PRESSURE EVOLUTION OF OVERLYING ROCK STRATA USING GRADUAL INCREASE SUPPORT MINING METHOD

To improve the recovery for corner coal left over in mines, taking the Xin'an Mine in China as the research object, the gradual increase support mining method for recovering corner coal is proposed in this study and the evolution of the overlying strata pressure is investigated. The dynamic process of the overburden roof in the corner coal and the hydraulic support were simulated by using FLAC 3D software. Results show that, under the gradual increase support mining, the abutment pressure over the mining working face is less than 21 MPa. The overlying rock over the coal seam roof forms a periodic breaking - collapse cycle with a periodic pressure step distance of 10 m and the hydraulic support load is 13 - 25 MPa. Based on that, the gradual increase support mining method including a scheme of three supports and three chutes adding for every 9 m is designed and the corner coal is fully recovered. The obtained conclusions provide a significant reference for predicting strata movement over the corner coal, which can help aid in designing such mining method in engineering applications.