A semi-analytical model for coupled THM consolidation of saturated clays improved by PVTD considering thermal contraction

Previous studies have demonstrated that saturated normally consolidated and lightly over-consolidated clays undergo contraction when heated due to a reduction in preconsolidation pressure. A linear constitutive model is proposed to describe the thermal contraction, with this model, governing equations are developed for the coupled thermo-hydro-mechanical (THM) consolidation induced by a prefabricated vertical thermo-drain (PVTD). Corresponding semi-analytical solutions are derived employing the Laplace transform and validated via comparison with experimental results, existing numerical model, and custom finite element method (FEM) model. Subsequently, comprehensive parametric analyses are carried out to investigate the THM coupling consolidation behaviors of the clays. Outcomes show that aside from surcharge load, generation of excess pore water pressure in soils can also be induced by thermal contraction, difference in thermal expansibility between pore water and soil grains, and thermo-osmosis, where the influence of thermal contraction on the excess pore water pressure is the most prominent among the three factors.