Study of the Entire Space–Time Stress Field Inversion and Stress Factors Leading to Outbursts in Coal Mines

Stress serves as a crucial foundation for underground engineering design of mines and plays a pivotal role as an early warning indicator of underground dynamic disasters. In this study, the Sangshuping coal mine is considered a case study to investigate the evolution characteristics of the entire space–time stress field in a mine. Initially, an equal-scale digital model of the mine is constructed, followed by the application of the developed equal-scale digital model assimilation method. The assimilation of the mine entity and digital model is achieved by integrating measured in situ stress, mining disturbance stress, roadway deformation, and surface rock movement data. Further, the entire time–space stress field inversion is calculated based on the actual mining sequence. Specifically, the findings reveal that both the topography and geological structure exert significant control over the distribution of the in situ stress field. Notably, the vertical stress gradient undergoes significant changes within the outburst area, whereas the maximum horizontal principal stress is approximately perpendicular to the mining direction. Regions exhibiting continuous shifts in the direction of the maximum principal stress owing to geological structural control are more susceptible to outbursts. Mining concludes with the formation of a stress field influencing an area exceeding 100 m around the mining face. Vertical stress is the most sensitive to various disturbance factors. Among the five proposed stress evolution paths (continuous concentration, continuous relief, relief first and then concentration, concentration first and then relief, and no disturbance), continuous concentration emerges as the primary path of stress evolution induced by mining at outburst points. The study underscores the importance of space–time stress field inversion in guiding effective coal and gas outburst prevention and control strategies, offering valuable insights into rational underground mine design and safe mining.