Based on three aspects: (1) the great deal of data in field experimental study of piled raft or piled box foundations for 17 buildings at home and abroad; (2) calculated results using four methods: simple pratical method, semi-theoretical and semi-empirical method, FEM integrated with statistic method and theoretical method; (3) mechanism analysis taking the piled raft foundation with 20d 20d as a model, this paper synthetically demonstrates the resonableness for loading between pile and raft or box. Especially, the calculated results are satisfactory in agreement with the data obtained from 8 piled raft or box foundations for buildings. Finally, the available suggestions have also been proposed in detail for reference of drawing up a new item in foundation code.

Taking the sand clay as test material, the dynamic cyclic loading experiments for it with different initial consolidation levels are carried out, The history of pore water pressure and residual shear strain is studied. The prediction method of pore water pressure and residual shear strain is discussed, when the anisotropic consolidation is looked as two stress situations, i.e. initial shear stress and isotropic consolidation. And two unified models are established for the relationships between total energy dissipation and excess pore water pressure; and between residual shear strain and effective stress ratio.

With the improved triaxial equipment for unsaturated soil, we tested and studied soil water characteristics of Yellow River dyke’s unsaturated soil under different confining pressures simulating the real condition exposed on unsaturated soil in engineering. And according to fest results, the curves of soil-water characteristics of unsaturated soil are obtained and the water-soil characteristics and their rules under additional load are discussed. At the same time, the function of fitted curves is gained. Based on the water-soil curves, the results are known that the matric suctions reduce with increasing the surrounding pressure and water content. To the same type soil, the matric suction changes small with change of water content when the water content is higher than 20 %, but it changes greatly when the water content is less than 20 %. The engineering characteristics become weak with increasing water contents.

To simulate the sea bed strength’s loss and recovery due to the wave load, we chose typical study areas on the tidal flat of the Yellow River Mouth, and carried out in-situ impactive vibration test. We got the silt’s penetration value before and just after the vibration, also the silt’s penetration value after several periods of time. Using these penetration values,we have done some research on the procedure and influential factors of silt strength’s loss and recovery. From the reseach, we found that the strength loss caused by vibration occurs at certain depth under the sea bed, and the variation of silt strength’s loss and recovery appears like a parabola along the depth. After the vibration, water and fine object appear at the surface layer of the silt, and a series of minimal mud volcanoes come into being around the vibration site. The silt’s maximum strength recovery appears at the same depth as the maximum loss. After three-hour recovery, the silt strength surpassed the silt strength before the vibration. The following factors remarkably affect the silt strength’s loss and recovery, the hydrodynamic action that the silt had experienced, the silt’s original strength, circular times of vibration load, the vibration energy, the silt depth and the time of recovery, etc. The mechanism of silt’s strength variation due to vibration and recovery is very special and further study of the mechanism is required.

Rockburst is provided with the representative slip characters and the two state variable model could simulate the characters very well. On the study of the dynamics behavior of rockburst system, according to mechanics conditions and geological circumstances of rockburst, the two state variable model is introduced to describe the dynamics behavior and evolvement behavior of rockburst. The research shows that the parameters k and β greatly affected the dynamics behavior and evolvement behavior of rockburst; and , f contributed much to the model also. This model well simulated the stick-slip character relative to single state variable model. And the two state variable model truly describes the process of failure of rockburst system which explains the mechanism of rockburst and provides the theoretical foundation to forecast rockburst.

Mechanical behaviors of lining structure and stability of surrounding rock under high hydraulic pressure are analyzed with plane finite element numerical model. The values of hydraulic pressure, thickness of inject grouting area and the influences of reduction coefficient of external hydraulic pressure on mechanical behavior of lining structure and plastic zone of surrounding rock, are studied. The results show that the lining internal force and plastic zone increase remarkably with the increase of reduction coefficient of external hydraulic pressure; and increase with the increase of total hydraulic pressure; and decrease with the increase of thickness of inject grouting area. The reduction coefficient of external hydraulic pressure is an important factor, which influence on internal force of lining and plastic zone of surrounding rock.

The soil-cement is one of materials that used for ground treatment in soft soil engineering. In the high degree of mineralization zone , the ettringite(3CaO•Al2O3•3CaSO4•31H2O ), which is the reaction product of hydration of cement(AlO3-,Ca2+) and SO42-, can cause expansion and crack to soil-cement and makes the strength of soil-cement decrease. The activated fly ash is mixed into the soil-cement, which can set free the activated SiO2 to increase the concentration of SiO32- and promoted the reacting speed of hydrated calcium silicate(CSH). Meanwhile, the probability of formation of ettringite is decreased. The expansion inhibiting mechanism of soil-cement is that the activated fly ash absorbs Ca2+ and changes the reaction process; and the reaction product (CSH) fills the hole of soil-cement with its micro-granule. The mechanism of activating fly-ash is the powdery sodium silicate destroys the high network polymerization surface of fly-ash, reaches the inner part of the fly ash and makes the active substance to set free.

Based on a certain assumptions and the improved dynamic beam-on-Winkler’s foundation model, a simplified analytic method for computing the vertical dynamic harmonic response of single pile embedded in nonhomogeneous soil layers are established by using the principle of soil dynamics and structural dynamics. Both nonhomogeneity of soil strata and softening effect of soil layers around pile are simultaneously taken into account in the proposed computational method. The comparative study on a numerical example shows that the dynamic response of single pile computed by the simplified analytic method are relatively rational and can well agree with the numerical results obtained by the well-known finite element program. Finally the parametric studies are made to examine the effects of main relevant parameters on dynamic response of single pile embedded in nonhomogeneous layered soils.

Based on the theories of coupled interaction in saturated soil and dynamic soil-structure interaction, the response of subway structure in fully saturated liquefiable soil under earthquake excitation is investigated using the effective-stress based finite element program Dyna-Swandyne-II. A generalized plasticity model, Pastor-Zienkiewicz III model, is used to model the cyclic behavior of soil; and finite element procedure based on the u-p form of Biot theory is employed to conduct the coupled analysis. The nonlinearity of the interaction between soil and subway structure is fully considered. The dynamic response of subway structure, including the internal forces, the acceleration, and the vertical and horizontal displacements, are analyzed. The results showed that the subway structure may uplift due to the earthquake induced liquefaction, which shall lead to severe damage in the structure; and that the maximum seismic internal forces occurred at the connections of the structure elements and their reinforcement must be carefully designed.

The settlement-time relation of foundation during the whole process of construction and operation can be described by a sigmoid or S-shaped curve, which can be modeled by the logistic growth model. However the range of applicability and the prediction accuracy is seldom considered when using this model. According to the field data from practical engineering, Three methods for parameter estimation of the Logistic growth model are compared, and The comparison indicates that the nonlinear regression method has a better accuracy. The applicability and the prediction performance of the model are evaluated by using chaos theory. The dynamic behavior of Logistic growth model is controlled by parameter a, namely transient settlement rate. When parameter a is in the interval [0, 2], the final settlement predicted by Logistic growth model is stable.

It is not very long since the flat dilatometer test (DMT) has been used in China, so it needs to be explored how to explain and apply the results of DMT rationally. It may be a better method to compare the results of DMT with other in-situ tests. In this paper, the application of regression analysis in geotechnical engineering is introduced. Based on the data of DMT, vane shear test (VST), standard penetration test (SPT) and static cone penetration test (CPT) in Shanghai, the correlation relationship between DMT and other in-situ tests are concluded through choosing elements and regression analysis. These conclusions can be used for reference by the related designers.

With the rapid development of expressway construction, more and more engineering problems related to expansive soil occur. Based on a real expressway project, the physico-mechanical properties of mid-expansive soil and its lime-treatment effect were studied by laboratory and field tests. It is discovered that mid-expansive soil without lime treatment has high strength at the optimum water content and in the immersion test it behaves as large swelling, decreasing strength and very bad water stability. While the strength of mid-expansive soil after lime treatment is largely increased and it has good water stability. All of those show the fact that with effective treatment and rational construction, mid-expansive soil can be used in the embankment fill of expressway.

Simulated Annealing Gauss-Newton algorithm applied to neural network is put forward. It overcomes some limitation of the traditional BP neural network. Taking iterative convergence of sine function for example, the correction, efficiency and superiority of the algorithm are proved. At the same time, this algorithm is applied to seepage back analysis of Tongleping dam, using seepage coefficient to calculate seepage flow field. And forecasted water heads approach to the observed values, which illuminates the back analysis result is correct and the algorithm is feasible in the practical seepage parameters identification.

This paper describes the algorithm of force distribution method(FDM) for geotechnical analysis. The formulae are deduced. Because the proposed method belongs to distribution method, it has the advantages: it is no need to form the global matrix and solve the global equations, while the unbalanced force on each node is eliminated gradually node-by-node; the conception is clear and easy to understand, the algorithm is easy to learn and to be programed by computer as well. As its features mentioned above, the FDM will be widely applied study of many geotechnical cases.

Drained triaxial compression creep tests of sliding zone soils of Xietan landslide in the Three Gorges area have been carried out. Based on these tests, given is Singh-Mitchell’s creep model, in which exponential function is adopted for shear stress-strain behavior and a power function for strain-time behavior. A modified Singh-Mitchell’s shear stress-strain-time behavior is presented too, in which strain-time power behavior has been simulated by subsection. Through using the different power values , which correspond to the three phases of creep, that is , damply phase, steady phase and invariable phase respectively; the capability of simulation the creep characters of the sliding zone clay can be greatly improved. So for the clay which has less creep characters, modified Singh-Mitchell’s creep model is more reasonable than Singh-Mitchell’s creep model.

In allusion to the characteristic of easily losing stability for reservoir slopes when water level descending rapidly, the mechanism of losing stability resulting from ground water for reservoir slopes is analyzed. The important factors influencing the stability of reservoir slopes, such as decrease of physico-mechanical parameters, buoyancy and seepage force, are pointed out. The formulas for calculating the stability of reservoir slopes considering groundwater are given. A slope project in the Three Gorges is illustrated. The results show that the resisting force of potential sliding face decreases due to softening, that the buoyancy at a certain extent helps to enhance the stability of slopes, and that the seepage force in slope body is a key factor resulting in a slope losing its stability. In addition, for designing a slope project, it is necessary to adopt some reasonable measures effectively decreasing the disadvantageous influence of groundwater on the stability of slope, such as setting protecting, inversely filtrating and draining systems.

Using random field theory, a method for analyzing variability of empirical formulas for foundation bearing capacity, such as foundation bearing capacity table and CPT, is studied. And it is pointed out that the variability of foundation bearing capacity is constituted by the variability of empirical formula oneself and variability of soil parameters. We put forward an analysis method of foundation bearing capacity variability determined by empirical formula with considering self-correlation properties of soil parameters. By the analysis and calculation of the data which workout the empirical formula, the variation coefficient is obtained, which is 0.1-0.135 .

To study time-dependent airtight capacity, impermeability and breadth of mixing silt wall in vacuum preloading by soil-water character, comprehensive tests were carried out. It was found that mixing silt wall treated with pile cap at the intersection of two preloading areas and 2-rows’ inequilengthy pile wall using at the periphery was feasible to solve mixing silt wall subsiding and crazing and insure the durability of airtight capacity. A case study with large-scale area of 0.84 km2 is presented involving the hydraulic fill treated with vacuum preloading in Nansha Harbor; and airtight capacity of mixing silt wall and soil improving effects were analyzed by the distributing and changing in pore-water pressure, underground water table and vacuums; and it was concluded that mixing silt wall with breadth 1m and permeability less than 10-6 cm/s met the need of the airtight capacity under vacuum of 85 kPa.

Strain localization of soils as a stable behavior of soils can be understood as a bifurcation in the macroscopic constitutive properties in a special stress state. In this paper, a 3-D analytical solution for the criterion of onset of strain localization is deduced based on the finite deformation theory. The theoretical analysis shows that, onset of strain localization always occurs in the softening regime of constitutive response under axisymmetric conditions; and inception of strain localization generally occurs in the hardening regime under plane strain conditions, and shear bands’ orientation of theoretical prediction exhibits an agreement with that suggested by Arthur et al[1].

The dynamic property tests were done on the models of fly-ash dams at the elevations of 170m, 180m and 230m of a power station by the large-scale shaking table with two conditions of submerged and non-submerged beaches. The earthquake-resistance properties of the models of 180m-ash dams heightened by three mixtures of fly ash are analyzed and the conclusion is drawn that three mixtures have little influence on the dynamic property of dam. The tests also show that the natural frequency of dam and the acceleration amplification factor at the top of dam decrease with the increases of excitation acceleration and the height of dam; and both are lower under the condition of submerged beach.

As a new bracing structure, the portal double row piles have some advantages such as larger rigidity, less displacement in the top of the piles and large anti-force, which leads to the restriction of piles deformation. The key problem is concentrated on the determination of the action of soil between the double piles. On the basis of combining the front and the back row piles as well as connecting beams and soils as a whole structure, and simplifying the forces for the double row piles from the soils as elastic bearing, a new analytical mode and a new calculation model are proposed. From the viewpoint of the authors, the front row piles sustain not only the active earth pressure but also the additional one due to the press of the soils between the double piles. The ratio of the active earth pressure for the double row piles to the active earth pressure for the single ones is a parabola function of the ratio of interval of the piles to the diameter of the piles. The action of the soils to the back row piles is considered as elastic bearing; its mathematical and mechanical model for the internal force of portal double-row piles is established by finite element method and Winkler beam on elastic foundation method. The application of the models to the water supply reconstruction project from Dongjiang to Shenzhen shows that the new mode and the calculation model is reasonable and can be used in the similar engineering.

Based on laboratory experiment of physico-mechanical properties of the light soil mixed polystyrene, influences of composition and sample preparation etc. factors on density and compressive strength of the soil are discussed in detail. Finally, the main influential factors on soil’s physico-mechanical properties are suggested. The results obtained can be used in form light and high strength soil mixed polystyrene.

The technique of cable-anchored piles is an effective measure in landslide control works, which nowadays has wide application to the fields of infrastructure such as transportation construction projects and geo-hazard control in the reservoir area of Three Gorges Project in China. However the design and calculating method concerned need more attention and urgent studies. Questions are put forward about the cable-anchored piles that have been applied largely in the landslide prevention in the Three Gorges reservoir shore lines. During computing the cable’s prestresses of cable-anchored piles, we consider the changes of horizontal sliding force that act on the anti-slide pile at different conditions and suggest a method for computing the prestressing force. In the method, the cable, anti-slide pile are regarded as a whole. We can increase the cable’s horizontal pull which is formed because of the cable’s deformation but keep the cable’s prestresses constant. By this method ,we can reduce the cable’s pull. The computation results show that excessive prestressing force acting on the anti-slide piles leads the anti-slide pile and the cable to be at a disadvantageous internal force condition. The prestressed anchors will get accessional vertical loads that deteriorate its internal force and three prestress losses exit in the prestressed anchors as the water level is changed.

Based on the elastic foundation beam method this paper presents the ideas of back analysis of m constructive process, i.e., a construction process of excavation and support in stage is introduced into the common back analysis, and providing reliable guarantee for predicting the deformations in succession construction stages. Grounded on the incremental measured datum between two arbitrary stages, such as the horizontal deformation of retaining structures, and by use of the back-analysis method of FEM and simplex optimization techniques, the elastic models of several layers of soils are calculated and back-analysised. Finally the method is proved to be feasible to calculate and to predict the displacements of retaining structures on the basis of a deep foundation pit engineering.

In order to realize the calculation of the three-dimensional seepage field including the gate and earth dam, grids of the seepage field with the drain hole are set up by use of finite volume method; and consequently sluice seepage field is numerically simulated. According to numerical result, the effect of impervious wall in sluice foundation is weak; and the upright hydraulic slope of overflow point beyond the permission value. The corresponding reform measure is put forward.

The principle of the limit equilibrium method is discussed firstly; then the shortcoming of the residual thrust method is analyzed; and the improvement is conducted. The basic idea of the improvement is: when the yield occurs at a slice face, the Sarma method will be applied to calculate the action between slices, i.e., the shear force is calculated by the Mohr-Coulomb criterion while the horizontal thrust is unchanged. Finally, the verification of the improved residual thrust method is shown; and the engineering application to Sanbanxi Hydropower Project is illustrated.

In light of an investigation of geotechnical engineering for high-rise architectural complex in Wuhan , the clayey silty sand is recognized as a kind of mixed soil differing from general silty sand, silt or clay and is more close to clay rather than silty sand on engineering properties, based upon an analyzing results of consulting table of bearing capacity in code, theoretical formula calculation, and plate bearing test. Plate bearing test and theoretical formula calculation should be the main methods for determining bearing capacity of clayey silty sand; and the results from theoretical formula calculation must be close to the ones from plate bearing test.

Experiments were carried out to investigate the marble specimens with medium and coarse grains under conventional triaxial compression by the RMT-150B servo-controlling testing machine. Based on the experimental results, the strength and deformation properties of marble specimens with medium and coarse grains under conventional triaxial compression were studied. The results show that marble will manifest the property of strain softening when the material in the rock does not tend to uniform under the lower confining pressure. However, marble will show the property of plastic flowage when the material deformation becomes uniform under the higher confining pressure. The peak strain of rock material has a positive linear relation with the confining pressure. Although marble specimens with medium grains are different from that with coarse grains, the internal friction coefficient can show the mechanical property of material, and has no distinct relation with the grain size. The sensitivity of residual strength on the confining pressure is higher than that of peak strength.

The physical behavior of cut holes in the course of forming empty space was analyzed; and the mechanic model of empty space’s formation was established based on the typical borehole distribution in parallel cut blasting with cavity. The movement behavior of fragment pieces of rock in space was studied. The principle of the sizes of empty space resulted from cut blasting with cavity was put forward; and the related calculation method was given, of which the results coincide with the results of 48 trials in a coal mine. The research results show that the ratio of fragment pieces thrown out of space is relevant to the characteristic of explosive, parameters of rock and types of charge structure.

The stability of a certain dam is improved by the method of splitting grouting, which is a very effective reinforcement method. The advanced FLAC3D method based on 3-D explicit finite difference method, is used to analyze the stability of a certain dam in Guangdong Province before and after grouting. The simulation and analysis practice shows that the advanced FLAC3D method is suitable for stimulating the stability of grouting dam. The conclusion of analysis is consistent with the in-situ observation.

Taking the influence each other among the moisture field, thermal field, stress and deformation field of soil body into account, the necessity of research on coupled heat-moisture-stress issues about loess, amargosite, frozen soil and pedology is explored. Then the research progress in the issues is reviewed and summarized. After that based on the analysis of the research work up to now, the weakness of mechanism research of soil coupled heat-moisture-stress issues is revealed; and it is pointed that defining the coupled parameters should be the heart of the matter.

It is difficult to describe the strain softening of geo-materials. In order to analyze softening mechanism of geo-materials in essence, it is necessary to combine the researches of softening mechanism with the researches of strain localization evolvement. The developments of strain localization researches in geotechnical mechanics, such as experimental researches, theoretical modeling and numerical simulations, have been reviewed. When strain localization happened, the necessity to consider the strain-gradient was illuminated. Some primary ideas about the trends of strain localization researches in geotechnical mechanics were put forward.

The ultimate bearing capacity of foundations is analyzed by elastoplastic FEM through step loading. As the loads increase, the foundation status changes from elasticity to plasticity gradually, and finally the numerical non-convergence occurs. The solution of a classical Prandtl example shows that different yield criterions affect the results greatly; and only the use of the proper yield criterion can lead to the precise results. Under plane strain condition, the best solution can be obtained while Mohr-Coulomb inside-tangent circle yield criterion and associated flow rule, or Mohr-Coulomb matched D-P yield criterion and associated flow rule are used; and it can be applied to the analysis of practical engineering.