Coupling mechanism of pressure oscillation and CO migration during gas explosions in mesoscale semienclosed roadways

To address observational limitations in traditional models, this study integrated physical experiments and thermo-hydro-chemical numerical simulations to investigate the spatiotemporal coupling between pressure oscillations and CO migration in a semi-enclosed roadway. Experimental validations showed high consistency, with relative pressure errors strictly controlled within 2.33%–11.29%. Unlike traditional forward-only diffusion models, our results reveal that pressure oscillation fundamentally drives reverse CO migration. Specifically, a “wave-flow decoupling” phenomenon was identified: the pressure wave (327.2 m/s) propagates 1.62 times faster than the CO gas cloud (202.4 m/s), generating a 5.6 m CO lag spatial window. Furthermore, outlet venting induces a deep negative pressure (up to −42 kPa), forcing external cold air to compress the CO plume. This causes the CO front to retreat by 57.5% within 80 ms, resulting in abnormal secondary accumulation at the closed end. A simplified empirical formula was derived to predict peak CO backflow, capturing its lagging and antiphase fluctuation characteristics. Ultimately, based on these quantitative findings, an executable three-level dynamic risk zoning system and targeted ventilation strategies were established, providing a robust theoretical framework for post-disaster mine rescue.