and theoretical framework of soil mechanics; (2) the knowledge and understanding of unsaturated soil behaviours is insufficient; (3) lack of a unified, rational and theoretical framework for multifield coupling problems of soils under multiple environmental actions. Finally, some problems beyond the scope of the classical soil mechanics are discussed.

According to reference [1], calculation parameters of strain-hardening elastoplastic model in the strongly weathered granite region are obtained by back analysis. The CRD method, double-side-drift method and bench method are used to study the deformation behavior of the surrounding rock and support structure by the numerical simulation respectively. It is shown that the CRD method is the best method for undersea tunnel excavation after comparing the results. On this basis, considering the in-situ situation of section ZK8+257-ZK8 +307 of Xiamen undersea tunnel, a 3D numerical model is established to simulate the tunnel excavation process constructed by CRD method. Meanwhile, a comparative analysis between the calculation results and in-situ measurements is carried out. The results show that the numerical simulation technology as well as the strain-hardening elastoplastic model established here can well reflect the deformation behavior and damage rule of strongly weathered granite during Xiamen undersea tunnel excavation. The results can provide guidance for lining design, support technology and also tunnel construction for the same kind of tunnel construction.

For concrete faced rockfill dams, while the concrete face functions normally, the seepage stability of the dam is satisfied; while the concrete face cracks locally or does not work properly, it is pivotal for the transition zone to control seepage field in the dam and to keep seepage stability. Taking the concrete faced rockfill dam of Shuibuya Hydropower Station for example, the coefficient between cushion layer and transition zone is analyzed; it is indicated that tests are necessary to study filtering and protection of transition zone for cushion layer. Tests are performed with cushion layer and transition zone material of whole size gradation; and the seepage deformation and filtering effect is studied. Synthesizing the test results and the results in author’s papers published already, the mechanism for the transition zone to control the seepage field in superhigh concrete faced rockfill dam is concluded. The transition zone, together with the main rockfill zone, could drain efficiently water from cushion layer. Ones the concrete face cracks or does not work properly, the interior structure of the cushion layer would change with the fine particles moving downward along water flow. Fortunately, with the protection of transition zone, the particles would stop around the interface between the two zones; and seepage stability of the cushion layer would be maintained. In the first abnormal experience, some fine particles would move out from the transition zone; but the framework of the material would remain stable. With the support of the main rockfill zone, the transition zone could continue to function at both aspects of filtering and drainage.

In box culvert jacking and replacement full face pipe-roof method, steel pipes are jacked between the start well and the receiving well. Soil in the pipes is excavated and the full face pipe-roof forms the shape of the box culvert. Subsequently, box culvert is jacked and replaces the full face pipe-roof. Specific to the pipe-roof which is considered to be an elastic foundation beam, two mechanical calculation models of the pipe-roof are built; the deflection curve equation of pipe-roof and the relating settlement control conditional derivation equation can apply to analyze the vertical deformation. By using the elastic foundation method and the simulation test analogy method, it is found that the calculation result is similar to the test result, which means the deflection curve equation is rational and provides theoretical basis for real projects.

According to the design concept of pressure dispersed anchor cables, load distribution and effective compression anchorage length of pressure dispersed anchor cables of each unit body are tested under the effect of external load, so as to provide design reference for anchorage support design of anchor cables. In field test, the experimental anchor cables have the total length of 32 m, anchoring section’s length of 18 m which is divided into four segments; and have 200 mm diameter hole. By the method of installing micro strain sensor with high sensitivity at the position of anchoring section, load transfer law and distribution of anchoring section are obtained. Test results show that: each unit body of pressure dispersed anchor cables did not shared external load uniformly in accordance with the required standards of the existing regulation. With the increase of external load, load value which located at the position of the second unit body and the third unit body is significantly higher than the load value located at the position of the first unit body and the fourth unit body. The condition of anchoring section is not completely compressed; and the effective compressed anchoring length is also not equal, which the effective length of the first unit body, second unit body, third unit body and fourth unit body are respectively 1.9 m, 2.9 m, 2.8 m and 4.5 m. The distribution law of effective compressed anchoring length of each unit body is the first unit body the second unit bod the fourth unit body, and the effective compressed anchoring length of the second unit body is close to the third unit body.

Equivalent damage rheological model for jointed rock is preliminarily studied. Rock and jointed plane’s damage rheological functions are developed separately on the basis of supposing that the rock is isotropic body and isotropic damage and the jointed plane’s normal and tangential damage is different. Finite element method calculation function of equivalent damage rheological model for jointed rock is deduced; and its finite element method program is developed by assuming that the material is not damage and calculating stress adopting effective stress. Through case study, it is shown that the equivalent damage rheological model for jointed rock is feasible; it can reflect the damage process well.

Nowadays, Rankine’s earth pressure theory is still playing an important role on calculating soil earth pressure. Based on Rankine’s theory, active earth pressure behind the wall is distributed to reach a limit equilibrium state in which the sliding surface of limit soil mass is considered as a cluster of planes. Proceeding from limit equilibrium theory, it is pointed out that the boundary of limit soil mass is a combination of sliding surface and crack section. This proposed sliding-cracking surface, which is in full compliance with Rankine’s theory with regards to active earth pressure distribution and resulting force, can be considered as an actual sliding surface when the soil failure occurs under active earth pressure. On the other hand, Rankine’s theory is applied to evaluate the soil tensile stress behind the wall under passive earth pressure, verifying that the sliding surface of limit soil mass can also be considered as a cluster of planes under passive earth pressure. The study result enhances the application of the Rankine’s earth pressure theory.

Combined with swipe loading method, fixed displacement ratio method and fixed load ratio method, the bearing capacity of shallow skirted foundations subjected to horizontal and moment combined loadings is explored through plane strain finite element numerical studies. The effect of embedment and soil strength nonhomogeneity on the failure envelope of skirted foundations is investigated; and the soil deformation mechanism under various combinations of horizontal and moment loads is shown. The validity of two types of swipe loading methods is compared. From the results, it is indicated that for nonhomogeneous soil, under the condition that the ratio of embedment depth to width is larger than 0.3, the failure envelope of skirted foundations is positively oblique; however the failure envelope is negatively oblique when the ratio of embedment depth to width is lower than 0.3. The phenomena of negative obliquity does not occur for skirted foundation in uniform soil.

In order to analyze micromechanism and coupled behaviors of consolidation and creep of soft clay, the consolidation and creep test at different drainage conditions and different consolidation pressures and the scanning electron microscopy test of the undisturbed sample and sample after creep are carried out from soft clay in the Yellowstone region. The results show that the creep behaviors under undrained condition are even more significant compared with under drained condition. Under lower bias stress condition, the deformation under drained condition is larger comparatively and with the opposite conclusion under higher bias stress condition. The deformations under drained condition are induced by consolidation and creep which have linear creep properties; and the deformations under undrained condition are induced mainly by creep which has nonlinear creep properties. The particle distances and large pores are reducing and small pores are increasing with the transition from side - side, side - surface to surface- surface of particles contact form during creep process. The bound water with the form of penetration absorption is changed mainly into free water to excrete during consolidation process and the creep process is mainly controlled by bound water. With increasing pressure and decreasing pore volume, the hydrated film is thin to increase the viscosity of soil which takes on the behavior of creep in the long term. The drainage performance in soft-soil reinforcement can be improved to increase the consolidation degree of soil which can reduce the harms brought by creeping and improve the stability of building.

Microstructure of the flow-solidified soil of dredged clays was studied by mercury intrusion porosimetry (MIP). The influences of the solidification agent content and curing time on the volume and entrance pore size of the voids was analyzed. The relationship between the MIP results and macroscopic behavior was compared; and the results demonstrated that the MIP is successful and the microstructure characteristics is adequate to be used to explain the macro-mechanical properties. The volume of the voids and D50 changed markedly with the solidification agent content and curing time; and the entrance pore size changed correspondingly. The distribution range of the entrance pore diameters of the flow-solidified soils are mainly from 0.01 ?m to 10 ?m; and the maximum distribution diameters are mainly from 0.5 ?m to 2 ?m.

It formed a subsidence area and expanded the offset in surface because of underground mining. The mine waste reservoir was limited to storage much more tailings and expropriation was restricted by limited land. In order to solve these two problems, it was intended to backfill the disease area with semi-dry cemented blocks about the actualities in Jinshandian Iron Mine. When the overlying and surrounding strata collapse again, the filling block will be broken and pulverized easily, and which would induce debris flow in mined-out area. Therefore, there need to study the tailings' pulverization rate when the surface collapses again and the possibility of inducing debris flow. Accordingly, the cemented tailings blocks with strength of 1 MPa and 3 MPa were compressed level-to-level respectively. The mixture with the cemented tailings blocks with strength of 6 MPa was compressed level-to-level too. While it was compressed, the vertical stress and strain were recorded. When the cemented blocks were crushed and pulverized in some load level, some samples were taken to do screening test and study the curve of broken blocks’ particle size distribution. According to the results of experiments as follows, when the collapse appeared in mined-out area and the cemented blocks may be compressed, the failure fillings’ pulverulent ratio was 8%-15%. The failure fillings’ pulverulent ratio can be reduced by filling the mixture which contains cemented blocks and waste rocks when surrounding rocks collapse. Combined the results of debris flow test, the possibility of debris flow was little; even if it has, it can also ensure the normal production in underground mining area

Based on the theory of effective stress, consolidation solution around the pile which is taken into account the influence of strain softening, magnitude of pile radius and range of excess pore water pressure, a theoretical relationship about time-effect of bearing capacity of single pile is developed, which can be used to predict the variation of shaft bearing capacity of a jacked-in pile with time in saturated soft clay. Different from the traditional way, the effect of different stiffness indices and different consolidation coefficients on the consolidation process in varied clays and highly stratified deposits are considered in the new consolidation solution. Besides, the rationality of the solution is verified by the pile load tests in different time periods after installation.

In order to get the features of energy absorption and dissipation of sandstone under loading and unloading, the tests of uniaxial compression, triaxial compression and post-peak unloading confining pressure have been performed on sandstone with the MTS81.5 servo-controlled test machine. The results show that the dissipated energy of sandstone increases from uniaxial compression test through post-peak unloading test to triaxial compression test. The dissipated energy in triaxial compression and post-peak unloading confining pressure tests increases linearly with the confining pressure. Under uniaxial compression, the sandstone presents abrupt brittle failure and the elastic strain energy initially stored in the sandstone is instantly transformed into dissipated energy which is the power source of all phenomena of the rock failure. Under triaxial compression, the sandstone demonstrates progressive failure, i.e. the failure of sandstone is the process of from local cracking to global destruction in which the dissipated energy gradually increases with deformation. When the deformation reaches a critical level, the residual energy stored in sandstone will be rapidly released and the sandstone globally destructed.

The practical calculation formulas for torsional vibration of embedded lump foundations were established based on the elastic half-space theory and state-of-the-art results of comprehensive experimental and numerical calculation by using equation equivalence method. Exerting impulsive load to embedded lump foundation of 0.5 m×0.5 m and 1.0 m×0.5 m with pendulum hammer to make foundations happen free torsional vibration in pit of 20 m×10 m×4 m respectively, collecting its vibration response, the results of experiment are compared to the results of calculation performed with practical calculation formulas. The advantages of the formulas are clear concept and simple calculation. It is practical for power equipment lumped foundation of arbitrarily shaped and arbitrarily embedded lumped foundations. It has referential significance to the calculation of seismic response of structural engineering.

In order to evaluate expressway slope stability rapidly and accurately based on a small amount of indoor and field tests during initial survey, this paper presents a new slope stability assessment method. Based on slope data from Fujian expressways, field slope stability condition was investigated, and 14 factors that might affect the slope stability were collected; then the Logistic stepwise regression was used to select significant factors, and finally a slope stability evaluation Logistic regression model with significant factors as independent variables and field slope stability condition as dependent variable was established. This model meets goodness-of-fit test, it is very stable, and its predictive results are very accurate. Moreover, the factors investigated are relatively easy to obtain; the model can handle qualitative variables; it can also assess the slope stability conveniently and rapidly. Thus, the Logistic regression method for slope stability evaluation can be widely applied to expressway slope engineering.

Based on Geddes’ stress formula, the hypotheses are designed aiming at the influence of annular flange rib of new prestressed pipe-pile with rib: The force of annular flange rib can be equivalent to the compaction to its lower part soil, i.e. additional stress; for the convenience of calculation, this kind of additional stress is simplified to the rectangular distribution skin friction resistance along double length of the lower part of annular flange rib; and the formula for calculating the settlement suitable for the single pile of new prestressed pipe-pile with rib is given; then Matlab software is used to program calculations. The calculated results are consistent with the experimental test results; so they can be used to estimate for the project.

Grouted gravel pile is a new technique of piles for reinforcing soft soils. It has been successfully used in construction of projects of expressway and high-speed railway. In order to study the load transfer mechanism of the pile, under the assumption that the compression modulus is obeyed the exponential distribution in reinforced zone, and based on the solution of settlement in half-space under circular bearing plate, the settlements of different parts of grouted gravel pile composite foundation under loads are analyzed; and the formulas of axial force, lateral friction resistance along the grouted gravel pile, and settlement on the top of pile are derived. The practicability of this method is illustrated by a case study. It is shown that the theoretical calculation results are close to the actual measurement results. Therefore the deduced equations are reasonable.

Cobblestone-soil is a natural geological situation consisting of cobblestones surrounded by soils. The mechanical performance of cobblestone-soil is between soil and rock mass and significant different from any component. Through the investigation in Chengdu Metro Line 1, the geological situation can result in a few non-normal damages (such as cutter wear, jam of roller cutterhead) and affects heavily the TBM performance. It is a typical mixed-face ground, which has an adverse influence on TBM tunnelling. This paper is intended to address the deformation problem of cobblestone-soil. Based on strain uniform assumption, analytic solutions were derived from the theoretical approach for equivalent elastic modulus while the cobblestone is assumed perfect circle and ellipse. The analytic solutions were validated by numerical modelling method. The results indicate that the equivalent elastic modulus derived from theoretical model and numerical is rather closely. The analytic solutions are helpful for improving the understanding of deformation for such ground condition and further to enhance TBM’s performance

Taking the Wenzhuang tailings reservoir as project background, through indoor stacking model tests, the change law of saturation line and particle size distribution are obtained. Based on these results, a mathematical model of fluid-solid coupling in porous media is established; and by using the software of ABAQUS, a planar model of finite elements is established; and through finite element analysis, the stress field, deformation field as well as pore water pressure field in the dam are obtained. The results of model test and numerical simulation can provide instructor for the design, construction and safe production of tailings reservoirs.

The groundwater level and pore water pressure distribution of retaining excavation were analyzed based on the upper bound theorem. The work of water pressure was introduced into the upper bound work balance equation as external loading, and the Prandtl soil slip mode was chosen to analyze basal-heave stability of excavation considering groundwater level and pore water pressure changing. In addition, the effects of the groundwater level, soil strength, location of hard stratum and width of foundation pit on the basal-heave stability coefficient were discussed; and two practical cases were calculated to verify calculation formula applicability. Analysis results show that the groundwater level and pore water pressure influence basal-heave stability; and groundwater is an important adverse factor of excavation basal-heave stability. Comparing with Terzaghi’s method, Bjerrum & Eide’s method and Chang’s method, calculation method of this paper can reflect the influence of groundwater level and pore water pressure on basal-heave stability; and it provide a reasonable calculation method of excavation basal-heave stability in soft soil.

With the analysis of characteristics of subsea permeable channels, the pre-grouting and additional grouting in fracture grouting methods are successfully used to solve the problem of water off during tunnel construction. It has provided a guarantee for the construction safety, and proposed the principle, parameters, equipment, processes, materials and grouting effect of grouting methods for subsea cracks. The methods are also successfully applied to Jiaozhou bay subsea tunnel through the fracture zones. The results provide a reference for similar engineering.

In order to evaluate earthquake damage to earth dams quickly and accurately, more rational influence factors of the damage are chosen based on the empirical model. The least square method is used to re-analyze the earthquake damage data of earth dams. The regression coefficients of the influence factors of earthquake damage under different conditions are presented; and an improved empirical model to evaluate the earthquake damage to earth dams is set up. In the new model, irrational influence factors are eliminated; and the prediction accuracy of the regression model is improved with the correlation coefficient of 0.908 and the standard deviation of 0.459, which are better than the original model. By using both the improved and original model, 47 earth dams damaged in Wenchuan Earthquake are evaluated. The results are analyzed by comparing with the real seismic damages, preliminarily proving the improved model to be more satisfying.

The south waste dump of Jianshan Iron Mine located on weak loess slope foundation due to the unique-selection of the dump site, various degree failures sequentially occurred since 2008. Based on engineering analogism, in-situ investigation, field monitoring and tracking geologic survey technology were used to research the landslide formation evolution mechanism of the waste dumps located on loess foundation, specially the landslide types and failure modes (low-speed and slight-starting, rotational and retrogressive mode), formative mechanism and conditions(overload and lateral compression leading, precipitation trigger), landslide procedure, feature and distribution regulation (supporting course creep-floor heave-loess ridge tensile fracturing-rotational sliding -crack propagation-slip plane-retrogressive fallout). Starting with effect interaction characteristics between the waste dump and the loess slope foundation, the limit height of dumping-site determined by theoretical formula, failure range estimated by engineering analogism and statistical analysis, influence degree on environmental(equipments, human beings, building, etc.) were studied. It was the key countermeasure to adjust and control course safety of substructure, such as intelligently using dumping-site space, adjusting time-space relation during waste dumps emission, controlling emission speed. The conceptual design is submitted that moderately failure should be permited.

In anti-sliding pile designing for Reservoir landslide improvement, the reasonable pile position determination is very important, which effects the engineering safety and cost. Taking Zhanghuanhoumiao east landslide for example, based on the engineering geological condition investigation and with the GeoStudio software, according to the reservoir operation curve, considering 4 different pile positions, the numerical simulations were done. The results show that: ① When water level rising up, the displacement of front edge decreases, but the displacement of back edge increases. The maximum displacement of the front edge appears during water level drawing down and lowest water level. The maximum. displacement of the back edge appears during water level rising up and the highest water level. ② The reasonable pile position for the back, front and middle of the landslide are separately Ⅰ, Ⅱ pile positions. I pile is at the 175m, which residual pushing force is maximum the best pile is Ⅱ pile position, which is 130m from the shearing out point of landslide. At last, considering the influence of the water level fluctuation, the modified method of the safety factor for the anti-sliding pile design is presented, which will be important to the anti-sliding pile design for reservoir landslide.

Based on Biot’s theory and the minimum potential energy principle as well as the thin plate theory, the superstructure, raft and soil are assumed to be whole system according to the substructure method. The system must satisfy the continuity conditions at the interface between the superstructure, raft and soil surface. Considering the compatibility condition that the vertical displacement of the interface between the raft and the saturated soil should be equal, the integral equation accounting for the vertical coupling of the superstructure-raft system with the saturated soil subjected to a moving load is constructed. Using the numerical inverse transform technique, the forces and displacements of the superstructure, plate and saturated soil at any time are obtained. Some numerical results are presented to demonstrate the capacity of the proposed model. Numerical results show that the horizontal displacements and vertical displacements of each floor of the superstructure increase with increasing velocities of moving load. The vertical displacements in each floor have small change. Also, for a lower moving velocity, the curve of the horizontal displacements changes smoothly with the superstructure height increasing. When higher moving velocity, the curve of the horizontal displacements changes obviously with superstructure height increasing.

Buckling safety factor of the design for supporting structure of foundation pit engineering is unmeasurable in the process of construction; so the different types of monitoring projects for the different safe states of foundation pit engineering are stipulated by the JGJ120-99, which is Technical Specification for Retaining and Protection of Building Foundation Excavations (in Chinese), and the GB50497-2009, which is Technical Code for Monitoring of Building Foundation Pit Engineering (in Chinese). At same time, the safety alarming value is suggested respectively. Because of the asynchronism of monitoring data and with a view to avoid the burstiness of unsafe state of working progress of pit and demand for coping behavior of different safe states, the classifying method of safe state is suggested. In light of observed data of the different monitoring projects, the generalized stability factor is defined using the theory of fuzzy mathematics by which the destination is to estimate the safe state of work progress, and safe toplimit of the generalized stability factor is given. As a real example, the developing process of generalized stability factors for different monitoring projects are analyzed based on fuzzy calculation of observed data and the priority monitoring project of security control is pointed out.

Underground station of Shenyang Metro line 2 is the first underground engineering built by pipe-roof pre-construction method (PPM). The surface subsidence caused by the construction was monitored; and revised Peck model was developed to predict the subsidence. Some conclusions are drawn as follows. (1) The predicted result is consistent well with the monitoring data. (2) Surface subsidence caused by tunnel construction with PPM is characterized by the whole subsidence; and the subsidence value is pretty equal to the one of underground structure foundation, and it is effective to control surface subsidence by controlling the the sink of foundation of tunnel structure with PPM. (3) The underground permanent structure built before constructing tunnel with PPM could obviously constraint the surrounding rock with 0.0005%-0.0020% of stratum loss rate and 0.5 of width coefficient of sinking tank. (4) Surface subsidence caused by PPM is much less than the normal construction method, which has significantly social and environmental benefits; and this method is suitable to construct the underground urban traffic hub and tunnel projects that crossing traffic trunk lines and is worth to be studied and promoted further.

Bedding landslide is a type of landslides, it has higher frequency casualty of many provinces in China; it makes a lot of damage of economy and bad influence of society. In order to research regularity of bedding landslide, according to 81 bedding landslides in China to build data base that the authors engage in and successful control them, by using the contribution rate method to quantitatively analyze various interdependence about varied dip angle space of bedding landslide, the various correlations about varied dip angle space of bedding landslide are studied. It is found that the dip angles of bedding surface of 10°-25° have maximum contribution rate; the dip angles of bedding surface of 25°-35° have middling contribution rate; the dip angles of bedding surface greater than 35° or less than 10° that have minimal contribution rate. The research conclusions are consistent preferably with the fact, so as to provide potential gist to research and control bedding landslide in China in future.

Dynamic simple shear tests on different types of sands under multidirectional earthquake loading were simulated with finite element method. Reduced order bounding surface model was employed to study the effect of characteristics of earthquake loading on the seismic compression of sands. The parameters of model were determined based on results obtained from laboratory dynamic simple shear tests. The study results show that the characteristics of earthquake loading such as loading sequence, asymmetry, loading direction, loading type and input loading dimension have great influence on seismic compression of sand. The vertical strain of sand increases dramatically when sand specimen is subjected to high stress pulse; also its increment is greatly influenced by time and sequence of stress pulse; the vertical strain of sands increases as the asymmetry of earthquake loading grows under identical conditions; negative loading results in increase of vertical strain of sand due to its compaction effect, which is opposite to positive loading effect; 20 cycles were used simply as the number of equivalent cycle in some current codes for computation of seismic compression, whose equivalences for vibration-type and impact-type of seismic loading is greatly different; two times of seismic compression of sand induced by one component loading was taken as the sum of seismic compression of sand induced by actual multidirectional earthquake loading in Tokimatsu and Seed (1987) procedure, which is in doubt.

Settlement monitoring of a field-scale municipal solid waste landfill site in Shanghai Laogang Landfill was conducted since September 2006. The landfill site covered an area of 200 m×125 m and accepted about 150 000 tones of municipal solid waste from Shanghai. Maximum height of the wastes is about 9 m. Settlements at different depths of the landfill site during filling and after closure were monitored through horizontal inclinometers. The working principle of the horizontal inclinometer was introduced. Two years’ monitoring data showed that bottom horizontal inclinometers settled from -3.6 cm to -5.7 cm. Wastes under the middle horizontal inclinometers experienced large compression due to the deposition of overlying wastes. The compression strain from the beginning of the overlying wastes’ deposition to three months after the end of the deposition was about 0.197-0.242. Monitoring data from the top and middle horizontal inclinometers indicated that the time needed for the primary compression of wastes in the test site was about 3 months. Modified secondary compression index C’α was about 0.066-0.070, and was relatively large compared to published data which might due to the large amount of organic matter in the landfilled wastes.

Stability analysis of foundation pit support without considering the random uncertainty of soil parameters, and the uncertainty of soil physico-mechanical parameters may lead to unreasonable results. In view of this, the reliability theory is introduced. But the traditional methods of simple and quadratic of the two ranks quadrature require the transformation of basic random variables or the equivalent normalization. This transformation has also led to nonlinear performance function, thus becoming a source of error. The integration probability density function of the basic variable in the failure domain is adopted to calculate the failure probability of structure. In the maximum possible points of the failure, making the logarithm of the probability density function of basic variables into a Taylor series and taking development to the second item; the performance function is also as a Taylor series expansion. Using super tangent plane or quadratic hypersurface plane to approximate the actual failure surface, then the achievements of simple and quadratic of the two ranks quadrature methods are used to complete the asymptotic probability of failure points. A method of the asymptotic integration of reliability analysis is proposed for foundation pit support; and its application to the Hongzecheng projects of Tianjin shows that the method not only considers the randomness of the parameters, but also avoids errors of normal state changing or equivalent normalizatin. It provides an effective way for the reliability analysis of supporting structure.

Based on an engineering case of the construction of prefabricated piles for Chizhou Power Plant, the distribution and dissipation laws of excess static pore water pressures induced by pile driving (prefabricated square piles) in the saturated soft clay with driven plastic drainage plates are introduced. The factors influencing the distribution and dissipation of the excess static pore water pressures in soils are analyzed. The test results show that the spacing of prefabricated piles in the saturated soft clay during their construction should be larger than 3 m; and the time interval should be 6-8 h. The control parameter for the construction of prefabricated piles is that the ratio of excess static pore water pressure to effective weight of superimposed soil should not be larger than 1.

Principal component analysis (PCA) is a solution to the multicollinearity problem of dam regression models. However, uninformative principal components (PCs) may lead to the failure prediction of dam deformation. Thus a hybrid regression model using semi-parametric regression and PCA is proposed, where the PCs with the highest variance are treated as the semi-parametric component; the remaining PCs and model errors are treated as the non-parametric component to be estimated. The hybrid model is tested using the field observations of a dam in China. The result shows the hybrid model can circumvent the multicollinearity of dam causative effects and the ill-conditioned problem in semi-parametric penalized least squares regression. A comparative study with traditional PC regression and stepwise regression demonstrate the superior performance for dam deformation prediction

In order to probe into the effects of fracture continuity rate on coupled temperature field, seepage field and stress field, using the coupled thermo-hydro-mechanical model of dual-porosity medium for ubiquitous-joint rock mass established by the authors and taking a hypothetical nuclear waste repository located in an unsaturated stratum as a calculation example, the two-dimensional finite element analyses were carried out for four cases in which the continuity rates of fracture and pore are different; and the temperatures, negitive pore and fracture water pressures, flow velocities of groundwater, permeability correction factors for pore and fracture and stresses in the surrounding rock mass were investigated in the numerical simulation. The results show that the stiffness of dual-porosity medium is changed because of using different fracture continuity rates; so the state and level of stresses in the rock mass are modified, and then the porosity and permeability of pore and fracture are altered; therefore the variations of values, distributions of pore and fracture pressures as well as water flow velocities are caused.

The characteristics of Drucker-Prager yield surface transformation during the strength reduction process by strength reduction finite element method in slope stability analysis under the plane strain condition are analyzed. Currently, the Mohr-Coulomb hexagon circumcircle Drucker-Prager criterion is adopted in the ANSYS finite element analysis programme. So, the safety factor using ANSYS with the Mohr-Coulomb hexagon circumcircle Drucker-Prager criterion is calculated; thus the safety factor based on the Drucker-Prager yield criterion such as the Mohr-Coulomb matching Drucker-Prager yield criterion under the plane strain condition can be obtained using the deduced conversion formulae. Under the plane strain condition, the Mohr-Coulomb yield criterion in the ANSYS programme without secondary programming development through equivalent substitution is adopted. The safety factor conversion formula with different Drucker-Prager yield criteria is deduced. The safety factors calculated with conversion formula and those calculated by traditional method are compared through slope models analysis using ANSYS, and the error between the results obtained by strength reduction finite element method with different Drucker-Prager yield surfaces are investigated. A series of case studies indicate that the average error of safety factors between those obtained by conversion formula and those by calculation is slight. The applicability of the proposed method is clearly verified

For the case of narrow excavations such as subway stations and underground pipe, the width of the soil mass in passive zone is limited, so it’s unsuitable to use the classical Coulomb or Rankine earth pressure theory to calculate the passive earth pressure. A finite element numerical model for retaining wall in narrow excavations is presented. The slip surfaces in the soils at passive limiting state with different widths of soils when the walls translating are investigated. Based on the concept of Coulomb sliding soil wedge, a new theoretical model for determining passive earth pressures against translating rigid retaining walls in narrow excavations is proposed. The formulae of the inclination angles of slip surfaces and coefficients of the resultant passive pressures are obtained. Then the horizontal differential element method is introduced and the unit passive pressures and the points of application of the resultant earth pressures are proposed. The factors that influence the inclination angle of slip surface under this circumstance are studied in detail. The comparisons between theoretical and numerical values show that the proposed equations satisfactorily predict the earth pressure on the wall. It is also shown that if the width of soil mass in passive zone is less than a critical value and the wall friction can not be negligible, the inclination angles of slip surface and the passive earth pressures are larger; while the heights of points of application of pressures are less than Coulomb’s solution. The narrower the pit or the rougher the wall-soil interaction is, the more significant the differences are.

In order to solve the problem that transfer matrix in axisymmetric dynamic problem of single soil layer overlaid on elastic half-space is ill-conditioned, the error analysis method is presented. The disposal method for integrand is discussed in three conditions; then the disposal method for the inverse-Hankel transformation and the inverse-Laplace transformation is briefly introduced. Based on these, the method how to decrease the error is presented. The analysis result is verified through the degenerating model. The result indicates that the method presented can effectively decrease error. All this work can provide idea for solve the problem that transfer matrix in axisymmetric dynamic problem of layered elastic half space.

The pillarless sublevel caving is one of major mining methods in underground mine at home and abroad. As for the equipment constraint of rock drilling and blasting,the sublevel caving with small structural parameters has been applied for a long time processing with dynamite, and ore removal, which caused some problems such as serious ground pressure and low mining efficiency. In recent years, enlarging structural parameters is gradually used in pillarless sublevel caving, which improves both the mining stability and economic efficiency. Therefore, the analysis of underground pressure in pillarless sublevel caving favors the realistic safety, and the high effective mining. Three different structural parameters models (10 m×10 m, 15 m×15 m, 15 m×20 m) have been simulated. By adopting three-dimensional finite element method, and analysis has been done on the displacement and stress on the different processes of excavation and ore mining. The results are as follows: Firstly, compared 15 m×20 m with 10 m×10 m, the displacement of admission passage roof is reduced by 20.1% and the minor principal stress is also lowered by 18.8%. Secondly, the roof displacement and the stress in mining process is smaller than excavation process; the problems of underground pressure has been improved. Thirdly, the vertical displacement and principal stress is lowered with the increase of the structural parameters both in excavation and ore mining process. The results show the higher structural parameters possess better stability, and can improve the underground pressure. Therefore, using the large-spacing pillarless sublevel caving is safe and feasible

Based on anti-explosion engineering of surrounding rock, with the method of little charge model test and numerical simulation, by changing the location, shape, and combination form of cavities, the attenuation and screening effects of defense layer with cavities on planar and spherical blast waves are studied. The results show that defense layer with cavities can weaken peak pressure of blast waves greatly and protect the underground structure. The attenuation effect of staggered cavities on peak value of blast pressure is better than ordered queue cavities obviously; and the attenuation effect of rectangular cavities on blast pressure is better than circular cavities. The results can provide references for new-type anti-explosion technique of surrounding rock.

For the Three Gorges granite, a finite difference software package FLAC is used to study failure process of heterogeneous rock material. Firstly, proper scale of finite difference grids is under consideration with scanning electron microscopy photo of the granite. Based on mineral components identification results of the granite and fuzzy clustering method, the actual image data are transformed into the finite difference grid by applying image processing techniques. A convenient and efficient two-dimensional numerical modeling method for heterogeneous geomaterials is presented. Furthermore, shear bond propagation and failure process of the granite are simulated in uniaxial compression test based on experimental strain soft model; and stress concentration phenomena are analyzed. Finally, numerical simulation of granite samples under different triaxial compression tests is studied. The results show that the numerical modeling method based on digital image processing can be used to calculate the mechanical responses of geomaterials by taking their heterogeneities into considerations.

Based on the multi-arch tunnel #2 for the JK-2 Contract Section in the Zhangjiakou-Shijiazhuang Expressway, the information monitoring platform based on in situ multi-source sensors combined with the regression analysis and parametric feedback information concerning the highly confident models have been developed to investigate and analyze the monitored data. The dynamic characteristics of surrounding rock stress, displacement, deformation, plastic zones and supporting structures in different construction processes are analyzed. Through complete analysis and research, various abnormal phenomena are analyzed; and the stability and effectiveness of the tunnel surrounding rocks have been described. Moreover, based on MIDAS/GTS (rock and tunnel analyzing system)—professional finite element software and topographic contours, the tunnel construction simulation is implemented by establishing 3D model. Tunnel structures and supporting systems of the different construction methods have been compared with the result of numerical simulation. Aiming at the designed construction method of asymmetrical pressure and unfavorable geological setting, some suggestions and the optimization scheme have been proposed, which could also be recommended for similar future projects.

In order to consider spatial effect of excavation engineering, Duncan-Chang nonlinear elastic model and Mohr-Coulomb ideal elastoplastic model attained by K0 consolidation and normal consolidation samples with CU tests are adopted; and the whole 3D finite element analysis of soft soil excavation engineering in Fuzhou city using 3D solid elements, shell elements and beam elements considering contact interactions is built which applies ABAQUS software. The response of the whole system during the construction of the foundation pit is done by numerical simulation “object tests”; and it is compared with the field measurements and 2D numerical simulation results. It is shown that compared with Mohr-Coulomb ideal elastoplastic model and 2D results, the results from 3D numerical simulation analysis using Duncan-Chang constitutive model parameters attained by K0 consolidation samples with CU tests are more reliable. It has distinct advantages and possesses of tremendous popularization and application value.

When dealing with discontinuous issues such as fracture and crack in geo-engineering, conventional finite element method (CFEM) need to refine mesh in the local zone including crack tip; furthermore, the mesh must be reconfigured and re-partitioned once the crack propagation happened. The extended finite element method (XFEM), based on the idea of partition of unit method, can successfully solve these problems easily, which may hardly be deposed by CFEM. Usually, contact problem of crack surface must be considered when studying some compound fracture. Based on the complementary theory, the complementary equation between relative displacement and contact force of the crack surface can be established, and solved by Newton's method without considering opening and closing iteration. Finally, as a numerical example, a plate with crack is compressed to indicate the effectiveness of this method. The results indicate that the method can prevent mesh penetration from one side of the crack into the other side effectively; and also obtain the stress distribution that is consistent with the actual on the crack surfaces.

The result of presplit blasting influenced by geometrical characteristics of joints are combining studied by the software AUTODYN 2D and UDEC. By calculating, the impact of geometrical characteristics of joints can be found through the crack extension between the blasting hole. The straight level of the cracks between the blasting hole are gradually enhanced with the increasing of angle between the joints and the borehole connection; and the angle of 90-degree can get the best result that the crack will be coincided with the borehole connection; and it is also in accord with the theoretical analysis. Joints space has significant impact on the presplit blasting; and the smaller joint space the rock has the more difficult the cracks connected. Reducing the space of boreholes is conducive to form the linked up cracks.

At present, in particle flow theory, mesomechanical parameters can only be obtained by varying them until the macro mechanical parameters of the numerical sample match that of the laboratory rock-soil mass sample. The adjustment process is inefficient with some blindness; so a new method should be introduced to establish the relationship between macro mechanical parameters and mesomechanical parameters. Based on PFC3D program, a nonlinear network model linked macro mechanical parameters and mesomechanical parameters is founded by adopting back propagation (BP) neural network; so mesomechanical parameters can be inversed rapidly and accurately by inputting macro mechanical parameters. Some study results are gained as follows: (1) Precision of macro mechanical parameters calculated by inversed results are generally over 90%. (2) Inversion performance of BP neural network model is best when RES, which means the number of particles across the minimum scale of the model, is equals to 10 and the hidden layer has six neurons. Application results show that BP neural network model exhibits an excellent inversion ability of mesomechanical parameters of rock-soil mass and provides a new technical approach for application of particle flow theory.

It is crucial to analyze the limit aseismic capacity and the failure mode for high core rockfill dam. The process of failure for high core rockfill dam is comprehensively studied on the basis of analyzing dynamic response, dynamic strength and seismic permanent deformation. The dynamic strength appears to be severely deficient in the impervious body and the upstream filter layer as the dam falls into the limit state. It is considered that the deficiency of dynamic strength will induce seismic fracture and liquefaction in the upstream filter layer, which finally will lead to failure of upstream and downstream slopes.

How to accurately and nondestructively obtain inner stress evolutional data of rock and soil material is helpful to study physical mechanism of material failure affected by confining pressures. The triaxial compression tests of sandstone under confining pressures of 0.0, 0.5 and 1.0 MPa are designed based on the particle flow code (PFC) software. According to failure shape, macro-stress- strain curve and stress data in x, y, xy directions at nine monitoring points on left and right sides or middle of specimen, mechanical mechanism and influence by confining pressure of material failure process are analysed. It is found that the shear band located from upper left corner to lower right one develops enough than shear band situated from upper right corner to lower left corner, which is limited with increase of confining pressure; that is to say shear band tends to expand with same velocity because of confining pressure. It can also be indirectly proved by failure shape explained by microcracks; and that confining pressure makes strain more obvious.