Effect of Diaphragm Wall Stiffness for a Deep Excavation on Adjacent Tunnel Deformation

Deep excavations in urban areas pose a risk to nearby structures, as it can significantly alter the stress and displacement fields around existing infrastructures. Therefore, it is very critical to ensure that the deep excavation process has minimal impact on the nearby structures. Traditional methods commonly use diaphragm walls to prevent soil from collapsing when it comes to deep excavation. However, these methods sometimes still result in large displacements of surrounding structures. It is a must to have a novel method that is effective in reducing displacements of existing structures during excavation procedures. This paper presents an application of a hybrid system, including diaphragm wall and buttress, to reduce the displacements of adjacent tunnels. A three-dimensional finite element method was initially validated with observational data and subsequently was used to perform a parametric study considering the variation in length, thickness, and depth of buttress wall. The findings of this study provide recommendations on the geometric parameters of the buttress wall.