Shear-induced changes in smooth geomembrane surface topography at different ambient temperatures

Abstract

The shear strength of particulate material–smooth geomembrane interfaces results predominantly from ploughing and/or sliding of the particles at the interface. The relative contribution of particle sliding and ploughing for a given smooth geomembrane surface is principally a function of relative material hardness, particle angularity, and normal stress. The relative material hardness is ambient temperature dependent since the geomembrane is polymer based. When ploughing occurs at any temperature, the geomembrane surface wears, resulting in altered surface topography and different interface strength. This paper summarises the results of a study that quantified changes in the surface roughness of geomembranes as a function of ambient temperature, normal stress, and particle angularity. Surface roughness measurements were made on both virgin and post-shear smooth geomembrane specimens using a stylus profilometer to quantify the extent of wear resulting from shearing against different counterface materials at different temperatures under different normal stresses. Increased ambient temperature and particle angularity significantly increased the geomembrane surface roughness and provided quantitative insight into the wear mechanisms at granular material–smooth geomembrane interfaces.