CPT report and penetration profile: CPTu scope

What the tool calculates

• Depth-based log, layer descriptions and groundwater observations
• Cone resistance qc, sleeve friction fs and friction ratio Rf from mechanical cone reduction
• Reading table and plots with project and equipment identification
• Printable sheet and notices for missing or inconsistent readings and declared instrument limitations

What you enter

• Depth z (m), Cone qc (MPa) and Cone+friction (MPa) for each mechanical reading
• Soil descriptions, groundwater levels, coordinates, dates and termination condition
• Equipment identification and data, cone and sleeve areas, and project information

What you receive

• Table of qc, fs and Rf and plots against depth
• Profile with user-entered layer descriptions and groundwater records
• Printable cone penetration log with identification, equipment and observations; no foundation design calculation report or quantities

References and limits of applicability

• References available in the selector: ASTM D3441 / D5778 and EN ISO 22476-1. Check the procedure applicable to the instrument and contract; selecting a reference does not certify test compliance.
• The module catalog labels ABNT NBR 12069:1991 as withdrawn. It is not presented as a current Brazilian standard or as a replacement for a verified contractual procedure.

Checks and considerations

• Missing or unrecognized readings require review; a blank field is not a measured zero
• Cone+friction below Cone, negative depths or readings outside the tool's domain require checking against the field record
• Declaring CPTu or SCPTu does not enable u2, qt, Bq, seismic measurements or electrical cone interpretation in this module

How it works

The module accepts z, Cone (qc) and Cone+friction, with input resistances in MPa. It calculates fs = (Cone+friction − qc) × cone area/sleeve area and Rf = 100 × fs/qc for positive qc. Default areas are 10 and 150 cm²; the reduction uses valid areas supplied with a reading. The table displays qc in kgf/cm² and fs in kPa. Soil descriptions are entered by the user. The selector also identifies CPTu and SCPTu, but the module has no pore pressure u2 input, does not calculate corrected qt or Bq, and does not process seismic data or independently measured fs. Selecting those test types does not turn the mechanical reduction into piezocone interpretation. Correlations used by other tools must be reviewed against their stated method and application domain; this log is neither a foundation design nor certification of the field test.

Example of use

For a mechanical cone exercise at 2.00 m, enter qc = 6.00 MPa, Cone+friction = 10.00 MPa, cone area = 10 cm² and sleeve area = 150 cm². The 4.00 MPa difference gives fs = 0.2667 MPa, approximately 266.67 kPa, and Rf = 4.44%. Check these values in the table and plots, and identify the equipment and observations as hypothetical exercise data. The exercise contains no u2 and is not a complete CPTu interpretation.

Frequently asked questions

Can I enter u2 and perform a complete CPTu piezocone interpretation?

Not in this module at present. The available inputs are the mechanical Cone and Cone+friction readings. There is no u2 input, qc-to-qt correction, Bq or seismic processing. The declared test type appears on the sheet with the corresponding scope note.

How are fs and Rf calculated?

For the mechanical cone, fs is the difference between Cone+friction and Cone multiplied by the cone-to-sleeve area ratio. For positive qc, Rf is 100 × fs/qc, with both resistances expressed in the same stress unit. Check the areas and do not confuse Cone+friction with directly measured fs.

Does the log classify soil automatically or design foundations?

Layer descriptions are entered by the user and the sheet organizes the readings. The log does not design foundations, issue a foundation design calculation report or certify the field procedure. When using the profile in another tool, review that calculation's correlations, limits and checks.