Study on jackup spudcan punch-through

Abstract

Owing to peculiar subsurface seabed condition of stiff soil overlying soft soil, the possibility of punch-through of jackup spudcan during installation in Southeast Asia is reported to be higher than that in other parts of the world. In general, the spudcan will punch through if the underlying soft soil is unable to resist the relatively large load required to install the spudcan through the upper stiff soil. Centrifuge model tests have been carried out at the National University of Singapore to investigate the spudcan punch-through phenomenon. The measured spudcan bearing resistance profiles for cases with various thicknesses of overlying stiff soil highlight the significance of this thickness parameter to the bearing resistance provided by the layered soil system. Traditionally, SNAME recommends the use of Hanna & Meyerhof's method of bearing capacity of shallow foundation in layered soils and the projected area method to evaluate the spudcan installation resistance. The centrifuge test results reveal that the above traditional theories are unable to determine the spudcan resistance accurately and hence fail to predict the punch-through phenomenon in most cases. This paper presents the centrifuge test results, the comparison of the test results with theoretical predictions and the recommendations arising from the comparison. © 2007 Taylor & Francis Group.