Stability of Geosynthetic-Soil Layered Systems on Slopes

Abstract

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.

Evaluation of Interface Shear Strength between Geosynthetics Under Wet Condition

“…Then, the eŠect of water or water-‰ow on interface shear strength is also taken into account (Koerner and Hwu, 1991;Giroud et al, 1995). On calculating the safety factor of slope stability, Briancon et al (2002) suggested from the inclined plane test results that water has diŠerent eŠects on friction angle, cover soil weight and friction force due to the water pressure at the interface.…”

Deterministic and reliability-based design: veneer cover soil stability

“…The modified formulations inherit limitations and assumptions similar to those asserted in Giroud et al (1995). They include uniform thickness of the cover soil, dry conditions, which assume that the drainage system is working efficiently, and no other slippage except at the weakest interface.…”

“…Other symbols used are defined in the Notations section. Formulations used to produce the design charts are derived using force diagrams similar to the ones given in Giroud et al (1995). The geometry and forces acting on the active and passive wedges, which are denoted with the subscripts 'A' and 'P', respectively, are shown in Figures 2 and 3.…”

“…In this study, the limit equilibrium wedge method with modified formulations from Giroud et al (1995) is used to produce design charts. A design chart provides an explicit graphical solution, which can be useful for preliminary design.…”

“…These are used to formulate the factor of safety against sliding mode of failure. Unlike most researchers, who defined the factor of safety in the limit equilibrium two-wedge method as the ratio between the available and mobilised values of the strength parameters, Giroud et al (1995) defined the factor of safety in the two-wedge method as the ratio of the resistance over the driving forces. Their proposed formulations are adopted in this study because they are computationally simple and reduce geometric manipulation.…”