Temporal and spatial evolution mechanism of deformation and failure of lower mining roadway in near residual coal pillar area

Abstract

In order to demonstrate the temporal and spatial evolution mechanism of deformation and failure of the lower mining roadway in the residual coal pillar area during the mining process of close coal seam, this paper takes the close coal seam mining of Tashan Coal Mine of China Coal Group as the research background, adopts the roof borehole and peeping technology to detect the failure situation of the roof surrounding rock of the roadway, and determines the approximate failure area of the roadway surrounding rock. The stress evolution law of roadway surrounding rock and the failure characteristics of plastic zone are studied by theoretical analysis and numerical simulation. The results show that there is a positive correlation between the size of the plastic zone and the deformation of the surrounding rock, that is, the larger the plastic zone, the more severe the deformation of the surrounding rock. The stress concentration area under the residual coal pillar and the new stress field in the mining face are superimposed on each other, resulting in asymmetric deformation and failure in the surrounding rock of the return air roadway, and the shape is approximately "butterfly". The stress on one side of the surrounding rock will be deflected, resulting in a significant difference in stress concentration on both sides of the roadway, and the extension of asymmetry in the plastic zone will also occur, which will lead to the large asymmetric deformation and failure of the surrounding rock of the roadway.