Research on the Mechanism of Floor Heave and Borehole Pressure Relief Technology in Deep Soft Rock Roadway

In order to solve the problem of floor heave in soft rock roadway under deep well mining condition, taking the 020202 transportation drift of Qingyun Coal Mine as the engineering background, the mechanical model of roadway floor heave was established, and the characteristics and influencing factors of them were theoretically analyzed. It is concluded through analysis that the rock is in the plastic state of limit equilibrium, when the concentrated stress exceeds the bearing capacity of it, the equilibrium state is destroyed, the rock in the bottom plate is extruded along the shear sliding surface of the floor and finally reaches a new equilibrium, resulting in floor heave. Through the analysis of elastic-plastic theory, the relationship between the pressure relief range and the floor heave was obtained, and according to the actual geological conditions of coal mine, the method of borehole pressure relief for the side of the roadway was put forward to transfer the peak stress point of the side of the roadway to the deep. FLAC^3D numerical simulation method was used to analyze the influence of different pressure relief borehole depths on the surrounding rock stress field, plastic zone and displacement of roof and floor, and the reasonable depth of pressure relief borehole was finally determined to be 4 m.The field industrial test shows that the deformation of roadway surrounding rock is effectively controlled and good economic benefit is obtained.