Effects of lattice legs and sleeves on spudcan penetration performance

Abstract

Offshore industry professionals frequently face challenges when predicting spudcan foundation bearing capacity of jack-up rigs with deep leg penetration in both normally consolidated and over-consolidated clays.

In the present study, centrifuge modeling technique was adopted to simulate a simplified operation of an individual spudcan with and without lattice legs in both normally consolidated and over-consolidated clays. With an intensively instrumented centrifuge setup, the experiments were performed to quantify the bearing responses and penetration with special attention paid to the influence of lattice legs or truss-work.

The experimental results presented that the sleeve resistance of the lattice legs and spudcan end bearing capacity constitute to the ultimate bearing responses. The sleeve resistance component was substantially influenced by the opening ratio of the lattice legs of jack-up rigs which is also directly associated with the spudcan end bearing capacity coefficient. From the centrifuge tests, it was observed that the some similarities between bearing capacity spudcan with lattice legs and pile bearing capacity. It was also established that the spudcan with lattice legs would perform better than those without sleeve as the bearing capacity coefficients decreased with the increase in opening ratio for both normally consolidated and over-consolidated clays. Under the high g environment in the centrifuge laboratory, the proposed method was proven capable of estimating the bearing capacity of spudcan with lattice legs as well as the penetration depth.