This study investigates the impact of varying soil cover thicknesses on the damage sustained by subway station roofs during leakage and explosion events involving sub-high-pressure gas pipelines. Taking a station on Zhengzhou Metro Line 12 as the case study, the TNT equivalent method was employed to quantify the explosion load. A full-scale numerical simulation model was developed using ANSYS / LS-DYNA, and the accuracy of the finite element model was validated through experimental data and theoretical calculations. The influence of different soil cover thicknesses on the structure of the subway station roof slab under the action of medium-pressure gas pipeline leakage and explosion was simulated. The damage effect of the subway station roof slab was comprehensively analyzed from three aspects: structural damage, failure mode, and dynamic response. The damage function of the subway station roof slab was established by the dimensional analysis method, and the relationship between the damage of the subway station roof slab and the ratio of soil cover thickness was analyzed through the damage threshold line. It was found that the ratio of soil cover thickness on the upper part of the subway station roof slab has a significant impact on the damage effect of the subway station roof slab. The research results provide a reference basis for evaluating the explosion resistance capacity of subway stations and designing and implementing efficient protection strategies.

The study aims to investigate the explosion characteristics of methane/air premixed gas across various temperatures and ignition positions. Under winter and summer conditions, respectively, using a custom-designed methane/air premixed gas explosion test apparatus, tests are conducted with different aspect ratios for a variety of concentrations of methane/air premixed gas explosion test, systematically analyzes the influence of temperature, aspect ratio, and concentration of the premixed gas explosion on the overpressure peak and impulse characteristics of explosions. Furthermore, by utilizing magnitude analysis methods and data fitting techniques, the study identifies the primary factors influencing these overpressure peak and impulse characteristics, and proposes a corresponding approach. In conjunction with the process of magnitude analysis and data fitting, the main factors affecting the overpressure peak and impulse characteristics were systematically analyzed, leading to the development of prediction formulas for the overpressure peak and impulse of methane/air premixed gases. The results indicate that: (1) the trends of peak overpressure and impulse in relation to increasing L/D ratio are generally similar for a specific gas concentration. However, these trends differ between winter and summer temperatures. Specifically, at a gas concentration of 7.5%, both peak overpressure and impulse initially decreased, then increased, and subsequently decreased again under winter temperature conditions, while they continued to decline under summer temperatures. For gas concentrations of 9.5%, 11.5%, and 13.5%, both peak overpressure and impulse consistently showed a decline in both winter and summer temperature conditions. (2) The relationship equations for peak overpressure and impulse, concerning the L/D ratio and methane/air premixed concentration, were established using magnitude analysis and data fitting under winter temperature conditions. The theoretical data were compared with the experimental results to verify that the errors were within 15%. The overall data match well, which verifies its reliability, and can express the decay law of overpressure and impulse with the L/D ratio and gas concentration more intuitively, thereby facilitating the rapid prediction of overpressure peaks and impulses.

To explore the influence of ignition position change on overpressure characteristics of methane/air premixed explosion under different equivalence ratios, several tests with varying length-to-diameter and equivalence ratios on the rise rate of peak overpressure and positive pressure duration were carried out through a self-built explosion test system. The main influencing factors affecting the pressurization characteristics of methane/air premixed explosion were analyzed by the dimensional analysis method, and the calculation formulas of rise rate of overpressure peak and positive pressure during methane/air premixed explosion were proposed. The results show that the rise rate of the overpressure peak increases with the increase of the equivalence ratio, and the increase in length-to-diameter ratio makes the rise rate decrease gradually, which is different from the attenuation rate. The positive pressure duration is gradually prolonged with the rise of the length-to-diameter ratio. However, the maximum positive pressure duration corresponds to different equivalence ratios with the length-to-diameter ratio changes. Furthermore, the calculation formulas of the rise rate of overpressure peak and positive pressure duration of methane/air premixed explosion are obtained by the dimensional analysis method, and the feasibility of the formulas is verified by comparing the experimental values with the theoretical values. It was found that methane/air premixed explosion is significantly affected by the ignition position and equivalence ratio, which can provide a reference for the power evaluation and safety control of methane explosions.