Effect of geotextile constraint on geotextile/geomembrane interface shear behavior

Abstract

ABSTRACT: This paper examines the role of geotextile constraint during laboratory testing on geotextile/geomembrane interface shear behavior. This study specifically involved four needle-punched nonwoven geotextiles as well as a smooth and a textured HDPE geomembrane representative of products commonly used in practice. The effects of allowing geotextile strain on geotextile/geomembrane interface performance were quantified through a series of laboratory tests using an interface shear device that can be used to perform tests with geotextiles in both constrained and unconstrained conditions. Testing was conducted over a range of normal stresses between 10 and 400 kPa. Results showed that allowing geotextile strain decreased the peak interface shear resistance against a smooth geomembrane surface by 11% to 25% and by 13% to 33% for quasi-residual interface shear resistance. Decreases in interface shear resistance for unconstrained geotextiles against a moderately textured geomembrane were found to be 19% to 35% and 6% to 23% for peak and quasi-residual states, respectively. A distinct pattern of vertical displacements was observed for various combinations of materials and boundary conditions. This study provides quantitative insight into texture-filament interlocking mechanisms potentially relevant to in situ conditions. Based on the experimental observations, generalized interface shear mechanisms are proposed.