Deformation and failure mechanisms and active–passive coordinated support of roadways subjected to repeated mining disturbances

The failure mechanisms and support control of roadways subjected to repeated mining disturbances remain critical challenges in underground close-distance coal seam mining. This study investigates the effects of the mining coefficient and support resistance on the plastic zone distribution of surrounding rock in roadways subjected to repeated mining disturbances through field investigation, theoretical analysis, numerical simulation, similarity modeling, and engineering practice. An active–passive coordinated support system composed of bolt–cable support (active support) and a steel beam–concrete-filled steel tube (CFST) composite frame (passive support) is proposed and verified through field application. The results indicate that the plastic zone of surrounding rock continuously develops and expands under repeated mining disturbances. The mining coefficient is identified as a key parameter controlling the extent of the plastic zone, whereas increasing passive support resistance effectively restrains its development. Based on these findings, a steel beam–CFST composite frame is developed as the passive support structure. Parametric analyses using ABAQUS are conducted to evaluate the influence of steel pipe diameter, wall thickness, and steel beam length on the stress–strain behavior of the support system. Optimized design parameters suitable for engineering applications are proposed, forming an active–passive coordinated support system together with bolt–cable support. Similarity model tests of the active–passive coordinated support scheme demonstrate that the composite frame possesses adequate load-bearing capacity while accommodating controlled deformation of the roof and surrounding rock. Under the coordinated action of bolt–cable support and the steel beam–CFST composite frame, the stability of roadways subjected to repeated mining disturbances is significantly improved. Compared with the original support scheme, roof subsidence, sidewall convergence, and floor heave are reduced by 37.4%, 17.8%, and 40.4%, respectively. The proposed active–passive coordinated support system has been successfully applied in field engineering and achieved satisfactory control of roadway deformation.