Murphy International Limited (MIL) was employed by TLI Group, on behalf of ESB International, to construct 1200mm diameter bored piles. These were to support an electricity pylon and were designed by Byrne Looby Partners.
Murphy provided an innovative alternative piling solution, which reduced the programme and overall costs for the client. Instead of boring eight 300mm diameter piles under each leg (32 piles in total), Murphy proposed boring one 1200mm diameter pile instead (four piles in total).
The piles were expected to up to 18m in length, with casing all the way to the toe. The total weight of the casing was approx 18T so MIL decided to use its Bauer BG28 piling rig, which was well capable of installing the piles to these parameters.
Ground conditions were a soft overburden to 12.5m, sandy gravel to 14.0m and a shaley weathered rock to 18.2m.BLP designed the piles to go 3m into glacial till/weathered rock, in order to take the loads specified by the client. Lloyd Acoustics dynamically tested all of the piles and, using CAPWAP analysis, proved the piles able to take the loads with a factor of safety up to 4.0.