Water Inrush Mechanism Study On Seepage And Stress Coupling Damage Of Coal Floor Under Pressure

The water inrush accident is the most outstanding problem in the mine water disasters, it is an urgent problem in the coal mine production safety. With mining depth increasing, the high confined water threatened more and more obvious in the north China. The water inrush problem boils down to the stress field and seepage field caused by fluid-structure coupling interaction mechanics problems. The balance of surrounding rock stress state is broken in the process of coal mining. Under the stress coupling effect, with the rock crack generation, extension, cut-through, and the final fracture leads to failure, then the confined water pour into coal face, causing heavy loss. Based on the survey of several mining area in north China, understood and finishing the data of water inrush. Using the theoretical knowledge, the computer numerical simulation, and the study method of physical analog simulation test, studies floor deformation characteristics, stress distribution and the corresponding relationship between them according to the hydro-geological characteristic of “north China type coal”. The main results were as follows:(1) The paper studies the water inrush mechanism, describes the main factors affecting water inrush and the role of various factors. Mathematical model is set up, to express intuitively the water inrush modes in different conditions of floor, the stress of slab cracks and the different forms of crack fracture;(2) Combined with the geological data of north China and the characteristics of the rock mass mechanics, choose suitable material according to the different proportion to make specimen, with the SAS-2000 tester monitoring its mechanical properties, to choose reasonable ratio of materials for physical analog simulation test. Based on the curves of stress-displacement and the damage form of specimens performance by uni-axial compression test, analyzed the specimen characteristics of each stage in the process of uniform loading;(3) Based on the theory of seepage and stress coupling, using the RFPA2D-flow to test numerical simulation orthogonal experiment with different floor conditions and water environment. Through the contrast test, which leads to the theory of "broken to water-inrush" and “seepage to water-inrush”, judge the confined water has played a leading role, according to the theory of relative water-resisting layer, analyzed the role of "natural channel";(4) The physical simulation experiment was designed according to the geometric parameters of the similar ratio, recording, sorting and analysis the testing process of the floor deformation damage, tests showed that 60m~120m distance open cut-off area, the most cracks produced, the most floor heaved;...