Main control factors of rock burst and its disaster evolution mechanism

With the gradual transfer of shallow coal mining to deep coal mining in China, the rock burst disasters are becoming an increasingly serious problem. In the process of rock burst mechanism cognition to rock burst prevention engineering, the primary task is to clarify the main factors of rock burst and to identify its risk level. In this paper, four kinds of objective factors i.e., coal rock impact tendency, mining depth, hard roof and geological structure, and three kinds of human factors i.e., coal pillar, goaf and mining unloading effect, were proposed. And the disaster evolution mechanism of each factor was discussed in detail. In terms of objective controlling factors, the impact tendency is the inherent attribute of coal/rock to accumulate deformation energy and induce impact failure. The mining depth is positively correlated with the deformation energy accumulated in the surrounding rock of the roadway, which is an essential condition for the occurrence of rock burst. The impact dynamic load and kinetic energy formed by large-scale hard roof periodic fracture are the 'fuse' to rock burst. The influence of geological structure on rock burst is significant. For fault structure, the two walls will relatively ‘rebound’ under the sudden unloading caused by mining disturbance. And the equivalent elastic modulus of the thinning area of the coal seam becomes larger, and the advanced abutment pressure is distributed in a 'double peak' pattern, which expands the impact influence range. In terms of subjective controlling factors, coal pillar is a high stress concentration area, and its size, dip angle and relative position will directly affect the probability and strength of rock burst. The goaf will induce a sudden release of energy accumulated in the stress concentration area, especially under large mining height and insufficient roof collapse conditions. Mining unloading will lead to the rapid “migration” of the stress concentration area and release a large amount of energy stored in the coal/rock, which is an important external inducement of rock burst. On this basis, the differences of main control factors of rock burst disaster in the main rock burst mining area, such as Xinwen, Luxi, Erdos, Binchang, Xinjiang and Gansu were compared and analyzed. The study emphasized the importance of identifying the main control factors and their influence degree of rock burst from an entire mine, a panel to a working face. Also, it constructed the engineering management path of rock burst from energy-reducing, energy-releasing, energy-damping to energy-resisting.