Particle-geomembrane interface strength behavior as influenced by surface topography

Design of composite structural systems using soil in combination with materials such as concrete, steel or polymer is widespread. Knowledge of the shear resistance at interfaces between soils and other materials is a key design parameter and is of considerable interest to the geotechnical community. However, an advancement of current design practice cannot occur unless the role of the topographically influenced strength behavior is understood. Specifically, the goals of this research are to: (1) develop a method to characterize the topography of geotechnical interfaces, (2) study interface shear behavior for granular materials and geomembranes of varying topography, (3) examine shear mechanisms operative on smooth geomembranes, and (4) provide design recommendations for practice. This study begins by characterizing the interface region using quantitative methods and then uses soil mechanics and tribology principles to examine the friction behavior of granular soils and geomembranes.;A practical method is developed that allows quantitative determination of geomaterial surface roughness and is applicable to the wide range of asperity relief encountered in geotechnical practice. Using this methodology, a classification scale for surface roughness is developed for smooth and textured geomembranes. It is found that surface roughness has a first order effect on sand/geomembrane interface strength but there is a limit to the beneficial effect with increasing degrees of surface texturing. Experimental and theoretical analyses show that the shear mechanisms for smooth geomembrane/sand interfaces are elastic-plastic sliding and plowing.