Mobilizable Strength Design for Multibench Retained Excavation

Abstract

Multibench retaining systems can be used in large area excavations for the purpose of eliminating horizontal struts. However, there is no design method for this retaining system. Based on the mobilizable strength design (MSD) concept, a design procedure for a two-bench retaining system considering the interaction of the first and second retaining structures was proposed and tested. Based on an admissible strain field for a two-bench retained excavation in undrained condition, the shear strain in the superimposed strain and the lateral earth pressure distribution acting on the retaining structures can be determined. Then, the mobilized shear strength corresponding to the strain field could be calculated by the equations of force and moment equilibrium. Further, the crest displacements, earth pressures, and bending moment in a two-bench retained excavation can be calculated. The calculated results using MSD were verified by the finite difference analysis.