The creation of ground pass shield tunnelling(GPST) method has conquered the disadvantage of constructing working shaft for shield launching and arrival which is a typical of  traditional tunnelling method，and making an innovative turning point on shield tunnelling history. This paper first presents a detail investigation on the key problems of GPST method by adopting large-scale model test，numerical simulation and in-situ monitoring. The surface settlement characteristics of different crossing stages of GPST method have been revealed. In addition，an engineering application of this new method was carried out in Moling-Jiangjun interval of Nanjing intercity fast track；some key tunnelling parameters and effective measures were explored. Comparison was also done between the monitoring data，model test results and numerical results；it is shown a good agreement with each other；and a sound basis is established for the broad application of GPST method.

Unlike metals，rock materials show the Lode angle dependence and other characters in mechanical behavior as a result of frictional effect. Its yield process depends not only on generalized shear stress but also on hydrostatic pressure. In order to construct the unified yield criterion which is widely used and accordant with characters of rock，work and results are as follows. Firstly，considering shear slide and normal compaction，energy related to yield is divided into the sum of shear strain energy on combined mobilized plane together with volumetric strain energy and their formulas are also derived. Secondly，test results show that when rock yields the relationship between the two kinds of strain energy is linear. Based on the result，rock unified yield criterion is established and it can describe basic yield characters such as curves on meridian plane and Lode angle dependence. Thirdly，after the analysis of some widely used rock yield criterions，it is proposed that unified energy yield criterion is a generalized form of these yield criterions. Lastly，the yield strength is calculated and with the following criterions respectively：the unified energy yield criterion，the triple shear energy yield criterion，Mohr-Coulomb yield criterion，Drucker-Prager yield criterion，twin-shear strength theory，Hoek-Brown yield criterion and Murrell yield criterion. The result by the unified energy yield criterion is more accurate and the error is more stable as well especially under high confining pressure and hydrostatic pressure. The intrinsic mechanism of above-mentioned result is analyzed and the qualification of the traditional assumption that shear strain energy retains to be constant when rock yields is confirmed. So the unified energy yield criterion established in this paper breaks through the traditional assumption. The factor such as volumetric strain energy should be considered reasonably in the yield criterion by analyzing the influencing rule of it，which is significant for the accurate quantitative analysis of rock yield characters.

An anisotropic damage model was established for fluid-saturated crystalline rocks of low permeability in coupled thermo-hydro-mechanical(THM) loading conditions by using the micromechanical approach in the framework of thermodynamics. The proposed damage model accounts for the impacts of some important micromechanisms，such as the interstitial water pressure，normal stiffness recovery induced by compressed microcracks and sliding and shear dilatancy of closed microcracks，on the macromechanical properties of rocks under non-isothermal condition. On this basis，using various homogenization approaches，estimates were presented for the variations in effective permeability of cracked rocks induced by anisotropic damage propagation. The predictive limitations associated with the lower bound estimates for the effective permeability of damaged rocks were discussed；and a rigorous upper bound estimate was then presented to account for the influence of some important microstructural features，such as the connectivity and persistence of microcrack system，on the permeability variation. Existing laboratory tests on granite samples for damage-induced variation in permeability in triaxial condition and for uniaxial mechanical response after high-temperature thermal treatment，together with the in-situ measurements of excavation-induced damage zone and permeability variation in the surrounding rock of the TSX tunnel，were used to validate the proposed models.

This paper proposes an experimental system to monitor the phenomenon of electromagnetic radiation during the granite failure. By conducting the self-expanding experiment of granite，the electromagnetic response on basis of cracking procedure is studied. The experimental results show that：in rock main rupture instantly，the largest electromagnetic radiation occurs with value of about 0.2 mV. The propagation，coalescence of microcracks lead rock to catastrophe failure accompanied by a strong electromagnetic signal. Electromagnetic radiation has directionality during rock fracture process；the frequency of the electromagnetic signal is low；and there is a characteristic frequency for releasing radiate energy in rupture process.

A coupled thermo-poroelastic model is proposed with integration of a damage factor. The proposed thermo-poroelastic model is firstly utilized to simulate the thermo-hydro-mechanical(THM) response of homogeneous elastic medium；and its accuracy of the numerical results is verified through comparing to the decoupled analytical solution. Secondly，the thermo-poroelastic model is employed to predict stress response and damage propagation around the wellbore due to CO2 injection. Finally，this model is applied to heterogeneous rock under a Weibull distribution to predict stress response and permeability change. The experimental results indicate that the supercritical CO2 injection can change the rock?s strength state and permeability distribution significantly. Too high injection rates will facilitate the tensile damage and extend the tensile damage zone. Heterogeneous rock material is more vulnerable to tensile damage and permeability increase.

A new approach is introduced to measure tunnel deformation by means of terrestrial laser scanning (TLS)；and problems about data collection and data processing are solved. On the one hand，in order to balance accuracy with efficiency during data collection，recommendations about setting distance of adjacent stations and scan resolution are given through geometrical analysis. Besides，approaches to register data collected from different scan stations and the precision of registration are discussed. It is recommended to use global registration method to reduce registration error. One the other hand，since the raw data of TLS called “point cloud” is unable to display the tunnel deformation explicitly，a new 3D modeling algorithm is proposed so that the tunnel deformation is visualized. The new algorithm combines cylindrical fitting method with elliptical fitting method and reduces noise based on error distribution theory. Using the total station as reference，the reliability of TLS is verified and the difference between total station and TLS is less than 2 mm for tunnel deformation measurement. Finally，two cases of Shanghai Xizang Road cable tunnel and Shanghai West Changjiang Road tunnel are introduced. The first case gives details about data collection and data processing in a single-hole tunnel and shows the results of deformation. The second case focuses on how to set the positions of scan stations and targets in a multi-hole tunnel.

In order to construct the reliability discriminant of Mohr-Coulomb strength criterion，it is essential to study the probability distribution of shear strength parameters. Based on normal information diffusion principle，a probability model deduction method of shear strength parameters with small sample size is presented. Considering that the sample size of rock shear strength parameters is small in general，the testing data of rock uniaxial and triaxial compression were regarded as basic information，and information base of shear strength parameters with small size was constructed according to the permutation and combination theory. And the sample data of cohesion c，internal friction angle φ and friction coefficient f were also obtained using robust regression estimation method. Finally，based on the normal information diffusion theory，the probability distribution functions of c，φ and f were deduced. K-S test method was used to compare the results of traditional fitting-test method and presented method. The results show that the probability distribution of shear strength parameters based on normal information diffusion principle is more close to the actual probability distribution. Whether in terms of test value and the cumulative probability，the results of presented method are better than those of the traditional fitting-test method.

In high stress condition，the sharp conflict between rock mass strength and stress will lead to damage to surrounding rock. Damage is the direct embodiment of the state of surrounding rock. The acoustic detection and borehole television are used to test a whole section in Jinping II deep diversion tunnel. The acoustic test results show that the section shape of low wave velocity zone is not symmetrical；and stress distribution is not completely corresponding. The borehole television was added in each acoustic drilling，a more intuitive understanding on fracture development depth and internal actual structure features of surrounding rock is obtained. In order to describe the damage zone characteristics more accurately，FLAC3D is used to calculate the stress path of the key points in different positions and analyze the stress states of the key points. Based on the discretization by UDEC voronoi polygons，adding the joint description，the influence of joint on excavation damaged zone(EDZ) is analyzed. The simulation results show that the presence of joint changes the stress distribution after excavation and leads to the difference in damage and fracture zones. With the help of particle flow code(PFC) in advantage of describing microscopic fracture characteristics，the damage zone is simulated. It is revealed the damage localization characteristics and damage zone，fracture zone distribution characteristics have the very good consistency with actual ones.

The effects of cracking of Xiaowan arch dam on the possibility of cracking propagation，and on the stress，displacement and stability should be considered seriously after phased realistic impounding. The basic principle is three-dimensional nonlinear numerical computation by simulation of the construction process of Xiaowan arch dam and the cracks in the dam based on reasonable material parameters which are obtained by the multipoint displacement back analysis on the basis of the monitoring data. The result indicates that the parameters obtained by the displacement back analysis are reasonable and accurate；and the prediction of the dam displacement is of high precision，which can provide a good stability estimation of the dam. The predicting results fit well with the monitoring data and the results of geomechanical model test. The global deformation of the dam accords with the general pattern；and the possibility of crack propagation is very small under the normal water load. The effects of cracking on the global stability of the dam are very small；and the limit state of the dam is similar to that of no cracking working condition. Both of them crack from the surface to the inside，instead of cracking from the internal cracking.

In general，a coal bump refers to a sudden and violent failure of a coal seam that releases contained elastic energy and expels a large amount of coal and rock into the roadway or working face where men and machinery are present. Coal bumps occur more frequently in an island longwall panel，which is surrounded by previously mined panels，than in other longwall panels because of its high-stress concentration. Based on the geological conditions of island longwall panel in the Tangshan coal mine in Tangshan，China，numerical simulations were conducted to investigate the dynamical character of elastic strain energy relief and to understand the mechanism of energy explosion during periodic weighting of the island longwall panel. The advance of mining will cause continuously increasing of the goaf space because of the constant collapse of immediate roof. The accumulated elastic strain energy in main roof will abruptly release when the periodic weighting occurs. At this moment，the coal bumps occur more frequently. Numerical results suggest that elastic strain energy explosion of main roof and coal seam during periodic weighting is considered to be an important precursor of coal bump occurrence during the extraction of an island longwall panel. Therefore，it can be revealed that the one of significant reason of occurrence of coal bump is the suddenly elastic strain energy explosion during the periodic weighting of main roof. Based on these analyses，microseismic observation can be chosen to forecast the occurrence of coal bumps. Additionally，technology of forced roof caving and stress relief in coal seam is effective method to prevent the coal bump of island longwall panel.

It is difficult to properly simulate the whole excavation process during slurry shield tunneling and also to exactly explain its corresponding modeling results. Combined with the complex ground condition in Qianjiang tunnel and Shanghai Yangtze tunnel，the paper suggests a more comprehensive numerical simulation method to describe the characteristic of the whole tunneling process，and with respect to the modeling results handling，the mechanical property and its microscopic structure are connected to quantitatively analyze the face failure mechanism and estimate the mechanical behavior step-by-step. The main results show that：the discrete numerical approach can be considered as an effective way to model the excavation problem for the whole slurry shield process；for example，the volume of excavated soil is well proportional to the soil density and the pressure exerted on excavation face，i.e.，when the stiffness of the particle is larger than that of the wall，then soil is excavated under the pressure；contrariwise，the shield stops tunneling. The research results are well applied to the background projects and good results are achieved；and the established particle flow code(PFC) approach for the whole tunneling process also provides a reference for similar projects.

The broken rock masses with poor mechanical and permeability properties in fault f2 at Jinping I hydropower station have an adverse effect on the bearing capacity of foundation；and cement-chemical compound technology was used to reinforce it in the engineering practice. Through the wave velocity，deformation modulus in hole and physico-mechanical test in laboratory，the major indexes such as porosity，compressive and shear strengths have been deeply studied. Furthermore，the scanning electron microscope(SEM) was adopted to analyze the microstructure and the filling situation of rock after grouting. Experimental results show that wave velocity and shear strength of rock mass in fault are increased obviously and meet the requirement of design；microcracks in rock are well filled by chemical material；and the minimum crack is only 0.01 mm. The cement-chemical compound grouting technology can improve the integrity and mechanical properties of the rock mass in fault zone；and it is an effective method to reinforce weak structural plane in rock masses.

Bathe algorithm converts the locating of the phreatic surface to a nonlinear constitutive problem. And the implication of Signorini condition can simulate a seepage face as a head-fixed boundary through iterative calculation. Because an unsaturated seepage problem is also a nonlinear flow problem，the implication of Bathe algorithm and Signorini condition makes it possible to model both saturated and unsaturated seepage problems with a unified method by a minimal modification to an ordinary finite element method，and avoiding solving a variational inequality system. The followings are discussed mainly：(1) the improvements of Bathe algorithm in converge and its generalized form in a three-dimensional model；(2) the implement of the switching algorithm of Signorini condition to solving seepage problems；and (3) the under-relaxation scheme to improve the mass conservation and converge properties when an unsteady unsaturated problem is solved. Finally，some numerical examples are solved to evaluate the applicability of the proposed method；and the results are compared with those available in the literature.

For sake of disclosing dynamic loading distribution on straight-wall arch lining，the time-history curve of free field stress and the radial interface loading on the arch structure in soil are measured through field model test which subjected to blast loads. Through data fitting and normalization method，the envelope diagram of peak loading distribution on cross and longitudinal sections of arch structure are obtained. The results of theoretical and numerical methods are verified and compared with the measured loading distribution law. Results show a good agreement between experimental data and theoretical calculation and finite element computation. The dynamic loading on buried arch structure approximates a triangular distribution. Making use of equivalent principle of load distribution scale，a simplified linear function of local dynamic load is proposed and the loading calculation procedure of buried arch structure anti-blast loading is developed.

The three-dimensional(3D) equivalent viscoelastic boundary element is introduced based on the theory of viscoelastic artificial boundary. The wave input method of wave scattering problems in free field is stated and used in 3D layered half space. The seismic waves can be transformed into equivalent forces adding on the artificial boundary nodes. The equivalent forces are calculated by finite element model with lumped mass and finite difference method. A 3D finite element model of soil-structure interaction system is built in the platform of ABAQUS software. Seismic responses of subway station structure are analyzed including factors that influence it. The open system is turned to a closed-system by adding local artificial boundary. The modal characteristics of the soil and station are obtained by modal analysis. The seismic responses of the subway station structure in horizontal and vertical directions are analyzed under SV and P waves. The corresponding regulations and distribution of internal force are studied to examine the most vulnerable positions. The results show that the SV waves inputted in transverse direction is the worst case to the subway station. The forces of the members suddenly changes in position at where the stiffness of the structure is changed greatly. The P waves have greatly effect on the axial force of the structure.

A full-scale test is carried out to study the ultimate bearing capacity of the shield tunnel reinforced by full-ring steel plate. The failure phenomena are described；and the load-displacement curve is obtained. The key performance point of the reinforced structure is also analyzed. The result shows that：the full-ring steel plate reinforcement can improve the structural strength and stiffness of the tunnel efficiently；the bond failure between the steel plate and the segments leads to the failure of the reinforced structure.

For rock masses under freeze-thaw and loading in engineering structures in cold regions，using rock-like materials produced rock specimens with different geometric characteristics，based on the freeze-thaw experiments  and uniaxial compression test，the influence of crack dip angle and crack length on the rock masses strength were studied；and combining mesoscopic damage theory and macroscopic statistical damage model，the damage model of freeze-thaw and loading rock masses were established；at the same time，damage degradation mechanism of jointed rock masses under the coupling action of freeze-thaw and loading were discussed. The research results show that：(1) The freeze-thaw damage is a process of fatigue damage；and loading damage is an uneven distribution process of stress field and deformation. (2) Freeze-thaw and loading with different mechanisms promote rock crack initiation and propagation；hence induced damages couple with each other，the coupling of the two will make the total damage deterioration. (3) Crack length and freeze-thaw cycles on total damage is larger；the influence of crack dip angle on the total damage is relatively small. (4) under the same cycles of freeze-thaw，damage degradation of cracking rocks is more serious than the intact samples.

The three-dimensional finite element models for two construction procedures were established separately for making comparisons on deformation and internal force characteristics between different construction procedures；then deformation and internal force of steel sheet pile on the two construction procedures were analyzed and compared with the monitoring values. It has been found that deformation and bending moment were greatly reduced on improved construction procedure that could play a strong role in coordination，improving safety and expanding application range of steel sheet pile cofferdam. At the same time，it was also shown that characteristics of deformation and internal force on improved construction procedure were different with conventional construction procedure owing to its outstanding three-dimensional feature；and some dangerous zone ignored regularly should be noticed extremely in design and construction.

Aiming at the defects that the Cam-clay model cannot reflect the mechanics and strength characteristics of the remolded clay，based on the test research，the critical state line is improved. Through the undrained triaxial test，it is found that the critical state line of the remolded unsaturated clay has a shape of hyperbola. Therefore，the improved Cam-clay model is established based on the combination of hyperbolic critical state and the traditional Cam-clay model，and its secondary development is carried out in FLAC3D program. At the same time，Newton-Simpson iterative method is used to improve the relatively complex algorithm for plastic factor in FLAC3D. Finally，three axis numerical simulation tests on soil samples with different compactness are carried out using the improved Cam-clay model. The results show that，the mechanics characteristics of remolded unsaturated soil can be well reflected by the improved Cam-clay model；and the improved algorithm has higher precision and better performance.

The laboratory triaxial tests and numerical tests of Qingdao sea sands with different grain size gradations under different stress paths are carried out by using the GDS stress path triaxial system and particle flow code in two dimensions(PFC2D)，in order to study the mesomechanism of the influence of stress path and grain size gradation on sands mechanical behavior. The macromechanical properties of Qingdao sea sands are obtained by three stress paths triaxial tests；and the deformation mechanism is analyzed preliminarily. Numerical tests are presented as the match and complement of laboratory tests. Some meso-information such as particle coordination number，rotational velocity and particle displacement，which cannot be obtained from laboratory tests，are extracted to explain quantitatively the meso-reasons of the peculiar mechanical behavior of sands with different gradations and stress paths. The numerical tests of different gradations particles under cyclic loads are also presented；and the macromechanical behavior and its mesomechanism are given.

As the present main design method of excavation engineering，the bar-load-spring model，naturally induces several problems which need to be solved. A unified calculation method of the pressure on the supporting structure considering the soil-water interaction is presented，which is more reasonable in the load calculation. Since safety factors system based on the bar-load-spring theory may not be enough to incorporate all the failure modes of foundation pits，new safety factors controlling stability of foundation pits and existing safety factor modified to reflect the size effect should be recommended. Current excavation design method took the influence of safety factor on deformation into account，which was different from the idea of traditional safety factors. Two bar system FEMs such as the bar-load-spring model of circular pits and double stiffness model of soil spring at the passive zone are proposed，which can consider size effect of circular pits and space effect of soil excavation divided into block in strip foundation. Some future research directions on excavation are pointed out.

According to the size and connecting characters of soil particles，soil is discomposed into two components as matrix and reinforcement particles respectively with a certain size demarcation to investigate the influence of the microstructures on soil strength. Based on the strain gradient theory and the notion of coordinated microcracks required for the compatible deformation between the matrix and the reinforcement particles，a multi-scale “matrix-reinforcement particle” model is established to study the size effect of soil strength which indicates that the soil strength is related to the intrinsic length scale，the strain gradient，the properties of the matrix as well as the size and gradation of the reinforcement particles. A series of consolidated and undrained triaxial compression tests on unsaturated remoulded soil were designed to study the size effect of soil strength and to determine the intrinsic length scale quantitatively. The results show that：the yield stress of soil increases with the decrease in the reinforcement particle size and has a linear relation on the reinforcement particle content；moreover，the relationship between the yield stress and the intrinsic length scale could be presented as parabolic function；the intrinsic length scale increases with the increase in the matrix liquidity index，the particle size and particle content of the reinforcement particles；and the relationship between the intrinsic length scale and the reinforcement particle content can be presented as parabolic function. The experimental data can be well fitted to the “matrix-reinforcement particle” model. The research results are significant to the development of strength theory of soil.

The piping channel expansion in double-layer dike foundation is determined by the characteristics of particles in sand layer，water flow in the channel and the seepage force in the surface of the channel. By analyzing the mechanical balance of the particles in the surface of the channel and introducing some formulae of river dynamics as well as considering the relative exposure degree of the particles，fluctuating velocity，criteria of the particles? incipient motion and flow characteristics，the critical condition of piping channel expansion is proposed. Two sand box model experiments were done to study the combination impacts of the flow and seepage force on channel expansion. And the one-dimensional seepage experiment has proved that the hydraulic gradient near the overflow surface is much less than average gradient. It shows the rationality of the effective ratio between the actual and calculated seepage forces. Based on the experiments，a finite element method which is controlled by the critical condition of the stability of channel?s surface is built. It was used to simulate the expansion of piping channel. By comparing the calculated results and the experimental results，it is shown the proposed methods are reasonable.