48 / 2025-07-20 18:37:28

Temperature effects on the deformation and failure mechanisms of horizontally layered rock surrounding a tunnel in tests with a physical model

Temperature effect; Physical model test; Layered rock; High-temperature tunnel; Failure mechanism

To investigate the deformation and failure mechanisms of horizontally layered surrounding rock under high-temperature conditions, physical model tests were performed at 20 °C, 40 °C, 60 °C, and 80 °C using a self-developed stratified heating device. The device enables uniform heating of large-scale models (temperature fluctuation ≤ ±1 °C) by integrating nickel–chromium heating wires with tin foil to simulate bedding planes, while significantly reducing the internal stress interference typically caused by traditional heating rods. Experimental results show that: (1) At 20 °C and 40 °C, the surrounding rock mainly undergoes compression–tension controlled elastoplastic deformation without evident thermal damage; (2) At 60 °C and 80 °C, thermal damage becomes dominant, resulting in shear-controlled plastic deformation and progressive mechanical degradation; (3) The failure modes evolve from tensile failure along bedding planes (20 °C), to shear failure (40 °C), and then to compound shear failure (60–80 °C), indicating a clear temperature-dependent transition; (4) At 80 °C, the cumulative acoustic emission energy due to crack propagation is approximately 3.2 times higher than that at 20 °C, demonstrating significantly reduced rock mass stability at elevated temperatures. These findings offer an effective experimental approach for simulating thermal–mechanical behavior in layered rocks and enhance the understanding of deformation and failure characteristics of tunnel surrounding rock in high geothermal regions.