Study on CO migration characteristics and hazard potential function under ventilation after roof cutting blasting

Multiple toxic gases, such as carbon monoxide (CO), are generated by roof-cutting blasting (RCB) in the automatically formed roadway without coal pillars (AFRCP). To eliminate potential hazards in time, a ventilation model was established based on field data from Dianping Coal Mine. The spatial and temporal evolution characteristics of CO under different conditions after roof-cutting by shaped-charge blasting (SCB) and shaped-charge hydraulic blasting (SCHB), respectively, were investigated by using the Computational Fluid Dynamics (CFD) method. The results demonstrate that the CO gas cloud presents the coupling effect of movement and dilution under ventilation. The charge mainly affects the peak value of CO concentration (PVC). The air velocity affects the PVC and the CO gas cloud's over-limit time (OLT) and migration velocity. Roadway cross-sectional area and corner structure affect the PVC by influencing local air velocity. The CO hazard potential functions of the roadway after RCB were established, indicating a Gaussian-like distribution. The maximum hazard potential of SCHB was found to be 60% lower than that of SCB, and the re-entry time for personnel reduced by 36%. This study can serve as a guide for optimizing the ventilation design of roadways after RCB and contribute to the promotion of AFRCP.