Study On The Mechanism Of Water Inrush From Bed-separation In Shilawusu Coalmine

Shilawsu coal mine is a typical deep coal mine in the Jurassic coal field in northwest China.Roof aquifer is uneven and hydrogeological conditions are complex.Water inrush from bed separation occurred in the first mining face of the south wing of the mining area which seriously affects the normal progress of the mining and threatens the safe production of coal mine.This paper starts from the analysis of water inrush incident at the first mining face,the mechanism of water inrush from bed separation on the first mining face of south wing of Shilawusu coal mine was determined by means of analysis of water inrush characteristics and hydrogeological condition,numerical simulation analysis and theoretical research.Then put forward control measure for this kind of water hazard,it is of great significance to the prevention and control of bed-separation water hazard in the remaining mining sections of the first mining face and similar working faces.The analysis of the change of water inflow and the change of water level in the observation drillhole of aquifer shows that the luohe aquifer is involved in this water inrush accident.Through the analysis of the hydrogeological characteristics,the discrete element numerical simulation results and theoretical calculation,it is shown that the water-inrush bed-separation developed between the super-thick cretaceous sandstone strata and its lower soft rock contact surface,and received the filling of the luohe aquifer.Based on the measured data of water flowing fracture zone of similar mining conditions mine in Jurassic coal field northwest of China,the prediction formula for the water flowing fracture zone in full-mechanized top-coal caving of Shilawusu mine was applied,and the water flowing fracture zone was calculated to be between 236.80?278.98 m when the mining thickness of the first mining face was 8.7?10.78 m.The numerical simulation results of roof deformation and failure are consistent with the theoretical analysis and shows the development law of bed separation in time and space.According to the calculation results,there is a residual aquifuge of 4.92?63.29 m between cretaceous bed-separation and the top interface of water flowing fracture zone,due to luohe aquifer hydrostatic pressure of 2.91 MPa was transfered to anding formation by water in bed separation,the strata between water flowing fracture zone and bed separation broken under deadweight and luohe aquifer hydrostatic pressure.Through the improvement and application of the water inrush coefficient method,it is determined that the thickness of the limit aquifuge thickness at the lower part of the bed separation is 56.8m.Based on the above analysis of the mechanism of water inrush form bed separation in the first mining face,the prevention methods of underground borehole was put forward to prevent and control bed separation hazard.The thesis has 48 figures,15 tables and 82 references.