Analysis of coal mine surrounding rock characteristics based on geomechanical testing

To tackle issues such as unreasonable roadway support design, poor support performance, and frequent disasters caused by inaccurate understanding of the geomechanical properties of roadway surrounding rock, the No. 5 coal seam of a coal mine in Northwest China was selected as the research object. Three monitoring stations were established in the excavated roadway, and the surrounding rock characteristics were analyzed based on field measurement data. Borehole endoscopy was used to observe the structure of the surrounding rock, revealing that the roof is mainly composed of hard sandstone, and the site for hydraulic fracturing tests was selected accordingly. In situ stress measurements using a hydraulic fracturing geo-stress meter indicated that the geo-stress state of the No. 5 coal seam is σ_H>σ_v>σ_h, which overall represents a low-stress zone dominated by tectonic stress. The results of the borehole probing tests indicate that the average strength of the sandstone within the upper 10 meters of the roof is 101.35 MPa, indicating that the roof is classified as a hard roof. The average strength of the coal body in the No. 5 coal seam is 16.74 MPa. The aforementioned in-situ test data provide a scientific basis for the support design of the roadway in the coal seam.