Static Probing > Equipment

This window may be used to select an instrument in the list of the ones in the database, review its characteristics, add those of a new one or remove an existing one. The window may be reached from the Home > General data menu.

Three categories of instruments, Mechanical Cone, Electric Cone, and Piezoelectric cone, may be specified, under the headings: CPT, CPTE, CPTU.

Under each category the individual equipment items recorded are listed.

Click on one equipment from the list to select it for use or for editing.

To add a new instrument, right click the root ("Equipment" at the top of the list). This enables the "New" function that opens a blank window in which the new characteristics may be entered.

To delete an instrument, right click the name. This enables the "Delete" function.

As regards the Electric cone generally this instrument allows to obtain continuous data with a very close step (even 2 cm), compared to the Mechanical cone (20 cm). For the Piezocone data insertion in addition to those of LP and LT are the measured neutral pressure and the dissipation time. This measurement is generally done by measuring the overpressure obtained in the thrust phase and the neutral pressure ( dissipation over time) measured at rod thrust lightening (penetration arrest). The program allows to enter U1 - U2 - U3 ie neutral overpressure measured respectively with a porous filter positioned in the cone, around the cone or around the sleeve, depending on the type of piezocone used. This overpressure (that is the sum of the hydrostatic pressure existing before penetration and pore pressures produced by compression) can be positive or negative and generally varies from -1 to max. + 10-20 kg/cm2 and is produced by compression or expansion of the soil as a result of the penetration. For the calculation in addition to the general instrumental data must be entered for a correction of input values:

Area of the cone tip is the outside tip area.

Internal area of the cone tip (area of the narrowing in the vicinity of the porous septum - internal cone-sleeve). Generally the ratio of the areas varies from (0.70 - 1.00).

Step of the penetrometer is the interval within it performs the reading, generally for normal penetrometers is 20 cm, but can be can be 2 cm for electric cone or piezocone.

The program processes the data of tip and side resistance fs with appropriate corrections due to the normalization (with the lithostatic stress and the pore pressure).

Robertson defines the characteristic value of the Ic (soil behavior type index) and Fine content FC % (ie the percentage of clay content <2 microns).