Applied Mechanics and Materials Vols. 170-173

Abstract: Regarding the soil skeleton as viscoelastic medium with fractional derivative constitutive behavior, the influences of the soil skeleton viscosity and the soil layer thickness of saturated fractional derivative viscoelastic soil layer on the vertical vibration amplification coefficient is studied in the frequency domain by using the theory of Biot and one dimensional wave. The analytical expressions of the displacement, stress and pore water pressure of saturated soil layer are obtained by decoupling dynamic control equations and bounding the soil layer boundary conditions. The influences of physical and geometrical parameters of the saturated soil on vertical vibration amplification are investigated, and it is revealed that the vertical vibration amplification of the saturated classic elastic, fractional derivative type viscoelastic saturated soil and saturated classic viscoelastic soil are different when the soil layer thickness are changed; the material parameters of the fractional derivative model have great influences on the vertical vibration amplification coefficient.

Abstract: Physical model experiments are conducted to study the potential deformation and failure mechanism of Zhaoshuling landslide in the reservoir area of the Three Gorges project under the action of reservoir impoundment, water level fluctuation, building load and possible seismic load. Dial gauges, grid lines and digital cameras are used to monitor and record the deformations and displacements of the models. Research results indicate that the landslide will be basically stable while covered with seven-floor buildings whether the water level be at 145m or 175m, or falls abruptly from 175m to 145m. When the intensity of an earthquake is beyond certain degree, the rock mass will deforms and lose stability partly; and its stability will be worst when the water level falls from 175m to 145m, stability will be better when the level being at 145m and it will be best when the level being at 175m. It also indicate from deformation and failure mechanism revealed by the experiments that the best position of reinforcement measures is in Yanjiang Avenue, and the sliding resistance of the rock mass in the front part of the landslide can be used.

Abstract: According to field measurement datum in disturbed overburden stratum of five drillings, disturbed overburden stratum movement characteristics were analyzed. Negative exponent function model of measurement points movement law was also constructed. Moreover, variation law of stratum subsidence speed and relation between overburden stratum subsidence factor and surface subsidence factor were deeply researched. The results show that starting-distance of panel is nearly 70m, bedrock and alluvium subside synchronically and key-stratum isn’t exist in overburden stratum. Also, displacement curve of measurement points in stratum submits negative exponent function model and mutagenesis of surveying points subsidence speed is the key position where face passed drilling 100m. Furthermore, subsidence factor of overburden stratum and surface submits exponent function model.

Abstract: The research on slope is concentrated on stability analysis at present. Although there is little research on slope surface shape, it has important theoretical and practical significance. Based on guaranteeing the same earthwork, the shape of slope surfaces between single gradient slope surface and two-gradient slope surface whose lower part is steeper than upper part are compared. It’s concluded that (1) based on guaranteeing the same earthwork, two-gradient slope surface, whose lower part is steeper than upper part, is stabler than single gradient slope surface and when the lower part is vertical wall, the slope is stablest; (2) the height of vertical wall has a knee point, i.e. when more than this value ,the stability of slope decreases.

Abstract: The high cambrian black rock series of clay under Zhijin, Kaiyang, Xifeng and other areas of Guizhou , are high carbon black shale - clay rocks characterized by containing illite ores[1]. After deep processing, it will be served as illite ores belonging to a useful clay minerals, and the main directions of development and application include filler, new building materials and ceramics. After the activation, potassium can be extracted from illite that is often rich in potassium which can be prepared for potash fertilizer. Carrying out the study of mineral material science of high carbon black clay mineral rock , the aim is developing and using this type of non-metallic mineral. Based on this study, recoverying useful metal elements by exploring the reasonable technical process will be significant to enhance the comprehensive value of the type of deposit and improve its economic efficiency.

Abstract: In this paper, the slope before failure is considered as an elastic body subjected to gravity only. With known stress distribution in the slope, stability analysis is carried out by the limit equilibrium method according to the Mohr-Coulomb criterion satisfied by the slip plane. The method proposed in this paper is different from the previous methods, as there is no need to divide the slope into vertical elements or to assume the normal stress distribution on the slip surface. Instead, the solutions are found by directly using the elastic stress solutions in the slope. The equations derived are straightforward and most of them are explicit expressions, which facilitate analyses on the effects of mechanical properties and geometric parameters on the slope stability. This method has clear physical meaning and few assumptions are made.

Abstract: Aiming at researching on stability of slope affected by precipitation intensity, transient saturated-unsaturated seepage finite element method and slope stability finite element method are combined in this paper. Vadose field of slope is simulated in different precipitation intensity. Based on vadose field, the writers analyzed the stability of slope affected by precipitation intensity. The research results indicate that water is brought together in the interface first. Then the water level moves toward up and down respectively from the both sides of the interface. On the basis of saturated-unsaturated seepage theory, precipitation intensity has little effect on the slope stability in the first 6 hours after precipitation. After that, slope safety coefficient is relatively high when precipitation intensity is smaller, and vice versa.

Abstract: The hydraulic conductivity fracture zone is the main channel causing inrush disaster in mine. This paper makes a few analysis on the effect of the location of primary key stratum through the theoretical analysis and numerical simulation. The results show that: (1). When the distance from key stratum to coal seam is about 3 times than the height of coal seam, the hydraulic conductivity fracture zone is higher than normal but the caving zone is lower than normal. When the distance from key stratum to coal seam is about 11 times than the height of coal seam, the hydraulic conductivity fracture zone is lower than normal but the caving zone is higher than normal; (2). The effect of Winkler foundation is obvious when the distance from key stratum to coal seam is 7 times than the height of coal seam, more even but the inverse is not; (3). We can certain whether the key stratum is fractured or not according to the hypothetical rock cohesive force expediently.

Abstract: Colabed methane system is a natural system that consists of coal seams, coalbed methane in them and surrounding rocks. As an unconventional natural gas, reservoir and conservation of coalbed methane are different from those of conventional hydrocarbon. The Qinshui Basin, covering an area about 30,000sq.km in southeastern Shanxi Province, has abundant coalbed methane resources in the carboniferous Taiyuan formation and permian Shanxi formation, with an in-situ methane resource 3.3×10¹² m³.In this study, the structural deformation and tectonic evolution of coalbed methane system in Qinshui basin were reported. Relationships between structural deformation and the formation of coalbed methane reservoir in Qinshui Basin were also discussed. The results show that Yangquan-Shouyang area in the north part of the basin and Tunliu-Xiangyuan area in the east are favorable for formation coalbed methane system. In contrast, Jincheng-Qinshui area in the south part of basin and the Qinyuan area in the middle of basin are favorable for both the formation of coalbed methane reservoirs and high yields as well.

Abstract: Based on the saturated-unsaturated seepage theory and the unsaturated shear strength, the numerical simulations of soil slope seepage field in short-time heavy rainfall was carried out, and on this basis calculated the slope safety coefficient at different rainfall time. The research shows that: the rainfall infiltration will cause the slope soil matrix suction decreased or even disappeared which leads to the slope shear strength reduce; Rainwater infiltration increases the transient water load of infiltration area; and under the dual role of matrix suction reduction and transient water load increasing, the slope safety coefficient has the downward trend obviously.