The Research On Space-time Evolution Of Confined Water In Mining Coal Floor Fractures

At present most of the mines in our country has entered the stage of deep mining, with the increase of mining depth, the coal bearing strata basement of the ordovician limestone confined aquifer water pressure increasing, water inrush risk increase; Some mining face in coal resources dried up, and then into the next set of coal seam mining face mining floor water-resisting layer thickness is thin, big issues such as water pressure, coal floor water inrush risk efforts to prevent inrush and thus become an important problem faced in the process of mining. Confined water exploitation, due to the mine mining floor strata stress, ground stress and confined water osmotic pressure coupling effect to cause floor cracks, if the water pressure exceeds the critical value criterion may make bottom fracture penetration formation water channel accident caused flooding Wells. In this paper, through theoretical calculation, numerical simulation and similarity simulation of three kinds of methods of confined water extraction from different aspects of coal floor damage and crack generation and evolution in the study of the system. Now the research results are summarized as follows:(1) using elastic-plastic mechanics of fracture mechanics and damage under the condition of additional confined water pressure to calculate bottom rock damage and fracture of maximum depth formula, combined with huaibei mine geological data using a formula to calculate calculate floor destroy the maximum depth of17.5m, floor cracks through maximum depth of17.6m, the calculation results with the field measured close to.(2) through the state of the numerical simulation software of different length, respectively under different confined water pressure, different velocity floor rock fissure formation and evolution of the system the research, with the working face advancing constantly produce floor strata fracture and fracture with the working face advancing transfixion crack expanding formed horizontal and vertical, in the process of mining and near crack occurred in coal wall and cut a saddle type distribution; With the increase of confined water hydraulic floor rock fissure extension penetration depth increasing, with the speeding up of the advancing speed slab fracture extension of continuously reduce (3) through analog simulation under different working face advancing length and different velocity of floor strata crack formation and evolution of extended research, with the working face advancing constantly produce floor strata fracture and fracture with the working face advancing transfixion crack expanding formed horizontal and vertical, in the process of mining near crack occurred in coal wall and cut and a saddle type distribution; With the speeding up of the advancing speed slab fracture extension of continuously decreased.