【摘要】 为探索煤矿矿震(冲击地压)的机制,通过现场高精度微震观测及震源调查资料,分析震源的空间秩序,提出煤矿矿震存在"三个特征震源深度"问题,即初始震源深度、采空区顶板上限临界震源深度和底板下限临界震源影响深度。这三个特征震源深度取决于地面和震源、采空区顶板及底板和震源的相对距离。对三个特征震源深度的力学机制进行分析:用煤体抗压强度和施加于煤体作用力强度的幂律关系解释初始震源深度;用拉、压不同模量梁板弯曲模型和煤体强度与远场最大主应力比值的两种模式解释采空区顶板上限临界震源深度;用卸荷弹性恢复与侧向泊松效应复合作用和断层活动解释底板下限临界震源影响深度。最后讨论三个特征震源深度在采矿工程安全中的应用。更多还原

【Abstract】 In the current study,three characteristic focal depths of mining-induced seismicity in coalmines,i.e. initiation depth,roof upper-bound depth,and floor lower-bound influence depth,are identified from field microseismic monitoring data. These characteristic depths depend on the relative distance between the hypocenter of a seismic event and ground surface or the location of the roof and floor of the coal seam. The initiation depth is the one beyond which rockbursts will happen. The roof upper-bound depth is defined as the depth of the seismic events located above the roof whose magnitudes are greater than certain thresholds;and the floor lower-bound influence depth is defined as the difference between the depth of the observed maximum seismic event below the floor and the depth of the floor. The mechanisms of the characteristic focal depths are also discussed. The initiation depth is explained by a power law model considering coal strength and the stress acting on the coal body,the roof upper-bound depth is explained by a bending model of a thick plate or beam;and the floor lower-bound influence depth is explained by the combined effect of elastic rebound due to unloading and the effect of Poisson′s ratio as well as the influence of active faults. Finally,the impact of understanding the characteristic focal depths on mining safety is discussed. It is expected that a better understanding of these characteristic depths will facilitate the mitigation and control of mining-induced seismic hazards in underground coalmines.更多还原