Stability Enhancement of Landfills on Sloping Ground Using Earthen Berms at the Toe

Abstract

This paper presents the results of a study undertaken to enhance the stability of a landfill on sloping ground of a hilly region. The base of the landfill has a significant elevation difference from one end to the other causing an overall inclination of the base with the horizontal. The study highlights the influence of the following factors on the base sliding stability along the geomembrane interface as: (a) leachate head; (b) pore water pressures in wet waste; (c) seismic forces and (d) smooth versus textured geomembrane (GM). Limit equilibrium methodology is adopted for analyses and three types of failure surfaces are analysed – circular, planar (single straight line) and planar (two straight lines). The study reveals that stability against sliding along liner is low, whenever (a) pore pressures/leachate head are high; (b) earthquake forces are large and (c) smooth GM are used. Usually planar failure surface (two straight lines) is observed as the critical surface.

Furthermore, it is also observed that the stability of the sloping liner can be enhanced significantly by providing adequate size of earthen berm at the toe. After application of the berm at the toe, the possible critical failure surface may pass over the back slope of the berm or pass under the bottom of the berm. This depends on the geometric dimensions (height & base-width/back slope) of the berm. Planar failure surfaces (two and three straight lines) are analysed to check the stability. The study reveals that by varying the berm height as well as the base width, one can arrive at an optimal solution for stability.