The development of wear on the textured geomembrane interface has a significant influence on the reduction of post-peak interface shear strength. This study aims to examine and quantify the development of shear-driven wear on geosynthetic interfaces. New interfacial parameters are introduced to systematically describe the changes in the surface morphology of a geomembrane during the shearing process by combining quantitative and qualitative digital imaging techniques. Based on the developed surface roughness geometric parameters, an intensive quantitative and stereoscopic analysis of the wear development of the geomembrane surface morphology has been conducted during interfacial shear. The geometric parameters of the textured surface, namely asperity height, top angle, top radius, approach angle, and departure angle, can capture the changes in surface topography of the geomembrane in pre- and post-shearing. The top angle and radius, as well as the approach and departure angles, change significantly during the early stages of shearing (5 mm–20 mm). In general, the changes in the adopted geometric parameters resulted from a shearing rise associated with the increase in normal pressure. Furthermore, they could be used to better define the evolution of wear through complex stress histories that geomembranes frequently experience. • Using tribology and digital imaging to profile textured geomembrane surfaces. • New framework with geometric parameters to quantify interface shear wear. • Post-peak strength loss linked to changes in asperity top radius and angles. • Wear indicators evolve early in shearing.

The behaviour of a geotextile filter in contact with internally unstable cohesionless soils depends on interaction between filter pore size distribution and base soil particles and on fraction of particles free to move inside soil skeleton. These particles can accumulate at soil-filter interface leading to blinding or remain entrapped within filter pores leading to clogging or pass through geotextile. The openings of geotextile should allow the passing of soil particles not belonging to soil skeleton keeping the same stable to avoid base soil erosion and minimize the geotextile filter clogging and/or blinding. The upper limit of filter characteristic opening size meets requirement of retention criterion while the lower limit of filter avoids blinding and/or clogging phenomena. Among different geotextile filter design criteria for internally unstable cohesionless soils, Moraci (1996) criterion considers as lower limit of filtration opening size the critical diameter of suffusion. In this paper, a database of many soil-geotextile filtration tests, for which this criterion has not yet been tested, was created to assess its reliability, compared to other existing design criteria. Finally, a new methodology proposed recently by the Authors is also applied to evaluate internally unstable cohesionless soil-geotextile filter compatibility to all interfaces analysed in database. • Particles free to move in bordering pores in internally unstable cohesionless soils. • Lower limit of geotextile filter design criterion for internally unstable cohesionless soils. • Application of a geometrical, experimental and microstructural new methodology. • New approach to design geotextile filters in contact with internally unstable cohesionless soils.