Shear behavior at interface between compacted clay liner–geomembrane under freeze-thaw cycles

Abstract

Bentonite sand mixtures (BSMs) are commonly used in compacted clay liners (CCLs) in waste disposal facilities when the local soil is not suitable for use in the liners. Given that the temperature tends to vary drastically in many cold regions, it is important to have a good understanding of the interface shear behavior of composite liners that are affected by freeze-thaw (F-T) cycles. However, no studies on the shear behaviour at the interface between a compacted clay liner and high-density polyethylene (HDPE) geomembrane that are subjected to F-T cycles have been conducted in the literature. Therefore, an experimental investigation on the influence of F-T cycles on the shear behaviour at the interface between a BSM and smooth HDPE geomembrane is conducted in this study. The obtained results show that the shear strength at the interface is lower than that of the BSM itself. In addition, the shear strength decreases with increasing numbers of F-T cycles, and the total reduction in the interface shear strength of the samples without undergoing any F-T cycles is 23%, 15.2% and 11.4% under normal stresses of 150 kPa, 250 and 350 kPa, respectively (in comparison to the samples that are subjected to 10 F-T cycles).