Alberni by Kengo Kuma (1550 Alberni) | 133m | 42Fl | Completed

[mcminsen]

July 7 '19, my pics

[Zepfancouver]

Thanks mcminsen, appreciate the effort on these shots. Every week they keep adding more defense on viewing this pit. I'm looking for an elevated public space (nearby building) to capture the iron work for the foundation.

[mcminsen]

Maybe I should get myself a long selfie stick.




July 3 '19, my pic


July 7 '19, my pic

[VancouverOfTheFuture]

what do they do with the crane base once the building is done? use it as part of the foundation or is it just a forever entombed useless piece of concrete?

[osirisboy]

My guess is that from the base of the crane down to the bottom of the pit in that area is all going to be rebar and poured concrete

[officedweller]

That's what I think too.
.. as a counterweight for the lopsided tower above.

[Zepfancouver]

[QUOTE=mcminsen;8626283]Maybe I should get myself a long selfie stick.

Was thinking the same. Being a public forum, Graham construction are counter striking right now by doubling the height of the fence and hoarding...Bring it on

[Zepfancouver]

This is why I had some concerns about that crane pedestal http://forum.skyscraperpage.com/showthread.php?p=8627303#post8627303

[MrFreeze]

I saw that Saturday, I have a good view on the crane from my flat and the crane was balancing, what seemed a lot, by just carrying a load. Hopefully the operator does not have motion sickness

[Zepfancouver]

Unable to capture the work, no site-line in the public area and on the private property, building manager is on you quick (maybe try early morning before office hours).
Got a small glimpse, looks epic. Graham Construction will be proud of it and most likely will post it on their Twitter Page https://twitter.com/GrahamBuilds

[officedweller]

Originally Posted by Zepfancouver

...

Graham Construction will be proud of it and most likely will post it on their Twitter Page https://twitter.com/GrahamBuilds

There's a time lapse of the excavation at their twitter...

[Zepfancouver]

Nice time lapse. I tried to get access to that camera view today but no luck, no elevator access to the top floors without a key pass.

[Zepfancouver]

The day I missed the heavy lift of the excavators

Graham Construction Time lapse https://twitter.com/GrahamBuilds/status/1151142795643510785

[logan5]

Anybody know how deep the piles go for these taller towers? Is there bedrock at a shallow enough depth for the piles to rest on? Inquiring minds want to know.

[Changing City]

Originally Posted by logan5

Anybody know how deep the piles go for these taller towers? Is there bedrock at a shallow enough depth for the piles to rest on? Inquiring minds want to know.

Piles? With very rare exceptions buildings in the City of Vancouver don't have piled foundations. In a few examples the edges of the excavation are piled before it's dug out, if the test boreholes have shown potential instability.

It's unlikely that the excavation here has reached bedrock. It certainly looks like glacial material, although once they've dug down 100 feet or so, it's usually pretty compacted, and can start behaving like rock. There are parts of the city where there's rock near the surface, like near QE Park, but that's not generally the case Downtown.

[cairnstone]

Originally Posted by Changing City

Piles? With very rare exceptions buildings in the City of Vancouver don't have piled foundations. In a few examples the edges of the excavation are piled before it's dug out, if the test boreholes have shown potential instability.

It's unlikely that the excavation here has reached bedrock. It certainly looks like glacial material, although once they've dug down 100 feet or so, it's usually pretty compacted, and can start behaving like rock. There are parts of the city where there's rock near the surface, like near QE Park, but that's not generally the case Downtown.

Sandstone layer is typical and very dense material that supports the load. Piles are used on the out skirts of downtown typically as the material is of different composition. Shaw tower sits on Piles and so does some of the properties around False Creek.

[Changing City]

Originally Posted by cairnstone

Sandstone layer is typical and very dense material that supports the load. Piles are used on the out skirts of downtown typically as the material is of different composition. Shaw tower sits on Piles and so does some of the properties around False Creek.

Can you point to a source for that? Generally, my understanding was Downtown sites (like this one) have 30 to 60 metres of glacial till. [source] The sandstone layer would be quite a bit lower down, unless it's a spot where the glacial till is thinner (like where a stream flowed in the past, for example).

Obviously round the northern edge of Downtown there's a lot of infill on top of a natural beach, so buildings might need piles. Similarly, as you say, False Creek (which used to go to Clark Drive) was filled, so buildings along Terminal Avenue for example might be piled, and so were some Concord buildings near False Creek (although usually as coffer dams to stop the sides collapsing, rather than supporting piles).

I'm not aware of any deep underground parking excavations (like this one) having any additional piling. Unless the glacial till isn't compacted (which doesn't generally occur Downtown) it's perfectly capable of taking the weight of the building above. "Some tills are compact and concrete-like, whereas others are sandy and loose. Till commonly has a high bearing capacity and thus is an excellent foundation material." [source] There's a different story in other parts of the Lower mainland, as geology changes quite a bit further east, but my observation of Downtown holes (and looking at McMinsen's pictures) are that they're dug, and then filled, without piles in most cases.

[logan5]

Originally Posted by Changing City

Piles? With very rare exceptions buildings in the City of Vancouver don't have piled foundations. In a few examples the edges of the excavation are piled before it's dug out, if the test boreholes have shown potential instability.

It's unlikely that the excavation here has reached bedrock. It certainly looks like glacial material, although once they've dug down 100 feet or so, it's usually pretty compacted, and can start behaving like rock. There are parts of the city where there's rock near the surface, like near QE Park, but that's not generally the case Downtown.

Hmm. A 40 story building that’s not anchored to the earth doesn’t sound right. No piles would mean the building could potentially sink into the ground or start leaning to one side. So I thought.

[SFUVancouver]

Originally Posted by logan5

Hmm. A 40 story building that’s not anchored to the earth doesn’t sound right. No piles would mean the building could potentially sink into the ground or start leaning to one side. So I thought.

Properly engineered and constructed, a tower built on bedrock should have no risk of settling or leaning. Piles aren't necessarily anchors, either. They're effectively stilts. They let a building's structure reach down through soft or unstable soils to firmer ground, ideally bedrock, that can better and more predictably bear the building's weight.

Imagine trying to stand on a big pile of laundry. It would be pretty unstable and would compress unpredictably under your weight. Now imagine you worked in a step stool into the laundry pile so that its feet touched the ground. Standing on the far more stable and predictable stool would be like night and day vs standing on the laundry. Ultimately, the floor beneath is taking the weight either way.

[Changing City]

Originally Posted by logan5

Hmm. A 40 story building that’s not anchored to the earth doesn’t sound right. No piles would mean the building could potentially sink into the ground or start leaning to one side. So I thought.

If the ground underneath the bottom of the hole was potentially unstable, the design might have to take that into account, but the glacial till was compressed for several thousand years by up to a mile of ice, so it's pretty compressed, and it has sandstone bedrock (or volcanic rock in a few spots) underneath, so it's stable.

Have you ever seen a piling machine at the bottom of a parkade hole? If they were piling below the base, they'd have to have a pile driver to install the piles. I've seen a lot of holes, and McMinsen's pictures of even more, and I've never seen a piledriver at the bottom. I'm not sure how they would get anything bigger than an excavator out of the hole!