Risk assessment of floor water inrush by weighted rank sum ratio based on combination weighting

Deep mining of the coal seam causes frequent water hazards in the coal mine floor. As the disadvantages of traditional water inrush risk assessment methods, such as single evaluation index and deviation of the evaluation results from reality are gradually revealed, many new assessment methods are emerging. In this paper, Donghuantuo Coal Mine, a North China type coalfield, in Hebei province is taken as the research object. The evaluation factor sets including aquifer capacity, aquifuge capacity, geological conditions and coal seam conditions are selected, and with ten evaluation factors being considered, a floor water inrush risk evaluation index system applicable to Donghuantuo Coal Mine is established. AHP and CRITIC methods are adopted to determine the subjective weight and objective weight of each index, and then the two parts are coupled to obtain the comprehensive weight. In the process, the subjective experience of experts and objective data are taken into account to ensure the comprehensiveness of weight determination. By using the weighted rank sum ratio method, an evaluation matrix is constructed. And indexes are divided into high-optimality and low-optimality according to their impacts on the evaluation objects. By ranking and calculating the WRSR value, and sorting the data based on grades, an evaluation model is formed in which four evaluation levels are determined, including safe, safer, more dangerous and dangerous. The results are displayed by using powerful spatial management and information processing function of GIS. By comparing the evaluation results with water outlet positions in the actual project, it is found that these positions are in the more dangerous area of floor water inrush. The effectiveness of the evaluation model is proved by comparing the new method with the traditional water inrush coefficient method. The research forms a new method for assessing the risk of water inrush from the coal seam floor, which enriches the existing assessment methods and provides a new thought for coal mine water control workers.