Influence of Water Flow on the Stability of Geosynthetic-Soil Layered Systems on Slopes

This paper presents an analysis of the stability of geosynthetic-soil layered systems constructed on slopes when water is flowing along the slope. Equations are presented for the factor of safety of infinite slopes as well as slopes of finite height. In the case of an infinite slope, only the interface shear strength along the slip surface contributes to the stability. In the case of a slope of finite height, the contributions of the buttressing at the toe of the slope and of geosynthetic tension are taken into account, in addition to interface shear strength. The analysis shows that the influence of water flowon the stability of a geosynthetic-soil layered system can be very significant if the slip surface is above the geomembrane. In this case, the factor of safety of a layered system with water flow can be as low as one half of the factor of safety without water flow. The analysis shows that the influence of water is small, and in some cases negligible or even zero, if the slip surface is below the geomembrane.