Simulation on distribution characteristics of mining-induced fractures field in overburden of Yunjialing Coal Mine

In order to study the distribution and evolution law of mining-induced fractures field in overburden of Yunjialing Coal Mine, the subsidence curve and fracture field distribution characteristics of overlying strata after mining are explored by physical simulation and UDEC numerical simulation methods, and the spatial distribution of fracture rate of overlying strata is calculated. The paper concludes that with the continuous progress of excavation, the mining-induced fractures field is characterized by trapezoidal distribution, and gradually develops toward higher layers and advancing direction. The lower fractures are compacted, and the fractures at both sides are relatively developed. The overall fracture density is gradually reduced, going through three stages of fracture generation, expansion and compaction. The fracture rate has experienced two distribution patterns, namely, “single peak” and “double peak”. The evolution law of mining-induced fractures in the middle of the goaf is quite different from that in the area behind the coal wall and near the open-off cut. The mining-induced fractures in the middle of the goaf gradually decrease with the compaction of the caving rock layer by the overlying rock layer. In the area behind the coal wall and near the open-off cut, the boundary coal pillar and the caving rock layer form a triangular mining-induced fracture area. The affected area of mining overburden displacement field develops towards the high layer and the advancing direction with the advance of the working face. At the initial stage of mining, it presents a rectangular distribution. Then, with the advance of the working face, the affected area of mining overburden displacement field presents a trapezoidal distribution. The displacement vector arrow in the middle is perpendicular to the floor, and the displacement vector at the open cut and the working face end deflects counterclockwise and clockwise respectively.