Investigation and Modification of a CSSM-Based Elastic–Thermoviscoplastic Model for Clay

Abstract

This paper examines the accuracy of a new elastic-thermoviscoplastic (E-TVP) constitutive model developed based on Critical State Soil Mechanics. The model can be used for simulating the temperature dependent, and strain-rate dependent behavior of clay soils. The study compares the E-TVP behavior of a single soil element with previously published thermo-mechanical experimental results performed on saturated clay specimens at different temperatures. Suggestions regarding unloading and reloading at constant temperatures as well as thermal consolidation under constant loads are presented. A modification for unloading-reloading adds a new criterion to the volumetric thermoviscoplastic strain rate formulation. A physics-based term is added to the current specific volume of the soil to include the viscous effect induced by temperature change. These modifications improve the convergence of laboratory data and simulated model responses. Comparisons of 1 Fathalikhani, February 10, 2022 results from an earlier E-TVP model and the newly improved model provide evidence of improved predictive capabilities.

A thermal elastic visco-plastic model for soft clayey soils

“…For one-dimensional (1D) and isotropic compression, existing studies have described the decrease of yielding stress with increasing temperature using various forms of mathematical 7 equations, such as power function (Moritz 1995;Wang et al 2016), exponential function , and logarithmic function (Laloui and Cekerevac 2003;Fathalikhani et al 2022). To consider the combined effects of temperature and time dependency, different constitutive equations have been developed, as summarized in Table 1.…”

“…The main reason is that due to the unavoidable inter-specimen differences and disturbance, the initial void ratios might not be identical for all specimens, which may cause scattering yielding stress under the same temperature. For the temperature-dependent shear behaviour of clayey soils, several three-dimensional (3D) thermal elastic-plastic models (Cui et al 2000;Graham et al 2001;Laloui and François 2009;Kurz et al 2016;Fathalikhani et al 2022) and thermal visco-plastic models (Kurz et al 2016;Fathalikhani et al 2022) have been proposed based on the critical state theory and the abovereviewed 1D temperature-dependent models. The anisotropy effect of clayey soils has been considered in some of the studies (Abuel-Naga et al 2009;Wang et al 2016; with the inclined elliptical yielding surfaces (Masad et al 1998;Wheeler et al 2003).…”