JACK-UP INSTALLATION ON AN UNEVEN SEABED: RECOMMENDATIONS FROM MODEL TESTING IN OVERCONSOLIDATED CLAY

This paper presents results of a laboratory testing program employing a reduced-scaled model of a three-legged jack-up to investigate the influence of an adjacent footprint on spudcan installation. This study focused on the installation of the full jack-up with a single leg located adjacent to a surface discontinuity. This contrasts previous studies that focused on the behavior of a single leg model and aims to account for the coupled interaction of the three legs and hull. The investigation was conducted using a 1:200 model scale jack-up designed to represent an average commonly used field jack-up. It was fully instrumented for leg bending and axial force measurement, and allowed unconstrained horizontal motion and rotation in the plane of foundation-footprint offset. Installation was performed at foundation-footprint centerline offsets of 0.75, 0.89, and 1.0 times the footprint diameter in overconsolidated kaolin clay adjacent to three different footprint types. The three footprint types - spudcan generated, a similarly shaped vertical walled auger generated, and shallow slope - were used to analyze separately the effect of shape and soil disturbance.