Abstract: Aiming at the boundary conditions of one side mined working face, a plate model with three clamper edges and one simply supported edge was established as the mechanical model of high-position hard thick strata, and an energy releasing formula of hard thick strata fracturing was proposed. Deformation and rupture law of hard thick strata was revealed by comparing the maximum tension stresses in clamped edges of rock plate’s upper surface and the middle of lower surface. In addition, characteristics of microseismic energy distribution during the mining operation under high-position hard thick strata were analyzed combined with the microseismic monitoring data in field. Research results show that fracture happens at the same time in both lateral clamper side and the central of the lower surface when λ<1.024, the fracture form is an offset transverse “O-X” type, while the lateral span of the clamper side is lager than that of the simply support side. Otherwise, fracture first happens along the strike clamper edge, and the fracture form is a symmetrical vertical “O-X” type. During the mining process, small energy seismic events are mainly distributed in the rock mass below the thick key strata, and seismic events are easily triggered in the neighboring gob by the movement of lower rock mass. The high energy seismic events mainly happen in the fracturing process and losing stability of high-position thick key strata, mainly distribute near the fracture line of thick key strata, and concentrate in the vicinity of the internal and lower parts.

Key words: hard thick key strata, three clamper edges and one simply supported edge, fracture law, energy spread, microseismic