ABSTRACT
In a land-scarce country like Singapore, it is inevitable that demands for new space has led to the creation of complex underground networks. As our underground network becomes increasingly built up, the relationship between underground infrastructures in the urban areas also becomes progressively intricate, which presents multifaceted challenges in underground tunnel construction where potential occurrence of ground settlement is the main drawback. With the volume loss induced by tunnel excavation as the main determinant of ground settlement, this paper presents the studies on the volume loss caused by bored tunnelling in different geological conditions in Singapore with a variation of tunnel boring machines (TBM) used in some of the recent Metro line projects such as Downtown Line (DTL), Thomson-East Coast Line (TEL) and Circle Line 6 (CCL6). Back analysis on trough width parameter from the available data is also discussed. The main findings of this study also provide references for impact assessment of bored tunnelling in future projects.
