FE Modeling for the Shallow Fort Canning Tunnel

Synopsis:

The Fort Canning Tunnel, Singapore, is an approximately 15m wide vehicular tunnel that has been mainly constructed according to the principles of NATM. Within close proximity of the tunnel are several man-made and natural features of great historical importance that demanded the selection of a construction method that will give rise to the least possible amount of disturbance. The shallow location of the tunnel, high ground water level and large excavation face poses a challenge for construction. This called for special design considerations combined with a rigorous monitoring scheme. During the design phase, a series of numerical analyses including 2D and 3D FE calculations have been carried out to predict the ground behaviour and tunnel support performance during the tunnel construction. 2D FE analyses were primarily used to predict the performance of the tunnel support systems during short-term and long-term conditions.

3D FE analyses were aimed at predicting the stability during tunnel construction, in relation to the grouted steel pipe arch pre-support, hardening of shotcrete, construction cycle duration, staged excavations and support installation.During the construction phase, surface, subsurface and in-tunnel instrumentation were installed to monitor the performance of the ground and tunnel support during construction. The remarkable density of monitoring points provided a wealth of data on the ground and support behaviour. This paper will provide insight in the modeling techniques and the comparison of field readings with the 2D and 3D FE analyses results.

FE Modeling for the Shallow Fort Canning Tunnel
EURO: TUN 2007
August 27-29, 2007
Vienna, Austria