Deformation and Energy Evolution of Roadway-Surrounding Rock Under High In Situ Stress: Implications for Safe and Sustainable Deep Energy Extraction

In situ stress is a primary driver of deformation and failure in surrounding rock masses, posing a critical challenge to the stability of deep roadways in energy extraction (e.g., deep coal mining and geothermal development). To investigate this issue, this study introduces an enhanced numerical approach within the Y-Mat program. The method improves tangential contact force calculation by incorporating slip change rate and maximum static friction and adopts an elastoplastic criterion to model rock yield behavior. The improved Y-Mat program is validated against analytical solutions for the elastic stress distribution around a circular roadway, and the simulation results show a high level of agreement. Using this validated tool, we simulate the mechanical responses of roadway-surrounding rock under both uniform-stress and stress-gradient conditions. The results indicate that while high in situ stress does not alter the primary deformation modes (roof subsidence and floor heave), it significantly exacerbates damage, and both the total deformation and the deformation rate increase continuously with the increase in stress level. Under a stress gradient, the failure zone exhibits a trapezoidal shape; shear cracks dominate the macroscopic fracture pattern, and crack propagation is primarily vertical—opposite to the direction of major displacement. Furthermore, the evolution of the stress field is intrinsically linked to changes in the strain energy density field; when the local strain energy density reaches a critical value under the new stress state, yielding or failure is triggered, accompanied by the release of strain energy, which governs the timing and location of failure. These findings offer a theoretical foundation for stability assessment and support system design in deep underground excavations, contributing to safer and more sustainable exploitation of deep energy resources.