In-site study on development rule of fractured zone height by fully-mechanized mining in Lu'an Minefield

In order to study development rule of water conducted zone caused by different mining technologies in Lu'an mining area, roof fracture distribution was s tudied by drilling 20 boreholes on ground and by using hydrological observation and water injection test. Statistical analysis was done based on large numbers of in-site data, for studying relationship between height of fractured zone with mining height and slicing, developing laws of fractured zones with different mining technology were compared and analyzed. The results showed that, the height of fractured zone by fully-mechanized top coal caving was much more higher than other mining ways. The height of fractured zone with two slicing mining had reduced by 24% than that with fully-mechanized top coal caving. The ratio of height of fractured zone to the mining height by caving was basically same as that of primary recovery by slicing, the value was 20. The empirical formula was provided for calculating height of fractured zon e in Lu'an mining district, and the basic scheme of mining under water body was determined. The research had been successfully used for mining under Zhanghe river i n Wuyang Coal Mine, which has verified the relability of studying results.