Applied Mechanics and Materials Vols. 353-356

Abstract: Yangpu Port has inhomogeneous soft soil with the properties of high water content, high void ratio, high compressibility and low shear strength. Based on soft soil ground treatment engineering practice, the geological characteristics are summarized, the ground treatment methods are comparatively analyzed, static-dynamic drainage consolidation method is chosen to treat the soft soil ground, the reinforcing mechanism of vertical and horizontal drainage system are discussed, the design of drainage system, preloading and dynamic consolidation are researched and the surface settlement monitoring, pore water pressure monitoring, side piling displacement monitoring, laboratory soil test and plate loading tests are carried out. The results show that average surface settlement is 1170.8 mm, the physical and mechanical properties of soft soil are improved and the characteristic value of foundation bearing capacity is greater than 120kPa.

Abstract: The function of three fields coupling of water-heat-mechanics is derived and established. The finite difference software FLAC3D is applied to simulate the affection of three fields coupling of water-heat-mechanics of the slope in the saturated state. The mechanism of instability and failure of the slope is revealed from two aspects like freezing depth and frost heaving deformation in the condition extreme snow hazard. The results show that freezing only occurs on the slope surface in the short time which makes no affection on the deep part; with the time lapsed the temperature in each depth decreases gradually and additionally with the increasing of the depth the effect of the surface temperature slows down. In the shallow part the temperature declines with the surface temperature declining and slows down with the increasing of depth. In the process of freezing the displacements occur on the surface to the direction of free boundary. In addition, the frost displacements increase with the time lapsing.

Abstract: The primary causes of non-uniform settlement for buildings on collapsible loess are large settlement of subsoil, local subsidence foundation, frost heaving of ground, infusion foundation, underground water level decrease and the influence of adjacent buildings and so on. According to the characteristics of the project, analysis the reasons of building that non-uniform settlement and fissure on the wall. Combine the method of reinforce the rectification for original building, put forward the method of reinforce the rectification which is applicable to the project. And put forward some suggestions for collapsible loess area construction, for the colleague reference.

Abstract: Soil-rock mixture is a special kind of geological media,which is mixed of soil particles with weak intensity and rock blocks with strong stiffness and irregular shape. The rock blocks and soil particles cement with each other. The mechanical property of soil-rock mixture is different from rock and soil mass. This paper apply The digital image analysis technique is used to distinguish the features of rock and soil mass,and the model according to the corresponding relationship of cell and pixel is established ,then the numerical statistical laws of pixel can be obtained. As for the pixel between rock and soil mass that cant be distinguished distinctly, the cellular automata theory that with the mean function as the 2-dimensional transformation function is used to transform the image.Then the pixel of rock and soil mass can be distinguished.At the same time it can remove the effect of islanding pixels. Thus it can realize the more effective recognition for soil-rock mixture. It shows good effect through comparison.

Abstract: Saturated frozen soil is composed of soil, unfrozen water and ice, whose subgrade deformation is due to the weakened of internal structure which coursed by damage of the materials in the process of the cycle of freezing and thawing. Considing of the heterogeneity of saturated frozen soil and the phase transition between water and ice, and using of the damage mechanics theory, thermodynamics theory, filtration mechanics theory, a constitutive model of saturated frozen soil is setted up, which is of the coupfing problem of temperature field, water field and stress field. The rationality and validity of the model is verified by the experiment. It is also provided a new method for the study of frozen soil.

Abstract: The foundation settlement of soft soil highway engineering is too large, resulting in pavement wave-like because of differential settlement between the structure and adjacent soft soil foundation, which seriously impacts on traffic safety. Considering the soft soil foundation in the foundation treatment methods of CFG pile, sand bag well, powder spraying pile, we analyze differential settlement on the degree of influence structure internal force distribution, then provide the reference for the design and calculation.

Abstract: The circulating water pump house pit excavation of Chen Jiagang power plant is characterized with complex geological and hydrological condition, high water level, and weakly permeable silt layer within the scope of pit excavation. Based on design and construction principles of safety, feasibility, rationality and economy, different foundation pit dewatering and support programs were analyzed and compared, a excavation method featured with well dewatering and steel pipe soil nails hanging net and stakes was elaborately designed, and establish a monitoring feedback system. And in the base of mathematical statistics, Taylor series method is used to analyze the reliability probability problems of excavation slope stability analysis. The successful implementation of the project indicated that the design and parameters of Chen Jiagang power plant circulating water pump house pit excavation is feasible, and Taylor series method combined with conventional safety factor is able to analyze the influence of material parameters variation on the excavation of the slopes safety.

Abstract: Aimed to the problem of excavation and stability for a high and steep rocky slope, with the design excavation height of 90.23m, this paper grasped the engineering geological conditions and physical and mechanical properties of rock mass by such following methods as the field engineering geological survey, measuring, drilling sampling and laboratory test. Based on this, a comparative analysis of two different excavation ways was conducted using the large discrete element program-UDEC. The analysis included the stress-strain law and deformation failure trends of the slope when adopting slow excavation and steep excavation respectively. Moreover, the environmental damage caused by the two excavation ways was discussed. The results show that the slope has a better engineering geological condition and stability. In order to avoid disturbing hills and protect the natural environment, the steep excavation way is suggested for excavation and reinforcement of this slope.

Abstract: The principal objective of this study is to make use of medium and strong motion data from instrumented shaking table tests to evaluate the effects of kinematic soil-structure interaction on foundation input motion (FIM). The shaking table tests consisted of a 2×2 pile group in two-and three-layered liquefiable soils (models 1 and 2). Each test model was subjected to three realistic earthquake motions with peak accelerations ranging from 0.13g to 0.50g, and time step ranging from 0.006 to 0.02 sec. The three input earthquake motion represented the realistic earthquake motion with high frequency, low frequency and high amplitude. The foundation/free-field ground motion variations were quantified in terms of acceleration time histories and Fourier amplitude spectrum. Preliminary analysis of the data suggests that (1) regarding the input motion with high frequency, the higher peak acceleration of the foundation indicates the structure feedback and kinematic interaction between the soil and foundation during shaking; soil layering has little effect on foundation input motion, (2) regarding the input motion with low frequency, the kinematic soil-structure interaction increases the foundation response for model 2 while reduces it for model 1. The soil profile has significant effect on the predominant frequency, (3) regarding the input motion with high amplitude, the higher response of foundation in model 1 indicates the stronger kinematic SSI effect. The small deviation between the free field and foundation in model 2 indicates the coherent motion of the foundation with soil and no obvious kinematic SSI effect, (4) soil liquefaction has significant effect on the values of peak acceleration and peak Fourier amplitude.

Abstract: The limit equilibrium method based on the results of numerical calculation is an important method for slope stability analysis. In this paper, PSO is used to control the locations of trailing edge and shear outlet, while the progressive approach method is used to control the radius of slope sliding surface. It achieves the location search of the potential sliding surface as well as the calculation of the corresponding safety factor. So the minimum safety factor and the location of the most dangerous potential sliding surface are determined. Taking a slope section plane of Xiluodu Hydropower Station as an example, the most dangerous sliding surface having been searched out is compared with the results of field surveys. It shows that the results of the proposed method are in good agreement with the actual engineering, and the validity and the correctness of the approach are also verified.