Non-uniform failure and differential pressure relief technology of roadway under irregular goafs in deep close-distance coal seams

Abstract

In response to the control problems of large-deformation roadways in close-distance coal seams, taking a typical roadway under irregular goafs and residual coal pillar in deep close-distance coal seams as the background, the characteristics of mine pressure and key difficulties in surrounding rock control of roadway are explored and an improvement strategy for controlling surrounding rock is proposed. The stress expression in roadway floor under the influence of residual coal pillar is derived by theoretical calculation. The peak lines of deviatoric stress and vertical stress in roadway after the mining of the upper coal seam are obtained by numerical simulation. The roadway is divided into two key zones: ordinary zone and disturbance zone by residual coal pillar, and the disturbance range of roadway below residual coal pillar is determined to be 44.60 m. It reveals the differential, asymmetric, and non-uniform distortion and failure laws of roadway at different positions under irregular goafs and residual coal pillar. The differential control technology named asymmetric support in ordinary zone of roadway and combined support and drilling pressure relief in disturbance zone below residual coal pillar is proposed. The feasibility of differential pressure relief and control technology has been verified through on-site engineering test, which ensures the safety and stability of roadway and provides technical references for surrounding rock control in similar deep and complex roadways.