Lateral Structure of Multi-Layer Thick Hard Roofs and Hydraulic Roof-Cutting Pressure Relief in Xiao Jihan Mine

This study aims to address the pronounced stress concentration in roadway-surrounding rock under conditions of multiple thick and hard roof strata at Xiao jihan coal mine, China. The work was carried out on the 13216 working mining face as the engineering background. A systematic investigation was conducted using a combination of theoretical analysis, numerical simulation, and field experiments. Under double mining disturbance, the lower thick hard roof behaves as a cantilever beam and the upper hard roof strata form a masonry beam structure, producing strong stress transfer to the roadway. The mechanical model indicates a peak stress of 28.90 MPa, 18.34 MPa higher than the in situ stress. Hydraulic roof cutting was designed at the upper thick hard roof horizon. UDEC simulations show that the vertical stress decreases from 26.10 MPa to 13.20 MPa. Field monitoring confirms pressure relief: the non-cutting zone shows a peak of 30.75 MPa, while the roof-cutting zone drops to 22.51 MPa, a 24.62% reduction. The findings of this study provide practical guidance for lateral structure regulation under similar geological and mining conditions.