Foundation on a 3meter(9ft) thick Compacted Fill, Problems? 5

[IJR]

Pals

I am going to have to put a structure on a thick compacted fill, because the geotech says 4m(12ft) of soil layer must be removed(poor vegetation layer) and then structure be set up. So we will fill up 3m(9ft) and then let the structure rest 1m(3ft) below ground level

I have done this with single footings before, specifying gravel fills, sometimes concrete fills, at 95percent proctor.

But this time I am going to put a huge structure on top.

I am going to specify a 1m (3ft) thick raft on a large area, and specify a good fill and compaction.

Any problems you expect? Consider thick raft and a large area?

respects

 

[VAD]

you have not mentioned the nature of the subsoil below the 12 ft thick layer. Settlement and differential settlement caused by load in excess of raft may be required to be checked. Settlement could have some influence on your raft or raft reinforcement design. Otherwise, I do not see too much of a problem

 

[IJR]

VAD

Below that is good soil, dense and sandy, with bearing capacity higher than I need.

Problem is, the area used to be agricultural before.

respects
IJR

 

[BigH]

Might want to check out (free download) the following:

http://www.isddc.dot.gov/OLPFiles/FHWA/009760.pdf

About bridge abutments on compacted fill.

 

[IJR]

BigH

something is wrong with the adress you gave me. What to recheck and give me the correct one?

respects
IJR

 

[Panars]

There should not be a "www" in front of the address.
The correct address is:

http://isddc.dot.gov/OLPFiles/FHWA/009760.pdf

The publication is Number FHWA-RD-81-184
"Performance of Highway Bridge Abutments Supported By Spread Footings on Compacted Fill"

All FHWA geotech publications can be found here:

http://www.fhwa.dot.gov/engineering/geotech/library_listing.cfm

 

[BigH]

 

[DRC1]

Technology is great except when it does not work.
IJR,
Since the compacted fill will proably stiffer than the underlying soils, Make the pad legth and width of the pad the length or width of the Strucure, plus at least three times the depth of the strucure. This will allow the fill to distribute the load to the lower soils and lower the net contact stress on the soil layer.

 

[IJR]

DRC1

What do you exactly mean by three times the depth of the structure?, you mean 3times the depth of foundation?

Anyway, I have a really large and thick mat(raft) foundation, and yes, my rule of thumb is to extend the raft 1.5xthickness from the column line.

But let us hear from you more clearly

 

[DRC1]

I'm sorry I ment structeral fill., Thus if your fill is 3m, the min. length of the fill should be the length of the building plus 9m, with the building in the center.