Failure mechanisms and stability control of roadways in thermally damaged rock under asymmetric stress: a case study

Stability maintenance of deep roadways in thermally damaged rock masses presents complex challenges under asymmetric stress conditions. This study investigates the failure mechanisms and proposes a control strategy using an integrated methodology of laboratory testing, theoretical analysis, and field validation. Triaxial compression tests with Acoustic Emission monitoring indicated that the mechanical degradation of thermally damaged rock is primarily influenced by the propagation of pre-existing microcracks. An analytical model based on the complex variable method quantified the stress field around a rectangular opening, incorporating the effect of principal stress rotation. The analysis revealed a coupled failure mechanism where stress asymmetry governs the inclined X-shaped plastic failure geometry while degraded rock properties determine the extent of the plastic zone. To address this mechanism, a Reinforcement-Anchorage-Confinement (RAC) collaborative support system was developed. Numerical simulations and a field application demonstrated that the RAC system controls fracture propagation and maintains roadway deformation within acceptable operational limits. This research provides a mechanistic framework for roadway stability control in similar geomechanical environments.