Firstly，a brief information of domestic and abroad undersea tunnels as well as their designing，construction and special features of research work is presented. The comprehensive exploration techniques of engineering and hydrogeology of the seabed rock and the determination factors on minimum buried depth of the undersea tunnels are discussed. The problems are analyzed and addressed，which include exploration and treatment of the ground-water under tunneling，prediction and warning alarm against the collapse danger of the surrounding rock of undersea tunnels，and its stability evaluation，adjustment and correction on preliminary design parameters of tunnel lining during construction etc.. Secondly，some opinions on the technical problems of material selection for undersea tunnel lining(marine engineering concrete) with high quality and durable anti-corrosive property，disaster prevention and emergency aid for long and large undersea tunnels in highway and city expressway are presented. Some key issues related with excavation by a super-large shield machine and the design and construction of immersed tunnel in deep seawater and torrent conditions are also listed. Issues mentioned above may have a consulting value to design and construction of several undersea tunnels which are just under or awaiting for construction in China.

The fundamental principle of strength reduction is adopted in RFPA(rock failure process analysis) code；and a RFPA based numerical code RFPA-SRM (strength reduction method) is developed for rock and soil engineerings. In this code，the finite element method is employed to obtain the stress fields. RFPA-SRM not only satisfies the global equilibrium，strain consistent and nonlinear constitutive relationship of rock and soil materials，but also can consider the heterogeneous characteristics of materials at mesoscopic level. The advantages of RFPA method in failure process analysis to reproduce the damage-induced failure process due to the strength degradation of rock and soil structures is an important feature in RFPA-SRM code. Practical applicability of the proposed technique to complicated cases is demonstrated. The failure criterion of slope failure is employed by assuming that the counts of failed elements with reduction steps reach to maximum values. As the proposed method is used to conduct the stability analysis of slope，the failure surface of slope as well as the safety factor can be achieved directly without any assumption on the failure surface. RFPA-SRM provides a powerfully alternative and effective approach for the stability analysis of slope. Especially the fracture process obtained with RFPA-SRM is significantly meaningful for the investigation of failure mechanism of slope，which is beneficial to fundamentally guide the in-situ design of slope. Finally，the stability analysis is conduced on a divaricately multi-arch tunnel. The safety factors and failure surface of the tunnel are numerically obtained，which show that RFPA-SRM is suitable for stability analysis of rock and soil structures.

Mesomechanics analysis is adopted to analyze the effects of pore water pressure，which has close relation not only with the volumetric deformation of concrete，but also with the developing velocity of cracks，on the mechanical properties of wet concrete. In terms of the growth characteristics of cracks in the wet concrete and fracture mechanics，the wing crack model is employed to investigate the compressive strength and the stress-strain relation of wet concrete. The studies of constitutive equation and damage value of wet concrete are based on the energy equilibrium theory. The results of this investigation show that the wing crack model is suitable for describing the volumetric deformation and compressive strength of wet concrete. The free water in the cracks decreases the friction force，which baffles the development of cracks and accelerates the damage of wet concrete，decreasing the compressive strength of wet concrete compared with the dry sample. The critical compressive strain of wet concrete is smaller；but the lateral deformation of wet concrete is larger than that of dry concrete under the same stress level.

The complicated evolvement of stress load，which is produced by excavating underground engineering under high stress conditions，is simulated through true triaxial experiment. Under the given loading method，the experimental results about new granite in Laxiwa show that the resilient deformation is found and acoustic emission counts rate is evidently enhanced when the minor principal stress is unloaded. The enhancing extent of acoustic emission counts rate increases with the intermediate principal stress. The constitutive relation is elasto-brittle. The peak value of strength increases with the intermediate principal stress；and the ratio of increasing value of limit strength and the intermediate principal stress decrease with the intermediate principal stress. The peak value of acoustic emission counts rate depends on stress state；and the amount of peak value is equal to that of major crack after failure. Finally，the failure mechanism is discussed.

In traditional landslide stability analysis，the shape and position of slip surface depend on drilling investigation and engineering experience to some extent. Especially，the complicated landslides are found with potential multi-shear outlets and multi-slip surfaces；and mistakes and leaks are usually encountered when estimating the slip surface，thus the results will lead to the failure of landslide treatment. The strength reduction FEM is an effective method to study landslides slip surface for it can automatically find out the accurate critical slip surfaces and corresponding safety factors；and the numerical non-convergence occurs simultaneously through the parameters reduction of soils of landslides. Moreover，it can still find out the glide order of each slip surface. By restraining shear outlets successively，a landslide is studied to find out all slip surfaces and shear outlets accurately in which safety factors are lower than the ones calculated by strength reduction FEM. The proposed method overcomes the deficiencies of traditional methods in determining complicated landslide slip surfaces；and it can provide basis for the projects of landslide treatment.

The aseismic design of the reservoir faced wholly with asphalt concrete under construction is addressed，which is the largest one in Japan for this type of reservoir. Due to the complex geomorphologic features and geological structures of the site as well as the complicated construction processes of embankments，general response characteristics of the entire reservoir were firstly investigated by 3D dynamic analyses，and then the maximum strains of the asphalt concrete facing for typical cross-sections of the reservoir with potentially great deformation were determined by detailed 2D dynamic analyses. The results show as follows：(1) both acceleration and strain are with a similar distribution character independent on the direction of the seismic excitation，concentrating in the high banking areas of the main dam，the left-side bank，and from the subsidiary dam to the right-side bank；(2) maximum values of acceleration and strain occur in the main dam although they slightly vary with the excitation direction of the seismic motion；(3) a 2D analytical result is slightly greater than that of a 3D analytical result；and (4) maximum strains of the facing for Levels 1 and 2 seismic waves considering the regional factors of this reservoir site are 0.019% and 0.030%，respectively. At the same time，a series of material tests of asphalt concrete mixtures，including mix design and mechanical behavior，are carried out to obtain an appropriate mix proportion. According to the results of numerical analyses and material tests，the seismic safety of the facing was evaluated by using the proposed limit state design method based on the concept of two-level seismic motions and the characteristics of facing structure. The evaluating result indicated that the facing satisfies the safety criterion during Levels 1 and 2 seismic motions at the reservoir site.

Based on the typical high gassy mine，taking Sunjiawan Mine in Fuxin for example，the experiment of desorption and seepage of coalbed methane(CBM) was performed continuously through first loading and last unloading after the sample was placed into the home-made triaxial osmoscope. The exploration and transportation processes of CBM were simulated under the condition of the complicated stresses. The relationships among effective stress，desorption character，and seepage character were presented. The relationship expressions were studied. Some novel interaction laws were obtained as follows：(1) the variation laws among desorption quality，desorption time and effective stress all have negative exponential decrement relationship，and the relationship is not correlated with the loading method. (2) a cut-off point in the effective stress exists，and the desorption quality and time will increase rapidly with the increase of effective stress when it is smaller than the cut-off point value. On the contrary，the increase extent will become smaller. For the Sun sample No.2，the cut-off point value is about 3.0 MPa. (3) a critical effective stress(such as critical desorption pressure) is found. The desorption quantity and time will be approached to zero when the effective stress is larger than the critical value. The critical value is about 10.0 MPa for Sun sample No.2. (4) in the loading processes，the relationship curves among effective stress，permeability and permeability coefficient show positive exponential decrement. This above indicates that the adsorption of CBM is the main control factor for the scope of smaller effective stress in the process of pore pressure increase. (5) in the unloading process，the relationship curves among effective stress，permeability and permeability coefficient are found with parabolic shapes. This demonstrates the existence of three main phases in the exploration of CBM in the experimental view：they are effective stress，matrix shrinkage and slippage effects.

As for the Wuyi Hydraulic Project on the Dina River in Xinjiang Uygur Autonomous Region of China，the study shows that an arch dam will have a larger economical advantage over an earth dam for the spillway；and drain holes can be emerged into the dam body. No more separate constructions such as floodway，which is a necessary part for earth dams，are required. However，another key issue appears in the determination of the possibility for building an arch dam on sandy gravel：the deformation of the dam in both vertical and horizontal directions；and the corresponding stress distribution in the some situations can exert a great threat to the arch dam safety. The stress-displacement relation of sandy gravel has the two features as follows：(1) the irrecoverable deformation cannot be ignored even in lower stress status；and (2) the tangent deformation modulus is varied under the different stress conditions. Some in-situ tests have been carried out in the adits at different elevations of the dam site；and a nonlinear constitutive model is derived analyzing the effect of stress on rock deformation moduli. This model is capable of simulating the stress-deformation relation；and it can be applied to the assistant in the project layout and design by considering the stress and deformation in the dam body. As an example，this nonlinear model is compared with the linear-elastic model in low stress status，which is corresponding to low mountains at both ends of the dam. It is found out that，by using the nonlinear model，the deformations reduce both in vertical direction and along river direction. However，little change is found in the stress along the dam axial direction. In this case，certain measures can be taken to improve the problem：enlarging the dam bottom locally，mounting concrete piers at both sides of the downstream dam abutment，and setting up artificial short joints and so on.

A circular increment step load and unload method with many advantages is employed；and a set of creep experiments are performed to study the viscoelasto-plastic characteristics of soft and intricate ore-rock in Jinchuan Mine III. The experimental data were analyzed according to the retrievable instantaneous elastic strain and lagged viscoplastic strain，and the post-retrievable instantaneous plastic strain and viscoplastic strain，and the essential rules of viscoelasto-plastic characteristic of the soft and intricate ore-rock are obtained. Based on scientific analysis and comparative study，Burgers creep model was combined with Mohr-Coulomb criterion；and a new viscoelasto-plastic model was formed to study the characteristics of soft rock creep under intricate conditions. Some programs about Burgers model were developed to deal with the experimental data. The creep characteristic curves were obtained；and the model parameters and the values were achieved through weighted means. The test results show that the creep testing curves of the ore-rock of Jinchuan Mine III are coincident well with the theoretic curves；and the modified Burgers creep model can be applied to characterize the creep of Jinchuan ore-rock.

According to the theories of fracture mechanics and damage mechanics，the constitutive model and fracture damage mechanism of brittle discontinuous jointed rockmass are systematically studied under the state of complex stresses. Firstly，with the equivalent strain energy，the constitutive relation of anchored brittle discontinuous jointed rockmass is derived under compression-shear stresses. The constitutive relation under tension-shear is also developed according to the theory of self-consistence. Secondly，the damage evolution equations of discontinuous multi-crack rockmass under compression-shear and tension-shear are put forward according to the wing crack-initiating criterion. Finally，based on the above constitutive models and the damage evolution equations，the three-dimensional finite element procedures have been developed to model the ground movements that occur when underground power-houses of Langyashan Pumped-storage Power Station are installed in discontinuous jointed rockmass. The anchor supporting is an important component of this underground powerhouses excavation works. Besides the displacement fields and the secondary state of stresses induced by excavation disturbance，the effects of anchorage and the damage evolution around the power-houses have been particularly described during the processes of installation. The obtained numerical results are compared with the in-situ monitoring ones in order to verify the validity of the proposed models and equations. Some useful conclusions are drawn and they have great significances to the project.

As a new numerical method，explicit Lagrangian finite difference method(FDM) is accepted abroad and applied widely in geotechnical and hydraulic engineering in recent years. However，code implementation and careful investigation on the method are rarely reported. Despite the fast development of computer hardware，it is still a great challenge for regular serial numerical analytical technology to perform either highly simulated numerical analysis or real-time fast back analysis on super-scale geotechnical and hydraulic engineering. Hence，the research on parallel algorithm based on network information transfer is received great attention. Up to now，studies on parallel finite element method or parallel boundary element method have gained great success，but on parallel explicit Lagrangian FDM，there are still many things to do. Thus the method is investigated and serial code is developed. The method¢s parallel ability，data assignment，communication mode and calculation order are examined. Parallel explicit Lagrangian FDM is designed in domain decomposition method，master-slave mode and non-block communication. The parallel code is also implemented in C language and MPI(message passing interface) on parallel cluster. Two numerical examples，i.e. circular tunnel and strip footing，are presented to demonstrate that the serial and parallel methods are implemented correctly. More tests with parallel code are undertaken on DeepSuper–21C supercomputer and parallel efficiency above 0.8 can be obtained under condition that number of elements is 912 000 and the number of computing nodes is 32，which shows that the parallel method has good scalability. Research on the serial and parallel explicit Lagrangian FDM can be used in large-scale numerical simulation in geotechnical and hydraulic engineering practices.

The three-dimensional finite element analysis of anisotropic brittle dynamic damage mechanism for gravity dam and rock foundation subjected to the blast-impact load has been carried out. The concepts of effective stress and damage strain energy release rate have been taken into account to develop the dynamic damage evolution model，which is employed to develop the three-dimensional anisotropic dynamic damage finite element program. The processes of dynamic response including the fields of displacements，stresses，damage state，strain energy release rates as well as failure situation in the dam under the blast-impact load have been simulated and presented by three-dimensional counter graphics and animations. The analytical results can provide a useful method to improve the further studies.

Usually，there are densely distributed small instable rocks in a low-angled stratofabric rock slope. Topographical condition，lithologic characteristics and rock mass structure of the slope control small instable rocks¢ stability，and the influencing factors include strong rainfall，earthquake，and human¢s cutting works，etc.. The failure models for a small instable rock distributed on a low-angled stratofabric rock slope are suggested with tilting-collapsing，splitting-collapsing and sliding-collapsing. If the slope¢s rockmass is low counter-inclined or thick-interbedded with soft interlayer，its failure model is inclined to be tilting-collapsing；if the slope¢s rockmass is homogeneous and thin-bedded with hard discontinuity，its failure model is inclined to be splitting-collapsing；if the slope¢s rockmass is low sequence-inclined with densely deep tectonic joints and weathering fissures，its failure model is inclined to be sliding-collapsing. Then，the stability evaluation methods for these failure models are deduced respectively. By taking a steep slope behind the reparation workshop for example，the stability evaluation methods for small instable rocks distributed on low-angled stratofabric rock slope are systematically discussed. The research result shows，it is indispensable to investigate rockmass structure and analyze slope¢s failure model in small instable rocks¢ stability evaluation.

First，the main factors for the classification of rock quality are selected by carefully analyzing all the influencing factors of rock quality in underground structures. Then，on the basic of analyzing the relationship of the influencing factors and fuzzification of rock quality，the model of two-stage fuzzy synthetic judgment is established to classify the rock quality by using fuzzy mathematics theory. After solving the problems of determining degrees of membership，basic weight value，and erecting their algorithm，a method of two-stage fuzzy synthetic judgment is developed. Finally，by using the idea of changing weight value，the theory and method of two-stage fuzzy synthetic judgment with changing weight value on the classification for rock quality is brought out，which can reduce the influence of subjectivity of judgment on the classification of rock quality and make it more reasonable. Compared with other classification methods，it shows that the proposed classification method is both practicable and reasonable.

The influences of nonlinear characteristics of concrete and soil on bending moment of foundation beam are investigated by the finite element method(FEM). Four kinds of different calculation modes are considered，in which soil and concrete are taken as linear or nonlinear materials. It is concluded that the bending moment considering the nonlinear characteristics of concrete and soil is smaller than that of assuming concrete and soil as linear materials. Nonlinear characteristics of concrete and soil should be considered in order to obtain a more accurate bending moment；and it is，for the minimal demand，to consider the nonlinear characteristic of soil for the rigid beam and the nonlinear characteristics of concrete for the flexible beam，if it is very difficulty to consider nonlinear characteristics of concrete and soil at some time. The influence of reinforcement ratio on bending moment under design load is not obvious. Besides，a formula of the discount coefficient of the bending moments is presented，which is defined as the ratio of the bending moment considering the nonlinear characteristic of concrete to bending moment from the Guo¢s Tables. Using the discount coefficient，bending moment considering the nonlinear characteristic of concrete is easily obtained by the bending moment from the Guo¢s Tables.

The complete stress-strain curve of rock could be divided into pre-failure and post-failure regions according to the peak stress. The post-failure mechanical characteristics of rock are important to many rock engineering cases，such as underground excavation，pillar，rock burst and so on. Therefore，the research on the post-failure characteristics of rock is of great significance to both theory and practice. In general，the post-failure region of rock shows instability in the mechanical response，which is difficult to be described by the strength softening model；and it should be described by the brittle-plastic model. Taking the axial strain rate as a constant，a series of triaxial conventional compress failure tests of Ya¢an marbles were performed by RMT–150B rock mechanics test system；and the complete stress-strain curves of rock specimens under different confining pressurees were obtained. Utilizing the stress-strain curves，the relation functions between brittle stress drop and confining pressure of marble are obtained. The achieved results can provide references，when using brittle-plastic model，to the numerical analysis of marble and its structures as well.

During the construction of double-arched tunnel，the role of center pillar is of great importance. As a key load-bearing component in double-arched tunnel support，it will influence the stability and construction cost as well as long-term safety of double-arched tunnel. Therefore，the assumption of loads acting on center pillar is of an important consideration in structure design. Through the analysis of the loads acting on center pillar during double-arched tunnel construction procedure，the mechanical model for calculation of practical loads acting on center pillar is set up. By using FLAC，twenty-one kinds of cases for double-arched tunnel in surrounding rock masses with Classes II–IV are studied. The covering depths from 0.5D to 2.0D as well as the three construction methods consisting of three-drift and center-drift coupled with bench cut and full-face methods are considered. Based on analysis of the loaded characteristics of center pillar and magnitude changes of actual loads，the two estimation formulae of loads acting on the center pillar in place of the assumption of the total overburden load for design of center pillar structure are proposed. Furthermore，the optimum construction methods corresponding to the different classes of rock masses are recommended. The achieved results are successfully applied to the modification design of double-arched tunnels of Jinhua—Lishui—Wenzhou Expressway in East China. The results demonstrate that the assumption of proposed loads acting on center pillar is reasonable，and the optimum construction methods can save construction cost and shorten construction period of double-arched tunnel.

The seismic responses of site will be influenced to certain extension when seasonal frozen soil and permafrost exist. According to one-dimensional fluctuation theory，the seismic responses field of Classes I and II in permafrost and seasonal frozen soils are calculated under multifarious earthquakes by using equivalent linearization program of plane-stratum earthquake response. The influences of seismic responses in field are analyzed due to the thickness change of frozen soil layer. It indicates that in seasonal frozen regions，the peak value of ground surface acceleration decreases when seasonal frozen soil exists；and its acceleration peak value decreases with decrease of temperature of frozen soil and with increase of thickness of frozen soil. The influences of frozen soil/site of Class I are greater than that of Class II. The calculated results also show that in permafrost，the deeper of frozen soil layer is，the more decrescent of the site ground acceleration peak value for site of Class II is. However，the rule is not suitable for site of Class I. When the overlay of permafrost is thawy soil，the acceleration peak value is greater than that when the overlay permafrost changes into frozen soil.

In the last researches，it is usually considered that rock revetment and cracked rock embankments have the thermal diode effects，which can protect the frozen soil beneath the embankments from thawing in high temperature regions. But this is not the case completely，the effect of the larger diurnal-nocturnal air temperature difference，and the strong wind in Qinghai—Tibet Plateau will weaken or vanish the thermal diode effects，which are mainly caused by the forced convection in slope. To study the heat transfer mechanism and the cooling effects on the permafrost of the ripraped embankment under different boundary conditions，four kinds of embankments are studied with numerical simulation as follows：(1) normal embankment，consisting of sandy soil without crushed rock layer；(2) open rock revetment；(3) insulation slope being covered with insulation material；and (4) enclosed embankment. It is concluded that the traditional rock revetment can not take the advantages of the thermal diode effects to the full extension，and it is not satisfactory in maintaining the permafrost. This kind of temperature field effect caused by forced convection through numerical method is proposed；and a new type rock revetment is put forward，which can also be called sunshade-blocking-wind rock revetment. Through the numerical simulation，it is found that the new kind of crushed embankment has a better cooling effect；at the same time，the sand blocking problem and the temperature difference of the south and north slopes caused by solar radiation are properly solved.

A large-scale shield experimental platform and a shield model with diameter of 1.8m are considered to simulate the earth pressure around shield machine. Excavation experiments of shield model are conducted in clay，sand and gravel soils. Two different open ratios of 30% and 70% of cutter head，respectively，are applied to the model experiment. The working parameters including thrust force，torque of cutter head and earth pressure of soil cabin are collected during the processes of excavation. Special attentions are focused on the change of earth pressure and effects of open ratio on cutter head with different earth pressures inside and outside of soil cabin. A finite difference model is constructed for the numerical analysis of excavation process，in which the effect of open ratio of cutter head is considered carefully. This numerical model gives the dynamic change of earth pressure in the soil around the shield model；and the calculated values are compared with those monitored in the model experiment.

By analyzing the mechanical characteristics of prestressed bearing of the slope body，the stability of prestressed anchored slope should be calculated according to coupling and decoupling between slope body and anchors，respectively. The characteristics and the composing of the anchoring forces in decoupling moment are studied. The long-term observations are developed on a practical slope engineering reinforced by prestressed-cable frame；and the tension forces in the cables and earth pressure along the beam bottoms are synchronistically measured，which are founded in existence of the decoupling between slope body and anchors. The practical slope engineering lies in the Yuanjiang—Mohei Expressway of Yunnan Province，China. In fact，the value of the anchoring force in decoupling moment has a close harmonic connection with the displacement of the unstable mass along the underlying weaker plane. The conclusion can be drawn from the theoretical analysis and the long-term observations that the anchoring force in decoupling moment is made up of the residual prestressed force and the shearing resistance between soil and grouting. On the assumption that the slope body is homogeneous and that the prestressing anchored slope is a plane strain system considering the groundwater，secondary forces and the bending of the anchor cables，the calculation method of the slope stability in decoupling moment is then advanced on the basis of the displacements of the soil along the potential sliding surface. The proposed calculation method can consider the actually working conditions of the anchor cables and the slope body，so it has the advantages against existing methods；and the result achieved from the new method is more reasonable. A case study proves the feasibility of the new method.

Deformation is an important index for the structure of geotechnical engineering；and the deformation monitoring is a key issue for the design and construction of geotechnical engineering. Technical staffs are interested in how to use the monitoring data to guide construction. Up to now，various approximate methods have been used for deformation predications. According to the method of time series analysis，a new method—particle swarm optimization(PSO) was presented and applied to the deformation predication of slope. It takes the deformation of slope as a time series variable and combines the time series analysis with PSO. The proposed method，having good characteristics of global optimization and better performance in practical engineering，can identify the structure and the relative parameters of predicted model. The method was successfully applied to predict the deformation of high slope of the permanent shiplock in the Three Gorges Project；and the achieved results show considerable satisfactoriness in the engineering application. The proposed method is quick and precise；and it can provide a good approach to the information construction and management in geotechnical engineering.

With the traffic increase，old road widening is found to be an important issue in the road construction. In order to reduce the different settlement and improve the stability of the embankment，the geosynthetics have been successfully adopted in the joint between the old and new embankments. Based on the features of the geosynthetics- reinforced old road widening，the old and new embankments and the pavement are regarded as a whole structure；and the numerical model is performed on the basis of the assumption. Adopting the FLAC，the mechanism of geosynthetics-reinforced old road widening is discussed mainly from three factors as follows：(1) the displacements of embankment；(2) the stress distributions on the crest of embankment；and (3) the tensions developed in geosynthetics. In addition，the different effects under the different layer numbers of geosynthetics and heights of embankments are studied. The results show that using geosynthetics in the reinforcement of embankment is effective not only in reducing the differential settlements and horizontal displacements on the crest of the embankments，but also in uniform stress distribution that is reflected from embankment to the pavement.

The highly contained silts are found in the entrance of weak-tide terrestrial facies of the Yellow River，and eighty percent sediments are rapidly deposited at Yellow River Estuary. The consolidation process of such sediments is not clear at present. A series of experiments have been conducted on the tide flat of Diaokou delta-lobe that lies in the north of Yellow River Delta，which can provide a more realistic simulation than the laboratory methods. In order to reveal the consolidation process of rapidly deposited silts，the fluid sediments imitating the rapidly deposited seabed silts at the Yellow River Estuary have been made in field；and the fluid sediments are promptly filled into a one-meter deep testing pit excavated at the tide flat. By field testing methods，such as static cone penetration test，field vane shear test and pore water piezometer test，the variation strength and dissipation of pore water pressure of rapidly deposited seabed silts have been measured at real time. It is shown from the experimental data that the consolidation speed of the rapidly deposited seabed silts measured by water piezometer at Yellow River Estuary in field is much quicker than the speed calculated through the Terzaghi¢s one-dimensional consolidation theory. It is also shown that，after consolidation compression is completed，the strengths of such silts still increase gradually along with the development of time，showing an ununiformity increase along the depth. Thus the rapidly deposited silts have taken on a quasi-overconsolidated state，which is similar to undisturbed soils of Yellow River Estuary. The analyses show that the formation of such quasi- overconsolidated state is attributable to the influence of the cementation effect and sedimentary environment.

By the microtremors array observation and velocity structure inversion in the field of an engineering project，the accuracy of microtremors array methods(MAM) for exploring the detailed shallow velocity structure is studied with observation system，dispersion curve extraction and inversion methods. The shallow S-wave velocity structure is inversed by the hybrid method of genetic algorithm(GA) and simplex algorithm(SA) from the surface wave dispersion curve，which is inferred by the spatial auto-correlation method(SAC) from microtremors array records. The studies show that the relative average error of each layer is about 20% compared with that detected by borehole method. The average velocity obtained by SAC method and frequency wave-number method(F-K) is almost the same. However，F-K method only gives an average velocity for the upper 20-meter layer. The accuracy is compared with that of spectral analysis of surface wave(SASW) method. In the fields of geotechnical engineering and earthquake engineering，the direct goal of velocity structure exploration is site dynamic characterization. From the viewpoint of site seismic responses，the accuracy of MAM is further validated by 1D equivalent linearized analysis. The analytical results show that the difference between the response spectra from inversed velocity structure and that measured in borehole is really acceptable，whereas that for the simplified single layer model with the average velocity is quite large. The study suggests that it is not a good idea in seismic design to characterize site condition only by the average velocity；and the MAM has the potential to be an effective method for the shallow velocity structure exploration.

Material transportation in water fluid mainly depends on two main movements, which are rolling transportation and suspending transportation. The transportation and deposit regulation are different in the two different transportation modes. Since the two kinds of sediments produced by the two kinds of transportation movements may have different fractal characteristics；sedimentary rock and soil display the mixtures of the two kinds of sediments with different fractal characteristics. The traditional fractal model does not consider the larger error that may be produced when the traditional fractal model is employed in describing the size distribution of sedimentary rock and soil. On the assumption that common sedimentary rock and soil are mixtures of the two kinds of sediments with different fractal characteristics，an improved fractal model of size distribution is conducted；and the physical meaning of parameters of the model is validated too. Compared with traditional fractal model，the fractal dimension of suspend transportation deposit of the improved model varies greatly with different kinds of sedimentary rocks and soils. Finally，the improved model is adopted to analyze the differential slaking properties of red beds soft rock in Hunan Province.

The conventional basic function can not completely simulate the deformation pattern of bolted rock，which is complex and highly nonlinear. Subdivision of the mesh can solve the problem，but it makes the preprocess more difficult. Using hierarchical technique，hierarchical composite element method(CEM) is adopted for the rock mass reinforced by bolt. The basic idea is to extend the tolerant function by adding virtual nodes，to improve the numerical precision by using hierarchical basic function，and to analyze the composite elements under the generalized nodes. With basic function upgrading，the hierarchical composite element method can better simulate the complex characters of bolted rock in physical hypostasis，which makes calculation results be closer to the true ones with coarse mesh. The analytic process of hierarchical composite element method is explained；and the way to realize this method in bolted rock is introduced. The comparison of the calculation results with finite element method(FEM) and conventional CEM shows the robustness of the proposed method. It is proven that upgrading composite element method can improve the calculation results evidently with fewer meshes.

Hard roof fall will have great adverse impacts on mining engineering；and it will affect the safety of mining. Generally，the value of distortion or bedding separation of roof may be used as the indicator of roof fall，but it is very difficult to give a definite separation value to forecast roof fall because the separation threshold of roof fall changes with the lithology of roof. A new method using the curve peak segment pattern of separation velocity in roof is presented to forecast the roof fall below separation. A new computer-controlled remote monitoring roof separation and a forecasting roof fall system have been invented. It is shown by the hard roof fall forecast practices in Muchengjian Mine in China that the system is accurate and reliable；and it can forecast roof fall ahead 15–29 hours. The system can provide references to the roof fall predication in various underground engineerings.

It is well known that the bearing capacity of a driven pile changes with time after installation. There are many researches focused on the phenomenon of time-dependent bearing capacity related to pile driving. However，very few data have been published on methods of predicting the variation of load-settlement curves with time after driving. A brief review is presented for the current state of knowledge of time effect on driven piles. Based on the load-transfer methods，a new method is proposed to estimate the load-settlement behavior of a single pile after being driven. Two dimensionless time factors are added to the traditional load-transfer functions in order to describe the increase in both shaft friction and base resistance with time respectively. The modified load-transfer functions can consider load-settlement behavior at an actual time after pile installation. For verification，the proposed approach is used to calculate the load-settlement behavior after pile installation in a case study. Good agreement is found between calculated and measured load-settlement curves of static load tests.

By using a set of self-designed experimental device，a series of experiments on rock cutting by abrasive waterjet under deep water are conducted. To study the main factors influencing the depth of rock cutting，a series of simulation experiments about variations of target distance，cutting times，jet horizontally moving velocity and the different depths of water have been performed to understand the rules of the depths of rock cutting，the main cutting parameters，and the effects of depths of water. The rock cutting techniques under deep water of practical application should consider the relations between cutting times，jet horizontally moving velocity and efficiency. The reasonable target distance of the materials such as rock and so on is one of key issues；and it has the practical significance only if the effective target distance is controlled.

By using a set of self-designed experimental device，a series of experiments on rock cutting by abrasive waterjet under deep water are conducted. To study the main factors influencing the depth of rock cutting，a series of simulation experiments about variations of target distance，cutting times，jet horizontally moving velocity and the different depths of water have been performed to understand the rules of the depths of rock cutting，the main cutting parameters，and the effects of depths of water. The rock cutting techniques under deep water of practical application should consider the relations between cutting times，jet horizontally moving velocity and efficiency. The reasonable target distance of the materials such as rock and so on is one of key issues；and it has the practical significance only if the effective target distance is controlled.

The physical parameters of viscoelastic media from their dynamic responses in time domain are inversed，which include more information than the quasi-static movement or response in frequency domain. Moreover，the movement in time domain is easy to measure；and the inversed results are reasonable and practicable. According to principle that the computed and measured dynamic responses should be fitted，the parametric inversion problem in viscoelastic media is deduced to solve a problem of nonlinear zero-equation by the homotopy method with wide convergence. It is a newly developed powerful device for solving nonlinear problem. This method is used to inverse material parameters of 3D halfspace viscoelastic media. Numerical results show that the homotopy method is nearly independent of the original value；and the method has high accuracy and validity for the dynamical identification problems of viscoelastic parameters.

The double-arched highway tunnel was constructed with unsymmetrical pressure，complex geological condition of shallow depth zone in Hunan Province. In order to guarantee the safety of tunnel construction，in-situ monitoring was carried out at the section of tunnel. Based on the field measurements，the deformation of surrounding rocks was analyzed，and the process of construction was simulated by finite element method(FEM). According to the comparisons of numerical results with field measurements，the proposed numerical procedure was found to be an effective approach for predicting the deformation of surrounding rocks；and the achieved results can provide important guidance to tunnel construction. The example shows that the finite element simulation analysis is useful to the construction of unsymmetrical pressure double-arched highway tunnel.