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Temporary Shoring, Retaining Walls and Demolition
An important niche discipline at SDA is the design of temporary shoring for major construction projects. We have supported major highways, railway lines and rivers for the construction of bridge and building foundations. Often the shoring pit is dug very close to major underground services that have to be fully protected against any movement during the construction process.
Some typical recent shoring projects are shown here:
Pearson
International Airport Expansion
SDA designed numerous pits for the construction of bridge piers for the new roadway system. Most were straightforward, but one or two posed major technical challenges, like the one shown here that had to be dug right next to gas lines, water mains, an existing bridge and most important of all, a huge concrete tunnel carrying the power and communications to Terminal 2. The tunnel was located at the top left of the picture and the piles were drilled almost touching its sides. The picture also conveys just how deep the hole was.
This
huge retaining wall had to carry
the load of a massive scaffolding system, right along the top, supporting the
formwork for the construction of one of the
big flyovers. This imposed a surcharge load of 6,000 psf for the entire length
of the retaining wall - equivalent to an additional 45ft of wall height!
Once the new roads and bridges were built, the old ones had to be demolished. Naturally Canada's busiest airport could not be shut down while this was going on, so special procedures had to be adopted for the demolition process. The bridge illustrated here had to be taken down in stages, however it was a post-tensioned design and as soon as the reinforcing tendons were cut it was probable that the entire bridge would collapse under its own weight onto the active roadway below. SDA were hired to support the bridge using massive steel beams so that the demolition could proceed safely.