Stability Analysis of Unsupported Deep Excavated Soil Wall and Nailed Soil Wall

With increase in the need of high-rise buildings in metropolis, there is a growing demand for underground basements. Underground basements maximize the availability of space for purposes other than inhabitation, such as parking, recreational activities, etc. Construction of these underground basements employ the aid of earth retaining structures like retaining walls, anchor piles, soldier piles etc. to ensure stability of deep excavations. However, these earth retaining techniques are expensive and require highly skilled staff and equipment. Thus, in the sites where cohesive soil deposits are present, builders often go for cheaper alternatives like open unsupported excavations or temporary nailed walls. These unsupported excavations and nailed walls, which may go as deep as 15–20 m from the ground level, are often found to be unstable and thus pose risk to life and machinery at the construction sites.

This paper presents the results of a study which was conducted to check the stability of unsupported deep excavation and temporary nailed wall, which were made for construction of underground basement of a forty storey high building in National Capital Region. The objectives of this study were, (a) to obtain a stable geometry for unsupported excavation for the given site conditions, and (b) to obtain a stable configuration of temporary nailed wall.