This standard outlines the method for conducting a Static Cone Penetration Test (CPT) to determine soil properties for geotechnical investigation. It specifies the dimensions of the apparatus (cone and friction sleeve), the procedure for pushing the cone into the ground at a constant rate, and the requirements for recording and reporting the cone resistance (qc) and sleeve friction (fs). This data is used for soil profiling and estimating engineering properties of soil strata.
Describes the method for conducting the static cone penetration test (CPT) for subsurface investigations.
Quick Reference Values
Weight of driving hammer65 kg
Free fall height of hammer75 cm
Cone apex angle60 degrees
Cone base diameter50 mm
Penetration increment for recording blows10 cm
Key Formulas
qc = Q_c / A_c — Cone resistance = Total force on cone / Area of cone base
fs = (Q_t - Q_c) / A_s — Local sleeve friction = (Total force - Cone force) / Surface area of sleeve
Rf = (fs / qc) * 100 — Friction Ratio (%)
Practical Notes
This is the 'Heavy' DCPT, distinct from the lighter versions used for pavement subgrade analysis. The 65 kg hammer is the key differentiator.
The test is faster and more mobile than the Standard Penetration Test (SPT), making it suitable for preliminary investigations or sites with difficult access.
Results (Nc values) are often correlated with SPT 'N' values and soil parameters like CBR, but these correlations are site-specific and should be used with caution.