Thermo-Hydro-Mechanical Dynamics of a Rock Slope: Integrated Field and Numerical Analysis

Understanding strain and fracture evolution in rock masses under climate change is crucial for slope stability. This study presents a fully coupled thermo-hydro-mechanical (THM) simulation of a rock slope at the Požáry test site in the Czech Republic, integrating field tests and laboratory analyses. The simulations used the exactly measured slope geometry and incorporated a pre-existing upper slope fracture. Key constitutive models for fluid and vapor flow, heat conduction, and porosity-dependent permeability were coupled with a viscoplastic damage model to capture the THM behavior of the rock slope. Laboratory tests on three rock samples (A, B, and C) with varying elastic moduli and porosities informed the material properties for three corresponding models. Simulation results showed greater thermal changes in the upper sections of the slope due to increased exposure to thermal effects. Model A, with the highest elastic modulus, exhibited lower initial strain changes, while Model C showed significant early strain variations. After 30 d, Model A experienced a sudden strain decrease due to thermal contraction-induced damage. The critical fractured zone (CFZ) analysis revealed that rock contraction under cooling led to an increase in pore water pressure, exacerbating the damage. Model B highlighted the impact of geometrical asymmetry on the propagation of the damaged zone. Over time, the thermal effects increased plastic deformation in Model A, while Model C remained elastic and exhibited no damage. These findings have significant implications for assessing rock slope stability, particularly in predicting failure zones due to permeability reduction and pore water pressure generation.