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Fugro Engineering Services Limited has recently taken delivery of a new multi purpose Cone
Penetration Testing rig. Fugro's new "put down" crawler cone penetrating testing (CPT) rig has been
100% utilised since it arrived in the U.K.
Whenever CPT work is carried out on a site there are only 2 options for clients.
Option 1 for dry sites is the standard all wheel drive truck. Option 2 for sites which are too
soft or wet for the truck is a heavy tracked CPT rig, which is more expensive because it has to
be mobilised by a haulage contractor.
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So to provide CPT rigs at cost effective rates Fugro have invested in a heavy tracked CPT
rig (20 tonnes self weight) which can unload (and load) itself off (and onto) its own purpose
built carrier truck.. This means that this 'put down' crawler is fast and cost effective to
mobilise to site and is ideally suited to linear site investigations such as road schemes,
pipelines or large site developments. Thunderbird equipment is a reality!
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One of the sites the rig has been used on since arriving in the UK was for the A71 road
improvement scheme in Lanarkshire, Scotland. The heavy tracked rig was used because
despite the soft upper layer at the site the client needed to penetrate into the very dense
sands, to depths of 30m. To push to these depths thrusts of over 14 tonnes were made. The
underlying dense sands were variable and the CPT tests were used to determine this variability
along the site.
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There were a number of areas across fields to investigate which meant that the rig had to be
moved between sites. Usually a rig would depend upon an external haulage contractor to be
moved but with it's own carrier Fugro were able to efficiently move between the sites without
delay.
The "put down" crawler rig can be off loaded from the truck in less than five minutes which
is very fast and does not impact the time schedule for the site investigation works.
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Using Fugro's "put down" crawler saved nearly 20% on the cost of the site investigation compared
to using a normal crawler rig.
A total of 25 friction and piezo-friction cone penetration tests (PCPT) were performed to average
depths of 24 metres. Over 450m of CPT was completed in only 3 days.
Soil conditions were typically:-
- 0.5 to 1m thick top soil
- 7m to 30m thick very dense gravely SAND
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