International - CPT 2022
Lange, D. de, Duinen, A. van, Peters, D. (2022): What is an appropriate criterium fort he transition from a wider penetrometer to smaller pushing rods? Geotechniek 2022, International Special CPT 2022, p.6
As 15 cm2 cone penetrometers are pushed by Ø 3.6 cm rods, a transition from the wider penetrometer to the smaller pushing rods is needed. It has been noticed in practice that CPT sounding companies prefer and use configurations in which the transition is in between 5 to 7 times the cone diameter, D, above the cone shoulder. However, according to NEN-EN-ISO 22476, the transition should be positioned at least 11.2D above the cone shoulder. In order to fuel discussion, a first step was made by performing two series of 9 CPTs with different penetrometer configurations. The results have been analysed and no systematic differences between the different penetrometers are found. Better understanding and validation is needed, but if all results point in the same directions, the standards can be updated. Geotechniek 2022, International Special CPT 2022, p.6
McConnell, A. (2022): Cone penetration testing in extremely soft soil-solving the problem of poor sleeve friction measurements. Geotechniek 2022, International Special CPT 2022, p.4.
This article is an extract from the CPT’22 paper referenced herein.
Measurement of extremely low sleeve friction (fs) values during CPT testing is an industry-wide problem, often treated as an “elephant in the room”.
The paper describes the development of an innovative new CPT cone that the authors believe has largely solved this problem.
The solution has involved shifting of the paradigm, that “if you want to most accurately measure sleeve friction, you must use a Compression Cone”. This solution involved the use of a Subtraction Cone design.
The solution also involved development of more-responsive-than-conventional load cells using a special alloy for the load cell base, rather than steel.
So far the new CPT, calibrated and managed as described in this paper, is meeting or exceeding the authors’ expectations.
Verbeek, G. (2022): CPT – an old and proven soil investigation method with a bright and exciting future. Geotechniek 2022, International Special CPT 2022, p.12.
While the official reason for this special issue of Geotechniek is the CPT’22 conference, another equally good reason for this issue could have been that Cone Penetration Testing turns 90 this year. Over the years this soil investigation technique, which started out as a simple solid mechanical cone that was pushed by hand into the soil, has developed into a sophisticated testing method, where a digital instrument with multiple sensors is pushed down using a hydraulic pusher. But as pointed out in this article, the developments continue and that is why CPT is an old and proven soil investigation method with a bright and exciting future.
Woollard, M. (2022): Coson-ST: from manually operated to CPT robot. Geotechniek 2022, International Special CPT 2022, p.8.
The Cone Penetration Test (CPT) cabin as working environment, built on trucks, crawlers or Track-Trucks®, will more and more develop from a workshop into an office. Before, operators were mainly dealing with manual operations to keep the production going. Nowadays and in the future, it can be increasingly expected that time "on board" will be spend on design or other office-related work next to performing CPTs. By integrating the patented SingleTwist™ technology in a CPT cabin with the COSON continuous pushing system, A.P. van den Berg has developed an automatic and hands-free CPT machine.