Stability of Geosynthetic-Soil Layered Systems on Slopes

This paper presents a method based on limit equilibrium to evaluate the stability of geosynthetic-soil layered systems on slopes. Examples of geosynthetic-soil layered systems constructed on slopes include liner systems used in landfills, liquid impoundments, dams and canals, and cover systems used on landfills and sludge ponds. The method, which is applicable whether the thickness of the layered system is uniform or not, takes into account all mechanisms that contribute to the stability of the layered system: the interface shear strength along the slip surface, the toe buttressing effect that results from the internal shear strength of the soil components of the layered system located above the slip surface, and the reinforcement provided by all geosynthetics located above the slip surface. The factor of safety against sliding is expressed by an equation as the sum of five terms, making it possible to readily identify the contribution of each term to the factor of safety. A parametric study shows that the factor of safety calculated with this method is very close to the factor of safety obtained using a rigorous method, which consists of defining the factor of safety as the ratio between the assumed and mobilized values of the strength parameters. Furthermore, factor of safety calculations using the proposed method are much easier than with the rigorous method.