Quote:
Originally Posted by RabidMoose
|
If you look at a site where there's already a building that's been built next door, as they dig the basement hole for the parking for the new building, they just remove the pins as they come across them. Their purpose was only to hold the sides of the hole from caving in during construction, so they don't have any structural role once the reinforced concrete walls of the basement have been cast and hardened.
Sometimes there can be a problem in putting in new tie rods where the adjacent building has a shallower parkade, or some other underground services. When Onni were building The Mark, on Seymour Street, about 10 years ago, their parkade went deeper than that of the adjacent building, which was a recently completed non-market housing building called Karis Place. The problem was not in the tie rods, which could be removed, but with the geothermal heating and cooling system that had been installed under the new non-market building. I believe Onni had to use some sort of penetrating imaging system to make sure they knew exactly where the vertical pipes were, so that the tie rods they were installing while they dug out their deeper parkade didn't hit the heating system.
You can see construction of a coffer dam, using interlocking steel sheet piles, if you look at the thread for some of the more recent Concord buildings like The Arc. The ground conditions weren't good enough to risk the shotcrete approach.
For the most recent use of secant piles, check out the St Paul's thread (or the hole that's on the site there at the moment). Rather than sheet steel, they're drilled rotary piles with a steel 'I' beam down the middle, and concrete poured into the steel tube to make a column. The columns are spaced so that they overlap, and you end up with a ridged concrete face (like corduroy) with steel beams embedded in the columns. The concrete is waterproof, so the box you end up with, once the base layer is tied in, should be totally waterproof, and if groundwater levels rise in future, it shouldn't be an issue. Again, this system was used there because the site was once False Creek, which was filled in to build a station and railyards, so the ground wasn't stable. The good news there, is that the Creek was quite shallow, and the bottom of the hole reached the same rock-like compressed glacial material you find almost everywhere else Downtown, so there will be no issues with the stability of the underlying ground.
Prev
- Tower 2
- Tower 2
- Tower 1 
- Tower 1
- "Tower 3"
Linear Mode
