What Is a Cone Penetration Test (CPT)?

How CPT works

The push (the 2 cm/s — the quasi-static; the 20-ton's — the rig), the cone (the 60° — the 10 cm²; the qc's), the sleeve (the 150 cm² — the fs's; the friction's), the pore (the u2 — the filter's; the dissipation's), and the speed (the 60-foot — the hour's; the continuous's).

The parameters

The qc (the tip — the resistance; the normalized's — the Qt), the fs (the sleeve — the friction; the ratio's — the Rf), the u2 (the pore — the Bq's; the dissipation's — the ch's), the SBT (the Robertson's — the 9-zone; the behavior's), and the Vs (the SCPT's — the seismic's; the shear wave's).

Applications

The stratigraphy (the continuous's — the 2cm; the lenses'), the liquefaction (the triggering's — the Boulanger/Idriss's; the standard), the piles' (the direct — the LCPC's; the qc's), the settlement (the constrained's — the modulus), and the dissipation (the ch's — the consolidation's; the rate's). The CPT is the modern — the continuous, the repeatable.

The bottom line

Use CPT (2 cm/s push, qc/fs/u2) for continuous stratigraphy and Robertson SBT classification — standard for liquefaction triggering (Boulanger/Idriss), pile design (LCPC), and dissipation testing.

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