Transient Dynamics and Spatiotemporal Patterns of Gas Superposition in Multi-Shaft Asynchronous Reverse Ventilation

Abstract Reverse ventilation in multishaft mines is a complex transient process, referred to as asynchronous reverse ventilation. To clarify the transient dynamics and mechanisms of gas migration and superposition, we developed a 3D high-fidelity dynamic simulation model of the ventilation network. Taking Shaqu No. 2 Mine’s two-wing ventilation system as a case study and using the TF1M3D platform, we simulated dynamic parameter variations and gas migration superposition during asynchronous reversal between the return-air inclined shaft and the Baijiapo return-air vertical shaft. The results show that two-wing asynchronous reversal adjustments induced air-volume variations of less than 9.2% in the return airways and less than 17.6% at the working face. Analysis of the impact of reverse ventilation on gas superposition and exceedance revealed distinct spatiotemporal patterns. At the 4903 working face, the gas concentration fluctuated, peaking at 1.69% at 510 s due to reversal superposition, and at 1.70% at 1550 s after ventilation restoration, exceeding the limit. At the 5303 working face, it peaked at 0.81% at 780 s and 0.95% at 1500 s postrestoration, approaching the thresholds. Fan adjustments during two-wing asynchronous reversals caused gas-concentration fluctuations at each working face, and mining haulage roadways also exhibited fluctuations and exceedance events.