Under the conditions of according with strain nonlinear softening constitutive model of having inflexion point after peak stress of practical rock and considering rock deformation influence due to intermediate principal stress ，stress distribution laws of surrounding rock plastic zone of circular cavern under the condition of uniform pressure，the mechanism of load bearing and acting relation between surrounding rock and support are studied. Some important conceptions of working status of practical cavern surrounding rock are obtained；such superior certain limit sup{pos} of self-support geo-stress and inferior certain limit inf{pa} of supportless cavern surrounding rock. The expressions of sup{pos}, inf{pa} and the relation formula between sup{pos}and geo-stress ，between inf{pa}and geo-stress p0 are given. The research results of plastic zone stress，plastic zone radius，surrounding rock pressure，and surrounding rock displacement are more nearly actual correspondence values of cavern surrounding rock with Fenner solution based on ideal elastoplastic materials.

On the basis of the cyclic shear apparatus for soil-structure interface in Tsinghua University, a laminar-ring simple shear apparatus for the study of the mechanical behavior of interface between granular materials is developed. A series of experiments are conducted with the embankment materials used in Nuozhadu high earth core dam. It is confirmed that the shear strength envelope of the interface is the lower shear strength envelope of the two granular materials. When the failure strength is reached, concentrated rigid plastic shear deformation takes place in an area near the interface with the lowest strength. The rigid-plastic model can be used to simulate the deformation behavior of the interface between two granular materials.

The Eshelby equivalent inclusion method is a effective method to establish the constitutive models for seeping damage rock. There are a few paper discussed using Eshelby equivalent inclusion method to establish the constitutive models until now..Using Eshelby equivalent inclusion method, a Helmholtz free energy for seeping damage rock is set up in this paper. A constitutive model for seeping damage rock is resulted from the Helmholtz free energy function with the theory of continuum damage mechanics. A failure rule for seeping damage rock is brought up. Then a statistical seepage model for rock is proposed. The presented models are verified as reasonable and practical by compared with the experiment data.

In order to research into initial latent causes of roof damage for some Grotto No.4, the viscoelastic thin plate theory is used for setting up analytical solution of viscoelastic deformation and stress for the generalized Kelvin model, based on the laws of deformation and damage and structural boundary conditions for Grotto No.4 .To obtain the stress field and the displacement field of whole region at any time, a searching method of analytical total area point by point is presented, in which total region is divided into many small zones and each zone stress and each gridpoint displacement are calculated by given analytic formulas. By calculation and analysis，the displacement field and varied deformation and tensile damage region with time are given for the grotto top plate, where two dividing lines of possible tensile damage region are almost identical with in-situ measurement. This shows the boundaries of initial tensile region are unstable source of later real damage. The conclusion is useful to protecting and maintaining the grottoes. The case analysis has shown that presented model and analytical method are correct and rational. The method and conclusion can be in common use.

A numerical analysis for the cracks in the parapet in a water gate in a water conservancy project is carried out with the unique crack elements simulating the cracks and the special bolts crossing crack element imitating the reinforcement bars across the cracks. Results of the numerical analysis show that the deformation of the cracks under the external loads can be unstable if the cracks are not treated. The treatment parameters of grouting are also given by the simulation analysis.

This paper assumes that the volume of the subsurface settlement troughs due to tunneling is equal to the ground loss and the shape of the troughs can still be represented by a Gaussian distribution . It is firstly presented by this paper that researchers can study the width parameters of the settlement troughs with different depths through analyzing the settlements above the center line of the tunnel, and then a regression equation used to calculate the width parameters of the settlement troughs with different depths can be derived; as a result, the settlement of every point above the tunnel due to tunneling can be attained. The applicability of this method has been demonstrated by the calculation of actual projects.

The three aspects with respect to micro-properties of the completely decomposed granite (CDG) as the distribution of pore radius, particle diameters and mineral content play a major role in determining the engineering geological features of the CDG. In theoretical study and engineering practice the following parameters are used to describe the characteristics in the three aspects: large, middle and small, micro-pores, gravel, sand, silt and clay particles, three major mineral components (quartz, feldspar and clay minerals), etc. How large of the variation range of these indices in one certain size of trial pits and blocks? How about the correlation of the indices in the three parts? As factors of soil structure, how large of their weight ratios once the soil structure is to be under considerations? In this paper, a total of 51 nos. specimens from 18 nos. blocks from three trial pits of two slopes in Kowloon, Hong Kong, were taken as examples. The test is carried out by means of the mercury injection, particle size distribution and X-ray diffraction. After preliminary analysis, it is found that the CDG with coarse particle portions is very different from that with fine particle portions. The former belongs to gravel soil and sandy gravel soil, and some of it is gravel-bearing soil, with more big pores, more quartz and clay minerals. The latter belongs to gravel-bearing soil, some is fine sandy soil and sub-sandy soil, with more micropores, more feldspars. Variations of feldspar and clay mineral contents are inverse to each other. Furthermore, the interaction matrix is applied for analysis of the correlation of the 9 indices. As a result, it is found that the correlation coefficient varies to a great extent. According to the value of the correlation coefficient, those indices with larger ones are: gravel and sand particles (0.948), big pores and middle-small pores (0.846), quartz and feldspar (0.827), feldspar and clay minerals (0.747). If the soil structure factors are under considerations, the 9 indices are in sequence of weight ratio from large to small: micro-pores, feldspar, clay minerals, sandy particles, gravel, large pores, middle-small pores, silt and clay particles, quartz. These indices, quantified after their correlations and weight ratios, provide bases for the study of micro-features in detail and classifications of the CDG, and perhaps act as one of the basement for the constitution equations of microstructure mechanics of soils to be built.

Stage construction is a typical procedure for expressway embankments on soft ground. Based on the traditional hyperbolic method, a new model for prediction of settlement of stage constructed embankment on soft ground is presented. In the proposed model, soil deforms nonlinearly, and its consolidation properties vary with the magnitude of the load. The parameter a related to consolidation properties of soft soil is determined by the settlements measured at the forestage with longer preloading duration; the other parameter, the final settlement Sf , is determined by the settlements measured in shorter preloading duration at which stage settlements are to be predicted. A case study shows predicted settlements are fairly consistent with measured settlements. The proposed model is accurate and easy to operate, and can predict settlements in practical engineering in time.

The variation regularity of swelling pressure p and expansion ratio under 50 kPa pressure with dry density ，degree of saturation and water content w were investigated. The results show that:the relations between p, and , , , ;and between p and can be illustrated in power exponent function；the variation of p and under various conditions can be better described by one or two factors that are w， ， ；in general，w is epuivalent to while high w； is equwalent to while lower w；and is equivalent to while certain w；there is a critical value of dry density，p decreases as increase when more than the critical value，otherwise the conclusion is opposite.

Using pore pressure incorporated rock failure process analysis (RFPA2D) code, the deformation and strength properties of coal/rock under pore pressure is numerically studied. The numerically simulated results indicate that the Young’s modulus and compressive strength of coal/rock gradually increase with the increase of the confining pressure for a given pore pressure; and for a given confining pressure, the Young’s modulus and compressive strength of coal/rock gradually decrease with the increase of the pore pressure. In addition, the characteristics of acoustic emission during the failure process of coal/rock are also numerically investigated under various confining pressures and pore pressures.

Rigorous limit equilibrium methods of slices should be used in slope stability analysis, especially for general slip surfaces. However, different assumptions regarding the inter-slice forces have resulted in different calculating formulations for the factor of safety of slope stability, thereby rendering the calculation process complicated and concealing the advantages and disadvantages of different procedures., In this paper, the assumptions regarding the inter-slice forces that made by the existing rigorous limit equilibrium methods of slices are expressed into the unified formulation for the first time, the simple and clear recurrence equations of the inter-slice forces and inter-slice moments are derived based on force equilibrium and moment equilibrium. Based on the recurrence equations of the inter-slice forces and inter-slice moments, the unified calculating formulation for the factor of safety based on rigorous equilibrium in the context of conventional methods of slices is developed by Newton-Raphson method. The relevant derivatives that it needs can be computed by using recurrence formulas, and its nature is analytic solution, therefore its computer formulation is of the good stability and convergence. All of its formulas are algebraic expressions. It facilitates the application and dissemination in engineering.

The prediction model for liquefaction potential of site based on artificial neural networks is presented. The spatial data structural characteristics of liquefaction potential of site can be mapped by different spread values. The optimal spread value can be determined by means of cross-validation technique of geostatistics. Study results indicate that the generalized regression neural networks can map the structural characteristics of liquefaction potential under the condition of the optimal spread. The result obtained is consistent with that of Kriging estimator. The model can be applied to the prediction of two-dimensional spatial data and the decision system based on GIS.

The stress-strain relationship, strength and particle breakage properties of coarse aggregates under high and low confining pressures are analyzed detailedly. The influence of the content of mudstone on the strength behavior of rockfill is also studied. Test results indicate that under high confining pressures coarse aggregates are characterized by strain hardening and volumetric compression, Mohr-Coulomb envelope and relationship between peak principal stress ratio and dilatancy approximate to linear, while under low confining pressures they exhibit strain softening, volumetric dilatancy and nonlinear respectively. With the increasing of confining pressure principal stress ratio and internal friction angle decrease, while particle breakage index increases. The increasing content of mudstone results in the decrease of rockfill strength.

The seepage in unsaturated expansive soils contained fissures is a time-depended process. Time-travel expansive curves determined by normal expansive swelling test are used to describe the healing of fissure during the infiltration process. Numerical model for unsaturated expansive soils slope infiltration is set up considered fissures influence. Finite element simulation is used to analyze the influences of fissures’ position, depth and seepage characteristics on slope rainfall infiltration. The results show that the fissures on the upper part of slope make greater influence. Deeper the fissures, greater influence on slope infiltration. While, the influence has a maximum extend. Fissure existence accelerates the infiltration rate. Longer duration is needed to reach balance state while considered the healing of fissures with seepage process.

The stress-strain relationship behavior of coarse grained soil was investigated through a series of large-scale triaxial compression tests. The test results show that the coarse grained soil would dilate under low confining pressure and contract under high confining pressure. Duncan-Chang model is not able to properly simulate such significant volumetric strain behavior of the coarse grained soil. A modified model of coarse grained soil is then developed through presenting new volumetric strain assumptions according to the test results. The model is convenient to practical application due to its simplicity in programming and few model parameters which could be easily determined with a similar approach as Duncan-Chang model. The validity of the modified model is preliminarily confirmed in predicting the volumetric strain response of coarse grained soil by triaxial compression test results of several kinds of coarse grained soils.

Almost all the problems of geotechnical engineering have to deal with the interaction between geotechnical media and the structures. Therefore, the simulation of interface plays an important role in the computation. At present, usually the Goodman joint element, Desai thin-layer element etc. are employed to simulate the interface, which is convenient in use but not so reasonable. In contrast, taking as a contact problem, the principal mechanical characters of the interfaces can be reflected as follows: (1) the contact interface is of shear strength which implies that a generic pair of contact points on the interface will displace coincidentally if the tangential force at this point has not reached the limit resistance, else, relative slide between the points will occur along the tangential direction; (2) no matter the relative slide occurs or not, the contact bodies cannot penetrate each other in any wise. A finite element approach to solve deformable body-rigid body contact problems is developed. The finite element formulae are constructed on the basis of the virtual work principle. Also, the techniques to solve the elastoplastic contact problem are given. The examples concerning pressure distribution beneath rigid strip footing and the lateral earth pressure on retaining wall are solved successfully, which verifies the validity of this method.

The critical edge load, which is defined as the load strength on the ground when the plastic region just appears at the foot of a strip foundation, was proposed based on Mohr-Coulomb strength criterion. A formula of the critical edge load is modified based on the twin shear stress strength criterion, which is a three-dimensional strength criterion expressed in a linear form and is used widely in China now. Compared with the original formula, bigger value of the critical edge load can be calculated by using the modified formula for the effect of intermediate principal stress is considered in plane strain condition.

Pile foundation is widely used in platform foundation. The reliability design method has been adopted worldwide. When it was introduced into China, it is pointed out that designers could refer to the standard (Recommended practice for planning, designing and constructing fixed offshore platforms-load and resistance factor desing ) when the environment conditions and the design method were coincided with those in China. Otherwise, difference criterion and data should be taken according to the specified environment conditions in China. As a result, more attentions should be paid on studying the foundation design method of offshore structures. In this paper, a database management system has been established, in order to manage and analyze the data of the geotechnical properties of foundation soils. This database includes almost all the borehole logs and properties of the soils of SZ36-1 Oil Field. Based on the database, the stationarity and ergodicity of a soil profile in SZ36-1 Oil Field have been examined and a random field modeling has been established. The correlation function, correlation distance and variation reduction function of SZ36-1 Oil Field have been simulated. A calculating model for pile foundations has been established, on the basis of the established database and design experiences. As an example, reliability analysis for a pile foundation has been performed. The influence of variations of soil properties and loads on the reliability index has been analyzed, and the calculated partial factors compared with those recommended by the API (American petroleum instituted) Criterion.

Rock failure process analysis (RFPA) code is used to study the failure process of rock disks with pre-existing cracks when subjected to static loading. The numerical simulation reproduces the failure characteristics of rock disks with different inclinations of pre-existing crack, and compare well with the experimental results. By contrast, the numerical simulation can also capture the stress distribution and failure mechanism during the failure process, which cannot be observed from laboratory test.

The interaction between loading pile and anchor-piles in the anchor-pile loading test is studied. A method which based on the Poulos elastic theory to take account of the influences of the interaction on the P?s curves of the loading pile, is presented. Then, the data of a test have been analyzed using this method. The conclusion is that the result from the original data analysis is larger than its actual bearing capacity.

According to the characteristic of the foundation beam with prestressed anchor-cable reinforcing slopes, a detailed analysis is carried out for different working stages and loading status of the foundation beam; and on the basis of it, a method for computing the limit state of foundation beam, is suggested;and the concretely computing process is given. An engineering case is calculated using the method; and the comparison shows that it is necessary to calculate the limit state of the foundation beam for designing when the anchor-cable is in the limit state.

The parameters of foundation dynamic properties are the necessary data for analysis of dynamic response and stability of all constructions under dynamic loading. At present, prestressed high strength concrete piles（PHC） are applied broadly to civil engineering. The properties of PHC under static force have been studied much, but rarely under dynamic force. This paper expounds the principles and methods of dynamic properties tests as vertical forced vibration test， forced vibration coupled with translating and rocking test，twisting free vibration test，and three PHC piles of a thermal power plant to be built are measured by this dynamic properties test. The analyzed results show that compressing rigidity （Kz），shearing rigidity （Kx）， bending rigidity （K?）， twisting rigidity(K?), and some damping coefficients (?z , ?x?1, ??) have little variety and good regularity. However，piles are usually constructed to form base slab，which increases lateral loading capacity of single pile, so the values of Kx , K? , K? , ?x?1, ?? should be properly increased according to the type and lateral fill of base slab, contact property between the lower face of base slab and subsoil.

This paper describes the lower bound theory of 3-D plastic limit analysis. The static stress field is established by means of 3-D finite element technique. Based on the lower bound principles of limit analysis, a mathematical model is established by means of finite element method. The lower bound solution of the model is obtained by nonlinear programming. As an example, the bearing capacity of a homogeneous slope is analyzed, and the comparison between lower bound limit analysis and classical plasticity theory illustrates the correctness of the method.

When earth-pressure balance (EPB) shield is used in high permeability ground as well as high groundwater pressure, groundwater will flows through screw conveyor (Flowwing), this will lead the loss of great quantity of groundwater and even the halt of excavation. Based on the steady-flow seepage theory and shield driving principle, a method for judge Flowing is provided, and a model for study the seepage of groundwater in chamber and screw conveyor is built to explain the mechanism of Flowing. With the model, the parameters such as soil condition, shield geometry, excavation instruction which relate with Flowing are analyzed and the results give some useful conclusions and suggestions to predict and avoid flowing. The model can also be used to calculate the discharge of groundwater.

Based on considering the effect of smear layer, 6-node constant thickness contact interface elements coupled with 4-node isoparametric elements are used to simulate the smear layer of drain wells. A relevant program is made to analyse two practical examples. The result is verified to be reasonable. It is shown that the coupled element model is effective and can be used in numerical analysis in engineering practice.

Bolt and grouting reinforcement is an ideal measure for improving performance of bearing capacity of soft surrounding rock around tunnel in soft rock. Based on the test and research for fluidity，performance of separating water and compressive strength of fly ash and cement grouting material in laboratory，grouting material with a proper mixture rate is found (fly ash colume fraction is less thom 20 %,water to cement ratio is from 0.65 to 0.70) An engineering practical example is given that fly ash and cement grouting has been used in very soft rock roadway at the Xinji NO.3 mine in Huainan.

Based on the project of a cylindrical deep foundation excavation, the informative supervision system for excavation construction and its application under complex geological conditions is introduced. Numerical back analysis and informative supervision is conducted by selecting a reasonable calculating model. Deformation of the retaining structure and variation of the deep confined water pressure induced by dewatering are monitored and analyzed in detail. According to the supervision data, the model is modified and the calculating result is reasonable. The example showed that the informative supervision system is feasible.

The cast-in-situ concrete thin-wall pipe pile (PCC pile) is a kind of rigid pile applied mainly to soft foundation treatment. Based on the working performance and mutual influence of the system of PCC pile-soil-cushion, PCC pile composite foundation is discussed in elastic method. A new calculation method of composite modulus of the PCC pile composite foundation is developed. Furthermore, pile-soil stress ratio and settlement can be derived from the proposed method. And it is proved that the method is practicable and applicable in the field by a practical engineering.

Of so many uncertainty methods, traditional destruction probability and random simulation theory is widely applied to stability analysis of landslide. However, in practical work, the effects from factor correlation are not considered in the method. Due to this limitation, principal component-stepwise regression algorithm is introduced, and PCR-SPA-MC coupling model is founded. Based on theoretical discussion, an engineering instance analysis of the Zhaoshuling landslide is presented. The analysis shows that the result from PCR-SPA-MC model is more ideal than that from traditional destruction probability method.

Fuzziness and randomness are two main uncertainties in the study of stability of deep foundation pit, randomness implies kinds of design parameters being random variables, and fuzziness means that the judgement criterion of stability should be regarded as a vague criterion, which has inexplicit outline, it is in accord with the fact of failure process. This paper emphasizes to study the fuzziness of stability analysis of deep foundation pit, by adopting fuzzy sets and probability theory, a generalized model of fuzzy-random has been put forward to evaluate the stability degree, in this model, the random character of mechanical parameters and the fuzziness of failure criterion, are considered. And it also discusses the failure probability standard of deep foundation pit. Finally, an example is given to calculate the fuzzy failure probability of soil uplift in the bottom of pit, the result indicates that the fuzzy-random method can reflect the actual stability of the foundation pit roundly and rationally.

The core technique of CFG-pile (cement fly-ash gravel pile) composite foundation is the setting of cushion, of which the rationality will greatly affect the foundation carrying capacity and distortion characteristic. Based on Terzaghi’s consolidation theory the mechanism of cushion for CFG-pile composite foundation is discussed in detail; and on this way the optimum space between piles, the thickness of cushion, the pile-soil stress ratio and the actual ratio of replacement are deduced. Compared to engineering example , these solutions are quite accurate so as to actually instruct the design of CFG-pile composite foundation.

In-situ tests of the behaviour of grouting under tip of precast concrete short piles in sand and gravel layer were performed and The test process was presented in details. The results of bearing capacity tests of short piles in sand and gravel before and after grouting show that the vertical ultimate carrying capacity of single grouted precast concrete short pile in sand and gravel layer can be enhanced very much.

A strong rockburst took place at one part of transportation tunnel at Zhouning Hydropower station while excavation. Underground tunnel, high pressure bifurcated pipe, water inlet tunnel designing and their lining style need know crustal stress too. So stress measurement with hydraulic fracturing was adopted in 3 deep drillholes from surface and in the rockburst measuring point. The results indicated that planar stress increased linearity with the depth of drillholes, the maximal value of crustal stress was 13－15 MPa near the site of rockburst and underground tunnel with the dominant horizontal extrusion direction NW. Based on the data of crustal stress and interrelated theory and criterion, it concluded that, first, major axis at NW direction was the best to underground plant building’s stability; secondly, reinforced concrete lining was practicable in high pressure bifurcated pipe and water inlet tunnel, thirdly, the reason why local rockburst took place was that stress concentration came into being near tunnel heading for stress in wall rock readjusted during tunnel excavation.

Blasting directional slippage method（BDSM） is a new silt replacement method . It can be widely used to build hydraulic projects（for examples: bulwark，dock and so on） in thick silt. The mechanism of BDSM is introduced. The structure of silt around and under bulwark is destroyed by shock and vibration of explosive blasting in silt. And the silt strength would be dropped because of the pore water pressure rising. It is very difficult to resume the silt’s strength in a short time. All these are conditions of riprap directional slippage，the silt would be replaced by riprap. Taking the engineering in Shenzhen-Hongkong western corridor as an example with BDSM on thick silt，the control standard of implementation quality and quality examination results are put forward. The results show that the method is effective.