Applied Mechanics and Materials Vols. 405-408

Abstract: Based on the one-dimensional constitutive relationship of unsaturated soils, this thesis has established the calculation model for embankment settlement with lateral deformation and without lateral deformation in accordance with the mechanic characteristics and in consideration of the influence of water environment. In addition, the thesis has provided the calculation methods for embankment settlement under various working situations (like under the situations of external load function, self-weight effect, increasing of the groundwater level, the invasion effect of rain water and the comprehensive effect of various working conditions) and used the settlement deformation results from the experiments of embankment models to check the calculation method. The method put forward in this thesis could not only be used in the calculation of the settlement deformation under load, but also could be used for the calculation of the deformation caused by the changes of water content in the embankment.

Abstract: The sublevel caving mining method is widely applied in China's underground mines, in particular of iron mines. Its mining work is under the protection of loose coverage rock. The loose coverage rock is located in the stope for a long time, and its frequently squeezed from production blasting, impact effect and the colliding and breaking in the falling process, it comes into being a large number of powder and small pieces of rocks. The rock powder and small fragments have such characteristics-good mobility and strong permeability. With the increasement of mining depth, the rock powder and small fragments in the loose coverage rock will be earlier to reach the ores than the big fragments of the same level. As a result, ore dilution will prematurely appear. To better know the phenomenon, this paper explores ore dilution of different fragment distribution of loose coverage rock by physical simulation experimental method. The research results have certain guiding significance for the actual production of underground mines.

Abstract: Based on the load transfer mechanism of bolts, the relationship between the axial load and shear displacement of bolt changing with the dilatancy of joint was analyzed, then the theoretical solutions of axial load of the bolt were verified by the direct shear test of bolted rock mass with different normal stress (0.5MPa, 0.7MPa, 1.0MPa) applied on the joint. The results show that the calculated values fit well with the results of tests; the increment of dilation angle can enhance the axial force of bolt quickly, but decrease the length of crushing failure zone.

Abstract: In order to describe the failure behavior of anisotropy sand, a failure criterion with the method of macro-micro incorporation is employ. A fabric tensor employed in the method describes the material microstructure and a novel anisotropy state variable is properly defined in the term of the two joint invariant of loading direction tensor and fabric tensor, then a failure criterion of anisotropic soil is proposed with the novel anisotropy state. The failure criterion is compared with experimental results from the literature to show that it is able to capture the conditions obtained in three-dimensional experiments without and with stress rotations. The limitations of the criterion are demonstrated by its failure to capture the behavior of some sand with particular micro-structures.

Abstract: Based on the construction of diaphragm wall groove of Hangzhou metro station engineering and combined with construction practice, detection and simulation, the groove stability of diaphragm wall in high confined water stratum was studied in aspects of construction parameters and geological conditions. Studies have shown that, the high confined water stratum is an important factor in the groove stability of diaphragm wall, the buried depth of head should be reduced; the deformation of groove wall reduces significantly with increasing in mud specific weight; and the width of groove should be control well.

Abstract: Keywords： Scour Depth, Water flow Force, Finite Element Method ABSTRACT. In recent years, the researches on the impact stability of piers based on river erosion are concerned in Taiwan. Therefore, it is an important issue to estimate accurately the scour depth, to calculate the water flow force on bridge pier, and to establish the close mechanism of bridge for saving lives. This research is a case study on Paulon Bridge by finite element method (FEM) Plaxis 3D Foundation for simulating analysis the caisson foundation in bridge pier scour. Firstly, we infer the flood level, the speed of flow in the different frequency year, the whole bridge safety coefficient, and the inclination angle of pile based on the simulating analysis to build the warning system. We compare the data by FEM and observing data in order to confirm the validity of FEM.

Abstract: To investigate the shear strength properties of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m³, the moisture content is 17.0%, the plasticity index is 9.4, the cohesion force varies from 20.8 to 28.3kPa, and the internal friction angle varies from 12.3 to 31.8degree. Finally, the properties of the shear strength are studied, and find that the relationship between the shear stress and the shear strain is conformity with the strain hardening curve, and the relationship between the shear strength and the vertical pressure applied on the soil samples is linear, and agrees with the Coulombs law.

Abstract: Direct shear test is broadly used to get the strength of soil, joints, and specific material in the field of geotechnical engineering because its simple structure and easier operation. But the current direct shear strength calculation does not concern on the variation of the shearing surface during the test, has no regard for the effects of the shearing area on the shear strength, so the test result is not the really strength of the samples. To discovery the affection of the shearing surface on the direct shear strength, three different calculation methods of shear surface and its affection on the shear strength were put forward based on the new mathematical model and large number of experimental with improvement direct shear apparatus, the new calculation method makes the result more accuracy and closer to the really shear strength of the samples.

Abstract: approximate analysis formula for the water flow of single fracture and variable water temperature has been deduced considering the impact of water temperature to rock fracture seepage. Following conclusions were drawn: (1) The water head and the hydraulic gradient in single-fissure have nonlinear relation. Seepage curve was convex curve if water flows from higher temperature areas to lower temperature area. On this condition, the water head slants low under liner seepage simplification. On the contrary, Seepage curve is convex curve if water flows from lower temperature areas to higher temperature areas, and the water head slants high. (2) In a single fracture, the hydraulic gradient is smaller in the higher temperature zone and is larger in the lower temperature zone. The higher the mean water temperature of fracture was, and the faster the flow velocity was.

Abstract: The original iterative method of the saturated-unsaturated unsteady seepage FEM analysis is presented. According to the character of the iterative process, an iterative coefficient is introduced, and a new method is formed. The improved iterative method can enhance and accelerate convergence of the computation efficiently by selecting suitable , and make the saturated-unsaturated unsteady seepage FEM analysis have broader engineering applicability. Three-dimensional FEM analysis program for saturated-unsaturated unsteady seepage is compiled based on the improved algorithm. The algorithm is validated by an analysis example.