Evaluation of the Effects of Pre-Grouting in Combination with Group Holes on the Risk of Water Inrush through Coal Seam Floors

Coal mine pre-grouting is an important means to reduce the risk of coal seam floor water inrush, and the scientific evaluation of its effects is an important basis for the formulation of water control countermeasures and the realization of safe mining. This paper takes the Guhanshan Mine 15,051 working face grouting project as the research object and selects the grouting volume, the length of the meter grouting, the dry material value in tons of water, the complexity of faults, and the threat of water inrush at the working face as the index factors with which to evaluate the effectiveness of the grouting. The geological structure is quantified by fractal theory. The subjective, objective, and comprehensive weights of the index factors are determined by the analytic hierarchy process, the CRITIC method, and the combination weighting method. The grouting effect on the working face is quantitatively identified by the fuzzy variable set comprehensive evaluation model, and zoning is carried out. The research shows that the areas with optimal, good, qualified, and poor grouting effect at the 15,051 working face account for 4.66%, 74.34%, 21.00%, and 0% of the working face area, respectively, and the proportion at the level of qualified or above accounts for 100%. The safety results at the 15,051 working face prove that the selected evaluation index factors are representative, the established model is reliable, and the evaluation results are in line with actual conditions.