Foundation tests for Water Tower

Question

Foundation tests for Water Tower

larssun (Civil/Environmental)

(OP)

6 May 02 15:04

Assuming a ring-wall foundation for a 75,000 gal (100 ft tall x 20 ft diameter) single pedestal spheroid Water Tower on clayey soils:

How deep should the borings be specified to conservatively evaluate foundation bearing pressure, differential settlement, lateral pressures and compaction requirements?

What tests beside blow counts are recommended?

Thanx,

larssun

ishvaaag (Structural) · Answer 1 · 2002-05-07 14:03:11

I suggest you making searches akin to...

http://www.google.com/search?q=Water+Tower+foundation+tests+settlement&hl=es&btnG=B%FAsqueda+en+Google&lr=

and browse the results for what suits you.

Of course in more than strength, some identification is also required for proper bracketing of the settlement, and also to identify the whys of the mechanical strength results.

Then upon identification one may choose to further test.

TAC (Geotechnical) · Answer 2 · 2002-05-08 11:26:03

The depth of the borings is relative to the types of soil you expect. If you are likely to encounter soft compressible soils where settlement will be an issue, than the borings should be deep enough so that you have sufficient information to deisgn deep foundations if necessary. If you have good soil conditions (i..e stiff over-consolidated clays or relatively dense sands) and anticipate that shallow foundations won't be a problem, than I typically like to see at least one boring to about 40 feet and the other borings to 20 feet --- again this would depend on the soil expected.

Lab testing should include moisture content, unconfined compressive strength, and consolidation testing (if we don't have a good feel for estimated consolidation parameters for settlement analysis).

A local geotechnical engineer would be able to provide these answers for you.

Sean2 (Geotechnical) · Answer 3 · 2002-05-13 09:17:02

The purpose of any "borings" you may sink is to investigate the ground conditions and measure soil and/or rock properties.  As this is to be an investigation, you can not be SURE (100%) in advance of the investigation how deep the boreholes need to be.  An educated guess is made, based ideally on a Desk Study of the site, and this guess must be reviewed CONTINUOUSLY by a competent geotechnical engineer during the investigation.  The depths may be changed, and the sampling and in-situ testing regime may also be changed.  These changes will be made based on the information obtained at that time.

You (or your client) will want to control costs.  If further investigation is indicated by the information coming from the ground, then two options are available:

1. Carry out the extra investigation recommended by the expert(s).

2. Do not carry out the extra investigation work, and accept the risks.  The specialist must advise on these risks.

TAC's advice seems very reasonable in the first instance.

Good luck.

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Foundation tests for Water Tower