Study on surrounding rock support of composite roof roadway under expansion stress

Faced with significant challenges of composite roof management and roadway support in the Chenghe mining area, which severely hinder safe mining operations, this study utilized the 1501 return air roadway of the No. 5 coal seam in Shanyang Coal Mine as a case study to explore the failure mechanisms and support strategies for soft rock roadways beneath composite roofs. By conducting physical and mechanical experiments, the study identified the physical parameters of each rock layer within the roof and analyzed the stress distribution characteristics of the composite roof through both field measurements and theoretical analysis. This process led to the development of a comprehensive mechanical model for the composite roof of the roadway in Shanyang Coal Mine. The study proposed a support scheme that employs full anchor cable support for the roof and a combination of metal mesh, steel straps, and anchor rods for the roadway sides. The effectiveness of this scheme was then validated through numerical simulation and field measurements. The results indicated that the sandy mudstone layer in the upper part of the mine's composite roof is an expansive rock with a maximum expansion rate of 42.3% and a maximum expansion stress of 198.2 kPa, making the medium-grained sandstone layer K4 a key layer. The proposed support scheme successfully meets on-site production needs, proving the feasibility of this new approach and offering a valuable reference for managing similar geological conditions in other mines. © 2024 Editorial Office of Journal of Mining and Strata Control Engineering. All rights reserved.