Papers by Author: Qiang Xu

Abstract: Stability analysis of steep rock bedding slope with weak structure planes using strength reduction method was simulated in this paper. The post processing function can display the development condition of the plastic zone, which is the criterion for instability of the slope. Analysis with working conditions of natural circumstance, after excavation, and the slope reinforced by anchor shank after excavation were put forward. Failure modes and safety coefficients of the slope proved that weak plane is the main factor controlling slope failure. Simulation results shown that strength reduction method is appropriate in predict the shape and position of the potential failure surface of steep rock bedding slope.

Abstract: Based on the fluid-solid coupling theory, we study the stability of surrounding rock mass around underground oil storage in Huangdao, Shandong province, analyze the stress of the surrounding rock mass around three chambers and the displacement change of several key monitoring points after excavation and evaluate the stability of surrounding rock mass using COMSOL Multiphysics software. Research results show that the stress at both sides of the straight wall of cavern increases, especially obvious stress concentration forms at the corners of the cavern, and the surrounding rock mass moves towards the cavern after excavation. The stress and displacement of the surrounding rock mass will increase accordingly after setting the water curtains, but the change does not have a substantive impact on the stability of surrounding rock mass.

Abstract: This article analyses the characteristics of the engineering geology and engineering geological thinking connotation: geological evolution thinking, geological structure thinking, the combination thinking of geology, engineering and the environment, and systems thinking, discusses the relation of engineering geological thinking and innovative thinking (associative thinking, integrated thinking divergent thinking and systems thinking). The analysis and discussion fits to the current higher education requirements of innovation capacity. It comes to a conclusion that practice of engineering geology teaching can gradually develop correct professional thinking and completes the transformation the professional thinking and innovative thinking. At the same time, the students can grasp professional quality and master the entire engineering geology field of thought patterns and characteristics by the teaching. So the teaching can build the solid foundation that they can become high-quality engineering geology workers with the truly innovative ability.

Abstract: Residual soils are weathering products of rocks that are commonly found under unsaturated conditions. Residual soil is one of special soils, and its engineering geology property is usually different because of the difference of resource rock type, the geology environment and weathering condition. By the means of analysis of the data attained by the methods of field exploration, laboratory test and testing in-situ, the physical and mechanical properties of the residual diorite in Jinan were studied deeply. It is proved that the stratigraphic section of the soil can be classified as two layers on the perpendicular direction. Considering the inhomogeneity of the residual soil mass and the widely divergence of the value of mechanics properties, the suggestion value of c, Φ , a, Es, fak were put forward for further guiding the engineering practice , on the base of physics and mechanics properties tests and the region practice experience. At the same time, it is pointed out that, at that region, the interlayer and inhomogeneity of the weathering layers should be emphasized in the process of projecting and constructing when the residual diorite acts as the foundation of the construction or one of the geologic layers.

Abstract: The principle of the structure of displacement function, the establishment of governing equations, level set method were briefly outlined in this paper. Numerical simulations on three dimensional single edge notched specimens with different crack length in tension were performed using Abaqus software based on extended finite element method (XFEM), the stress intensity factor at static crack front was analyzed and the simulated results were in good agreement with analytical solutions. Numerical simulations in the present paper indicated that the extended finite element method is very suitable to deal with nonlinear fracture problems.

Abstract: The strongly weathered rock zone is a special kind of rocks and soils mass. For its larger burial depth and low utilization of natural foundation, the physical and mechanical properties of the strongly weathered diorite were grasped poorly. In the article, the normal investigation together with test in-situ has been applied in the project. The physical and mechanical properties of the strongly weathered diorite were analyzed deeply by the methods of field exploration, laboratory test and testing in-situ. It is feasible for the intensively weathered diorite to serve as natural foundation after lucubrate research and the evaluation of bearing capacity and settlement deformation in the project of the office building of China Industrial and Commercial Bank, Shandong Branch..It is proved from practice that the item of foundation treatment saved about two million Yuan compared with the pile foundation. Moreover it speeded up the process of the construction enormously, lessened the difficulty of the construction and obtained tremendous economic and social benefits.

Abstract: Spatial distribution of slope mechanical parameters on its collapsing and sliding due to seismic load is studied by applying rock dynamic triaxial shear test and finite difference numerical simulation. The results show that a difference in elevation is evident in response of slope initial collapsing and sliding triggered by seismic dynamic influence, i.e., initial fracturing always originates in the place of slope shoulder. Secondly, critical failure strain of slope body unit decreases with its buried depth, and double factors that critical failure strain decreases and peak ground acceleration increases in slope shoulder result in its initial fracturing. Thirdly, dynamic shear strength of slope body unit decreases with its buried depth, and double factors that dynamic shear strength decreases and peak ground acceleration increases in slope shoulder lead to its initial fracturing. The above results contribute to revealing key controlling factors and dynamic process of slope collapsing and sliding triggered by seismic load.

Abstract: Slope of subhorizontal layer structure is among typical natural structures and the different soft and hard rock combinations in upper and lower slope parts differ in seismic response. Taking into consideration some slope failure phenomena of two-sided slopes with banded structure ridges in “5.12” Wenchuan Earthquake, simulation experiment are made to research two types of horizontal structure slopes with hard-upper and soft-lower and soft-upper and hard-lower parts, by means of numerical simulation analysis and simulating experiment on vibration table. Research results show that for slope with hard-upper and soft-lower parts, its upper hard rock body is inclined to undergo global shearing deformation, along contact layer with underlying soft rock body, and the upper slope body is apt to go through collapse and pull-crack. For slope with soft -upper and hard -lower parts, influenced relatively more strongly by its lower hard rock part, rock body possibly shows cracking deformation similar to sliding and compression cracking, which may extend upward or downward along the contact layer. Moreover, the shoulder of two-sided slope is apt to undergo pull-crack and that, to some degree, relieves integral stress and sliding deformation of the upper soft rocky body. Therefore the whole rock body goes through little sliding deformation. Research result confirms the actual shatter slope failure, which further verifies the view that horizontal seismic action force plays main role in slope failure.

Abstract: The matric suction has very important influence on the characteristics of unsaturated sand; and it is closely relevant to density. In order to discuss the relationship among the matric suction, water content and dry density, the matric suction of the eolian sand were measured in laboratory. The soil-water characteristics curves for unsaturated eolian sand with different dry densities are obtained. The test results show that the variation tendency of soil-water characteristics curves has been corresponding to the different densities.

Abstract: Sub-ground erosion often resulted in severe problems in various engineering constructions, most of which is due to the sub-erosion in loess. In this paper, the critical condition of “soil bursting” was analyzed and the formula describing the critical condition of soil bursting was derivated by the analytical method. Furthermore, the velocity of tunnel-erosion in loess and its influential factors were studied. A set of tests are designed to study the relationship between the tunnel-erosion velocity and the key influential factors. The key factors considered in the test include soil density as well as the initial water content. The other purpose is to reveal the characteristics of the tunnel-erosion process. Phenomena observed during the tests together with the data from field survey revealed the mechanism of tunneling in loess very well, and the work in this paper formed a theoretical basis for further study about sub-ground erosion in loess.