Shoring, decking, utility support

The subcontract for the design and construction of the shoring, decking systems and utility supports for TTC Yonge Station was awarded to The Anchor Group. This was the largest and most complicated of the new five-station Sheppard Subway Line under construction in Toronto, Ontario.

The Anchor Group’s scope of work included the design and installation of 1,000 soldier piles, 900 struts, 285,000 ft² of timber lagging, 35,000 ft² of contiguous caisson walls, 100,000 ft² of traffic decking, utility supports, and temporary support of existing stair structures and vent shafts. The excavation depths varied from 30 to 70 feet.

In order to meet the schedule The Anchor Group provided up to 4 drill rigs on site plus associated service cranes, vibratory hammers and loaders. This was the maximum amount of equipment which could work efficiently considering all the traffic and utility restrictions. The majority of the areas at the site required drilling below the water table and installation of temporary steel casings using vibratory hammers mounted on service cranes.

Performance of the shoring, decking, structure supports, and building response were monitored by TTC representatives during construction. Inclinometers were installed to monitor lateral movements of the shoring. The earth retention systems installed by The Anchor Group for this project successfully limited ground movements and satisfied the specified performance criteria.

The Anchor Group was proactive in planning each phase of the work. Communication of these plans to the other parties involved in the construction project was critical to ensure that the required traffic detours were arranged and that the work of other trades would not be interrupted. Cooperation between TTC, contractors and consultants was a key element in the successful early completion of this extremely complex project.