With the downward movement of crebody mining depth in Meishan Iron Mine, the ground cave-in area hasbecome larger and the ground pressure more evident and the undergrou ad joints, fissures, faults and drift cave-in more serious.

• 梅山铁矿随着矿体开采深度的下移，地表塌陷面积越来越大，地压显现越来越明显，井下节理、裂隙、断层、巷道跨冒现象越来越严重；