2014 International Ground Control Conference in Mining, July 29–31, Morgantown, West Virginia, USA Authors: Samrat Mohanty, Tom Vandergrift and Tim Ross (AAI), Gan Chin Hwi and Mee Nee Lee (Parsons Brinckerhoff Pty. Ltd., Singapore)
The construction of underground hydrocarbon storage caverns in Jurong Island, Singapore is nearing completion. The facility, located beneath the seabed of Banyan Basin, is comprised of five storage caverns with a storage capacity of approximately 1.5 million cubic meters. The galleries of each cavern are 20 meters (m) wide by 27 m high, and approximately 340 m long. In addition to the storage caverns, various access and operations tunnels are required to support the facility. Among these are water curtain galleries to ensure that hydrostatic pressures in excess of hydrocarbon storage pressure are maintained in the rock mass surrounding the storage caverns. Early in the design process, conventional steel rock bolts with resin polymer grout were considered for ground control. Owing to the corrosive hydrologic environment, weight and handling considerations, local construction preferences, and the requirement to have a cavern design life of 50 years, fiber-reinforced polymer (FRP) bolts with cement grout were proposed by the construction contractor. This paper discusses the properties of FRP bolt/cement grout bolting systems, their characteristics in relation to steel bolt/resin bolting systems, and numerical modeling results assessing their performance. FRP bolts with cement grout were ultimately chosen for the project. The FRP bolting system has proven to be very successful, with no ground failures experienced where systematic FRP bolting has been applied.