If you encounter a need to press sheet piles into difficult ground conditions, which may seem unsuitable for such an operation, you may need to consider water jetting.
Water Jetting is a process that sees a high-strength jetting pipe (lance) attached to the inner face of the sheet pile. The pressure of the jet of water that is then used to help insert the pile into the ground, is kept to the minimum required for ground penetration. This helps preven the lance needle from becoming blocked during installation, whilst allowing the sheet piling process to still be effective.
When a site is home to coarse granular soils, the main function of the water jet is to oscillate the particles below, so as to reduce the ground’s resistance to pile penetration.
When sheet piles are being installed into cohesive soils, the lubricating action of the water reduces the amount of adhesion that contributes to the pressing resistance. At the same time, at the toe end, the water reduces resistance, making it easier for the piles to penetrate the ground.
When using water-jetting in sheet piling, the volume and pressure of water can be adjusted according to the ground conditions in different parts of the site covered by a project. This ensures that water is only applied where needed and there is no waste of water. Soils parameters quickly return to their normal state post-piling and this can be proven during pile-driving, by checking on the reaction force available for pressing the subsequent pile.
As an additional benefit, water jetting can significantly improve the installation process, as well as optimising the sheet pile sections required for the job.