Plate tests 1

[parrot77]

Hi all,

I have recieved plate bearing tests on 'made ground' and the results have been issued as a modulus of subgrade reaction and CBR percentage. From these results can anyone indicte to me how I can estimate Bearing capacity for a design of a raft slab over? Thanks

 

[soiledup]

I'm not sure you can as I think you need more information especially from deeper ground. How can you be sure the Made Ground is uniform?

 

[parrot77]

It wound not be uniform, hence the provision of a raft slab to mitiagte the effects of soft spots in the supporting ground through local spanning action.

 

[oneintheeye]

plate loads only stress ground at surface, you will need to consider the deeeper layers that a raft would stress.

 

[parrot77]

Thanks Soiledup and Herewegothen,

How would you consider the deeper soil? Could you suggest a test? A penatration test maybe giving an N value which may be converted to bearing capacity?

 

[parrot77]

lighten up dgkhan!!

 

[fattdad]

(as posted on the other identical thread)

You cant. You need soil properties to depths of 10, 20, maybe even 30 ft to evaluate how the stresses of your raft slab will affect the underlying soil materials. The purpose of a plate test is to look at the affect of point loads at the much more localized near-surface.

Sorry if this is bad news, but that's just how I see it.

f-d
¡papá gordo ain't no madre flaca!


¡papá gordo ain’t no madre flaca!

 

[fattdad]

supplement:

There is some consideration to the size of the loaded area. You can use SPT N-value or Dilatometer data (for direct modulus values) to arrive at the elastic response to loading. You first need to make sure there is no concern for 1-dimensional consolidation however (i.e., soft clays, position of the water table, etc.).

f-d

¡papá gordo ain’t no madre flaca!

 

[oldestguy]

This looks like you will need a conventional subsoil investigation and a report with recommendations by an experienced geotechnical engineer. The plate bearing tests may be of some use, but I suspect little use in the overall design.