ABSTRACT
The multibillion-dollar Underground Transmission Cable Tunnels Project, also one of the world’s deepest electricity supply projects, is built at 60m average depth to replace Singapore’s aging power cables as well as to meet future energy needs and operational reliability. To facilitate the cable entry from the tunnel into the existing substation, a set of deep shaft and Y-shaped mined tunnels is designed and built as an extension contract of Cable Tunnels Project. This brings about design and construction challenges such as precision of tunnel alignment, transportation and installation of a temporary bracing at the adit break-out locations, opening and removal of a live tunnel segments, adit collar designs, waterproofing, and instrumentation monitoring of relevant structures. By and large, this paper shares the experiences in overcoming most of these challenges which are not commonly encountered in Singapore’s underground development works.
