Abstract
The design of NATM tunnels are often done in two dimensions, even though there are limitations. This paper uses the results from the simulation of a NATM tunnel using finite element method in three dimensions to illustrate a few observations that may aid in practical designs. These observations are three dimensional effects, which will not be apparent in two dimensional analyses. The finite element model was based on the construction of Fort Canning Tunnel, Singapore, which is an approximately 15m wide vehicular tunnel that has been constructed using NATM with applications of steel pipe umbrella method.
