Differentiated Fire Prevention and Control for Interconnected Goafs: Goaf Isolation and Nitrogen Inertization

Interconnected goafs form coupled air leakage networks in which local control can redistribute oxygen supply and spontaneous combustion risk among adjacent goafs. Taking the interconnected 1907, 1905, and 1903 goafs as the research object, this study combined field measurements and computational fluid dynamics (CFD) simulations to characterize multi-source air leakage, identify spontaneous combustion hazardous zones, and evaluate differentiated control measures. With the total intake airflow rate of the 1907 working face maintained at 3,240 m3/min, increasing the intake airflow ratio between 07-IR1 and 07-IR2 enlarged the total hazardous zone, while the 1:1 ratio produced the minimum total floor spontaneous combustion hazardous zone area of 59,411 m2 among the investigated cases. Air leakage sealing reduced the hazardous zone areas of the 1903 and 1905 goafs by 66.9% and 82.5%, respectively, but increased that of the 1907 goaf by 34.1%, demonstrating cross-goaf risk redistribution. Nitrogen inertization was therefore applied to the 1907 goaf. The preferred injection position and rate were 100 m behind the working face and 90 m3/min, reducing its hazardous zone area by 34.9%. After the combined measures, the total floor spontaneous combustion hazardous zone area decreased to 23,272 m2, representing an overall reduction of 60.8%. These results provide a quantitative basis for differentiated fire prevention and control in interconnected goafs.