Shear-Induced Changes in Smooth HDPE Geomembrane Surface Topography

The shear strength of particulate material-“smooth” high density polyethylene (HDPE) geomembrane interfaces results predominantly from plowing and/or sliding of the particles at the interface. The relative contribution of particle sliding and plowing for a given “smooth” geomembrane surface is principally a function of the relative material hardness, the particle size and angularity, the normal stress, and the soil density. When plowing occurs, the geomembrane surface wears, resulting in altered surface roughness and changed interface strength. This paper summarizes the results of a study that quantified changes in surface roughness as a function of shearing displacement, normal stress, and soil particle shape. Increased particle angularity significantly increased both the geomembrane surface wear and the interface strength. Change in surface topography occurred relatively early in the shearing process with continued displacement inducing additional wear, but not substantially altering the surface roughness further. This study provides quantitative insight into the wear mechanisms of smooth geomembranes during interface shearing.