Temporal-spatial laws of microseismic events induced by the fracture evolution of overburden strata and the relationship with gas emission during coal mining engineering

Abstract

Deep coal mining faces significant challenges due to high geostress, gas pressure, and geological complexity. This study leverages microseismic monitoring to establish spatiotemporal correlations between rock mechanical behavior and gas dynamics, critical for disaster early warning. Analysis of microseismic indices (event frequency, energy release, b-value, s-value) revealed three distinct spatial zones: Zone A (characterized by high frequency and high energy), Zone B (medium frequency and medium energy), and Zone C (low frequency and low energy), with roof-associated events concentrated at 20–30 m depth. Coal/rock instability manifested through intensified microseismic activity, decreasing b-values, and rising s-values. Gas emission thresholds showed clear ties to s-value variations: when absolute gas emissions exceeded 15 m³/min, s-values fluctuated around 0.135, while gas concentrations surpassing 0.2 % elevated s-values to 0.14. Maximum gas concentration (22 m roof depth) spatially aligned with microseismic patterns, confirming multi-parameter monitoring reliability. By integrating the spatial evolution of microseismic activity with temporal gas emission trends, we developed a predictive warning system for mining-induced gas outbursts. The proposed framework enhances operational safety in deep mining environments through three key advances: (1) quantitative linkage between microseismic zoning and gas distribution, (2) threshold-based b-value and s-value warning criteria, and (3) synergistic interpretation of Coal and rock mass fracture signals and gas dynamics. These findings provide actionable strategies for optimizing real-time monitoring systems and data-driven risk management in coal mines with similar geological conditions.