Advanced Materials Research Vols. 446-449

Abstract: The Various methods of optimization or random search have been developed for locating the critical slip surface of a slope and the related minimum safety factor in the limit equilibrium stability analysis of slope. But all these methods are based on a two-dimensional (2D) method and no one had been adapted for a search of the three-dimensional (3D) critical slip surface. In this paper, a new Monte Carlo random simulating method has been proposed to identify the 3D critical slip surface, in which assuming the initial slip to be the lower part of an ellipsoid, the 3D critical slip surface in the 3D slope stability analysis is located by minimizing the 3D safety factor of limit equilibrium approach. Based on the column-based three-dimensional limit equilibrium slope stability analysis models, new Geographic Information Systems (GIS) grid-based 3D deterministic limit equilibrium models are developed to calculate the 3D safety factors. Several practical examples, of obtained minimum safety factor and its critical slip surface by a 2D optimization or random technique, are extended to 3D slope problems to locate the 3D critical slip surface and to compare with the 2D results. The results shows that, comparing with the 2D results, the resulting 3D critical slip surface has no apparent difference only from a cross section, but the associated 3D safety factor is definitely higher.

Abstract: Combined with practical engineering application, the test researches were carried out to analyze the soil compacting effects of Cast-in-situ concrete pipe pile while the pile was driven by vibration hammer. This article is focused on the characteristics of soil uplift and lateral deformation around pile, included surface soil and deep soil. In addition, the change characteristic of pore water pressure of soil around pile is also analyzed, and some useful rules were concluded. All researches are helpful to optimize the construction parameters, such as distance between piles, pile diameter etc., to improve the quality of pile foundation, also to reduce the construction impact on environment.

Abstract: Constitutive modeling in unsaturated soil is always a big challenge in Geo-technique problems. Since Alonso et al suggested the Basic Barcelona Model (BBM) in 1990. Many researchers contribute works on constitutive models in last two decades. The SFG model presented by Sheng, Fredlund and Gens describes the mechanical and hydraulic behaviors of an unsaturated soil accurately. It is currently considered the most reasonable model for unsaturated soil. In this paper, the authors attempts to prove the volume change behavior in SFG model by two basic unsaturated soil experiments in testing two different soils. The experimental data and the fitting processes are provided.

Abstract: Based on a project, a numerical analysis model was established by the finite difference program and the process of the deep excavation and support was simulated by computer, the distribution of the horizontal displacement and settlement of the top of slope of the slope soil were obtained. The simulation result was consistent with the test results. It shows that the method of numerical analysis can be used to the simulation of the excavation and support of Deep Foundation Pit, and it will provide the basis for the design and construction of practice project.

Abstract: A 2-dimensional granular assembly, subjected to isotropic consolidation and biaxial compression, is simulated by applying discrete element method and the particle flow code of PFC2D. The contact force network and distribution are examined and compared to an analogous photoelastic experiment carried out by other studies. The current study shows that the assembly undergoes dilatation and strain-softening after peak strength, and the coordination number (average contact number of particles) increases a little in the initial stage of strain hardening followed by a sharp dropping before the onset of softening. This is correlated with the contact force chain establishment and the evolution of structural anisotropy. The distribution of the normal force and the ratio of tangential to normal force for both the isotropically compressed and sheared stages indicates that the strong normal contacts are crucial for the force chain transmitting stress through assembly. The angular distribution of the contact forces supported this point and could help visualizing the induced anisotropy. These issues are vital for gaining a deeper understanding of the macroscopic behavior of granular material from microscopic analysis.

Abstract: The large-size flexible shallow foundation （LFSF） can not be designed fully in accordance with the shallow foundation design specification, for there are differences between LFSF and traditional shallow foundation. Taking the foundation project of Shenzhen Mawan port for example, considering the interaction between foundation and ground base and adopting a non-linear foundation model, the impact of foundation parameters and load conditions on basal pressure and foundation settlement were simulated to value adoption of the height-width ratio by finite element method. Analysis showed that soil physical parameters of elastic modulus, Poisson's ratio had great impacts on basal pressure and foundation settlement, and the accuracy of these parameters should be ensure in modeling. However the effects of expansion angle and cohesion were relatively small. The values of expansion angle and cohesion can refer to design specification. Foundation of this type mainly focus on flexural design.

Abstract: Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

Abstract: The incorporation of virtual reality-based technology into architectural design is one of the directions developing the future architectural design. It is inevitable to bring profound effects to architectural design. This subject puts emphasis on limitations and deficiencies of expression and display in architectural design. Virtual reality-based technology, especially based on Web3D, is available to improve solutions and make certain accomplishments.

Abstract: The slope stability analysis in cold region is special for its non-uniform temperature field. Considering the special characteristic of the slope in cold region, the physical parameters of frozen soil are treated in this paper as the connection between temperature field and stress field. The temperature influences mechanical properties of frozen soil and forms freezing-thawing interface in the slope, which make great influence on the stability of slope. The critical slip surface searching algorithm for cold region is developed and the moment center solution method in the computation of slope’s stability coefficient is also improved. The critical slip surface and stability of 4m subgrade with 1: 1.5 slopes under different soil temperature condition is computed using the developed frozen subgrade stability computation program. The results shows that the line segment type slip surface is more accuracy than circle type slip surface in cold region slope stability analysis; moreover, the minimum stability coefficient of frozen subgrade does not happen in tenth months when the thawing soil goes to deepest, but show in the early time of warm season, forming the phenomenon of thaw slumping. And it is also found that the occurring time of yearly minimum landslide stability coefficient postpones as the decreasing of soil temperature.

Abstract: Multi-passage leakage often occurs in earth-dams, the locations of all seepage passages must be located actually to repair the dams absolutely. Fluxs and temperatures of water in passage and in pore of soil are different, so the special temperature distribution of this kind of dam is formed by heat transfer. Locations of concentrated leakage passages are assumed known. Analysis formula for temperature field of the dam with multi-passage leakage is established by that of the dam with single leakage passage. Coordinate is transformed by model of Bursa–Wolf with six parameters. Finally, the mathematic model for detecting multi-passage concentrated leapage in dam by temperature is put forward. In case, plane model for detecting column passage is established by simplifying conditions.