A novel DEM-based coupled 3D thermo-hydro-mechanical mesoscopic model with phase changes for modelling concrete behavior

A new DEM-based 3D model for fracture propagation was developed to simulate pore-scale thermal-hydro-mechanical processes, including heat transfer and phase changes (evaporation and condensation) in low-porosity, non-saturated frictional-cohesive materials (like concrete). Numerical simulations used a bonded granular specimen, combining DEM with CFD (based on a fluid flow network) and heat transfer to integrate discrete mechanics with fluid and heat transfer at the meso-scale. Both the fluid (through diffusion and advection) and bonded particles (via conduction) participated in heat transfer. The coupled thermal-hydraulic-mechanical (THM) model’s results were validated through a thermal contraction test with a bonded particle assembly during cooling, which led to the formation of a macro-crack. The study examined the impact of the macro-crack on the distribution of fluid pressure, density, velocity, and temperature.