Historical overview of foundation control by sonic coring


The CEBTP Company invented the sonic coring method to control foundations in the 60s, which is also called the transparency method.

The request to develop non destructive and very reliable foundation control methods originated from the Fédération Nationale des Travaux Publics (French Civil Engineering Union). The CEBTP team managed by Jean PAQUET along with Jean-Pierre CHIPART and André CABÉ tackled the task.

Les besoins dans ce domaine étaient en effet très importants, et aucune société au monde ne s’intéressait à l’époque, au test des pieux.

1966 : the first trials of the sonic coring method took place.

By the time, the measurement was performed discontinuously. While the probes stayed still at a given depth of the pile, a row of promptings were produced by an emission probe. The operator would view the signal received by the reception probe on an oscilloscope, and he would measure the time of flight between the two probes.

The probes were then lowered by 5 cm, and a new emission and a new measurement were carried out. After the whole pile length had been scanned, the points measuring the times of flight were plotted on a graph in order to draw a curve highlighting a possible delay, and hence a possible flaw in the pile.

Not all tubes were fitted with tubes right from the start. One therefore had to bore into the foundation in order to make room for the probes to pass. By the time, th eprobes had a 35 mm diameter, whereas the diameter of the probes of the new CS 97 has reduced to 25 mm.

The first real scale trials took place on the site of the thermal power plant of Le Havre, in France.

1967 :10 experimental piles were built on the site of Saint-Rémy-lès-Chevreuse, in France.These piles included flaws introduced purposefully in order to refine the method. Some were fitted with polymer tubes, some other were fitted with metallic tubes It is at this time the method became continuous. The signal was modulated in light intensity levels. The trace of it on a TEKTRONIX 560 oscilloscope was photographed by a POLAROID movie camera. This was the birth of the first sonic coring diagraphs..

1968 : Important trails of piles on the launching site of the ELDO spatial rocket at Kourou, in the French Guyane. Kourou is the place where the now reknown European ARIANE rockets are launched.

1987 : As computer science components were growing smaller and smaller, CEBTP engineers Jean-Pierre Chipart and Pierre Vaillant created the CS 87. The CS 87 was more compact than all that had been created ever before, and it allowed to get diagraphs on a paper tape by means of a thermal printer built in the material.

1997 : Birth of the CS 97. The CS 97 displays advanced performances, it is very handy to use and it is wholly automated. The diagraphs are stored inside, which makes it no longer necessary to paste the diagraphs on a sheet of paper : the CS 97 prints the diagraphs direcly onto an A4 sheet, which can be inserted into a report as it is.

2008 : En collaboration avec une société britannique, GINGER CEBTP propose un matériel toujours plus performant, le SC-XT2000. Cet équipement fonctionne sur batterie interne et permet d'exporter les mesures par liaison USB.

Frédéric BOURDET, 2009
The Material Sales Department of CEBTP

• Back to the charcteristics of the sonic coring SC-XT2000 equipment

You can obtain a complete set of documents about these new equipments quickly by simply placing a request at :

M. Frédéric BOURDET

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