We have been busy installing over 620 linear metres of sheet piling to retain Network Rail’s Chiltern Line in West Ruislip to facilitate the construction of HS2 (High Speed Two) Ltd where new high speed rail lines exit the London Tunnels section. These works were completed using vibration free HydroPress and low vibration techniques for Skanska Costain STRABAG Joint Venture into stiff London Clays.
On one particular section the site team had found historic embankment stabilisation works where 1.0m diameter limestone boulders were installed over a 3m depth. Our works required the installation of sheet piles through these boulders, as removal by excavation was not permitted. To do this we engaged a Delmag RH34, utilising rotary techniques, to remove the boulders and then backfilled and compacted with piling friendly material in advance of sheet pile installation. Rotary bore positions were controlled by an innovative reusable guide wall facilitating 880mm diameter bores at 650mm centres ensuring a clear line for sheet piling.