Numerical simulation of coal floor fault activation influenced by mining

By means of the numerical simulation software ANSYS, the activation regularity of coal floor faults caused by mining is simulated. The results indicate that the variation in horizontal, vertical and shear stresses, as well as the horizontal and vertical displacements in the upper and the lower fault blocks at the workface are almost identical. Influenced by mining of the floor rock, there are stress releasing and stress rising areas at the upper part and at the footwall of the fault. The distribution of stress is influenced by the fault so that the stress isolines are staggered by the fault face and the stress is focused on the rock seam around the two ends of the fault. But the influence in fault activation on the upper or the lower fault blocks of the workface is markedly different. When the workface is on the footwall of the fault, there is a horizontal tension stress area on the upper part of the fault; when the workface is on the upper part of the fault, it has a horizontal compressive stress area on the lower fault block. When the workface is at the lower fault block, the maximum vertical displacement is 5 times larger then when the workface is on the upper fault block, which greatly increases the chance of a fatal inrush of water from the coal floor.