This project was completed on behalf of Cahalane Bros. Dunmanway, Main Contractors, during significant alteration and renovation works in a large manufacturing plant in West Cork.
8 nr DYWI® R38-500 hollow bar micropiles (SWL =150kN) were installed to support 2 nr new RC columns. Based on available ground investigation, the draft design required a 16m length micropile installed with a 115mm drill bit. Micropiles had to be installed as close as possible to existing columns to maximise space and therefore had to be installed though the existing RC pad.
Details on the existing foundation detail was limited. However, on drilling it was noted that it was 3.5m thick!!!!!!!!!! This is where the hollow bar or ‘drilled’ micropile outclasses other pile types such as small displacement piles or screwpiles. The system was able to penetrate the slab and still form a two metre rock socket over 14m in depth.
As ground conditions may vary no matter how much GI you are provided with, we kept in close communications with the designer to confirm the draft design. Bedrock was encountered earlier than expected so a two metre rock socket was required to satisfy the design.
In respect of the tight schedule, micropiles were designed so that subsequent testing was not required and works were completed during unsociable hours to ensure works were not delayed.