Vertical drains including sand wells and prefabricated drains have been widely used to accelerate the consolidation of the ground consisting of soft clays. Various forms of analytical solutions have been proposed from time to time for evaluating the consolidation of homogeneous and isotropic ground with vertical drains under axisymmetrical conditions. In these solutions, however, the stress increases in the ground were assumed uniformly distributed along the depth of the vertical drain. It is evident that this assumption is not applicable to the cases where either the ratio of the depth of the vertical drain to the breadth of the surcharge-applied area is relatively high or the zone of influence of the vertical drain is in the vicinity of the edge of the surcharge-applied area. on the basis of an existing equal strain solution of radial and vertical coupled consolidation, this paper presents a solution for the situation that the stress increase in the ground is arbitrarily distributed along the depth of the vertical drain. In addition, the effects of the stress increase distribution and ramp loading rate on the ground consolidation are analysed. It has been found that the consolidation solution for a uniformly distributed stress increase underestimates the consolidation rate of the ground, whereas the solution for an instantaneously applied loading condition overestimates the consolidation rate.

Based on the relative independence of mathematical cover and physical grid, and considering the action of truely existent various equilibrant force in system for system balance, a method of simulation for excavation unloading using numerical manifold method in geotechnical engineering is proposed. Compared with the traditional numerical method, the numerical manifold method need not calculate the released load on excavation face, need not prepare special element for unloaded material part; simple mathematic grid can meet the arbitrary course of excavation; so it is more convenient and effective; at the same time, high-order manifold method has better precision for excavation.

According to a lot of field tests and numerical efforts, the spatial deformation mode of the top beam and pile is deduced for the cantilever soldier pile retaining structure in rectangular excavation; and the expression of the potential energy is derived for the total supporting system. Based on the principle of minimum potential energy, a new analytic solution to determine the maximum displacement of the pile head is derived; and the effects of the retaining structural parameters on the maximum displacement are discussed. Results show that the maximum displacement of the pile head increases with the increase of the surcharge and the spacing of the pile linearly. When the excavation length increases to a critical length, the maximum displacement will be a constant. In addition, the coefficient of the embedded depth of the pile has an dramatic effect on the maximum displacement. Finally, the result obtained from the proposed approach is compared with field tests and elastic resistance method.

In three-dimensional numerical manifold method (NMM), the total element test functions in the polynomial space are not entire when hexahedral solid meshes are given in mathematical cover. Non-entire high order terms cannot improve computational precision, but may play the contrary role. For avoiding the disadvantages, an additional incompatible manifold element rank formula is established based on the theory of Wilson incompatible element; Wilson incompatible numerical manifold method is presented. The element strain matrix and the element stiffness matrix are derived by eliminating the internal parameters. The method has high computing efficiency and accuracy under adding no generalized degrees of freedom. Finally several numerical examples are analyzed to illustrate the stability and convergence of the method. The results are shown that the method is highly validity and accuracy.

For the high strength reinforced concrete arc shaft wall, its mechanical characteristics including the radial displacement, the concrete stress, the reinforcing steel bar stress, the load carrying capacity and the position of crushing zone are analyzed by experiment and finite element calculation under uniform load. The results show that the radial displacement of the arc component is very small. The load under which the reinforcing steel bar is beginning to yield is 60 % of its load carrying capacity. The larger the ultimate uniaxial compressive strength of concrete, the higher is the carrying capacity of the high strength reinforced concrete arc shaft wall. As the strength grade of concrete increases 10 MPa, its carrying capacity raises 1.26 MPa. The crushing zones are both end of the arc component. So we design the arc shaft wall, both end of the arc component must be strengthened with the steel fiber concrete for enhancing the load carrying capacity of the shaft wall.

DX pile has a remarkable potential in uplift application. Comparing with the ordinary piles, the uplift failure mechanism of DX pile is discussed. Then the mechanism of loading transfer during uplift and the development of uplift friction on the main pile sides and on the branches of DX pile with depth are analyzed in detail. According to the structures of DX piles and the effects of the main-pile-side-friction and the soil-friction around the branches of DX piles, the equilibrium equation of DX piles’ uplift capacity in limiting conditions are deduced. After that, the calculation formula for uplift-bearing capacity of DX pile is drawn. Before presenting the design method and design procedure of DX piles, the related theoretical and experimental methods to decide the formula’s parameters are discussed. Finally, qualitative analysis of the major factors, such as the soil strength, the number of branches, the distances between adjacent braches and the angle between the surface of branches and the horizontal level, which will affect the uplift-bearing capacity of DX piles, are carried out.

The algorithm of three dimensional stratum (3D stratum) incision is the essential basis of the visualization of 3D-stratum and the calculation of excavated earth volume. For the moment, there is short of practical arithmetic in the cutting of stratum. Firstly, the 3D stratum is constructed by the method of modeling of triangular prisms, and then, by discussing all the cases of incised triangular prisms with an oblique plane, the incision algorithm for the stratum, which is composed by triangular prisms, are obtained. Thus, by taking the incision plane as an interface, a useful way to divide one triangle prism into several smaller ones is brought forward. The main principle is that, divide the top surface, bottom surface and the intersection of a triangle prism into several triangles according to a certain rule; and make the projections of these triangles in the horizontal plane coincided with each other; Constitute the three layered triangles into two layered small triangular prisms, which take the incision plane as an interface; thereby, the incision is finished. Further more, the calculation method of excavated earth volume is put forward too; i.e., given the boundary controlled equation for the excavated body; according to the inside boundary (which is limited by the equation), the excavated area can be easily obtained. By combining the excavated equation with the incision algorithm, incising triangular prisms with the planes that contain the excavated surfaces, aggregating all the triangle prisms that locate in the excavated volume, thus, the total volume of these triangular prisms will be equal to the excavated earth volume. Finally, by applying these two methods about triangular prism division and earth volume calculation to a certain major water supply project in Guangdong area, South China, the simulation of excavation for a foundation pit and its volume estimation is successfully realized.

A layered solid system with limited depth is cut off from a layered halfspace in horizontal direction. Rigid boundary is set for the bottom of the layered solid system. The layers of the solid system are divided into mini-layers. The dispersions of surface waves are obtained by stiffness matrix method. The dispersions of Rayleigh mode waves can be filtered out from dispersions of surface waves according to attenuation behaviour of vertical displacement of Rayleigh waves in bottom layer. The Rayleigh mode waves in the layered solid are corresponding to ones in layered halfspace within a certain range of frequency. The lower limit of frequency is related to thickness of layered solid. The bigger the thickness is, the smaller the lower limit of frequency is. The relationships between thicknesses of mini-layers, the thickness of layered solid and interested frequencies are analyzed.

Creep property of undisturbed and reconstituted Japanese clay was presented based on drained triaxial compression tests. Creep tests were performed several times during monotonic primary loading, unloading and reloading. Test results show that: (1) the amount of creep deformation during monotonic primary loading depends on strain rate before creep, creep stress level, and creep time; (2) during monotonic primary loading, the stiffness increasing magnificently shortly after creep; (3) the direction of creep will change from positive creep; to neutral creep and negative creep during unloading, while during reloading, it will change from negative, to neutral and positive creep.

Rock mass has much higher compressive strength than tensile strength, so engineers concern about not only plastic compressive-shear damage around charge hole but also tensile damage near the free-face when blast occurs in rock with a single free-face. These damages may touch upon construction safety and even property loss if the free-face is just ground surface. Previous researches ignore either compressive-shear damage or tensile damage, thus the conclusions drawn are difficult to meet the needs of engineering. Based on reasonable modes of stress revision, this paper incorporates an existing damage constitutive model which can separately consider tensile damage and compressive-shear damage into the commercial FEM software, LS-DYNA. Cylindrical and spherical explosions in rock mass with a single free-face are then numerically simulated. The results show that this method can well predict the distribution and evolution of blast-induced compressive and tensile damages.

The macroscopic mechanical characteristic of the rock material is integrated exhibition of the inner mechanical characteristic of this kind of material in mesoscopic view. While for the brittle rock material, the inner heterogeneity is important to its macroscopic crack form. The primary discussion on the heterogeneity of the brittle rock has been carried out with the method of evolving cellular automata. In this method, displacement, force, stress and strain are taken as basic variables of the system and the stress concentration and stress adjustment are reflected by quantitative analysis. In the macroscopic view, the brittle rock is a kind of heterogeneity material and its heterogeneity distribution is assumed as Weibull distribution. The slope parameter m is a important parameter that reflects the heterogeneity level of the heterogeneity distribution. From the numerical simulation examinations on the brittle rock material when it has different slope parameter in Weibull distribution, it can be drawn out that the heterogeneity expressed by the slope parameter in Weibull distribution is a important factor that influences the crack form of the brittle rock; and the more the slope parameter m is small, the more the composition of the rock is asymmetric, and the more the crack form is stochastic; while the more the slope parameter m is great, the more the composition of the rock is symmetrical, and the more the crack form is regular and similar to the elasticity material. It is consistent with the results of the experimentation.

Firstly, the momentum equilibrium equation, the continuity equation for water and the elastoplastic matrix are established. Secondly, by using the Galerkin method all the governing equations are discretized in the space domain and in the time domain respectively; then a two dimensional FEM code for coupling hydro-mechanical elastoplastic analysis of saturated-unsaturated porous medium is developed tentatively. Through a numerical computation for the assumed coupled hydro-mechanical problem of prestressed bolting support in a saturated- unsaturated soil body located a seepage field, it is shown that under the saturated-unsaturated condition , the prestressed bolting decreases mainly the plastic zone in the soil body; its restraint action for displacements changes according to the soil positions; and its influence on sepage field is not obvious.

It is important to evaluate the safety of large cylinderical structures against overturn under possible conditions. Elastoplastic FEM is employed to solve this problem. First, a load-displacement curve of a cylindrical structure under certain condition is obtained by varying the load amplitude in the finite element analysis. Then the ultimate load that the cylindrical structure can bear, can be obtained, which is the upper bound load value at the load-displacement curve. Finally, a factor defined as the ratio of the ultimate load to design load is used to estimate the safety against overturn. The proposed method can avoid the difficulty existing in the current limit equilibrium analysis method, in which the earth pressure on the cylinder surface and the center of rotation must be determined. Furthermore, FEM can consider the interaction between the cylinderical structure and soil around. A practical case is analyzed to validate the applicability of the method.

Influences of loading rate on the stress level when a system composed of fault band and elastic rock was formed, the size of plastic zones, the patterns of localized shear band, the maximum load-carrying capability of the system, and on the stress level when the snap-back of the system occurred were modeled numerically by FLAC (Fast Lagrangian Analysis of Continua). The adopted failure criterion was a composite Mohr-Coulomb criterion with tension cut-off; and a linear strain-softening post-peak constitutive relation of rock was adopted. In general, after fault band-elastic body system is generated, the load-carrying capability of the system reaches its maximum value. Thereafter, it begins to decrease so that the system is in strain-softening stage. If the post-peak stiffness of compressive stress-compressive displacement curve for the monitored element at loading end of plane strain specimen is high enough, the snap-back (unstable failure) of the system occurs. As loading rate increases, the stress level corresponding to the formation of the system and the corresponding displacement increase; the maximum load-carrying capability of the system and the corresponding displacement increase; the stress level when the snap-back of the system occurs and the corresponding displacement increase. As loading rate increases, the number of yielded elements increases and the thickness of fault band no loner remains a constant, leading to an increase in deformation resistant of the system. For higher loading rate, it is possible that higher shear strain rates are concentrated into both fault band and some elements remaining elastic outside the band.

Based on soil slope face grids, a new method is put forward to globally search critical slip surface on slopes. It has preferably utilized both optimization advantages of geometrical and numerical model. Furthermore, its theory is easily intelligible. If assisted by experience analysis on some degree, it will more efficiently get the critical slip surface on soil slope. Two examples are given; the results are both of good convergence and integrity. The method is applicable to some complex soil slopes.

In the study of piles jacking in soil, cavity expansion method（CEM）in infinite space is usually used to simulate the expansion of piles. But pile jacking took place in semi-infinite space, the difference of stresses in boundary between semi-infinite space and infinite space should be analyzed. Considered the surface stresses correction of semi-infinite problem and based on existing research, a new elastic method is presented to develop the CEM to satisfy the semi-infinite space by using stress function. Surface stresses can be corrected by using this method. It is proved to be advanced compared with existing methods and can be used for further research.

Binary medium modeling of the brittleness variety of geomaterials under different stress paths

3D strata model is useful to support underground engineering, and borehole data is the chief source for 3D geology modeling. For the complexity of geological entity and the sparsity of sample data, it is unable to control the accuracy of modeling outcome only using scattered borehole data. Based on the analysis of the source of modeling error, two approaches for error correction of 3D strata modeling from borehole data, called the cross-section method and the virtual borehole method, are presented. During the modeling process, cross-sections and/or virtual boreholes can be added directly to the 3D strata model in the proper place for the engineers’ demand and comprehension. Cross-sections and/or virtual boreholes, which represent the local variation character, restrict the model just as real boreholes to generate solid model accurately, and it is easy to correct the error of 3D strata model using those approaches.

By the method of Laplace transform, consolidation of viscoelastic soil under arbitrary loading was studied. The general solution in the Laplace transform field was obtained; and then the effective stress and average degree of consolidation in the soil under arbitrary loading could be calculated by the Laplace inversion. In addition, according to numerical examples, the influence of parameters of Merchant model on the consolidation was investigated. The results show that the rate of effective stress increment is different from that of settlement during the consolidation of viscoelastic soil and the viscous effect can result in faster effective stress increment in the early stage and slower effective stress increment in advanced stage. Obtained results also indicate that the consolidation of soil layer is more sensitive to the change of modulus in separated spring than that of modulus in Kelvin spring under cyclic loading.

The ANN model has great potential in predicting durability of geasynthetics, because of its unique learning. training and prediction characteristics. By contrast to the regression method , the ANN method doesn’t demand the regulation of the experiment data. Based on 31 groups of experimental data obtained from aging tests of non-woven polyester, a BP neural network model for predicting durability of geosynthetics is developed. The model proposed has four parameters (the temperature, relative humidity, aging time and ultraviolet radiation) at input layer and two parameters (strength and percentage elongation) at output layer. The comparison between the prediction values and experimental results shows that the model proposed has high accuracy for predicting durability of geocynthetics.

A series of static piling tests and SPTs were performed to investigate the behavior of jacked piles. The study focuses on the changing law of pile toe resistance and shaft resistance in different soil strata. Then an empirical formula is put forward to calculate the jacking resistance and a visual computer program is worked out. Two calculation engineering examples indicated that the method is feasible. The calculated jacking force satisfies the engineering precision requirement. It can be concluded that the method is convenient to judge driveability of pile, estimate the bearing capacity of pile and select the jacked piling equipment. The study is significant because the SPT data is commonly used can be easily obtained.

Light heterogeneous soil mixed expanded polystyrene is a new kind of fill materials. The test studies are very scarce in China. In present study, based on unconfined compressive tests, the relationships between failure strain and compression strength, and between deformation coefficient and compression strength are analyzed. And according to one-dimensional consolidation compression tests, yield stresses and compressive modulus under different conditions of mixture ratios are obtained so as to provide reference for the application in engineering.

At present, the method for determining anchorage angle of foundation beam with prestressed anchor-cable is usually the same as that in the prestressed anchorages engineering. Therefore, some slopes cannot be reinforced efficiently by foundation beam with prestressed cable because of the unreasonable designed anchorage-angle. A new method for designing the reasonable anchorage-angle is proposed. Firstly, an initial criterion there is no slip between the beam and the slope surface is proposed. Secondly, the highest possible anchorage power must be obtained in the design, and it is the design objective. Prestressed utilization-ratio is defined as the ratio of the real anchorage stress to anchor-cable prestress. So, the anchorage angle can be determined rationally considering the initial criterion and the utilization-ratio and giving attention to the economic and construction factors. Finally, an engineering example is given to explain how to use this method in practice.

Using the numerical calculation method, the relevant material parameters are stemming from the model test researching the anchored effect of partly cement-imbedded anchor cable on weak country rock cavern and supposing that the surface force of friction of cement body is in proportion to the relative displacement between the rock and the cable, this paper studies the anchored effect of the fully cement imbedded anchor cable on the same cavern with the model test; and gives the displacement curve of the cavern walls and the curve of the surface force of friction of cement body; and obtains such conclusions that the displacements of the anchored cavern are reduced etc.

The reduction theory for elastic modulus and Poisson’s ratio is given according to the stress-strain hyperbolic curve of the soil. The result of an example shows that the Poisson’s ratio has a significant influence on the safety factor and the plastic zone of the slope; but the elastic modulus don’t have a significant influence; the displacement controlled-method is suggested to take for the finite element analysis to solve the safety factor of slopes because of this method is good in stability and convergence.

By means of investigation on the engineering geological conditions, numerical modeling, and theoretical analysis, the mechanism of the karst water burst and its prevention countermeasures in Yuanliangshan tunnel are researched systematically. The results show that the karst water burst in tunnels is a gradually developed process, which is influenced by water pressure, different filling materials and the plastic zones around the tunnel. The mechanism of the karst water burst in tunnels is summarized; and in light of the karst conditions exposed in Yuanliangshan tunnel, the principles for preventing the karst waterburst are established. Thus, construction of tunnels under complex karst conditions with safety and high efficiency has been achieved.

The new K-G Model that considers the dilatancy and strain softening of soils and the widespread E-u model are applied to 2-D finite element aualysis of stress-strain of Zipingpu Concrete Faced Rockfill Dam. The result of the K-G model is compared with the results the E-u model and, 3-D FEM stress-strain analysis of the dam and the prototype observations of the other built projects to obtain the stress-displacement law of the dam. The result of the settlement and level displacement of the dam applied the new K-G model is normal. Especially, the new K-G model is more rational than the E-u model at the side of the horizontal displacement. The results test and verify the new K-G model’s rationality initially.

Time-settlement data of more than 60 different sections of the 31.2 km long Lianyungang-Xuzhou expressway in Lianyungang segment are analyzed. The results indicate that the time-settlement behavior could reasonably be represented by the hyperbolic relationship. According to the estimated long-term settlements, the consolidation characteristics of soft ground improved by using sand mat or dry jet mixed columns are analyzed. The relationships between average degree of consolidation and time in the filling-term and the preloading-term are studied respectively. Results indicate that the presence of dry jet mixed columns could accelerate the consolidation rates of soft ground; although soil-cement columns are considered to be impermeable. In addition, an empirical estimating formula for the magnitude and rate of consolidation settlement of Lianyungang marine clay are proposed by the method of statistics.

The field experiments on monitoring land subsidence in large area by GPS-RTK are carried out in different distances and different time intervals. The experiment results are analyzed; and some key parameters about effects of distance and observational duration on precision of monitoring are obtained so as to be helpful in practice of land subsidence monitoring using RTK and in formulating specifications.

The settlement trough induced by the shield construction is researched deeply based on the raw test material in situ in metro section between Longdong road and Century Park; the relationships between the shape of settlement, influence scope, width coefficient, the location where the largest settlement appears and the depth of the tunnel, are presented. And the quantitative relations between largest settlement, the width coefficient and the depth of the tunnel are given using the statistical method.

The wholesome soil nail wall is designed for the Xiaoguweidao metro station while part foundation segment is reinforced with steel pipe. Furthermore, the design of bored cast-in-place pile with prestressed interior support is taken for the shield work station and turning-back station. The theoretical calculation of foundation design is carried out with Lizheng software, the results prove that the foundation is safe. The supervision design is put forward in order to guarantee the foundation safety; supervised results. are analyzed It is obvious that the experience is worth for reference in the similar case.

Based on researching the principle and application of Sarma method, the traditional Sarma method has been improved considering the reservoir region slopes’ characteristic after storing water. Floatage is smartly added in calculation. Finally, the improved method has been applied to evaluating the stability of a creeping rocky slope at the left bank of Longtan Hydropower Station in China.

In the entrance zone of the tunnel with fleet mantle soil, loose and unstable wall rock, many slits appeared during the excavation. Through comparing several schemes, steel tube-grouting was adopted to reinforce the wall rock and the foundation of the tunnel. While grouting construction began, excavation also carried through inside the tunnel. This will unavoidably affect the stability and safety of the tunnel. Therefore, a practical project is offered and the monitoring data are analysed under the circumstance of several working procedure affected each other. Some preliminary conclusions are drawn.

The blast method to squeeze mud and replacement with controlled loading had been applied to the design and construction of breakwaters at the first stage of the project of Yangjiang Nuclear Power Plant. The method ensured the expectable bottom width and depth of the breakwaters. The problem of formation of wide platform underwater was also solved. At the meantime, the amount of work to trim slopes was reduced. It was a successful application of blast methods of marine soft foundation processing in the design and construction of breakwaters.

Direct shear tests on two different kinds of sand were conducted by the newly developed large direct shear apparatus designed for field and laboratory test. On basis of the illustration on direct shear characteristics of sands, the test data of sands from the large direct shear tests are analyzed in different views. The analytical results show that the test data from the large direct shear apparatus are consistent with high reliability; and it is shown that the basic shear capability of the large direct shear apparatus is better. The large direct shear apparatus can be applied to other corresponding geo-material investigations.