Three-Dimensional Simulation of Interaction Between Surface Buildings and Twin Tunnelling Regarding the Surface Settlement

Tunneling-induced strain and stress distribution in a soil medium is completely three dimensional. However, the issue is usually modeled in two-dimensions (2D) in order to lower the computational costs. In this study, full three-dimensional (3D) finite element (FE) analysis of twin tunnelling and surface building are carried out to compare the results with 2D ones and to find out surface settlement behavior during tunneling process considering the presence of a building on the surface. Conducting 3D FE parametric studies, a large database is created and the results are used to evaluate different aspects of 3D modeling. Based on the outcomes of this study, comparison between 2D and 3D modeling is conducted, the situations in which 3D analysis could be substituted by 2D plane strain models and the cases in which 3D modeling is necessary are defined. The effects of different parameters on surface settlement trough are assessed and a modification design graph for prediction of maximum 3D building settlement from 2D green-field analysis is suggested.