Spatial structure evolution of overlying strata and inducing mechanism of rockburst in coal mine

Spatial structure of overlying strata existed and evolved dynamically with the exploitation scope ( boundary conditions) changes in coal mines and to induce rockburst. Based on the "key strata" theory, the integrated spatial structure of overlying strata was put forward, which was composed of "O-X" structure in the plane section and "F" structure in the vertical section. The formation and ongoing instability of the "O-X" and "F" structures were called as dynamic evolution cycle of the overlying strata. Three basic categories of "O-X", "F" and "T" structures were defined, and the strata behaviors of each spatial structure were analyzed. According to energy theory, mechanism of rockburst induced by spatial structure instability was discussed. The research expanded the scope of traditional ground pressure theory and provided a guide for the prevention of rockburst and mining tremors induced by structure instability of overlying strata.