The Collis screw pile system is a foundation based on helical piling where a designated number of piles are ‘screwed’ in to the ground to a designed depth and torque.
The piles are then connected via a transfer plate allowing the structure to be installed.
The screw piling system cuts a clean path through the ground to minimise any disturbance or heave, meaning that the in-situ properties of the ground remain largely unchanged.
The system offers significant benefits for installation, mainly cutting the number of site visits and allowing the sub and superstructure to be erected in a single possession whilst utilising the same on-track plant.
Mini Piles – Hand Driven
The mini piling solution is a similar process to the Volute pile system, with the main difference being the diameter of the pile and installation method.
The mini piling method allows the work to be undertaken without on track plant. If the site is remote, the equipment and segmental pile sections can be manually handled onto a trolley and pushed to site. Once at site, trial holes will be dug and the first section of pile placed into the excavation. The rig will then be manually lifted onto the top of the pile and secured. 2 operatives will hold the rig stable as piling commences.
A leaver arm will be attached to the rig and be secured behind something solid, such as the rail, the ballast shoulder or another suitable structure to resist the body of the rig from rotating once driving commences.
Additional pile segments will be added until the required depth is achieved.
Usually for a standard signal post a group of 4 piles is used with a steel grillage to span the piles and provide a mounting plate for the post.