Rapid prototyping of geosynthetic interfaces: Investigation of peak strength using direct shear tests

Rapid prototyping offers a platform technology for investigations within the geosynthetics research and manufacturing sectors. This paper considers the application of rapid prototyping for the development of geosynthetic interfaces. The benefits and challenges of three rapid prototyping techniques (fused filament fabrication, selective laser sintering and laser thermal ablation) are considered and comparisons are presented between the three technologies. The paper then compares prototyped models of geomembrane texturing to those of a factory sourced reference geomembrane, leading on to a systematic geometric assessment using laser sintered model geomembranes. The geometric assessment highlights the benefits of hooked geomembrane asperities to interact with geotextiles in low normal stress applications, with a 69% increase in peak shear strength reported for hooked asperities, compared to the factory reference geometry. Asperity spacing is shown to influence the measured shear strength, with an increase for a geomembrane geotextile interfaces with closer asperities and an optimum spacing observed for geomembrane clay interfaces, below which the failure plane slides over the top of the texturing. Increases in asperity height correlated to smaller than expected increases in shear stresses for both geomembrane-geotextile and geomembrane clay interfaces.Whilst current rapid manufacturing techniques are shown to offer the ability to test the influence of variables on the performance characteristics of geosynthetic materials, the limitations of each technique, polymer utilised and resulting chemical and physical behaviour of the sample must be understood to allow these techniques to be successfully deployed.