Improving the Capacity Predictions of Drilled Displacement Piles Through the Use of Pile Installation Data

The future of performance-based foundation engineering includes combined empirical-analytical frameworks supported and improved using Measurement While Drilling (MWD) data to optimize design resiliency and construction efficiency of pile foundations. The most common uses of MWD data include site characterization, assessment of soil profile variability, design of drilled shafts (with real-time data aiding contractors in specifying the pile toe location), and quality control of piles. During the construction of Drilled Displacement Piles (DDPs) key measurements pertinent to pile quality and ground improvement include penetration rate (PR), rotational speed, downward trust, and torque. This paper offers insights gathered from more than a dozen cross-continental construction projects in Europe and the U.S. in which DDPs were installed using a rig with a traditional enlarged displacement body in a variety of soil profiles. DDP properties, such as pile diameter (D) and pile length (L), pile-installation torque (e.g., PKDK), and the penetration rate PR at different depths, are used along with CPT test data to evaluate load test results in comparison with traditional CPT-based methods.By integrating CPT data with DDP pile installation parameters, the paper demonstrates a way of enhancing the reliability of capacity predictions and maximizing the benefit gained from on-site monitoring data. The addition of the drilling parameters led to the development of adjustment factors to be applied to the analytical methods to better predict the piles capacity based on the installation procedure. The comparison of the piles performance within these projects, executed using American and European standards techniques offers additional insight into the different construction practices.