Mobilized Bearing Capacity Analysis of Global Stability for Walls Supported by Aggregate Piers

Abstract

Global stability analysis is a key component of mechanically stabilized earth (MSE) wall design, especially those constructed over marginal soils. When limit equilibrium analysis is used for MSE wall design, incorrect factors of safety can be predicted depending on the shape assumed for the failure surface. The use of ground improvement, such as aggregate piers (AP), further complicates the analysis. A mobilized bearing capacity (MBC) approach is presented which highlights the direct relationship between the factors of safety for global stability and bearing capacity. Results from the MBC approach are compared with finite element strength reduction analyses for a range of MSE wall geometries and AP replacement ratios. The factors of safety match well for global factors of safety between 1 and 1.5, considering both eccentricity and stress concentration. The MBC approach provides a tool to supplement and refine global stability analyses for retaining walls constructed over improved foundations.