Roof Broken Characteristics and Overburden Migration Law of Upper Seam in Upward Mining of Close Seam Group

Abstract

Aiming at the problem that the roof broken characteristics and overburden migration law of upper coal seam are not clear due to the disturbance of repeated mining in underlying coal seams, this paper takes a mine of Panjiang mining area as the background, the roof broken characteristics and overburden migration law of upper coal seam under repeated mining of close coal seam group are studied using rock mechanics test, similarity simulation and numerical simulation. The results show that the cracks of coal and rock mass are well developed, the strength is low, and the sensitivity to engineering disturbance is poor; The roof is fragmented due to repeated mining of underlying coal seam, and the rib spalling and roof caving occurs many times; The roof stress value on the coal face is 1.02 MPa, which shows that the roof pressure is not large, and the support selection should focus on preventing the roof caving of end face and the rib spalling of coal face; The pressure peak value point is close to the coal face. Although the roof weighting is frequent, the length of broken rock blocks is relatively small. The initial roof weighting interval is about 30 m, and the periodic weighting interval is about 10 m. The research results can provide basis for surrounding rock control of stope under similar conditions.