Classification, identification and monitoring methods for static-dynamic stress hazard sources of rock burst in coal mine

The prevention and control of rock burst in coal mines should begin from the source, where classification identification and monitoring of static-dynamic stress hazard sources are essential prerequisites for rock burst source control. Based on the theory of rock burst induced by the superposition of static and dynamic stresses, its hazard sources and the associated action modes are summarized. Here static stress hazard sources contain 16 common types, which could be grouped into geological deposition attributes, tectonic structures and mining-induced stress concentrations. Their action modes are demonstrated in the following three ways: The critical stress of rock burst is different due to different coal-rock properties, strong dynamic loads can be generated due to the breakage of extremely thick and hard rock strata and the fault movement, and the static stress is elevated in coal-rock masses due to sedimentary microfacies. Dynamic stress hazard sources are divided into seismic wave loads, forced vibration loads and explosive impact loads. Their action modes comprise instantaneous stress increase in coal-rock masses, reduced critical stress of rock burst under strong dynamic loads, and cumulative damage to coal-rock and support systems under prolonged fatigued dynamic loading. For identification of static stress hazard sources, a geologic sedimentation abnormal identification method is proposed based on the in-situ stress field inversion, where the mine-scale stress distribution is inversed and calibrated with field measurements to locate geological static stress hazard zones. Besides, a stress field inversion technology is developed by a large-scale periodic seismic CT inversion to identify high static stress hazard zones. For identification of dynamic stress hazard sources from roof strata, the key stratum theory for mine tremors is proposed, and thereby the discriminant model and method for the key stratum of mine tremors are established. For the monitoring of static stress hazard sources, a stress field monitoring technology of active and passive dual-source seismic waves is developed. This technology has integrated both advantages of active and passive seismic CT technologies, which can realize real-time and continuous stress field inversion analysis for the static stress hazard sources of rock burst. For the monitoring of dynamic stress hazard sources, an underground-ground integrated microseismic monitoring system is developed, which has overcome the limitations of traditional microseismic monitoring, such as poor vertical location accuracy and difficulty in pinpointing dynamic stress hazard sources. This system has significantly enhanced the accuracy and sensitivity of microseismic monitoring. The effectiveness of above methods has been validated through field applications, which could provide valuable insights into source control of rock burst hazards.