Niagara hydro diversion project
Robbins TBM ready and set to go
CASE STUDY: Had things gone to plan geologically, the 10km long Niagara TBM water diversion tunnel to increase the generating capacity of the Sir Adam Beck hydro complex on the Canadian side of the famous Niagara Falls, should have been completed by Fall 2009. As it was, the 14.4m diameter heading being excavated by still the world’s largest ever main beam gripper TBM was slowed by unfavourable geological conditions, conditions in which perhaps the original shielded machine concept with a precast segmental lining, rather than the adopted alternative, might have been the better choice. Site visits and reporting through the five years of TBM excavation, records exactly how geological conditions caused such havoc.
Plan of attack
SITE VISIT REPORT: DECEMBER 2006
A
n open gripper TBM; an in-situ concrete lining; on-site construction of the largest ever, 14.4m diameter hard rock TBM; and lining operations concurrent with excavation: these were some of the
• Client: Ontario Power Generation • Consultants: Hatch Mott MacDonald & Hatch Acres • Design-build Contractor: Strabag/Dufferin JV • Contract Engineers: ILF and Morrison Hershfield alternatives Strabag AG of Austria adopted to secure the competitive edge for the Niagara hydro power water diversion project. Figs 1 and 2. Plan and geological section of the TBM drive around the famous Falls
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