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.
Highlights
A large and deep excavation in a soft soil area typically uses a support system consisting of a retaining wall with one or more levels of horizontal struts, which is costly and requires a long construction period [1]
Zheng et al [2] designed and conducted a series of model tests to investigate the working and failure mechanism of the multibench retaining system and the three abovementioned failure modes were observed in these model tests
As the retaining structures were assumed to be rigid, the mobilizable strength design (MSD) calculated results are larger than the Finite Difference (FD) results
Summary
A large and deep excavation in a soft soil area typically uses a support system consisting of a retaining wall with one or more levels of horizontal struts, which is costly and requires a long construction period [1]. Because the multibench retaining system does not have generally accepted design procedure and its geometry is similar to that of the earth berm supported wall/piles [9,10,11,12,13,14], the analysis method for earth berm [15] was usually applied in the design of the multibench retaining system in practice This method neglects the restraint of the second retaining structure to the earth berm. Based on the MSD concept, a new design method for a two-bench retaining system considering the interaction of the first and second retaining structures is proposed in this paper. The results calculated using this method and those obtained by the finite difference method were well matched
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