TUBULAR STEEL PILE (low vibration level)
The tubular steel pile is the type of pile most often used when the working space is confined. The pile is built up of tubular steel sections welded together in situ. There is a gravel plug in the first tubular section. A drop hammer falls on to this gravel plug. The tube itself forms a leader for the hammer. When the tube is at the right depth, it is cut off at the correct height and filled with concrete and a reinforcing cage is fitted over the top few metres. It is possible to provide the pile with an enlarged base plate or an enlarged base made of reinforced concrete or to make an enlarged base after driving in the pile.

The tubular steel pile is extremely suitable for working inside existing buildings, or in small access openings. Depending on the type of work to be carried out, the dimensions of the pile and the soil conditions, it is possible to use very small dismountable machines on wheels (see photograph below) which can go through very narrow openings up to heavy machines mounted on crawler tracks (see photograph above).

Click to zoom
Since the mass of a tubular steel pile is much less than that of a concrete pile of the same size, a fairly light drop hammer is sufficient. As a result the vibration level in tubular steel piles is in proportion lower. Click to zoom


APPLICATIONS OF TUBULAR STEEL PILES:
  • when the working height is limited, e.g. in existing buildings, under viaducts, or in factory buildings under pipework, etc.;
  • in places which are difficult to reach, e.g. inside houses, in back gardens, or between factory systems and pipework, etc.;
  • where heavy pile-driving is not permitted;
  • where work has to be carried out at low vibration levels;
  • as a casing tube for hydraulic lifts.



TECHNICAL INFORMATION ON TUBULAR STEEL PILES:

  • Diameter of tubular steel sections: 114 mm, 133 mm, 168 mm, 219 mm, 273 mm, 324 mm, 355 mm, 406 mm, 457 mm, 508 mm, larger sizes are available on request;
  • Diameter of base plate (type b, see drawing below): usually no more than 1.4 x the diameter of the tube (preferred diameters are: 125 mm, 150 mm, 185 mm, 210 mm, 235 mm, 250 mm, 290 mm, 310 mm, 340 mm, 360 mm, 380 mm, 420 mm, 450 mm, 480 mm); type b is seldom used. Diameter of enlarged base (types c and d, see the drawings below): usually no more than 1.7 x the diameter of the tube (the following diameters of the base are preferred to be used for type c: see the above-mentioned series of diameters for tubular steel sections);
  • Length of pile: depending on the depth of the bearing stratum but in principle unrestricted;
  • Grade of concrete: C20/25 or C25/30;
  • Reinforcement: at least the upper 2 m; Tension piles: usually reinforced down to the base;
  • Maximum bearing capacity up to 2000 kN, depending on type of soil;
  • Maximum rake 2:1;
  • Length of tubular sections: adjusted to the working conditions;
  • Weight of drop hammer: 150 kg to 3000 kg, depending on the dimensions of the pile and type of soil;
  • If there is a danger of explosion, the pile sections can be connected together by means of a screw joint instead of electric welding;
  • Minimum working height: from 1.5 m, depending on the materials, the dimensions of the pile and type of soil;
  • Minimum distance from centre of pile to a wall: from half of the pile diameter + 50 mm, depending on the dimensions of pile and the pile-driving rig required;
  • Minimum access width: from 0.6 m, depending on the dimensions of the pile and the pile-driving rig required;
  • Monitoring and testing: recording the set of the pile per number of blows; visual inspection of the inside of the steel tube.

Subject to alteration

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