Porosity zoning characteristics of fault floor under fluid-solid coupling

During exploitation approaching to faults structure, due to the influence of mining stress, the rock mass inside the fault zone and between the fault and the coal pillar is prone to damage and activate, so it is the key research and protection position. The dynamic response of faults is closely related to the failure process of rocks, and the influence of the change in mining-induced stress will also result in the differential distribution of the mechanical properties of floor, and ultimately affects the failure of floor and the outburst process of the confined water. In order to quantitatively analyze the influence of mining pressure on the porosity change of floor and water pressure distribution in coal seam mining process, the change characteristics of rock material mechanics parameters such as Young’s modulus, porosity, and permeability under the action of mining disturbance and confined water pressure were studied. A similar material simulation study on the water pressure and stress distribution of floor at different depths under different mining distance conditions was carried out. According to the results, the energy dissipation of coal floor rock mass is closely related to the change of porosity. Meanwhile, the changes in the porosity of rock mass under the action of uneven water pressure and the partition and distribution model of pore water pressure of the floor were established. When mining is carried out near the faults, the spatiotemporal position when and where the upper and lower boundaries of the fault zone in the lower water-resisting layer release energy at the same time is critical to the occurrence of water inrush.