Dynamic hydro-thermo-mechanical response of the saturated cylindrical unlined tunnel based on the coupled poro-visco-thermoelastic model with new multi-dual-phase-lag heat conduction law

Abstract

The investigation of the dynamic hydro-thermo-mechanical coupled responses of unlined tunnels in some extreme geological engineering conditions (e.g., underground explosions and laser-induced thermal rock breaking) is imperatively crucial to guarantee the mechanical strength and avoid the unwanted vibration. Nevertheless, in such ultrafast heating conduction, the existing constitutive models and impact response predictions fail to characterize the inherent phase-lagging behavior of the higher-order heat flux and temperature gradient, resulting in current transient impact response analysis on this topic being inaccurate and challengeable. To address such deficiency, the present study aims to establish a new poro-visco-thermoelastic model for saturated medium based on multi-dual-phase-lag (MDPL) heat conduction law. The newly developed model is applied to explore the transient thermal shock for cylindrical unlined tunnels in poro-visco-thermoelastic medium via Laplace transform method. The dimensionless results reveal that the high-order heat flux term and temperature gradient relaxation parameter in MDPL heat transport model lift levels of temperature, pore water pressure, displacement and radial stress, characterizing the faster propagation speeds of thermal wave in saturated cylindrical unlined tunnel.