The Prefab Tunnel

by W. Victor Anderson, Associate and Head of Structural Engineering; Delcan Corp., North York (Toronto),

Serial Information: Civil Engineering—ASCE, 1990, Vol. 60, Issue 1, Pg. 64-65

Document Type: Feature article


Jacking a prefabricated concrete arch through a railroad embankment to provide a new access ramp to the Don Valley Parkway in Toronto was done for the first time in North America. In September 1989, after 11 months of intensive preparation, workers began to move the 2,200 ton arch, which was equipped with a composite structural steel and reinforced concrete tunneling shield. A 10,000 psi hydraulic jacking system rammed the structure into the embankment, and after each stroke, workers carefully excavated beneath the protection of the shield. The 105 ft long structure was jacked a total distance of 92 ft to its final position beneath the operating railway tracks in 12 round-the-clock days.

Subject Headings: Jacking | Tunnels | Arches | Reinforced concrete | Concrete structures | Railroad tracks | Prefabrication | Embankment (transportation) | Toronto | Ontario | Canada | North America

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