A Comparative Experiment on Heterogeneous Distributions of Stress Field for Underground Panels With Different Geological Setting in North China

Abstract

A comparative experiment was carried out to discuss the detectability and influence factors on heterogeneous distributions of the stress field for underground panels in North China. The panels are situated in the center and the eastern margin of the North China plate, having similar layouts and stress states. Seismic surveys were performed before coal extractions, and travel-time topographies for refracted P-waves from stiff roofs were computed with a ray-based inversion. The tomographic distributions of P-wave velocity were interpreted by a K-means clustering to categorize the stress fields. The estimated high-stress anomalies show strong correlations with the monitored dynamic roof ruptures and high-energy microseisms. Besides, the relationship among high-stress areas, geological factors, and mined-out voids is also discussed through feature comparisons, Monte–Carlo simulations, and point process statistics. Our results show that the curvature variations and the mined-out voids are dominant factors that affect the heterogeneous distribution of the stress field in the panels. However, the leading causes of the curvature variations in the small-scale panels are different, but they do follow the large-scale regional patterns of the geological regime.