If dense soils are anticipated, then pre-augering of the sheet pile line in advance of sheet pile installation, to reduce the in-situ ground density, can enable piles to be driven into ground conditions that might otherwise be deemed unsuitable.
Selective Sheet Piling (UK) LTd Telescopic Leader Rigs can be fitted with the MBDA 3000/MBDA 4200 auger motor. A 450mm/600mm diameter auger flight is attached to the auger motor and the ground is then augered through the dense soils. The auger flights are rotated into the ground in one direction and counter-rotated out of the ground leaving the soil in place without flighting the material. Only a small amount of spoil is generated to displace the volume of the auger flight itself.
Use of pre-augering reduces the in-situ density of the soils and prevents a large pressure bulb from forming during driving. The depth of pre-augering is dependent on both method of installation and ground conditions anticipated. Pre-augering can also help identify underground obstructions in advance of pile installation and the system minimises disturbance to the surrounding subsoil.