ABSTRACT
The Mass Rapid Transit (MRT) North-East Line (NEL) is the third major MRT line in Singapore which comprised 22 km long underground track and 16 stations. Contract 704 involved the construction of two cut and cover stations i.e. Woodleigh Station and Serangoon Station, 992 m twin tunnels from Woodleigh Station to Serangoon Station and 1522 m twin tunnels from Serangoon Station to Kovan Station. In addition, the package included the construction of a 1.9 km long dual-lane viaduct bridge. The viaduct bridge which consists of 2 abutments and 39 piers was constructed in parallel alignment with the new twin tunnels configuration and located in between the tunnels. The typical relative position of the pile foundation and the tunnels is shown in Figure 1. The piers are supported mainly on bored piles of 1.2 m diameter in a group of four piles. Along the alignment, the tunnels were located as close as 1.6 m between the extrados and pile edge. The tunnels were bored with two Earth Pressure Balance (EPB) machines of 6.5 m diameter and mainly went through the weathered Granite. An instrumentation
ABSTRACT: In this paper, the development of a three-dimensional finite element model to back-analyse a case history on the response of pile foundation subjected to shield tunnelling is described. The case history is from the construction of the MRT North-East Line Contract 704 in Singapore. The FE model was created to backanalyse the behaviour of one of the instrumented pile group at Pier 20 where the full shield tunnelling process, including the application of face pressure, shield tunnel advancement, over-cutting, tail void closure and installation of lining was simulated. The effect of single tunnel advancement was simulated and discussed. Good agreement between the results from analysis and measured data was obtained which validated the FE model.
