Thermo-hydro-mechanical behavior of a clayey rock: A constitutive approach and numerical validation

Temperature strongly affects the thermo-hydro-mechanical properties of clayey rocks. Using the Drucker–Prager Cap model and available experimental results, an advanced constitutive model is proposed to describe the influence of temperature on the hydro-mechanical properties of clayey rocks. To replicate the stress-strain behavior of clayey rock under the thermo-hydro-mechanical conditions, transverse isotropic properties are considered in the constitutive model. Attention is particularly focused on the stress-strain behavior of clayey rock at the plastic stage, the evolution laws of cohesion, friction angle, and pre-consolidation pressure are established by introducing factors such as elastic damage, plastic damage and hardening, and thermal damage. A hydraulic conductivity evolution law is presented, accounting for the thermal effect on water properties and porosity. Theoretical studies are implemented in the finite element method software ABAQUS FEA using the subroutine USDFLD. Some theory parameters are verified through back analysis. Finally, the experimental results and numerical simulations are compared, showing the superiority of the established theoretical model.