Full-scale load testing on long prefabricated concrete piles in the Port of Rotterdam

In 2017 the Dutch national standardization institute (NEN) released a new version of the National Annex to NEN-EN 1997-1 Eurocode 7, including revised reduced pile base factors. This has a significant impact on the dimensions of pile foundations. Consequently, in situ load tests were considered in the Port of Rotterdam. In this study, full-scale static load tests (SLT) were conducted on four prefabricated concrete piles (36 m long), in order to optimize the design of a new quay wall. The test piles were instrumented with several types of optical fibers along the length, enabling detailed registration of shaft friction and base resistance. Since the optical fibers were already installed at casting, unique insights have been acquired regarding the residual stresses in the piles after hardening. These stresses are commonly not taken into consideration, resulting in underestimation of base capacity in favor of shaft. Since the test piles were loaded after different time periods, the effect of aging was additionally investigated in this study. After the completion of the SLT’s, fully instrumented rapid load tests (RLT) were conducted on the same four piles. Subsequently, this provided the opportunity to compare and correlate the results of SLT and RLT for different soil types. This paper presents the results, conclusions and recommendations that follow from these tests. The results of this study have been used to optimize the design of the quay wall by reducing the number of piles by approximately 25% and hence, the overall construction costs by 5%.