Role of initial confinement, drainage, and heating rate in thermal consolidation

Thermal loading induces volumetric changes, with increasing temperature leading to volume contraction in normally consolidated (NC) clays. This behaviour can be utilised for ground improvement applications. Experimental studies have shown that thermal contraction varies with initial effective stress; however, the combined effects of drainage conditions, initial confinement, and heating rate have not been systematically investigated. This study examines the thermo-hydro-mechanical (THM) behaviour of fully saturated clays subjected to cyclic heating and cooling. A fully coupled finite element model is developed in COMSOL Multiphysics by integrating the modified Cam-Clay model and the Advanced Constitutive Model for Environmental Geomechanics with Thermal effects. Key material properties are modelled as temperature- and pressure-dependent. The model is validated against temperature-controlled triaxial test results under drained conditions. The validated model is then used to evaluate the effects of drainage systems, initial confinement, and heating rate on pore pressure evolution and volumetric strain. Based on the numerical results, a semi-theoretical–numerical predictive relationship is proposed to estimate thermal consolidation in NC clays. Results demonstrate that drainage conditions, heating rate, and initial confinement significantly influence thermal pressurisation and volumetric contraction, providing a practical framework for predicting THM behaviour under moderate temperatures and short-term thermal loading conditions.