Design of deep excavation with secant pile wall: a case study on performance of structure

Secant pile walls are often selected as shoring protection in deep excavation because they can deal with variable ground and groundwater conditions and overcome constraints associated with built-up environments. This paper presents a case study of an 18 m deep excavation in West Bengal, India, constructed by secant piling in a top-down manner using multiple levels of anchors, to minimise the extent of excavation required in an environmentally sensitive area. The design measures taken to overcome these challenges are summarised and the findings of the case study are provided. The study provides a reference for the design and construction of such structures in similar ground conditions. In this work, the selection of construction methodology, embedment depth calculations and evaluation of real-time monitoring data during excavation are all discussed. The required embedment depth and the mechanism of hinge formation in static and seismic analysis has also been studied. Finally, a comparison between the maximum wall displacement predicted from finite-element analysis and monitoring data as obtained from the site was studied to evaluate the performance of the structure post construction and during operation.