The Public Utilities Board (PUB) of Singapore is currently progressing Phase 2 of the Deep Tunnel Sewage System (DTSS) project. Leighton Contractors Asia Limited (LCAL) have been awarded Contract T-09 of the project which runs approximately 8 km from the intersection of Clementi Road and the Ayer Rajah Expressway (AYE) to the intersection at Jurong Pier Road and AYE. LCAL have appointed COWI to act as their designer. Contract T-09 includes eight shafts, including Shaft O1 located between the Jurong River to the west and Penjuru Road to the east in the Jurong region of south-west Singapore. This paper discusses the rock engineering aspects of Shaft O1, including the engineering geological aspects and the methods of analysis used to design the reinforcement and support of the section of the shaft excavated in rock. Finally, the conditions encountered and the support installed during the engineering geological mapping of the shaft are described. The geology at Shaft O1 comprises made ground overlying Kallang Formation deposits and then weathered rocks of the Jurong Formation. Development of the ground model included several stages of desk study and ground investigation and ultimately six boreholes and eight probeholes were carried out at and around the shaft location. The analysis methods used included the Q-system, analytical closed-form calculations, use of the Unwedge software package, rock bolt and sprayed concrete design and a stand-up time assessment. The design was prepared during 2018-19 and the shaft was successfully constructed during 2019.
Mullardoch Tunnel is a hydro-electric tunnel in the Highlands of Scotland, driven through metamorphic rocks of the Moine Series between 1947 and 1952. As with all large-scale hydro-electric projects, the geology exerted significant control and influence on the overall design and construction. However, although there was implicit and explicit consideration of geological aspects during the planning, design and construction of the schemes, the works largely predated the systematic application of engineering geology and rock engineering in the UK. Nonetheless, the geologists involved with the project were able to identify and effectively communicate the main geological issues relevant to the engineers. Given the continuing national import of hydro-electric schemes, this forms an interesting case study through which to retrospectively consider the geological input to hydro-electric tunnels. The geology, design, construction and maintenance of the tunnel are discussed together with the findings of recent inspections. Examples of good and bad practice are identified and implications for improved practice are drawn, including the continuing importance of high-quality geological input to engineering projects and the need for improved training in geological skills, particularly when applying modern practice to historical structures.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.