Shield tunnel machines have been widely used in the construction of metro tunnels, channels and underground pipelines. Compared with advanced construction technologies, current design theories of shield machine can not fit the properties of soil very well. In order to improve the design theory and principle applicable to soil-shield machine system, it is necessary to take more fundamental experiment research. In consideration of that it is impossible to do large quantities of field experiments, model tests should be needed to predict the performance of prototype. Therefore, the specific relationship between model and prototype should be investigated. According to similitude principle and model test method, the similitude rules of soil-shield machine system is investigated; and the design principle of similitude model test about soil-shield machine system is established. As an example, a prototype shield machine with diameter of 6 340 mm is simulated by a microtunnelling machine with diameter of 400 mm; the model machine will drive in artificial model soil; meanwhile, the results of machine working parameters and soil deformation will be recorded. Based on these data, it is possible to improve the design theory of shield machine to fit different soil grounds.

Four kinds of backfill with cement-tailing ratio of 0.250, 0.125, 0.100 and 0.083 respectively were tested; and their stress-strain curves were obtained. Analyzing the deformation and failure characters of different backfills, their damage constitutive equations investigated with damage mechanics whose calculating results coincide with experiment results well were proposed. The results of damage analysis show that there have different damage characters in different backfills, e. g. the lower the cement-tailing ratio the lower the damage value when stress reaches to peak value; the lower the content of cement the more rapid in damage and the more abrupt in failure process after peak value of stress. According to the principle that releasing energy from excavated rock mass corresponds with cumulative energy of deformation in backfill; the reasonable matches between backfill and rock mass whose coefficient correlates with earth stress, elastic modulus of rock mass, elastic modulus of backfill and damage parameters of backfill respectively were researched. In order to apply it to engineering conveniently, regressing the experimental results of backfill, a design formula of strength for cemented backfill was put forward; and the required strengths of backfill in deep deposit were researched.

The small-strain stiffness characteristic of artificially frozen soil in deep alluvium was investigated at different initial confining pressures and frozen temperatures by secant Young’s modulus representing the soil stiffness. The influence of freezing on stiffness is investigated by comparing the behavior of frozen and unfrozen soils with similar conditions. It is observed that the variation of Young’s modulus E0 with the confining pressure, represented the magnitude of the initial stiffness, mainly depends on the variation of ice in frozen soils with the confining pressure, not on the soil itself. The frozen soils secant Young’s modulus may decay with increasing strain after keeping a stage of constant value, the threshold yield strain was found to be approximately 0.05 % for all tested conditions. On the other hand, the stiffness of studied frozen soils and its degradation was heavily response to the initial confining pressure amplitude and temperature fluctuation.

Channel is the reason resulting in water seepage from Kunlun Mountain tunnel by analyzing relationship between location of seepage and terrain. Moving boundary is redefined to rediscovery permafrost; and the essential conditions resulting in moving boundary are presented too. A computational model of moving boundary is introduced to compute thawed depth of permafrost; and how to determine some parameters is discussed. The computational results are compared with the actual ones. The disciplinarian of variation of frozen-thaw range around Kunlun Mountain tunnel is drawn to treat disease of the tunnel finally.

The mechanism of the fracture coalescence for intermittently cracked rock mass is studied under uniaxial dynamic loading. The specimens made of sandstone-like modeling material contain three pre-existing flaws with different geometry distribution. Through the comparisons of the fracture propagation length, coalescence mode of the fractures and strength increase of the pre-cracked specimens under static and dynamic loading, the dynamic response of the fracture coalescence is found different with static loading under different geometric setting of the flaws. Furthermore, the inertia effect of the fracture propagation and coalescence is revealed under dynamic loading, that is to say, the growth of the secondary co-planar fracture and inclined fracture tends to the original propagation direction, and the immediate coalescence is taken place easily between two pre-existing flaws. But the fracture coalescence path is winding under static loading, which is different with dynamic loading. So, the inertia effect of the fracture propagation is regarded as the main cause of the strength increase of the brittle material under slow to medium strain rate. Moreover, the multiple coalescences among the flaws lead to the progressive failure for cracked specimens.

A uniaxial compression test on coal and rock was conducted with CT scanning to monitor the damage process of coal and rock in real-time. A mathematical model has been established to analyze the experimental results on the basis of modern nonlinear theories of bifurcation and chaos. The results show that the CT values and stress can be described by Logistic equation. The process of coal and rock damage has the characteristics of bifurcation and chaos.

The three-dimensional numerical manifold with high-order displacement functions has been developed based on the tetrahedron element meshes. The global equilibrium equations of high-order manifold method are established by minimizing the total potential energy. The stiffness matrix, the loading matrix and displacement resistance matrix are derived and added to the global equations. The example of the cantilever bending under the area loading is calculated by the high-order manifold method and the numerical results agree well with theoretical solutions.

Estimation of the post construction settlement of the ground improved by preloading drainage is one of the most critical problems. Based on the consolidation theory of ground with vertical drains under the condition of equal vertical strain, approximate theory settlement curve calculation method is put forward. The least squares optimization method is used to best fit the theory settlement curve with the measured settlements and to determine total primary settlement and average consolidation degree, consequently post construction settlement can be estimated. The method is applied to two cases histories of ground with vertical drains improved by vacuum preloading and surcharge respectively to predict post construction settlement. It is verified that the method is applicable to engineering.

The stability analysis of multi-zigzag plane base surface of concrete gravity dam is studied. For the equation specified in Gravity Dam Design Specification is not able to resolve the stability of three-dimensional base surface, a new limit equilibrium quasi-safety factor formula is educed for stability assessment, based on nonlinear finite element method (FEM) results. And the strength accumulation coefficient method is also adopted for investigation of damage model and safety checking. In those two methods the material parameters and loads are treated with each partial coefficient. Those two methods are suggested to use together for the base surface stability and an engineering project is given as example. The computation results show that these two methods are reasonable and convenient for the stability assessment of multi-zigzag plane base surface.

In traditional large strain analysis of roadbed consolidation, the constitutive relation with Jaumann stress rate is used, which can not consider neighborhood-deformation. In this paper, Truesdell stress rate considering not only rigid-body motion but also neighborhood-deformation was introduced into large strain consolidation (LSC) theory. Using both virtual work principle and Galerkin’s weighted residual method, the finite element formulations for LSC were derived, based on constitutive relations following objectivity principle. The corresponding plane-strain FEM programs were compiled and tested. The influences of Truesdell, Jaumann and simplified Jaumann stress rates on roadbed consolidation were mainly discussed. The results show that the settlement, lateral displacement and pore-water pressure calculated by traditional method are greater than those by the method based on the constitutive relation using Truesdell stress rate. The considerable magnitude of errors may occur for the case of using small-strain constitutive matrix, due to the dissatisfaction with objectivity principle. As far as common problems are concerned, the differences between the results by Jaumann or Truesdell stress rate could be neglected; and the traditional method is adequately accurate for the case of small deformation.

Permeability of the basalt and its scale effect have been discussed through three kinds of field hydraulic tests at the dam site of Xiluodu Hydroelectric Station. The permeability value K from water seepage test in adits with the test scale 1-2 m is dispersed between 10-4 and 101m/d. K from groundwater tracer test with the test scale 70-145 m is concentrated between 10-0.5 and 100.5m/d. K from water pressure test in borehole with the test scale 4-7 m is between 10-2 amd 100 m/d. Three kinds of test results indicate that K increases with the hydraulic test scale. This paper attributes the scale effect to heterogeneity of fractured rock. Small-scale tests are often performed in local matrix or single fracture with bad connectivity. Large-scale tests often cross a few large fractures or faults with better connectivity so that K is larger than the value from small-scale tests. When we study groundwater flow of fractured rock, for study areas with different scales, field hydraulic tests with corresponding scale should be selected to study the permeability of fractured rock.

The bucket foundation penetrated soil is analyzed. Constitutive relationship of marine soft clay has been studied by using the principle of J2 flow theory and isotropy. The volumetric strain model which is established by combining finite element method is provided to the theoretical model of dynamic physical parameter. According to the characteristic of bucket foundation during suction penetration, combining constitutive relationship and model of dynamic physical parameter, the stress equation is established by principle of effective stress; and the flow equation is established by instantaneous law of conservation of mass. And solvability condition of aforementioned equation is derived. A new mathematic model of fluid-soild coupled flow is established to solve flow field of bucket foundation during suction penetration.

Based on the cylindrical wave equation, a method of earthquake input and artificial boundary for seismic soil–structure interaction analysis is presented. The artificial boundary condition is local in both time and space and the earthquake input is implemented at the base of the finite computational domain through a set of nodal equivalent forces, which is proportional to the velocity of the incident seismic wave. The proposed method is simple but efficient; and it can be implemented in finite element method without difficulty. Moreover, the time-stepping algorithm based on Newmark’s method in conjunction with this method is unconditionally stable. Two Numerical examples were conducted to verify the validity and accuracy of the method.

It was summarized for the length of cavitation cloud versus different nozzles with different pump pressures and ambient pressures based on the forming process of cavitation cloud. It is pointed out that the length of cavitation cloud increases with pump pressures, while there has a best one with ambient pressures. The difference of erosion characteristic between converging-diverging nozzle and converging nozzle was analysed by experiment; and it is shown that the capability of average mass rock-erosion by cavitating water jet with converging-diverging nozzle are 7 times than converging nozzle in the same bump pressure. In contrast, it is shown that the depth and the diameter of erosion as well as mass erosion decrease with the increasing of ambient pressure; so that the influence on rock-erosion capability with converging-diverging nozzle in ambient pressure is disadvantageous.

Based on the consolidated undrained triaxial shear test of Wuhan soft clay, the behaviors of stress-strain relationship are analyzed. The soft clay appears to be strain stabilization or hardening under low confining pressure, but exhibits strain softening phenomenon under higher one. The stress-strain curves of Wuhan soft clay under various confining pressure conditions are all typical hyperbola pattern. The normalization of its stress-strain relationship is important for the study of stress-strain relationship of soft clay. In this paper, a new normalized condition is derived theoretically based on hyperbola function. In this condition, the concept of standard normalized factor, which is defined as the ultimate value of principal stress difference, is introduced. Compared with the confining pressure which is often adopted as the normalized factor, the standard normalized factor is much better at normalizing the stress-strain relationship of soft clay. Meanwhile, the normalized stress-strain relationship of Wuhan soft clay under consolidated undrained condition is established.

The significance of indexes is confirmed by calculating rough dependability between indexes and result for appraisement. The free expansion ratio is the most significant index to classify expansive soil with free expansion ratio, swelling force, expansion ratio under 50 kPa and swell-shrink total ratio. Swelling force, expansion ratio under 50kPa and swell-shrink total ratio are in descending order of significance. A new analyzing method is presented by the rough sets theory; and it is reasonable and effective for optimizing algorithm of expansive soil classification index system.

For the embankment constructed on soft clayey subsoil, the soft clay generally has large void ratio, high water content, high compressibility, low hydraulic conductivity, low shear strength. Not only large vertical and lateral displacement of soft subsoil will happen during the embankment construction but also sliding failure maybe occurs due to the insufficient bearing resistance of soft subsoil. For this reason, embankment is constructed stage by stage to make subsoil consolidation under embankment loading and to make the soft subsoil acquiring strength from consolidation. This paper presents a case history of a stage constructed embankment on soft high sensitive Ariake clay. In order to speed up the consolidation, prefabricated vertical drain was installed in soft subsoil to increase the vertical hydraulic conductivity of soft subsoil in the macro sense. Field measured results show that during consolidation, water content of soft subsoil decreased and its unit weight increased. The undrained shear strength increased to twice of the original value.

The affect factors on anchoring force of resin-grouted cable bolts are numerous and complicated. And the anchoring mechanism of cable bolts is not perfect enough at now. So the supporting parameters of cable bolts are always not suitable to the roadways’ condition. As the worst case, the reinforced surrounding rock may go into failure. Based on the observed results that more and more roof rock mass is bearing fracture water, some laboratory cable-bolt pull-out tests were carried out. The main factors include anchoring length, bore-hole diameter, resin capsule packaging, water, etc. A 7-wire high-strength stranded cable was used in the tests. The research results show that there are four models of cable force vs extension. The law of axial force distribution of cable bolt is obtained; and it is some different with the conventional Mindlin distribution. The achievement is valuable to the design of roadways supporting parameters and the work mechanism of cable bolts.

Based on the smeared cracking theory, a brittle fracture model for tensile state of compacted cohesive soil is proposed. When tensile strength is reached, cracks are smeared into solid elements by constructing anisotropic stiffness matrix. The finite element method for brittle fracture in compacted cohesive soil is built under the plane strain condition. By simulating of the process of uniaxial tensile tests on a certain cohesive soil, the applicability of the brittle fracture model and the corresponding calculation method for tensile failure and crack development is verified. More over, simple numerical tests to simulate the “wedging action” of water pressure in weak link are carried out; and the results show that the model and the method can simulate well the behavior of crack development.

Landfill settlement is a topic of concern in geoenvironmental research; Three important mechanisms that contribute to the compression of landfill are instantaneous compression in response to applied load, secondary mechanical creep and time-dependent biological decomposition. In this study, we investigated several approaches for calculating the compression of the municipal solid waste, and then discussed their validity in the South China.

Formulation of a bounding surface model was introduced briefly and implemented into FEM software - MARC. Cyclic simple shear tests were numerically modeled to validate the codes and show the performance of the model. Based on the model implemented, the seismic response of a homogenous level ground was analyzed; and the results were compared with that obtained by equivalent linear method to illustrate the reliability and effectiveness of the model and MARC. The techniques to perform seismic response analysis of earth dams were introduced taking an idealized model dam as an example.

The physical characteristics of mortar specimens made of cement:sand:water=1:3:0.5 and subjected to hydrochloric acid attack were investigated by means of the accelerated corrosion test. The variations of the longitudinal wave velocity of mortar specimens and the alternations of the concentration of hydrion and calcium ion in hydrochloric acid solution were inspected. The results show that the characteristic of chemical reactive stage is found; and the delayed action of the dissolved out Ca2+ is observed; then the scale effect of different specimens is analysed.

GT soil firming agent is a kind of new material that modifies and reinforces soil. Its main raw materials are industry waste materials of high calcium ash and desulfurated gypsum; and its minor constituents are quicklime, cement, plaster, sulfuric acid aluminum, alunite, etc. It is synthesized with ingredient method of full powder, by removing free water of desulfurated gypsum using counteraction way of quicklime. The improved soils were made by adding lime and GT soil firming agent with given proportion, and then were cured and submerged underwater. Compaction tests, direct shear tests, compression tests and permeability tests were carried out. The tests indicate that the engineering properties of GT soil firming agent improved soil, such as compaction effect, shearing strength, compressibility and resistance to permeability, are better than lime-improved soil. Improving mechanism of GT soil firming agent is studied further more. The results can be for reference to further study and engineering application.

Gravelly soils are made up of gravel, cobble, sand and cohesive soils and have been widely used in engineering such as earth-rock dams impervious fillings and stub cutoff walls. Their strength and mechanical property are affected by the content and bite extent and adhesive state of coarse grains and fine particles. The gravelly soil slope shape, soil mechanical property and slope stability under rainfall conditions, are researched through artificial rainfall field experiment, model experiment, indoor test and theoretical analysis. It is found that the gravelly soil slope likely exists criticality in the course of rainfalls and mechanics of thixotropic liquefaction. Result shows that the gravelly soil slope shape and sediment charge of the runoff has the character of phase, each representative phase moisture content is confine in some extent. Gravelly soil strength and slope stability has the character of criticality along with the moisture content; the critical point exists at the moisture content of 11 %.

The adaptive finite element method is used to analyze the stress fields in slopes. Based on the stress fields, a global optimization method to search the critical slip surface in slopes is proposed by parallel recombination simulated annealing algorithm. The method can be applied to slopes with any configuration, different layering and external load distribution. The parallel recombination simulated annealing algorithm is an effective combination of simulated annealing algorithm and genetic algorithm. The algorithm displays inherent parallelism, iterates a population of solutions rather than a single solution, and consistently converges to global optimum. The feasibility and efficiency of the proposed method are finally demonstrated with the stability analysis of a real landslide case.

The soil-nailing protecting structure is designed by limiting condition generally; and in all, to check its stability is important in design. According to the structure characteristics ,analyzing the breakage pattern of soil-nailing protecting structure, making use of the limit broke theories of the slope and the limit analysis method of the structure body, this paper studied that the revolving and gliding breakage of the soil-nailing protecting structure occurred possibly. Depending on this, the stability of the soil-nailing protecting structure was analyzed. The research results show that the soil-nailing structure was broken possibly itself in the weak foundation. The steel pipe shot buries soil-nailing was properly adopted in order to strengthen its bending resistance in engineering design.

Based on the results of the statistical analysis of a large amount of measured dada in slope engineering, a theoretical model for natural slope failure for underground mining of phosphorus ore-deposit in mountainous areas is established by using the artificial neural networks theory and applied to predict the stability factor of natural slope in Dingjiahe phosphorus mine. The agreement of the theoretical results with the actual situation of natural slope shows that the proposed model is satisfactory; and the theoretical models obtained are valid; and thus can be effectively used for predicting the slope failure due to underground mining of phosphorus ore-deposit in mountainous areas.

The logistic model can well predict the developing trend of foundation settlement with its own virtues. Firstly, it is extended to settlement predication of embankment subjected to multistage loadings due to filled soil, and then one new type logistic model coupled with rheological term of soft soil is put forward based on the secondary compression calculation formula under the absolute time coordinates. The relevant parameters are back-analyzed with the optimizing technology of mathematics according to filed measured settlements. It is seen that this new model has higher predicted accuracy and can reasonably reflect the creeping course of soft soil grain skeleton. Besides, the quantity of secondary compression at different times can also be accurately given. The results obtained in this paper may be useful in engineering.

At different times of sustained loading, the single pile tip load-settlement curve was analyzed by finite element method in saturated soil, considering the soil consolidation and creep. The initial pore pressure around the single pile is displayed. The influence of consolidation and creep on the pile settlement was evaluated. The results show that the influence of the soil consolidation on the single pile displacement is little. And the load is mainly transferred to the soil essentially by shear. The creep part of the pile settlement is related to the over consolidation ratio (OCR) degree of the soil.

Unsaturated soils will undergo deformation as ground is soaked or underground water table rises. The increase in water content can result in, on one hand, compression due to rise in specific weight of soil, and, on the other hand, rebound due to decrease in matric suction. The comprehensive effect is controlled by these two types of factors. Based on generalized Hook’s law of elasticity, Fredlund’s theory of two stress state variables and the empirical relationship between matric suction and saturation given by Brooks and Corey, an incremental-type of constitutive model is established for unsaturated soils loaded under the condition of K0- consoilidation. Combined with the layer-wise summation method; the proposed model can be used to assess deformation of unsaturated soils induced by the soaking of ground, rise or lowering of water table as well as over-evaporation. The proposed method is used to assess vertical deformation of a soil stratum as an example. It is displayed that deformation characteristics of the unsaturated soil is not only dependent on soil properties, but also associated with the variation of profile suction distribution and thickness of soil layer as well as stress states. The procedure can also be used to evaluate the settlement of footing on unsaturated soil foundation.

Critical height is a key problem in expressway engineering. When embankment height is less than the critical height, settlement and stability of foundations can be controlled. The critical height is considered as a constant in the previous research, and its time effect is rarely investigated and applied. In the paper, the consolidation theory is used to analyze soil’s strength improvement under embankment load. Later, time effect of the critical height is studied based on its former results. At last, the construction skill of the highway is discussed on the aging effect results.

Stress state of supporting structure and the retained soil was analyzed with elastoplastic FEM in foundation pit; and the value of limiting state function of retained soil was calculated. Based on the nodes and meshs, with “artificial participation” optimization, the shape and position of potential bulge fracture plane in foundation pit were searched with the DIJKSTRA optimization algorithm; and the relative safety factor was calculated. Large scale numeric calculation and in situ measurements show that the end point of potential fracture plane is insensitive to the insertion ratio of supporting pile, but, the start point of potential fracture plane is close to the supporting pile when the insertion of pile is increasing; and that the method of potential bulge fracture plane searching proposed in this paper is not restrict to the man-made fracture plane shape and limiting earth pressure assumption. The in-situ measurements show the availability and utilization of method of the potential bulge fracture plane searching based on the DIJKSTRA algorithm in composite optimization.

A reasonable method was proposed to calculate earth pressure on rigid retaining wall rotating outward about the top. Based on the progressive rupture mechanism of backfill and arching effect, the nonlinear relationships between the wall movement and the mobilized angles of internal friction and wall friction were developed; and the initial frictional angles were decided on the initial stress condition. The modified horizontal layer analysis method of active pressure was used to calculate lateral earth pressures, total lateral forces and the applied points under different rotating angles. Comparisons between the calculated results and observations from model test show that the proposed method can provide a good prediction of lateral earth pressures for walls rotating about the top.

CBR test is important compositive portion in design of pavement. The influential factors in CBR test are studied by combining with practical engineering; and sevsral problems about CBR test regulations are discussed. The conclusion can provide reference in engineering practice.

Hyperbola method can be used to predict the ultimate bearing capacity of pile, of which P-s curve is an adjustment curve. The ultimate bearing capacity of squeezed branch pile is predicted based on seven piles from two different sites by hyperbola method. The results indicate that the predicted curve is agree well with the field measurement curve below ultimate load; the hyperbola method is also suitable for squeezed branch pile; and the predicted results can be used in practice.

Soil softening and liquefaction due to earthquake cause permanent deformations and displacements of submerged slope. Based on finile element theory, a numerical method for lateral displacement analysis of submerged gentle slope is presented. Wave loads are simplified as constant pressure and initial pore pressure. Liquefaction analysis is performed by 2-d dynamic effective stress finite element method. In each time segment, gradually softened modulus are calculated based on module soften theory; lateral displacements analysis are performed with the new modulus by nonlinear static method. By examples, the influences on lateral displacements are studied with different slope angles, wave loads, thicknesses of liquefied layers and surface non-liquefied layers. Compared with the results of other researches, the validity of the new method was confirmed and it is applicable to solutions of earthquake geological hazards evaluating in offshore engineering field.

Based on Biot’s wave equation, the transmission of vibrations over the surface of the ground due to a harmonic strip moving load, is investigated theoretically under conditions of plane strain. The material of subgrade is idealized as a uniform, fully saturated poroelastic finite-layer of soil obeying Biot’s dynamic poroelastic theory. By introducing four scalar potential functions and Helmholtz decomposition theorem, the analytical solutions of stress, displacement and pore pressure are derived using the Fourier transform and the inverse Fourier transform. Numerical results are obtained by using the inverse fast Fourier transform (IFFT), and are used to analyze the influence of the moving load velocity, frequency and, the permeability and porous elastic constant of the ground on the vertical displacement on the surface of the ground and the distribution of pore pressure along the arbitrary depth of ground.

A quantitative way to predict the unconfined compressive strength of cement-mixed clays with a given organic content is proposed. The Yancheng lagoonal soft clays were used as an original clay to form cement-mixed clays through mixing with powder cement or slurry cement and organic matters. A series of tests were performed on the cement-mixed clays with various organic contents. A quantitative relationship is proposed between the strength ratio of the strength with a given organic content of to the experimental strength with an organic content of and the organic contents of and . The quantitative expression proposed can be effectively to predict quantitatively the effect of organic content on the unconfined compressive strength of cement-mixed clays within the organic contents of 5.5 %-17.5 %.

The deviation and the deviation rectification of a building with pile foundation are studied. The interaction analysis model of superstructure, pile foundation and ground is adopted. The deviation and displacement of building and the distribution of friction around piles are discussed when over loading is put on the ground with deep and thick flabby soil layer. The cause of deviation and subsidence of building is researched; and the applicability of excavating deviation rectification applied to pile foundation is studied. Based on these studies, the effective suggestion is offered for the further engineering measures.

As a kind of new ecological modifier, CMA has good application prospect. Based on Hefei－Luan－Yeji Expressway Project, laboratory comparative tests on basic physical, compacted, swelling-shrinkage and mechanical characteristics of CMA-treated expansive soils have been carried out. Compared with unmodified sample, the free swelling ratio of the modified samples lowers from 71 % to about 20 %; its liquid limit and plastic index also decrease obviously; hydrophilic nature falls down by a wide range as well as micelle content, but silt content increases sharply. The results also indicate that index for swelling-shrinkage property has reduced, swelling ratio without load is 2 %－3 % and swelling power is 5 % of those without modifying. The value of CBR reaches 50 % and deformation is small when soaked; soils have a high shear strength and unconfined compressive strength whether saturated or not, and possess better water stability. Conclusion can be drawn that CMA can change the properties of expansive soils notably and the first formula is suitable for Hefei expansive soils for its good treating effect.

The effect of the dynamic compaction method (DCM) on the ground foundation was investigated by means of the elections of void ratio of soil, the arranging forms in the silty soil and collapsible loess ground foundation, the weight of hammer, the height of drop in the collapsible loess ground based on DCM’s reinforced principle. Some suggestions are put forward for selecting parameters, with relation to DCM in the silt and loess ground: 1.The critical void-ratio may be a standard that checks the effect of tamping; when the critical void-ratio is close to that after tamping, the solum will be compacted thoroughly. 2.The compacting points may get better effect with an equilateral triangular arrangement for a small area reinforcement; if a reinforced area is enough big, and both of those arrangements can be satisfied with engineering inquirement, of which the arrangement is suggested after economical analysis.3.The heavy hammer and the low height of drop in the collapsible loess ground is preferred when choosing DCM. These suggestions are very valuable for the promotion of the DCM and engineering practice.

The random wedge usually occurs in the deep excavation of side slope of hydraulic structures. According to the three-dimensional network computer simulation, A numerical model of probability statistics for distribution of rockmass is established. A computational program for the method has been accomplished. With the program all polygons in trace figure are sought; and all the potential rocks can be found out of all the finite rock blocks which have free faces exposed by area-judgment method. The method is proved to be reasonable from simulated results of real engineering.

Triaxial compression experiments of slates under different saturated conditions were done through the XTR01 electric- fluid serving compression machine, which were taken from the engineering of the western route of Water Transfer from South to North China. Relative saturation was defined as the ratio of mass of natural saturated rock to complete saturated rock; and the saturation was used to analyze the change of mechanical parameters (rock strength, elastic modulus and Poisson’s ratio). And an attempt was made to explain the change mechanism by the micro-mechanics model. With all the efforts, some conclusions are drawn as follows: 1)the triaxial compression strength of slates fell down when saturated in water and the most descendent can be 46%; and this change can be described by a law with the relative saturation; 2)when saturated, the elastic modulus and the Poisson’s ratio increased with the accretion of the relative saturation, but the law was not too clear for the anisotropy of the slates; 3)theoretical analysis has proved that the saturated rocks in geology conditions will undergo two process as drained and undrained, when the saturation increased, the elastic modulus and the Poisson’s ratio will increase simultaneously, which has confirmed the experiment results; 4)the micro-mechanical model shows that, when saturated in water, the absorbtion of the slate surface and the decrease of the capillarity among the grain are the main reasons to the water-weakening effect appeared in the slates.

For evaluation of the Zishui Bridge of Xiang-Qian Railway Line, a method which uses the finite element method to calculate and analyse compressive stress of the foundation base and displacement of the pier top in influences of different scouring degrees, is presented. The method adopts an approach of changing support pattern of the foundation base to simulate the undercutting of foundation base. This method not only reveals the ultimate undercutting area when maximum compressive stress is equal to allowable compressive stress of the foundation base, but also offers the undercutting area of the foundation base for invalidation of the basement which results from the intense variation for different deformation and stress considering the factor of maximum transverse longitudinal and vertical displacement. A powerful reference is presented for the stability analysis of the scoured pier.