Influence of Flexible Material Elastic Modulus on Methane Explosions and Parameter Optimization

To address safety hazards posed by natural gas explosions in urban underground spaces and investigate the influence mechanism of flexible material elastic modulus on methane explosion protection, this study experimentally examined the regulatory effects of three flexible materials with distinct elastic moduli—rubber strip, pearl cotton, and foam cotton—on explosion characteristics. It further explored the optimal rigid and flexible spacing for the most effective flexible material. Experiments systematically analyzed protective efficacy under various conditions by measuring parameters including flame propagation velocity, explosion overpressure, and pressure change rate. Among the tested materials, pearl cotton exhibited the best protective performance, reducing the peak flame propagation velocity by 26.04% and the upstream and downstream peak explosion overpressures by 44.26% and 35.35%, respectively, compared with the rigid-only condition. In the optimization of rigid and flexible spacing, the explosion intensity index reached its lowest value when the gap between flexible and rigid materials was minimized, yielding the most pronounced suppression of explosion impact force and energy release. The study confirmed that flexible materials can mitigate explosion intensity through deformation buffering, energy absorption, and turbulence disruption. These results mainly reveal the attenuation mechanisms under the present experimental conditions and may provide a basis for further experimental and numerical studies related to explosion protection in urban underground spaces.