Observation and simulation research on development features of overlying strata failure in conditions of fully-mechanized top-coal caving mining under river

Coal resources of Xiagou Coal Mine locates under the Jing River,using fully-mechanized top-coal caving mining,therefore,it is difficult to calculate exactly the height of water conducted fissure zone by using the known methods.In order to master the overlying strata failure development features of great thick coal seam massive fully-mechanized top-coal caving mining under the Jing River,realization of safety mining under water,assigned 5 holes of Twozone in different positions of the study area working face,conducted observation of borehole flushing fluid leakage and colour television,and further study on the overlying strata failure process of mining method that remained the isolated pillar with a definite width between the working faces by physical simulation.Observation and simulation results indicate that the isolated pillar has effective control of the development height of overlying strata failure,and it is the key about mining safety under the Jing River.According to the results provide the largest ratio of fissure zone height and mining thick of single working face,and by the least vertical height calculating of the safe coal post preventing water,hold that geological conditions meet the requirements of the mining safety under the Jing River.