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Some very heavy structures (high rise towers, industrial buildings) need foundation piles which can each bear a load of several thousand tonnes. The solution lies in increasing the cross sectional area of the foundation, using multiform piles or circular piles up to 3 metres in diameter. If the ground does not display sufficient strength, the piles may be belled out (under-reamed) at the bottom.
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The Continuous Flight Auger (CFA) system is well known as a rapid and cost effective open site method of constructing load bearing and retaining structure piles where the appropriate ground conditions exist. This makes it suited to many construction projects and particularly for sensitive sites, where it provides a quiet and vibration free piling technique.
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Drilled piles, temporarily tubed
The drilling of this type of pile is carried out with l%u2019abri d%u2019un provisional casing so d%u2019éviter any landslide in the future deep foundation. The tools for drilling are adapted to each type of ground/rock so d%u2019optimizer the realization of the pile. Once the finished pile, its liaisonnement with the superstructure is facilitated by the precision of its establishment and the presence d%u2019une cage d%u2019armature installation at the desired and perfectly centered dimension.
The advantages of this type of pile are:
%u2022 drilling in n%u2019importe which type of ground
%u2022 obtaining the cut of ground with l%u2019endroit of the pile
%u2022 compressing quasi no one
%u2022 precise establishment
%u2022 cage d%u2019armature installation at the dimension desired and perfectly coated in the concrete
%u2022 quality of l%u2019élément finished
%u2022 possibility of checking d%u2019exécution quality of the pile a posteriori (sonic control, coring...)
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Definition:
pile drilled under provisional lining and water overpressure (if necessary), concreted with a plunger tube in order to avoid the segregation of the concrete
Properties:
standard diameter of the drilled piles: 600mm, 750mm, 900mm, 1070mm, 1280mm or 1500mm
possible not-concreted length
bearing capacity until 12500kN
possibility of injected the barrel and the point
drainage of grounds necessary
without vibrations
Scope of application:
vertical, horizontal high loads and/or in inflection
sat or embedding in hard or rock ground
in the event of obstacles in basement (old foundations, concrete) limiting other techniques
level of sitted very deep (until >50m).
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