NZ Geotechnical Society (NZGS) 22nd Symposium 2025 Auckland
This paper examines the collaboration between the design team and Early Contractor Involvement (ECI) piling contractor in developing a foundation solution which not only proved cost-effective but also significantly reduced embodied carbon by 3,300 tCOâ‚‚e compared to the alternative foundation options. The ground conditions at the project site presented a number of challenges for pile design and construction. Bottom driven steel tubes (BDSTs) were identified early in the project as a potential optimal solution with the advantage of a low carbon-footprint, but with several challenges around constructability and environmental noise and vibration effects. A pile trial during the ECI phase was used to validate the solution and investigate risks. The trial provided site-specific information on constructability, pile capacity, and noise and vibration effects. The use of BDSTs achieved carbon and cost savings which would not have been achieved without the validation provided by the trial. Data obtained from the trial also enabled design optimisation which resulted in further carbon and cost savings. With proper management of vibration and noise during construction, these piles offered the most cost-effective solution for the client, delivered optimal structural performance for the designers, and minimised environmental impact.
