【一般講演】 岩盤工学／ 資源開発技術

[2409-17-02] (学生発表：博士課程)採炭による応力擾乱に対する近傍断層の安定性評価

○李 亚涛¹、福山 英一¹、吉光 奈奈¹ (1. 京都大学)

司会：佐分利禎（国立研究開発法人産業技術総合研究所）

キーワード：誘発地震、断層すべり、クーロン破壊基準、採炭、応力擾乱

Coal has been one of the important energy resources, and its environmental and mine safety issues should be prioritized in the mineral resource development. In recent years, the mining depth has been increasing year by year, resulting in the generation of mining-induced earthquakes. This problem becomes more and more serious. Once mining-induced earthquakes occur, they may cause damage not only to a mining company but also to society. However, it was not well understood which factors control the generation of induced earthquakes that occur on the fault nearby the mining activities.

In this study, we investigate the effects of stress disturbance caused by coal mining to assess the conditions that control the faulting. We use a generic 2-D plane strain model generated by the FEM software Code-Aster to analyze a longwall mining activity that approaches a fault. Fault reactivation was evaluated by a quasi-static analysis during the mining process. The main parameters affecting fault reactivation were investigated, such as fault location, fault dip angle, and the thickness of the coal seam, by the numerical simulations with the Coulomb fracture criterion.

The modeling results suggest that the coal mining process can produce high-stress concentrations ahead of the working face. It affects the stress state along the pre-existing fault by increasing the shear stress or decreasing the normal stress along the fault around the coal seam depth. The critical stress disturbance that exceeds the coefficient of friction and leads to the fault failure is limited to a certain range on the fault. If this area becomes larger than the critical nucleation zone size, the pre-existing fault will be triggered for the dynamic rupture propagation.