Cone penetration testSince the company foundation in the year 1860, the present Keller Grundbau GmbH has developed from a well digging company to the leading company for ground engineering. At an early stage it was identified that the cone penetration test is an exceptional method for exploring construction ground which supplies information about the subsoil bedding rapidly and at low cost.

Development of the cone penetration test

The Dutch hydraulic engineer Pieter Barentsen developed the first pressure probe in 1932. For this, he took a commercially used metal tube used for gas lines with a diameter of 35 mm.

This cladding tube served as a guide for the bar linkage located inside, at whose lower end the probe tip was fixed.

And at this stage a 10 cm² tip, whose angle was 60°, was then already employed.Exactly the same as we still know and use it today.

It was the intention of Pieter Barentsen to develop a measurement process with which only the tip pressure is measured during penetration into the ground, without the sleeve friction of the probing bar linkage influencing the measurement.

At the beginning of the 1950‘s Begemann developed a device for the measurement of the local sleeve friction and a in 1965 published a graphic image with whose aida statement about the ground can be made, based on the relationship of sleeve friction and tip resistance.

years

Illustration: [BARENTSEN, P. (1936): Short description of a field testing method with cone-shaped sounding apparatus – in: Proceedings of the 1st International Con-ference on Soil Mechanics and Foundations Engineering]

Illustration: [BEGEMANN, H.K.S. Ph. (1965): The friction jacket cone as an aid in determining the soil profile. – in: Proceedings of the 6th International Conference on Soil Mechanics and Foundation Engineering]

Cone penetration test with Keller

The first electronic pressure probes were on the market in the year 1965. We at Keller identified the benefit of the pressure probe and acquired the first pressure probe in 1965. Due to its compact construction design, it was employed either assembled as SoloSonde or on a truck. (Illustration 1 shows our first „sounding trucks”)

Based on positive experience with the cone penetration test with all participants, we then dared to take an exploratory step. In the course of the following decades the most diverse projects were successfully used for building subsoil investigation in the north German ports, on shipping waterways, as well as in the North Sea and Baltic Sea. (Illustrations 2 and 3)

In the middle of the 1970‘s probe tips came onto the market with which the interstitial pressure can also be measured during sounding, as well as tip pressure and sleeve friction. With such tips (CPTu), dissipation tests can also be implemented in the ground. Thus the consolidation coefficient and the water permeability of the ground can be determined in situ.

Also larger depths (m >50) can be sounded. If compact ground horizons, such as rock layers, very densely layered sands or semi-solid clays, should prevent the sounding progress, then they can be overbored and the cone-shaped sounding continued until the final depth has been reached. (Illustration 4)

We have employed cone- penetration tests successfully for 50 years.Do you have any questions? We look forward to your call.

Keller Grundbau GmbHBecklinger Straße 21 · 29683 Bad Fallingbostel (Dorfmark) · GermanyTel. +49 5163 299-0 · Dorfmark@kellergrundbau.com · www.kellergrundbau.de

(Illustration 1) (Illustration 2)

(Illustration 4)

(Illustration 3)