Risk assessment of water inrush from coal seam floor based on the FAHP-TOPSIS model

Water inrush from floor damage accident is a serious threat to the safe mining of the mine. With the continuous increase of mining depth, the risk of water inrush from coal seam floor is increasing. The evaluation indexes of traditional water inrush risk evaluation methods mostly only consider the performance of the aquifer, geological conditions, waterproof layer, and coal seam conditions, without considering the water-blocking performance of the waterproof layer of coal seam floor. The evaluation indexes are not comprehensive enough, and there are discrepancies between the evaluation results and the actual situation. This paper takes a mine in Erdos East, Inner Mongolia Autonomous Region as the research object, incorporates the water-blocking performance of waterproof layer of coal seam floor water barrier into the evaluation indexes, and comprehensively considers 10 evaluation indexes as the decision-making layer to establish the evaluation index system of the danger of floor water breakout applicable to the mine. The fuzzy matrix is constructed by using FAHP model to determine the subjective weight value of each index, and then substituted into TOPSIS model to generate the positive and negative ideal solution and relative closeness of each index, which is ranked as the water-surge hazard coefficient, and six grade intervals are determined as safe area, safer area, general safe area, general hazardous area, more hazardous area, and hazardous area. GIS spatial and information processing system is utilized to complete the information display of the results, comparing the evaluation results with the actual production situation, found that the evaluation results are in line with the actual production situation. The research has proven that the evaluation system and model are effective, providing a new perspective for the risk assessment of water inrush from floor of other mining areas with the same geological background, and incorporating the water-blocking performance of the waterproof layer into the evaluation indicators, providing new ideas for coal mine water prevention and control workers.