Large-scale ramp model tests on geomembrane/geotextile interface

Composite liner systems are widely used in waste disposal landfills to minimize the potential contamination of the geo-environment. The shear stresses exerted by the gravity and settlement of waste may lead to tensile failure or sliding instability along the interfaces. Due to lack of understanding of shear stress transfer mechanism, the above engineering problems are still often occurring. A large-scale ramp model test apparatus is designed to study the shear stress transfer mechanism. Landfill process is successfully simulated by stacking sand bags, and progressive slope failure along the geomembrane/geotextile interface is revealed by the sliding control system. The test results show that when the shear stress induced by the vertical loading is less than the peak interface shear strength, the interface strength will not fall into a residual strength. However, when the shear stress exceeds the peak interface shear strength, the interface strength will quickly fall into a residual strength, which will result in sharp increase of the tension in the geotextile, and if it is serious, the geotextile will be completely broken.