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The tallest building under construction in Canada is underway right now at the southwest corner of Toronto's Yonge and Bloor intersection, still flying under the radar skyline-wise as below-grade work progresses. Under construction since mid-2017, Mizrahi Developments' The One is bringing a 308 metre 'supertall' tower designed by Foster + Partners and Core Architects to Bloor-Yorkville. Work continues on the building's complicated foundations.
We last checked in on the 85-storey condo and hotel tower at the end of January, when work had just begun on drilling the "mega caissons" that will support the tower's hybrid exoskeleton support system. After another month of work, 24 of the 32 mega caissons have now been created in the substrate, and the remaining 8 are expected to be completed by mid-March.
The caissons are being excavated with a Bauer BG 55 (BS 115) drilling rig, boring holes 3.65m in diameter and extending 30 metres into the earth below. Rebar cages weighing 40 metric tonnes each are then lowered into the boreholes with the site's specialized Link-Belt TG2300B crane, and are then filled in with concrete.
The massive volume of these boreholes requires large quantities of concrete—378 cubic metres per caisson. Coordinating these large concrete pours is a complex task, and recent photos show long processions of concrete trucks along Yonge Street. For each caisson, 18 truckloads worth of concrete is required.
Down in the pit, a red-painted Amherst concrete pump is being used to feed the liquid concrete into the boreholes, and that work is continuing today, despite the snow.
Additional information and images can be found in our database file for the project, linked below. Want to get involved in the discussion? Check out the associated Forum thread, or leave a comment in the field provided at the bottom of this page.
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