Deterministic seismic hazard assessment of coal fractures in underground coal mine: A case study

Mining seismicity induced by coal fractures can cause strong seismic motions in roadway and result in serious seismic hazards to mining personnel and equipment. In order to assess the seismic hazards induced by coal fractures, a deterministic methodology was proposed based on a coal fracture source model and further developed into a numerical program called Mining-induced Seismic Hazard Assessment software (MSHA). The program accepts user-input material constants of in-situ coal seam and calculates the resultant seismic motions in the roadway; the seismic motions were fully verified by a comparison between the numerical and in situ results. The methodology was further applied to assess the seismic hazards in the panel 92201 of the Sanhejian Coal Mine, the seismic hazards were characterized by the peak particle velocity (PPV) and octahedral shear stress (OSS). The results indicate that the tensile strength of coal constitutes the most significant parameter of the coal fracture source model. Moreover, a general and practical conclusion was obtained that the intensity and scope of seismic hazards in roadway are positively related to the tensile strength of coal, and the left and right sides of the roadway might encounter significant seismic damage under impact of coal fracture. The conclusion is useful for mining engineers to identify the potential seismic hazard in the roadway, and therefore make targeted strategies in mining support system.