Study on the relationship between microseismic evolution during coal rock rupture ahead of the mining face and gas emission

Conventional methods for analyzing coal and rock failure cannot directly capture or predict how fracturing develops or how abnormal gas emissions occur at mining faces. To address this gap, this study used an on-site microseismic (MS) monitoring system to examine the evolution of coal-rock failure and to predict abnormal gas emissions. The results show two MS concentration zones within 400 m ahead of the working face: a primary zone from 0 m to 160 m and a secondary zone from 160 m to 400 m. The primary zone follows a three-stage cyclic evolution: an increase in the maximum damage index D_KDE with expanding area S, "D_KDE reaches peaking and shrinking S", and "fusing and decreasing D_KDE with S rising first and then falling". The secondary zone also shows a three-stage cyclic evolution: "increasing D_KDE", "D_KDE reaches peaking" and "fusing and disappearing". Both D_KDE and S are positively correlated with gas emission per ton of coal (Q), while the distance (d) between the most severely damaged area and the working face is negatively correlated with Q. Based on these relationships, the comprehensive index Z can predict abnormal gas emission 0.9-3.6 days in advance. These findings provide a basis for predicting abnormal gas emission caused by mining-induced coal-rock fracturing in fully mechanized mining faces.