Multiscale modeling of environment-dependent heterogeneous media by a Thermo-Hydro-mechanical damage model

Evaluating the combined environmental effects, such as external loads, water saturation, and thermal variations, on the mechanical performance of porous media is challenge, mainly due to its inherent heterogeneity and complex multi-physical field mechanisms. This study developed a multiscale thermo-hydro-mechanical damage modeling framework to investigate environment-dependent heterogeneous porous media, with a specific focus on pavement infrastructure. The notable features of this framework comprise: (1) introducing an upscaling homogenization method to connect material thermo-mechanical properties across various scales while considering seasonal variations, (2) creating a downscaling transfer procedure to translate structural responses and temperature fields from macroscopic to mesoscopic scales, providing insights into their multiphysics mechanisms at different scales, and (3) proposing a new sequential coupled algorithm in multiscale simulations for comprehensive multi-field cross-scale calculations. The key findings demonstrated that under hydro-thermomechanical loading, shear transverse damage occurs mainly at the macro media surface, while tension longitudinal cracks appear at the bottom of the meso-scale material layer. Damage patterns vary with seasons, with more shear damage prevalent during the summer and an increased occurrence of tension cracks during the winter. Additionally, water-saturated media are more susceptible to "down-top" cracking compared to dry ones. The proposed model can be easily extended to investigate the mechanical behaviors of various heterogeneous porous media under a range of environmental conditions.