Mechanical model of safety thickness for resource recovery of complex & difficult mining ore body

In view of the difficulty in calculating the safe thickness of complex and difficult-to-mine orebody in the process of resource recovery, based on the elastic-plastic theory and mechanics method, the mechanical models of the safe thickness of orebody recovery above the collapse area and that of orebody recovery at the side of the collapse area are constructed respectively. The results show that: 1. Using the fixed beam model to calculate the safety thickness, the additional load on the roof, the volume weight and span of the rock stratum, the width of the rock stratum and the water pressure are the important influencing factors. When the water pressure exists, the safety thickness can be reduced; 2. When the safety thickness is calculated by the elastic plate model with fixed support around, the safety thickness decreases with the increase of the tensile strength or shear strength of rock mass, and increases with the increase of the external load; 3. When the collapse area is located at the side of the ore body to be mined, the safety thickness decreases with the increase of the tensile or shear strength of rock mass, and with the increase of the external force. The load increases with the increase of load. The research can provide theoretical support for mining residual mineral resources.