The Research on the Height of the 'Two zones' in Xiegou Mine Areas, Shanxi, China

The basis of roof water controlling, excavation layout, coal pillars and gas drainage designed can be provided by confirming the height of the water conducting zone in roof. There are many methods can be used to determine the height of 'two zones', such as water injected and the leakage tested in overhead boreholes, transient electromagnetic detected and simulation method, or empirical formula. The results show that height of the water conducted fractured zone for No.8 coal seam in Xiegou is 74.8 m, height of the caving zone is 32 m, and height of the fractured zone is 42.8 m. Compared with results calculated by different equations in Coal Mine Safety Regulation (CMSR), it found that some equations in the CMSR were imprecise when being applied to predicting heights of 'two zones' at mining conditions for fully mechanized mining in median thick seams. Therefore, the CMSR should be modified appropriately.