Water Jetting is primarily used to enable sheet piles to be pressed into difficult ground conditions which might otherwise be deemed unsuitable.
Water Jetting is effected by means of a High Strength Jetting Pipe (lance) attached to the inner face of the sheet pile.
The jet pressure is kept to the minimum required that allows the pile to continue to penetrate the ground and prevent the lance needle from becoming blocked during installation.
In ‘Coarse Granular’ soils, the main action of the water jet is to oscillate the particles reducing the resistance to pile penetration.
When sheet piles are installed into cohesive soils, the lubricating actions of the water reduces the amount of adhesion contributing to the pressing resistance whilst at the toe the water reduces the end resistance to ease the penetration of the piles.
The volume and pressure of water can be adjusted according to the ground conditions; thus, water is only applied where needed and large voids are not produced. Soils parameters quickly return to their normal state as is evidenced by the adequacy of the reaction force available for pressing the subsequent pile.
As an additional benefit, water jetting can significantly improve installation production as well as optimise the sheet pile section required.