In order to scientifically guide the water-preserved mining of the coal seam floor and make up for the shortcomings in the conventional evaluation of water blocking performance of the coal seam floor, according to the system resilience theory, the difference between the vulnerability and resilience of the coal seam floor is analyzed, and three elements and nine indicators for evaluating water resistance toughness of the coal seam floor are determined. In the evaluation process, first of all, the maximum difference normalization method is used to conduct a dimensionless analysis of quantifiable indicators to determine the importance of the corresponding indicators, and the AHP software yaahp10.1 is used to determine the weight vector of each indicator. Secondly, the single-factor membership degree is determined according to the single-factor resilience grade classification criterion and membership function and finally combined with the weight vector for fuzzy synthesis calculation and comprehensive evaluation. The model is applied to a specific project. Research has shown that in the water hazard threat area of No. 10 coal seam floor in Jiegou Coal Mine, Anhui Province, the performance of system vulnerability elements is weak, the performance of system recoverability elements is better, and the performance of system adaptability elements is extremely poor. From the perspective of the whole life cycle, determining the treatment target area, optimizing the rock formation modification and repairing materials, and enhancing the water resources carrying capacity can improve the water resistance toughness of the coal seam floor. Related conclusions verify the effectiveness of the evaluation model. Furthermore, an optimized strategy for coal seam floor water retention mining is proposed: the technology system of water-preserved mining for coal seam floor contains 3 stages and 3 detections, which provides a scientific basis for the in situ protection of high-pressure limestone water from coal seam floor.

This paper takes the gas cabin in the utility tunnel in the Xuwei District of Lianyungang as the study object. Based on the computational fluid dynamics (CFD) theory, a simulation model of the gas cabin in the utility tunnel is established. The propagation law of methane leakage and diffusion and the characteristics of methane explosion shock wave propagation were simulated under different conditions of the gas cabin. These conditions are the presence or absence, spacing and height of the air baffle. The results show that: (1) the gas baffle can limit the propagation of methane at the top of the gas cabin and slow down the velocity of diffusion so as to increase the concentration of methane near the baffle and speed up the time for the monitor to reach the alarm concentration; (2) the first peak pressure and the second peak pressure generated in the middle of the gas cabin are smaller than that when the gas baffle is installed. The gas baffle has the function of blocking the propagation of shock waves. However, due to the installation of the gas baffle, the superposition of the shock wave will make the pressure surge at the gas baffle; and (3) combined with the simulation results, it is recommended that the gas baffle spacing is not less than 50 m and the height setting is not greater than 0.5 m.