Hybrid soil nail, tieback, and soldier pile wall – case history and numerical simulation

Abstract

Excavations in congested urban areas are often carried out near and below the existing buildings. The primary cause of damages to nearby buildings is often associated with the excavation completed near and below the existing buildings. It is therefore imperative to minimise shoring wall displacement during the excavation. The paper describes the application of the hybrid soldier pile, tieback and soil nail shoring wall to reduce wall displacement below an acceptable limit. The project involved the construction of a 39-storey building with 5 levels of below-grade parking. The shoring of the below-grade parking was implemented with soil nails in the upper portion of the wall to prevent damages to the existing utilities. Tieback anchor was used below the existing building to limit the movements in the existing building. A three-dimensional non-linear analysis was used to study the behaviour of hybrid shoring wall. Field measurements on wall displacements and soil nail forces confirm the effect of the hybrid wall. However, numerical analyses indicated that the wall would have been constructed without soil nail due to a narrow space between the wall and existing building. This paper illustrates how detailed numerical simulation can be applied practically to design a shoring system in urban areas.