ABSTRACT
The paper presents results of field and theoretical studies of geomechanical state of rock mass in a coal mine prone to rock bursts. The filed study was based on the method of geodynamical zoning and involved analysis of block structure of the mine field, natural and technogenic cracks in overburden rocks. In addition the study involved analysis of the open crack generation from the day surface into the rock mass with respect to the sequence of mining works and used a geomechanical model based on the FEM and the theory of cracks. It is shown that tensile crack development should proceed in a quasi-static mode as coal excavation progresses and the span of excavated space increases. It is also shown that the situation is inevitable when one of the tensile cracks provokes further rock fracture from this crack towards the excavation space by a shear mechanism. The shear fracture is unstable and must manifest itself as a rock burst leading to hard “landing” of a large block of rock mass on the ruined rock and soil in the excavated seam under its own weight.
