Client: Land Transport Authority
Main Contractor: Obayashi
BSS Designer: SolExpert

Pipe Pile Roof/Umbrella Arch
Number: 32 piles
Length: 36m

Project Duration: 6 weeks

Pipe Pile Roof for the arrival of the C708 Nishimatsu tunnelling machine into the Dhoby Ghaut Station. As part of the C708 contract a pipe pile roof was required to protect the existing North South Line where the new tunnels cross over within several metres. To add to the problems, the geological conditions are not favourable with a fault zone lying very close to the area.

Additionally, as the pipe pile roof was to be drilled from the Dhoby Ghaut Station the Contractor, Obayashi, could not afford a large project window. This further constraint was taken into account by Bachy Soletanche in the selection of the equipment to execute the drilling and a Soilmec SM400 equiped with an ODEX down the hole hammer drilling system was used to complete the works within the 6 weeks required.

Special thanks are required for Hugh Burbidge of the BSG Hong Kong Drilling Department for the loan of the Maxibor!