Distribution characteristics of floor pore water pressure based on similarity simulation experiments

To analyse the impact of underground pressure on the variation in floor porosity and pore water pressure distribution during the coal seam mining process, this paper uses closed and open water pressure sensors to analyse rock pressure, water pressure zoning and layer distribution characteristics of the coal seam floor under mining effects based on a simulation analysis method using similar rock materials; the results determine that the separation characteristics of the pore water pressure distribution are affected by the rock pressure ‘barrier’ function, which is caused by changes in rock permeability under the coupling effect. To quantitatively analyse the rock pressure barrier’s impact on the floor mechanical structure, this paper proposes the ‘virtual separation layer’ concept and defines the virtual separation layer index to determine the scope of the floor tension fracture zone. Through monitored data of pore water pressure at different depths of the floor during field mining, the variation between the water pressure, porosity, mining distance and floor depth is obtained; similar material simulation results are verified, and a zonal distribution model of pore water pressure in the floor is established, providing a reference to investigate the distribution of pore water pressure in the floor under mining disturbances. The results show that the influence of changes in mining stress will also lead to a differential distribution of the floor mechanical properties and ultimately damage the floor and affect the inrush of the confined water. The research results play an important role in risk classification and prevention of water pressure distribution in coal seam floors.