Below ground level construction?

[Austin55]

ok,so Im new to enginereng,and Im a bit confused about was goes on in a highrises construction.what happens after cassions? would some one mind posting some info,maybe a timeline or something?thanks to all! cheers:cheers:

[Kelvin]

The nature of the structure depends on the geotech investigation, nature of building use, etc. How deep is the bedrock (or other suitable bearing strata), what bearing capacities are required, what settlements are allowed, how deep below grade will access be required (underground levels), how tall is the building (how much vertical & horizontal load will it generate), etc. etc.

Foundation systems can vary - piles, caissons, raft/matt, slurry wall, other.

However superstructure work generally can not take place until the substructure is complete.

[harryc]

Short answer - many different ways.
The link to CASE below shows a brief description of each.

List of types:
Hey guys, I need some help. Can someone who might possibly know tell me what "Service" method Case Foundation is using for the Spire. Check out there site (at bottom), and at the very bottom of there page it says "Services", and has like 7 different methods used (just click on one of the 7, it will show a diagram). My guess is there using the "Top Down Construction" Method, not sure though, a couple look very similar to the Spire plans I have seen. Thanks guys!!

http://www.casefoundation.com/

The method used for Trump Chicago, Waterview, 300 N LaSalle
No
They don't have to build a hole, 111 Illinois and The Chicago Aqua http://forum.skyscraperpage.com/showthread.php?t=99367&page=64&highlight=aqua
are examples.
The hole doesn't need to be first: excavation of the basement after the steel frame, and floors, are in ( block 37 )

That said, a 70' deep 7 floor parking garage is planned, it is expected that:
- the caissons are being put in
- steel sheeting will be installed to keep the dirt back
- the dirt will be dug out, exposing the caissons.
- a concrete and rebar mat will be laid.
- the "bathtub" created.
- THEN the tower will start rising.

Does anyone have a rough timeline on these steps ?

Any corrections or clarifications appreciated.


BUT Chicago Spire is using top-down
[They are in fact using top down construction. The Concrete mat will be the last part of the parking structure built. They will build the first floor and then dig from below it till they reach the level of the next floor below it and then lay that floor. Each floor they lay will act as lateral support for the slurry wall/double secant concrete wall. The wall will be built only 3 feet from the nearby town homes and consequently there is a lot of concerns about differential settlement. Top down construction promises much less settlement.

Here are pictures of the parking structure ( I really wish I had a better scanner):

http://img442.imageshack.us/img442/737/parking1zr3.jpg
http://img401.imageshack.us/img401/4690/parking2my1.jpg

[Austin55]

Thanks for the Info. Whats a slury wall?

[Coldrsx]

^depends on the case, but it can range from a sort of placecrete to i cast in place wall that acts as the retaining wall.

sorta like shoring but much quicker and easier, although not as strong.

[harryc]

Top down

May 9th - look ma no basement !

http://lh4.google.com/harry.r.carmichael/RzY0JrLXgMI/AAAAAAAAM1Q/4ZQrgCA0T1I/IMG_7475.jpg?imgmax=512

Oct 29 - exhaust vent.

http://lh3.google.com/harry.r.carmichael/RykTxepIlYI/AAAAAAAALeY/mULS39rbwCs/P1090537.JPG?imgmax=800

Scooping out clay.

http://lh5.google.com/harry.r.carmichael/RykTz-pIlZI/AAAAAAAALeo/O83OXyvbLbk/P1090538.JPG?imgmax=512
http://lh4.google.com/harry.r.carmichael/RykT1upIlaI/AAAAAAAALe0/zaaC01M_iAQ/P1090539.JPG?imgmax=512

Nov 1 -

http://lh3.google.com/harry.r.carmichael/RyqMFOpIm8I/AAAAAAAAL8s/QseQ_BvbjbM/P1090989.JPG?imgmax=512

Nov 9 - Looking down 2 sub levels

http://lh4.google.com/harry.r.carmichael/RzY0ArLXgLI/AAAAAAAAM1E/AEALQj2lD1E/2007_11_09f.JPG?imgmax=800