TPT September 2011

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S eptember 2011 89 ›
T echnology Update
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to conduct the job with seven intermediate stations, approximately
every 150m (three on the short stretch, four on the long), each of
which had a drive force equalling 1,078 tons. These were usually
put to service for initiating the drives.
Three manholes were installed 200 to 250m apart from each
other, and two special chambers, one hosting a flushing and the
other equipped with a vacuum system for deodorisation, were
included along the collector. Preparing for their installation, the
contractor neatly cut the soil and cast concrete to establish walls
around a part of the pipe route without prior excavation works,
and before the boring machine had passed the section. After the
concrete had cured, the bore head drilled through the established
walls, and the soil around the pipe in the concrete chamber was
excavated, either completely as for the flushing and deodorising
chambers or down to the pipe in order to install the tangential
manholes. The latter were erected by cutting and laminating a
Hobas DN 1000 GRP pipe vertically onto the DN 1800 jacking pipe.
The construction of the complete project, including the
installation of supplementary equipment and the pumping stations,
was finalised within 13.5 months – a short time, considering the
scope of the job and the difficult geological conditions, which
included inhomogeneous, abrasive soils soaked with ground
water.
Hobas Engineering GmbH – Austria
Fax: +43 463 482121
Email:
Website:
Hobas France SAS – France
Fax: +33 1 3435 0858
Email:
Website:
Jacking pit
in operation