On many occasions, projects have to be conducted in areas in which dense soils predominate, which makes pre-augering of the sheet pile line, in advance of sheet pile installation, advisable. This can help reduce the density of the ground and can enable piles to be driven into ground conditions that might otherwise be deemed unsuitable.
Some of Sheet Piling (UK) Ltd’s telescopic leader rigs can be fitted with the MBDA 3000/MBDA 4200 auger motor. When used in this way, 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 then 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.
By incorporating pre-augering into the project, a contractor can not only reduce the in-situ density of the soils but also prevent a large pressure bulb from forming during driving. The depth of pre-augering is dependent on both the method of installation and the anticipated ground conditions. Pre-augering can also help identify underground obstructions in advance of pile installation and the system minimises disturbance to the surrounding subsoil.