Multi-Scale Assessment of Geotextile-Geomembrane Interaction
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Geotextile and geomembrane sheets are typically used as a composite system rather than as a stand-alone solution because of their complementary properties of permeability and stiffness. Previous researchers have focused on the large-scale interaction of fiber-texture interfaces while the micromechanical behavior of the internal geotextile structure has received limited attention. Characterizing the variation in the arrangement and distribution of filaments/voids is essential to understanding the micro-scale mechanisms of nonwoven fabrics interacting with counterface materials. This presentation summarizes the results from a study that examined the micromechanical mechanisms involved at needle-punched nonwoven geotextile-textured HDPE geomembrane interfaces and relates the results to the observed macro-scale response. A large displacement direct interface shear device was developed and used in this study to reduce the system errors that often occur with conventional shear devices and to allow internal geotextile strains to occur during shear. Complimentary numerical modeling was undertaken to study interface response. An advanced image analysis technique was applied to allow the evolution of the filament microstructure under various boundary and load conditions to be quantified. The different phases within the geosynthetic interface zone were detected from images captured using high-resolution optical microscopy. The changes of geotextile inner structures were statistically quantified in terms of inter-filament distance changes as well as the local void ratio and inscribing void size distributions. The tensile response of single filaments was measured using a helium neon deflectometer and these measurements were used to evaluate the shear induced filament strain. The study provides insight into the combined role of geomembrane surface topography and geotextile filament structure on macro-scale geosynthetic interface response.