EFFECT OF CORNERS IN STRUTTED EXCAVATIONS - FIELD MONITORING AND CASE-HISTORIES

This paper discusses the effects of corners on wall deflection and gro und movement around multi-strutted deep excavations. To assess the sig nificance of such effects in a typical-sized excavation in Singapore, a field monitoring exercise was conducted into an excavation in soft m arine clay. Field data from this exercise indicate that the strengthen ing effect of the corner can lead to a significant reduction in wall d eflection and ground settlement. Finite-element back-analyses of the e xcavation also showed that, where corner effects are significant, thre e-dimensional analysis may be able to offer significantly better predi ctions of movement than two-dimensional analysis. Comparison with seve ral 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 st rutting system.