Direct approach for designing an excavation support system to limit ground movements

Traditionally, excavation support systems are designed solely on the basis of satisfying limit equilibrium, using apparent earth pressure diagrams. Using this approach, the support system design becomes a function of the maximum anticipated earth pressure and is governed by overall structural stability as opposed to maximum allowable horizontal or vertical deformation. This approach produces a support system that is adequate with regards to preventing structural failure, but may result in excessive wall deformations and ground movements. This paper presents a design methodology that facilitates the sizing of all components of the excavation support system in such a way that limits the maximum lateral and vertical excavation-induced deformations. Based on the fundamental approach of the presented design methodology, structural and basal stability is guaranteed.