Research on water inrush mechanism of fault coupling bed separation with fully-mechanized sublevel caving of ultra-thick coal seam

In order to research the water inrush mechanism of fault coupling bed separation under the complex condi- tion and formulate corresponding water disaster control measures. Based on the analysis of geological,hydrogeological and mining condition in Laohutai coal mine,combined with water inrush accident,numerical simulation and similar material simulation were used to research “two zones” development rule of working face,the space formation charac- teristics of fault and bed separation with fully-mechanized sublevel caving of ultra-thick coal seam. The caving to min- ing ratio and fracturing to mining ratio are 4. 98-5. 42 and 7. 10-7. 30. The spatial form and size of faults are mainly affected by the fault throw and the distance from the working face. The bed separation space is mainly formed near the contact surface of different stratum. Based on the analysis of formation,water filling and water inrush process of fault and bed separation on the roof of working face,water inrush mechanism of fault coupling bed separation were find out: the mining of upper layer working face led to fault and bed separation space,then the space were filled with water from aquifer continuous replenishment,the water inrush was happened when the caving zone connected water body after lower working face mined. Compared with the previous water disaster caused by fault and bed separation,the water in- rush of fault coupling bed separation has the following characteristics:the fault and bed separation are water filling source and channel of water disaster at the same time;The caving zone is the main cause of water disaster;The gesta- tion and occurrence of water disaster are in different working face. For water damage characteristics,the corresponding project of water control was put forward. First of all,the research area is partition according to water disaster threat de- gree. Then,the coal resources not threatened by water disaster can be mining. The coal resources threatened by water disaster can be mining after the following measures:grouting and filling the space of fault and bed separation,drainage the water of fault and bed separation and reducing the disturbance from working face mining to the water of fault and bed separation. According to the safety mining of typical working face,the correctness of water inrush mechanism and the reliability of water disaster control scheme are preliminarily verified. In the next step,the water disaster control measures will be supplemented and improved according to the engineering verification on the ground and underground.