Research on the Evolution Law of the Surrounding Rock Plastic Zone and the Separation Control Mechanism in Deep Gob-Side Entry with Composite Roof

To address the challenges of bedding separation and large deformation in deep gob-side roadways with composite roofs under the influence of stress deviation and weak interlayers, this study takes the 1692(1) rail roadway of Pansan Coal Mine as the research object. By combining numerical simulation, theoretical analysis, and field testing, the study thoroughly investigates the evolution patterns of the plastic zone in the surrounding rock and the mechanisms governing delamination. The results demonstrated that stress deviation induces shear failure of weak interlayers and causes bedding separation at the early excavation stage, which subsequently transforms into tensile failure and leads to coal pillar instability. The principal stress deviation angle determines the expansion direction of the plastic zone, while the thickness and number of weak interlayers are positively correlated with the degree of bedding separation. It is concluded that the coal pillar strength is a critical factor for bedding separation control. Based on these findings, a combined control scheme of “strengthening coal pillars, restraining shear damage, improving coordinated deformation” is proposed. Field engineering practice confirms that this proposed scheme effectively restrains the expansion of the plastic zone and ensures the long-term stability of the roadway.