Determining Acceptance Criteria to Optimise the Foundation Design and Installation

In traditional pile design and installation processes, the design phase sets the parameters for installation. However, practical considerations take centre stage once the project is handed over to the contractor and piling contractor. Integrating those considerations during the design phase is essential to optimise pile foundations for cost reduction, carbon footprint, and raw material consumption. This integration can also include factors such as (preliminary) pile load results, which help determine shaft friction unit values and the contribution of the pile toe to the total resistance. The paper illustrates the necessary interaction between design and construction-related aspects in the installation of precast prestressed concrete piles on a job site in The Netherlands. The soil investigation resulted in all CPTs with refusal within less than 0.5m into the bearing stratum. Consequently, the designer and piling contractor anticipated hard driving and possible pile damage, but they also expected to achieve sufficient capacity at shallow penetration into the bearing stratum. By utilising the available methods for pile driving prediction (PDP), pile driving analysis (PDA) during installation of trial piles and signal matching to establish mobilised static pile capacity for single hammer blows, acceptance criteria for pile installation were established. This approach ensured that both the piling contractor's requirements (limiting driving stresses and installation times) and the designer's requirements (sufficient pile capacity) were effectively met.