To prevent the percolation of leachate through the bottom of waste landfills, the liner system of various layers, such as compacted clay, geomembrane, geonet, geotextiles, and geocomposite is designed. Since the friction angle between a geomembrane an...
To prevent the percolation of leachate through the bottom of waste landfills, the liner system of various layers, such as compacted clay, geomembrane, geonet, geotextiles, and geocomposite is designed. Since the friction angle between a geomembrane and other geosynthetics is usually lower than that of the soil alone, the interfaces between soil and geosynthetic or geosynthetic-geosynthetic may become a possible plane of weakness, which leads to potential instability of the system under load of waste at side slopes. In this study, large triaxial tests are carried out with samples of remoulded wastes and direct shear interface friction tests are carried out to understand the frictional properties of either soil-geosynthetic or geosynthetic-geosynthetic interfaces, which are required for analyzing the safety of side-slope liner systems. Safety of side-slope liner system of various landfills is also analyzed using the properties obtained from the tests.
The results of triaxial tests showed that friction angle was increased gradually throughout the deformation up to 25% and the cohesion was increased rapidly in the range of deformation 10~20%. At the deformation = 15%, the friction angle of waste obtained was 27˚, and the cohesion, 0.75kg/㎠. The results of direct shear interface friction tests showed that the friction angle of HDPE/geocomposite interface was 11.9˚, HDPE/wastes 12.0˚, and geotextile/wastes 28.0˚. From the stability analyses, it was recognized that tensile stress of liner system was increased as the slope angle of the landfill is decreased. In case that a concrete anchor is used at the top of the liner system, the yield strength of geosynthetics must be considered in addition to the capacity of concrete anchor.