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Published By Lankelma

Lankelma is the foremost contractor for onshore in-situ soil testing in the UK. An acknowledged specialist in CPT, Lankelma also offers a worldwide consultancy and training service.

A.P. van den Berg develops, designs and manufactures geotechnical and environmental soil investigation equipment for onshore and offshore applications. Specialists in CPT systems and equipment.


Gardline Geosciences offers worldwide marine geotechnics, in-house consutancy and services with marine investigations ranging from nearshore to full ocean depth (down to 3000m).

About the Author

Hans Brouwer studied civil engineering at Delft University in The Netherlands. He has worked as a part-time lecturer at Amsterdam Polytechnic and was senior partner in a structural engineering consultancy. He has written a standard textbook in Dutch about the design of building foundations. He now lives in England where he writes technical textbooks in English, hopefully to reach a bigger readership.

Chapter 4

Part 3: Special cones: other cones

Neptune cone penetration test unit

For offshore geotechnical investigations, the penetration test is undertaken, remotely, on the sea bed.
The Neptune CPT unit (Figure 41) uses a coiled rod. The unit contains a 2 or 5 cm2 detachable cone with a 50 MPa push capability. Up to 10 m penetration from a compact and easily deployed seabed frame is possible. Furthermore, the Neptune CPT unit can be mounted on a remotely operated vehicle (ROV). See also Chapter 9.
Technical specification
 Dimensions 1.8m (l) x 1.8m (w) x 2m (h) 
 Weight in ari1500 kg approx 
 Weight in sea water 1200 kg approx 
 Thrust capacity 1000 kg (approx 10kN, 50 MPa) 
 Max penetration 10m 
 Depth rating 3000m 
 Cone type Detachable, analogue subtraction 
 Cone sensors Tip, sleeve friction and inclination 
 Optional sensors Piezo - ranges to suit 
 Cone tip area 2cm2 
 Cone sleeve area 30cm
 Penetration speed 2cm / sec ± 10% 
 Retract speed 5cm / sec approx 
 Power requirement 240V AC single-phase 50/60Hz 
 Umbilical voltage 600V AC 
 Telemetry link FSK
 Tip accuracy >100 kPa 
 Sleeve accuracy >10 kPa 
 Inclination accuracy > 1° 
 Cone data rate 20Hz
 Frame sensors Altimeters, tilt, pressure 
 Frame sensor data rate  1Hz 
 Operating system 
WindowsTM 98 and NT compatible

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