Experimental study of the activities of reverse fault induced by footwall coal mining

The reverse fault will slip with workface excavation in footwall. As the stresses loading on the combined sam- ple were equal in the X and Y direction,the stress and strain along the fault,as well as acoustic emission signals,were monitored during the coal excavation. The analytical results show that stress decrease zone,stress increase zone and in situ stress zone occurred around the gob and their evolution will cause fault slip. Compared with normal fault,reverse fault has higher slipping risk under the same mining condition. As the workface locating in the footwall of reverse fault advances forward,the ratio of vertical force and horizontal force caused by mining increases from 1 to 6,which means the slipping risk of reverse fault rise. The strain along the fault face is not even,and the strain of coal seam is higher than that of rock strata10-10 J and their focus mainly concentrate in the roof strata and unlikely transpass the fault face which means the fault can cut-off the stress disturbance of mining. The conjunction of coal seam and fault face tends to cause large acoustic events which means this area has high slip risk. Compared with the in situ seismicity in Zhaolou Coal Mine,the spatial location of seismic focus and experimental acoustic focus have similar features to some extent,which could prove the feasibility of the experimental method adopted in this paper.. The energy of 84% of the acoustic events caused by coal mining are between 10-13 J and