Cone Penetrometer Test

Cone Penetrometer Test (CPT)

A standard 10 sq.cm piezocone penetrometer (CPT) system has been installed on the PROD.

The CPT can penetrate to 100m below the mudline and operate to a water pressure of 25MPa

The system provides real time records of cone tip pressure, friction and pore water pressure. The CPT probes carry non-volatile onboard 18-bit backup memory, allowing full verification and enhanced resolution of the acoustically transmitted real time data.

The PROD CPT system consists of a 2m long standard 36mm diameter probe and push rod assembly, attached to customized drill rod. Multiple CPT probes can be deployed in conjunction with sampling tools.

In soft to firm fine grained soils, PROD can deploy a spherical ball
penetrometer to provide accurate shear strength profiles.

Key components of the PROD system are protected internationally by patents,
patents pending and patent applications.

CPT Specifications

CPT Probe Assembly	36 mm diameter x 2,000 mm long standard shoulder cone & rod, screwed into modified PROD drill rod, temperature compensated
Cone tip, qc, parameters	Maximum 50 MPa, tip area = 10 sq.cm
Friction sleeve, fs, parameters	Maximum 1 MPa, sleeve area = 150 sq.cm
Pore pressure, u, parameters	Maximum 25 MPa (total pressure)
Battery life	12 hours per probe
Max No. of probes deployed	3
Internal backup memory	Minimum 12 hours, maximum 1 reading/sec, non volatile
Data transmission	Acoustic transmission from probe via drill string to fibre optics in umbilical
Depth synchronisation relative to PROD	Electronic signal generated from PROD carriage position sensor and drill string length, resolution 1mm
Depth synchronisation relative to mudline	PROD baseplate penetration monitored with a visual depth gauge viewed via camera