November saw contractor and machine supplier SELI claim a new monthly advance record after completing 815m using a 6.18m diameter TBM DSU on its 14.5km long section of the 22.5km long Kishanganga Hydropower Headrace Tunnel in the Himalayas. The tunnel is being bored at an altitude of 2430m at depths of 750m-1000m.
SELI won the US$48M machine supply and construction sub-contract from main project contractor HCC Hindustan Construction Company Ltd. Excavation is through extremely challenging ground comprising schists prone to high squeezing conditions and a myriad of fault zones. A re-inforced 5.2m i.d. segmental ring is providing the tunnel lining.
SELI say the successes of November can be partly attributed to the TBM specifications including: 19” cutterhead design, 350mm of maximum total overcutting which is adjustable depending on geology, and the ability to rotate the cutterhead even in the presence of collapsing faces.
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Other characteristics of the TBM DSU KISHANGANGA:
– Length 12m (+ 229m Back-up)
– 8 motors of 325KW for installed power of 2600Kw
– 12 auxiliary cylinders for additional thrust capacity of 4427 tons.
SELI say this is the first tunnel in the Himalaya chain will be completed using TBM methodology. The scheduled date for completion is June, 2014.
The TBM was inaugurated at the SELI factory in Aprilia, Italy, and delivered to the project in May 2010