Robust Shotcrete reinforcements for Jurong Rock Cavern
Location: Singapore
Products used: MasterGlenium SKY 8403, MasterRoc HCA 10, MasterRoc SA 160
The background
Jurong Rock Cavern (JRC), an initiative launched by the Jurong Town Council to increase underground oil storage capacity on Jurong Island in Singapore, was built at subterranean depths beneath the seabed of Banyan Basin.
After completion, the project will feature a potential storage capacity of close to 3,000,000m3 (Phase 1 and 2) catering specifically to liquid hydrocarbons like crude oil, condensates, naphtha and diesel oil.
Development works for Phase 1 of JRC, with a storage capacity of about 1,500,000m3, commenced at the end of 2009. Upon completion, it would be filled with about nine million barrels of crude oil and other petrol products, making it the first oil storage cavern in Southeast Asia. Storage of petrochemical products beneath the seabed through the JRC will further enhance safety and security on Jurong Island.
In addition, the underground storage facility will free up land for higher value manufacturing operations. The size and storage capacity of the JRC translates to a saving of approximately 60 hectares of surface land space.
The challenge
The caverns were built using a technique that drills and blasts sedimentary rock, followed by removal of blasted rock and support of newly exposed rock. However, at a depth of 130m below ground level, it is critical to support the excavated opening and prevent potential collapse of the cavern, with robust and effective shotcrete reinforcements.
Our solution
Master Builders Solutions partnered with ready-mixed concrete supplier Pan-United Concrete Pte Ltd and contractor Hyundai Engineering & Construction Co.Ltd to develop an optimized mix design incorporating MasterGlenium SKY 8403, MasterRoc HCA 10 and an alkali-free accelerator MasterRoc SA 160 for the proposed shotcrete lining.
MasterGlenium SKY 8403 was recommended as it could impart superior workability and consistency to the shotcrete mix while MasterRoc HCA 10 helped extend the time for application. With the introduction of MasterRoc SA 160, the shotcrete was able to adhere securely to the rock face, achieving the early strength required for the contractor to proceed with their scheduled excavation work.
In addition, a large storage tank with special agitating pumps was installed on site to provide an uninterrupted supply of MasterRoc SA 160 round the clock. Shotcrete was then sprayed onto the walls with high-pressure hoses. Huge FRP bolts are driven into the walls every meter or so to minimize the chance of collapse.
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