*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

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

- isolated footings
- spread footings
- slab foundations...

Remember:

Fondsupallows for the design of rectangular or circular isolated and spread footings.Tasplaqhandles 3D modeling of pavements or rafts for any geometry and loading on a multilayer soil.Tasseldoprovides estimations of settlements and stresses in a multilayer soil.

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

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.

- : tip resistance [kPa]

The 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.

*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:

If :

If :

- for
- for

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 | < 1.2 | 2 to 8 |

Peat and organic clay | < 0.7 | 50%<w<100% â†’ 1.5<< 4 100%<w<200% â†’1<< 1.5 w>200% â†’ 0.4 < < 1.0 |

Chalk | 2 to 3 > 3 | 2 to 4 1.5 to 3 |

Sand | < 5 >10 | 2 1.5 |

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

piles (reinforced concrete, steel...)

micropiles

barrettes

pile-raft foundations

stiff inclusions...

Remember:

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

Taspie+handles :

- the calculation of pile and soil settlements in case of a single deep foundation under axial loading
- the design of stiff inclusions

Piecoef+provides fine calculations for single deep foundations under lateral loading.

Groupie+handles 3D calculations for a group of piles connected on top with an infinitely rigid footing.

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

First of all, define the design method as __ From penetrometer results__** in the

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__.

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

: tip resistance [kPa]

the Import wizard allows for the import a large amount of data from clipboard (button

*Import*).So, one may define all values in an Excel spreadsheet, select a range and then copy to clipboard.

The

values have to be imported by digits:__Soil class__*0*for No import*1*for Clays and silts*2*for Intermediate soils*3*for Sands and gravels*4*for Chalks*5*for Marls and marly limestones*6*for Weathered or fragmented rocks

: skin friction [kPa]

a Wizard may be used to automatically calculate the value for each input of .

wizard available in Layers tab

The ** and **** values may be defined by the user.**

**: minimal penetrometric factor for bearing capacity calculation (no unit)**- for clay
- for intermediate soil
- for sands and graves
- for other cases (chalk, marls, altered or fragmented rock)

**: maximal penetrometric factor for bearing capacity calculation (no unit)**

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