Installation and aging effects on the capacity of small displacement piles

Abstract

Pile setup is not fully understood, despite its high potential for cost saving and risk mitigation in onshore and offshore constructions. Studies indicate that the pile installation process has important influence on initial pile capacity and the subsequent setup. However, only few studies considered a wide range of installation methods (e.g., jacking, vibratory pile driving) when quantifying both initial capacity and setup characteristics. This study presents data of 88 static tension load tests conducted on 44 small piles at 1, 2, 10, and 100 days after their installation by four different methods. Piles made from mild and stainless steel exhibit strongly divergent setup characteristics, being a result of their different resistance to corrosion. Additional factors governing setup are the number of shear cycles induced during pile installation and the elapsed time after end of driving. We suggest a new approach considering the setup as a multidimensional effect, enabling the prediction of the initial capacity of a pile and its temporal development for the tested boundary conditions. This study provides a significant contribution to the understanding of the mechanisms governing setup by combining existing conceptual models, as friction fatigue and stress re-equilibration, together with corrosion under a time perspective.