Stability of geomembrane surface barrier of earth dam considering strain-softening characteristic of geosynthetic interface

Geosynthetic interfaces are characterized by strain-softening behaviors that exhibit a reduction in shear stress at relative shear displacements beyond peak strengths. The traditional practice in assessing the stability of geosynthetic barrier systems is based on Limit Equilibrium Method (LEM) which cannot consider the strain-softening behavior of interfaces. The safety factors calculated by LEM may overestimate the stability of geosynthetic barrier systems. A method combining LEM with numerical analysis for evaluating stability of geomembrane surface barrier of earth dam was proposed in this paper. The formula of calculating the factor of safety for geomembrane barrier systems taking account of the effect of interface strain-softening was derived. An example of composite geomembrane lined earth dam was numerically analyzed to verify the developed method. The calculated factor of safety is between the results that calculated from LEM using peak shear strength and residual shear strength. Through comparatively analysis with LEM results, it is suggested to use peak shear strengths along the basal interface and residual shear strength along the side slope interface in evaluating stability of geomembrane surface barrier of earth dam using LEM.