Interpreting Load-Settlement Curves of Pile Foundations by Graphical Methods

In Geotechnical Engineering, deep foundation systems, especially pile foundations, are typically used when shallow foundations are inadequate due to design criteria in terms of bearing capacity, settlement, liquefaction and stability. The load settlement behavior of the pile foundations can be determined realistically by full-scale loading tests conducted on the piles after the pile construction. In this study, it was tried to determine the ultimate bearing capacity of the diriven and bored piles manufactured in different soil conditions using the load-settlement data. For this, 9 different graphical methods such as Tangent, Fuller-Hoy, Butler-Hoy, De Beer-Wallays, Chin Kondner, Decourt, Brinch Hansen 80%, Mazurkiewicz and the Corps of Engineers have been used. Among these methods, there are considerable differences between the predicted ultimate bearing capacities of the piles which decreases to 35% for the piles loaded up/over to the collapse load, and increases up to 120% for the piles loaded below the failure load. In generally, methods of Brinch Hansen, Mazurkiewicz, Chin Kondner and Decourt predict the pile capacity greater than maximum test load and the other ones predict smaller than it. The closest average collapse load was obtained from methods of Corps of Engineering and Butller-Hoy.