ABSTRACT
This paper will discuss the development of the design of the bored running tunnel linings for C705, highlighting the decisions that resulted in the arrangement of the tunnel lining. The paper will also discuss some segment design related problems that have been highlighted during construction and lining improvements that could be incorporated in future projects. The C705 tunnels pass through a variety of Singapore soils ranging from soft Marine Clay and loose fluvial sands of the Kallang Formation to the cemented Old Alluvium. The paper will discuss the measures taken to ensure that the tunnel design was robust enough to cope with these varying conditions. Throughout the design, particular attention was paid to to reinforcement arrangements and segment connections. During the tender design period, the design and build contractor investigated the possibility of using steel fibres instead of conventional reinforcement for the running tunnel linings. The paper is aimed at providing engineers with limited tunnel design experience with a foundation on which to build their knowledge.
