Advanced Materials Research Vols. 1065-1069

Abstract: The main factors affecting landslide instability are landslides lithologic ,geological structure, topography, climate, hydrological conditions, earthquakes ,human and so on .The risk assessment of landslide is an effective method for analysis landslide stability ,but there has been little research for prediction of landslide in China .In this paper, particle flow procedures is used to analyze the landslide stability under natural conditions and forecast a possible landslide sliding surface ,and a scientific method will be provided for landslide prediction.

Abstract: The calculation parameters of foundation pit excavation are usually obtained by the conventional triaxial test regardless of the unloading process, which leads to supporting mobile,soil rebound caused by excavation unloading, and unreasonable and dangerous design. In recent years, some researches have been done on pit excavation under unloading condition. In this paper, a review on pit under excavation unloading according recent research was made including stress path tests, numerical simulation, and constitutive model.

Abstract: According to the Geological Diversity and Soil Characteristics in the Gorges Reservoir Area, the Statistical Analysis was Carried on the Content, Grade, Porosity and Permeability Coefficient (PC) of Gravel Soil, Respectively. the Value of Saturated Permeability Coefficient (SPC) is up to 10-3. the Value of the Total SPC is that Zigui is the Highest, Badong-Fengjie Area is Less than that in Zigui, and it is the Lowest in Fengjie-Chongqing Area in its Distribution. the Relationship between the Montmorillonite (MMT) Content, Stone Content, the Uneven Coefficient and PC are all Positive. the Curvature Coefficient and Void Ratio are all Negatively Correlated with PC. these Data Showed the Relationship between the Index of Material Composition and PC of Gravel Soil.

Abstract: The threshold shear strain is a fundamental property of the soil behavior subjected to cyclic loading. Starting from the unloading and reloading hysteretic curves of dynamic Ramberg-Osgood model, construct small-strain dynamic dissipation function and explain small-strain dynamic characteristics by use of the skeleton curve back stress assumption. The plotting results of yield curves in true stress space indicate that there exist two threshold shear strains which are defined as the first threshold shear strain and the second threshold shear strain respectively which represent boundaries between fundamentally different dynamic characteristics of cyclic soil behavior. The yields of soil are controlled by the constant friction coefficient, the variable friction coefficient and dilatancy-related microstructural changes respectively. Both the first threshold shear strain and the second threshold shear strain do depend significantly on the maximum dynamic shear modulus coefficient and exponent. Comparison between the two threshold shear strain values and shear modulus reduction curves obtained on exactly the same soils confirms that the soil behavior is considerably at nonlinear at , the secant shear modulus, Gs, of the four soils studied is between 0.6 and 0.8 of its maximum value.

Abstract: A single pile in soil is modeled as a vertical circular elastic prismatic bar, and the soil around the pile is regarded as transversely isotropic medium. The relationship between stress and displacement of the soil is described by fractional derivative viscoelastic model. Ignoring the radial and vertical displacement, the torsional vibration equation of the soil is built. It is solved by using the method of separation of variables and the boundary conditions of the soil. The torsional vibration of the single pile is also obtained. The torsional complex stiffness at pile head is investigated in particular. The results indicate that anisotropic parameters and model parameters of the soil have effects on the torsional complex stiffness, and the influence rules are different with the homogeneous soil.

Abstract: To study the weathered characteristics of silty mudstone in Hunan province, china, mineral analysis, softening test, disintegrability test, and weathering rate test are used. The test results show that with the increasing of weathering degree, the content of clay minerals increase from 34.1% to 57.2%, the content of quartz decrease from 58.6% to 38.7%. The content increasing ratio of Fe₂O₃ and Al₂O₃ are 52% and 44% respectively, the content decreasing ratio of K₂O is 52%. From lightly weathered rock to completely weathered rock, the decreasing ratio of dry density is 20%, the increasing ratio of water absorption is 40%, the increasing ratio of porosity is 190% nearly and the decreasing ratio of natural compressive strength is 84%. For strongly weathered silty mudstone, the softening coefficients of the first dry-wet cycle, the second cycle and the third cycle are 30%, 54% and 72% respectively. So when silty mudstone weathered further, the content of primary minerals decrease and the content of secondary minerals increase. The weak activity chemical composition increase and the strong activity chemical composition decrease. Weathering cause the mechanical properties of rock become worse. Repeated dry-wet cycle can accelerate the softening of rock. The larger the exposure area of rock is, the quicker the rock weathered.

Abstract: 3D quantitative prediction can be summarized as finding the combination parts of favorable metallogenic information based on the 3D geological models and cubic block models. Based on metallogenic prediction theory, relying on 3D visualization technology, 3D database technology and statistical calculations, this paper established the technical processes of 3D quantitative prediction and evaluation of deep mineral resources which including 3D geological modeling, prospecting model establishing, mineralization favorable information analysis and 3D quantitative prediction and evaluation.The favorable metallogenic information analysis and extraction which implemented based on 3D cubic block models extended the prospecting method from 2D to 3D space, and realized the visualization of deep quantitative geological information from the 3D point of view. The method of using 3D spatial exploration flag variable to realize 3D prediction of deep concealed ore provides a new way of prospecting prediction study of deep mineral resources.

Abstract: The paper describes development characteristics of underground aquifer in a coal mine. Analyzes the mining topography, surface water and development situation of vegetation, and determine the surface hydrological environment unit for the study area and its surrounding areas. Rich water of aquifer in the surface is predicted based on 1: 10000 DEM Figure. Finally combining the data of coal borehole, the characteristics of rich water of aquifer in the area is presented.

Abstract: Xihu Sag is the largest petroliferous sag in China offshore area, which is also the main oil and gas exploration battlefield in the East China Sea shelf basin. Source rock is the main material basis for oil and gas generation, its study has important significance on oil and gas exploration in Xihu Sag. By taking source rock of the Eocene Pinghu Formation and Oligocene Huagang Formation of Pingbei area in Xihu Sag as the research object, static characteristics of source rock in Pingbei Area are evaluated and analyzed in the following three aspects: organic matter abundance, types and maturity. The results show that, based on the organic matter abundance, lower member of Pinghu Formation has a high organic matter abundance, mainly gas, while lower member of Huagang Formation is mainly medium-better source rock, with a common hydrocarbon generating potential. Based on the organic matter types, Huagang Formation and Pinghu Formation are mainly type II and type III kerogen, having a certain hydrocarbon generating potential. While, from the point of view of maturity, lower member of Pinghu Formation is under low mature - mature stage, and the lower part of Huagang Formation mainly under mature to high mature stage. Its hydrocarbon generation peak is basically at present.

Abstract: Three types of tip-structure include open-end, semi-closed and full close are tested to verify the feasibility of improving the ultimate bearing capacity in stiff clay layer. Driving pile trials are carried out in the site. This paper presents the analysis of set, driving stresses and bearing capacity according to the survey of set, driving monitoring, high strain dynamic test and the axial compression static test. It is proved that the closed end is the most feasible structure in stiff clay layer.