Effect of corners in strutted excavations: Field monitoring and case histories

Abstract

This paper discusses the effects of corners on wall deflection and ground movement around multi-strutted deep excavations. To assess the significance of such effects in a typical-sized excavation in Singapore, a field monitoring exercise was conducted into an excavation in soft marine clay. Field data from this exercise indicate that the strengthening effect of the corner can lead to a significant reduction in wall deflection and ground settlement. Finite-element back-analyses of the excavation also showed that, where corner effects are significant, three-dimensional analysis may be able to offer significantly better predictions of movement than two-dimensional analysis. Comparison with several other excavation projects where corner effects were considered or observed suggests that the significance, or otherwise, of such effects depends on three factors: the length-to-depth ratio of the excavation, the depth to a relatively stiff stratum, and the stiffness of the strutting system.