Study On Floor Deformation And Destruction Above Confined Water In Mining Face

Many coal mines in China suffer from the water in limestone aquifers, so water inrush is one of the serious mine disasters. The floor damaged on both sides under abutment pressure and hydraulic pressure. The condition of water inrush is that both sides of the failure under mining are breakover.Based on the practical coal mining and practical geological conditions of1028workface in Suntuan mine of Huaibei mining group, the paper study on the factor which can affect the destruction of the floor, such as burial depth and dip, by using numerical simulation. And then combine the actual conditions of1028workface, obtained some achievements as follows:(1) According to two movement of roof beam (before first roof pressure and motion by roof beam law) and hydraulic pressure, an elastic mechanical model was established which calculated to any point stress of floor. Then it can be used to judge whether the soleplate damage combined with Mohr-Coulomb.(2) On the basis of the occurrence features of an inclined coal seam, using the software FLAC3D, the paper established a three-dimensional numerical calculation model of a seam workface with longwall mining, simulated and analyzed the distribution laws of stress and failure depth of floor along both directions of coal seam at different advancing speed, dip and rock assembles.The results show that:in the process of mining, the depth of destroyed floor increases as mining depth, the destroy depth and range of floor at a higher speed is smaller than slower to some extent. As the slope grows, the stress field and failure features of floor is markedly different from the nearly flat seam, the shear stresses affected zone on the upper part of workface grow closer and closer to the bottom part. The different lithologic association has different affection to the coal seam floor’s failure, it concluded that the anti-destructive of hard rock is higher than the anti-destructive power of soft rock, from the mechanics point of view.(3) It can be continuous and dynamical observation to the ground damage conditions of working face1028in Sun Tuan. Huaibei mining group in the process of mining, using resistivity method CT. The result shows that the depth of destroyed floor is away from aquifuge thickness, water inrush canift occur. According the above analysis, field test result accord with the correctness of the theoretical calculation and the numerical simulation, and the theoretical analysis result and the numerical simulation result can provide theoretical references before coal seam mining. Figure [61] table [3] reference [76]...