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Title:

"Geotechnical monitoring of a trial pit excavation toward the Boom clay in Antwerp (Belgium)"
Authors: ir. J. Couck, Flemish Government, MOW
ir. K. Van Royen, Denys NV
ir. G. Osselaer, BAM NV
ir. drs. R. de Nijs, THV ROTS (Witteveen + Bos)
ir. F. Kaalberg, THV ROTS (Witteveen + Bos)
Published in: This is the official paper that was the source for an article in the Dutch magazine Geotechniek number 5/December 2015, An independent magazine about geotechnical engineering. Uitgeverij Educom BV.
Abstract: In order to relieve the busy traffic arteries of Antwerp (Belgium), the closing of the ring around Antwerp was put to study by BAM (Beheersmaatschappij Antwerpen Mobiel). The design of this construction requires detailed insight in the behaviour of the overconsolidated Boom clay layer during and after dewatering and removal of the covering soil layers.

For this purpose a fully monitored excavation test was performed in order to assess soil behaviour and specific techniques to be used in anticipated projects in the Antwerp area. This paper specifically presents and evaluates the results regarding swell and pore pressures recorded in the Boom clay. From the monitoring results it can be derived that the Boom clay shows a quick response to a fluctuation in water level in the overlaying aquifer. The Boom clay also shows a severe pore pressure reduction as a result from loss on effective stress during excavation. These two effects should be considered separately. The underpressure is caused by swell hindered by a very low permeability of the Boom clay. Up to 50% of the effective stress reduction can be transferred into a pore pressure reduction. This condition results in a long term dissipation and swell process towards a gradient of approximately 25 kPa pressure increase per m depth increase. This effect intersects with the original hydraustatic pressure in the Boom clay.

BAT-sensors
In total 8 Profound BAT-sensors were used in this experiment. Monitoring results are part of the paper.

Download download 2015-GeotechnicalMonitoring_Trial_Oosterweel.pdf (size: 789 kB). To view this document you need the free Adobe Acrobat Reader.

 

 

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