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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 2

CF cone

CF cone (cone penetration test)


The test is performed using a cylindrical penetrometer with a conical tip
(cone) penetrating the ground at a constant rate. During the
penetration, the forces on the cone and the friction sleeve are
measured. The measurements are carried out using electronic transfer
and data logging, with a measurement frequency that can secure
detailed information about the soil conditions. Figure 3 shows an
electrical friction cone with cut-away friction sleeve.

The results from a cone penetration test can in principle be used to
  • stratification
  • soil type
  • soil density and in-situ stress conditions
  • shear strength parameters.

 The results from cone penetration tests may also be used, directly, for
design of piled foundations in sand and gravel. Indirectly, it can be used
(shear strength) for piles in clay.

The test results are presented as shown in Figure 2. From left to right,
the CPT plots show cone (tip) resistance, sleeve friction, friction ratio
and inclination of the cone while pushing the cone into the ground.

The friction ratio, Rf = (fs / qc). 100 %, can be used to identify the soil
type shown at the right-hand side of the plot.
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