Thermo-elasto-plastic analysis of geosynthetic clay liners exposed to thermal dehydration

Abstract

Geosynthetic clay liners (GCLs) are designed to minimise contaminant migration into subsoils in landfills and other waste containment systems. The so-called mixture theory has typically been chosen as a basis for numerical models describing the complicated behaviour of GCLs subjected to thermo-hydro-mechanical changes. Despite progress in this area in the past decade, some aspects of the response of GCLs have not been captured by these simulations. For example, a typical assumption of these analyses is that the mechanical response to thermal loads of GCLs can be described by linear or non-linear elastic constitutive equations. However, there is evidence that in many instances plastic deformation cannot be avoided. The primary aim of this study is to analyse the hydration and dehydration behaviour of GCLs within a thermo-elasto-plastic framework. First, a thermo-elasto-plastic constitutive model is introduced and numerically implemented. Next, the results of numerical simulations of the performance of GCLs are presented and discussed and the effects of deviations from elastic behaviour are identified. Finally, a parametric study is conducted to identify the influence of key parameters in the constitutive model on the horizontal stress in the GCL’s bentonite during restrained shrinkage driven by thermal dehydration.