Abstract:

Scientific understanding of the damage fracture characteristic of overlying strata after coal mining is the premise and foundation for clarifying the integrated linkage law of overlying strata and the discontinuous deformation of the surface. The damage and fracture characteristics of overlying strata were studied using theoretical analysis, similarity simulation, considering the cumulative effect of overlying strata damage caused by step-by-step mining. The results show that due to the damage

accumulation effect of step-by-step excavation, the maximum damage point at the end and middle of the suspended part of the strata lagged behind the maximum tensile stress point about 0.3NL0 and 0. 1NL0, respectively in the advancing direction, and the first fracture of the low rock stratum would be a partial “O-X”fracture. These phenomena were verified by the selfdeveloped three-dimensional similarity simulation experimental platform. The first exposure of overlying strata above coal seam

would produce damage accumulation effect, resulting in asymmetric failure. The surface skewed subsidence was caused by the combined action of the asymmetric failure of overlying strata.