In this research, the thermomechanical formulation proposed by Ziegler and formalized by Houslby and Puzrin to build up hyperplastic constitutive models is applied to the case of unsaturated materials. The mechanical model is based on two main equations: the free energy and the dissipation functions. The former represents the elastic behavior while the latter accounts for the plastic behavior of the material. The dissipation function can be split into two parts: one represents the flow rule and the other the yield surface. The shape of the yield surface can be modified by a single parameter while the plastic flow is of the non-associated type and can also be modified with a single parameter. The yield surface rotates at the origin depending on the anisotropy of the material. The volumetric behavior of the soil is related to the distance between its current state and the normally consolidated, the critical state, and the unloading-reloading lines. The model considers the phenomenon of suction hardening and employs Bishops equation to determine the effective stress on unsaturated materials. The mechanical model is coupled to a porous-solid model that can simulate the soil-water retention curves during wetting-drying cycles and accounts for the hydro-mechanical coupling phenomenon. In that sense, this procedure does not require pre-establishing the shape of the yield surface or the flow rule. The resulting model is a three-dimensional hyperplastic coupled model that requires few parameters. Comparisons between experimental and numerical results show that the proposed model can simulate the behavior of soils with fair precision.

This paper presents a thermomechanical constitutive model that captures temperature dependent evolutions of preconsolidation stress and stress anisotropy in normally consolidated and lightly overconsolidated saturated clays. Following a non-associative flow rule, the model was formulated to account for the rate of evolution of stress anisotropy as a function of temperature. A temperature-dependent rotational hardening parameter was introduced and calibrated employing a simple optimization algorithm for four different clays. The developed model was further implemented in a finite element (FE) analysis software for use in boundary value problems. Success of such numerical implementation and predictive performance of the constitutive model was further verified through FE simulations of drained and undrained triaxial tests on saturated clays at reference and elevated temperature. FEA results obtained from these simulations agreed very well with test data reported in the literature.

The thermomechanical behaviour of horizontally loaded energy piles in saturated clay was investigated in this study. Based on model-scale tests, a model energy pile underwent 10 heating-cooling cycles. The temperature variation, pore water pressure, soil pressure in front of the pile, pile top displacement, and pile bending moment were measured. The results showed that the thermally induced pore water pressure in the upper part of the surrounding soil gradually dissipated with increasing number of thermal cycles, whereas it gradually accumulated in the lower part of the soil. The thermally induced horizontal displacement of the pile top increased with an increasing number of thermal cycles, reaching 2.28% D (D is the pile diameter) but at a decreasing rate. In addition, the maximum bending moment, which affected the failure of the pile, occurred at a depth of 0.375L (L is the effective pile length) below the soil surface and increased with increasing number of thermal cycles.

Thermally induced volumetric strain of clay is crucial for geotechnical applications involving thermal loading. The volumetric response of clay shows a ratcheting pattern during thermal cycles until reaching a thermal stabilized state. It is also affected by the stress history of soil, including over-consolidation ratio (OCR) and recent stress history (RSH). This paper introduces a new bounding surface model to capture effects of OCR and RSH on thermo-mechanical behaviour of soil. A thermal state parameter is proposed to characterize the effects of stress history and thermal history. Based on the new thermal state parameter, the commonly recognised thermal softening mechanism is modified and incorporated with a bounding surface. The newly proposed model, with only 10 parameters, can provide an elegant approach to predict the volumetric response under thermal cycles coupled with different stress histories well.

Understanding the dynamics of glaciers is essential for the knowledge of global sea-level rise, local freshwater resources in high mountain and arid regions, and the potential glacial hazards. In this paper, we present a two-dimensional thermomechanically coupled ice flow model named PoLIM (Polythermal Land Ice Model). The velocity solver of PoLIM is developed based on the Blatter-Pattyn approximation of Stokes flow. It uses an enthalpy formulation of the energy balance, an approach that is suitable for modeling the polythermal glaciers. PoLIM also includes a scheme for gravity-driven drainage of water in temperate ice, a subglacial hydrology model coupled with ice dynamics, and multiple basal sliding laws. The model has been verified by standard benchmark problems, including the ISMIP-HOM experiments, the enthalpy benchmark experiments, and the SHMIP experiments. PoLIM shows good performances and agrees well with these benchmark results, indicating its robust capability of simulating the thermomechanical behaviors of glaciers.