Stabilization of an Excavation in a Confined Space
The Rogers Arena South Tower is part of the Aquilini Centre, a construction project in northern Vancouver. At this location, three new towers are being built around the Rogers Arena which makes the whole project a challenging one.
The South Tower with 5 underground parking decks and 31 levels above ground is being built on a small, triangular area near the entrance to the Rogers Arena. The realization of the excavation between the southern wall of the stadium, the Georgia Viaduct, Pacific Avenue and Griffiths Way was a special challenge because the space is extremely confined.
The Contractor had to use special care during excavation and shoring to ensure the stability of the existing structures surrounding the excavation. Furthermore, buried debris and the underground utilities complicated construction work.
A foundation consisting of micropiles and a retaining wall were employed to stabilize the excavation. Since the Georgia Viaduct is used by approximately 2,000 vehicles per hour during peak times, the foundation had to be built with special care in this area. The three viaduct piers were stabilized by installing 12 micropiles evenly around each pier.
Each of the 36 micropiles consisted of a 66mm Ø DYWIDAG THREADBAR® with Double Corrosion Protection that was installed to a depth of approximately 25.3m (83ft). The piers were additionally monitored during the entire construction work using a variety of instrumentation, and none of the piers showed any sign of movement.
The conventional shotcrete reinforced wall was tied back using 9-11 rows of tieback anchors. The anchors were installed with vertical spacing of about 1.2m-1.8m (4-6ft) and anchored against a horizontal shotcrete waler. For this purpose, DSI Construction Canada produced and supplied 25mm Ø DYWIDAG Bar Anchors and T40 DYWI® Drill Anchors with a total length of 15,240m. The anchor systems were installed at various angles from 5 to 45° and at depths of up to 24.4m (80ft). The Contractor completed all the anchoring and excavation work successfully and safely with no detrimental impact on the surrounding structures.