Numerical investigation of spudcan penetration in sand with interbedded clay

Jack-up units are extensively utilized in offshore geotechnical investigations and the recent installation of wind turbine foundations. Engineers require accurate predictions of spudcan penetration resistance to assess its final penetration depth and identify potential risks, e.g., punch-through, ensuring safety during the installation of jack-up units. Notably, for seabed stratigraphy comprising sand with interbedded clay layers, a significant discrepancy exists between the penetration resistance calculated using current industry guidelines and actual measured results. In this study, three-dimensional (3D) large deformation finite-element (LDFE) analyses were performed to model the spudcan penetration response in a seabed consisting of a sand-clay-sand soil profile. A comprehensive parametric study was conducted to examine the influence of soil strength and layer thickness on penetration resistance. The variations of the soil failure mechanisms are demonstrated and associated with the varying penetration resistance, which form the basis of the new calculation method developed for the sand seabed with interbedded clay.