Hong Kong’s MTR Corporation has awarded two more substantial tunnelling contracts on the 26km long, US$8.3bn Guangzhou-Shenzhen-Hong Kong Express Rail Link.
The US$177M Contract 821 – Shek Yam to Mei Lai Road tunnels, to be built by drill and blast, has been awarded to the Dragages/Bouygues JV, whilst the Maeda/China State JV has scooped the US$193M Contract 823A – Kam Tin Tunnels, to be constructed by TBM.
Contact 821, at some 3km, will be drill and blasted from Lai Chi Kok, under Butterfly Valley to Shek Yam. The alignment passes through the Tolo Harbour Fault, where water ingress is expected. “We carried out horizontal directional drilling through the fault locations, which is ten times more expensive than vertical holes but we were able to define the length of the fault to be 500m so we could define it more clearly in terms of risk,” MTR Project Manager – XRL Tunnel, Alan Morris told Tunnelling Journal.
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Contract 823A will involve an open cut excavation as well as 2 x 1.2km and 2 x 800m long mixed face TBM drives under villages and existing roads using one machine on turnaround.
Currently on the XRL project MTR has awarded:
Contract 811A: The West Kowloon Terminus Approach Tunnels North, to the Bachy/Laing O’Rourke JV
Contract 820: The 3km long TBM driven Mei Lai Road to Hoi Ting Road Tunnels, to the Dragages/Bouygues JV
Contract 822: The 7.6km long twin-tube drill and blast tunnels between Tse Uk Tsuen and Shek Yam, to Leighton Asia
Contract 825: The 2.19km long TBM twin tunnel section between Mai Po and Ngau Tam Mei, to Penta-Ocean Construction.
Contract 826: The 3.2km long dual TBM Huanggang to Mai Po tunnels, to the CRCC/Hsin Chong/CRCC 15th Bureau JV
Still to be awarded are Contract 823B for the Shek Kong Stabling Siding, and Contract 824 for the Ngau Tam Mei to Tai Kong Po Tunnels which should be announced next month.
The entire XRL project involves 14.2km of drill-and-blast excavation, 8.5km of mixed-ground TBM tunnelling, and 2km of open-cut excavation.
The TBM sections will have twin bores of an external diameter of 9.2m each with an i.d. of 8.5m lined with the reinforced concrete segments.
When completed in 2015 the XRL will allow commuters from Hong Kong to reach Shanghai in eight hours and Beijing in 10hrs, halving the present 20hr journey.