Influence of Spudcan Penetration on Adjacent Skirted Foundation in Uniform Clay

Abstract

Spudcans are commonly installed to support jack-up vessels in construction process of offshore wind turbines (OWTs), which may induce significant soil deformation that may impact existing foundations of established OWTs. Large-deformation finite-element (LDFE) analyses were performed to investigate movements of an adjacent skirted foundation induced by spudcan penetration. A LDFE model was generated and compared with a centrifuge test and good agreement was achieved. A detailed parametric study was then undertaken to examine the influence of spudcan penetration depths, spudcan–skirt clearance, soil shear strength, and foundation skirt length ratios. The outcome of this study leads to a conclusion that the behavior of the impacted skirt is closely related to soil flow mechanisms around the skirted foundation induced by spudcan penetration. The clearance distance between the spudcan and the skirt is the key factor. Significant skirt rotation occurs when the spudcan is less than one diameter distance from the skirt, especially for a short skirt installed in stiff clay. The soil flow mechanisms around the spudcan and skirted foundation are presented and approximating expressions for estimating the maximum rotation of skirt during spudcan penetration are proposed based on intensive numerical modeling results.