How to use Foxta with CPT data?

July 20, 2018 by Terrasol


This document aims to show and clarify how to use Foxta with Cone Penetration Testing data (CPT) for shallow and deep foundations.

How to use Foxta with CPT data?Shallow foundationsFondsupParameters tabSoil definition tabTasplaq and TasseldoDeep foundationsFondprofParameters tabLayers tabSkin frictionTip resistanceTaspie+Reaction lawsSkin reaction lawTip reaction lawLayers tabSoil/pile tabPiecoef+Lateral reaction lawParameters tabSoil/pile tabGroupie+Soils tab

Shallow foundations

Foxta is appropriate for the design of shallow foundations, including :

Remember:

 

Fondsup

Fondsup allows for the design of rectangular or circular isolated and spread footings based on CPT data.

Parameters tab

If CPT data are available, one has to define the design method as From penetrometer results.

In this case, we recommend to process by measurements.

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Soil definition tab

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1531744153972The import wizard allows for the import a lot of data from clipboard (button Import).

For example, one may define all values in an Excel spreadsheet, select the range of data and then copy to clipboard.

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Tasplaq and Tasseldo

 

Tasplaq model (Cuira & Simon 2006)

The Tasplaq and Tasseldo modules require the input of soil elastic modulus () values.

How to determine soil elastic modulus () from CPT data?

In case of an important level of shear strains (raft under localized load, shallow foundation, embankment or slope edge...), Eurocode 7 (NF P 94-261 J.2.2) suggest to use Robertson model:

In case of important volumetric strains () (embankment on soft soil...), Eurocode 7 (NF P 94-261 J.2.3) suggest to use Sanglerat model:

Soil type
(MPa)
Stiff clay (low plasticity)< 0.7
0.7 to 2
> 2
3 to 8
2 to 5
1 to 2.5
Silt (low plasticity)< 2
> 2
3 to 6
1 to 2
Soft clay
Soft silt
< 2
> 2
2 to 6
1 to 2
Organic silt< 1.22 to 8
Peat and organic clay< 0.750%<w<100% → 1.5<< 4
100%<w<200% →1<< 1.5
w>200% → 0.4 < < 1.0
Chalk2 to 3
> 3
2 to 4
1.5 to 3
Sand< 5
>10
2
1.5

 

 

Deep foundations

Here are a few examples of deep foundations which may be designed with Foxta:

Remember:

 

Fondprof

Fondprof is used to evaluate the bearing capacity of a single deep foundation.

Parameters tab

First of all, define the design method as From penetrometer results** in the Parameters tab.

After, you may chose to process by measurements or by layers. In the case of CPT data, it can be useful to process by measurements.

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Layers tab

We recommend to define one soil layer per value from CPT data.

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Skin friction

 

Tip resistance

The and values may be defined by the user.

 

Final penetrometric factor for bearing capacity calculation will be obtained from the following expression:

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