Thermodynamics-Based Elastoviscoplastic Thermal Consolidation Theory for Soil

An elastoviscoplastic thermal consolidation theory of soil and its analytical solutions are developed in this paper based on a thermodynamic thermohyperelastoviscoplastic model. The thermoelastic coupling is accounted for by a nonlinear state-dependent hyperelastic relation coupled with the elastic thermal expansion of soil skeleton, and the thermoviscoplasticity is described by a time- and state-dependent dissipative law incorporated with the concept of granular temperature. The corresponding analytical solutions of thermal consolidation in a representative soil element and soil foundation are derived based a transformed governing equation in terms of a transforming function. The proposed theory is validated by predicting the heating tests of Edgar plastic kaolin (EPK) clay under different stress and drainage conditions. It is shown that the theory comprehensively accounts for the effects of confining pressure, K0 value, porosity, preconsolidation history, drainage condition, heating rate, and thermal creep on the thermal consolidation responses of soil such as the thermally induced pore pressure, pore-water drainage, and volumetric strain. The volume of pore water drained out of soil under heating is shown to be composed of the viscoplastic thermal volumetric contraction and the difference of thermal expansions between soil particles and pore water.