Modelling the effect of temperature on unsaturated soil behaviour

Abstract

A simple thermohydromechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way.

Thermal volume change of poorly draining soils II: Model development and experimental validation

“…The total change in void ratio during heating was predicted using the relationships proposed in Eqs. (13) and (14) Good agreement between the model predictions and the experimental results in Fig. 7 is observed.…”

“…(13) and (14) have been utilized to present the general behavior of the newly proposed method for the prediction of thermal volume change. In Fig.…”

“…The model expression defined in Eqs. (13) and (14) will be used to predict the thermal volume change response observed for the compacted Bonny silt from the companion study of Coccia and Table 1 Summary of data for MC Clay from Towhata et al [35]. 9.…”

“…Dumont et al [13] developed a model that combines the unsaturated hydro-mechanical framework of Khalili and Loret [24] with the saturated THM model of Wenhua et al [38]. However, due to the use of capillary stress to define the effective stress, the soil-water retention curve (SWRC) is not required and changes in degree of saturation due to mechanical loading or changes in matric suction are not captured.…”

“…1(b). This type of yield surface is the most widely utilized approach to model the thermal volume change of saturated soils [1,17,21,26,28] and unsaturated soils [13,15,16,38]. Incorporation of a thermal softening mechanism into the pre-existing LC surface permits the transition from thermo-elastic expansion to thermo-elasto-plastic contraction to be captured for an overconsolidated soil at constant mean effective stress.…”