The risk assessment of water bursting based on combination rule of distance function

Mine water damage is one of the main disasters that threaten mine safety.The geological structure of Nantun coal mine is complicated and the ordovician limestone aquifer has high water pressure.To ensure the safe exploitation of coal mines, this paper analyzes and evaluates the coal floor water bursting risk of the ordovician limestone by analyzing geological and hydrogeological data and using distance function combination weighting method.The four main controlling factors of the water pressure of aquifer, water yield property, complexity of the fracture structure and thickness of the aquifer are determined by combined with the actual conditions of the mine.The water abundance of aquifer and the complexity of fault structure are quantified by unit water inflow q and fault fractal dimension respectively.The combined weighting coupling is conducted for the improved analytic hierarchy process and entropy weight method to determine the comprehensive weight of water bursting risk, and establish the calculation model of the water bursting risk index by introducing the distance function.The region evaluation for the water bursting risk is carried out by using Jenks's best natural fracture method, and the result shows that if the index of water bursting risk is less than 0.12, it is the safety zone, and the range of 0.12~0.19, 0.19~0.25, 0.25~0.31 and above 0.31 represents the relatively safe zone, relatively dangerous zone, dangerous zone and extremely dangerous zone. This method balances the influence of subjective and objective factors on weights, and improves the accuracy of water bursting risk prediction. This method provides a reference for the prevention and control of water damage in coal mine floor.