▶Background of the study

 The interactivity between the mobile jack-up rig’s spudcan footing and the piled foundation supporting the adjacent jacket platform is referred to as “spudcan-pile interaction”. Large soil movements arising from the installation of jack-up spudcan foundations may induce detrimental effects on piles supporting adjacent permanent jacket platforms. Particularly, in dense sand-over-clay profile, the risk of spudcan rapid penetration due to underlying clay bearing capacity failure known as the spudcan punch-through failure which can cause further damage to the piles in proximity.

▶Objectives

 This study investigates the foundation interaction between the spudcan and adjacent pile in sand overlying clay soil profile via centrifuge modeling. Issues investigated include thickness of upper sand layer with incidence of sand plug beneath the spudcan and spudcan-pile clearance.

▶Research development & Key findings

 Spudcan-pile interaction is predominantly influenced by the soil movement patterns within the spudcan proximity. The experimental results reveal that spudcan punch-through hazard and the magnitude of induced pile moments amplifies primarily due to the increase in the thickness of the upper sand. In addition, the magnitude of induced pile moment in sand-over-clay profile is significantly higher than that of single clay profile because of the post-peak bearing behavior observed in stratified soil yielding to greater risk of pile integrity. Two generalized induced soil pressure profiles are deduced with the first profile representing the onset of spudcan punch-through and the second profile denoting the situation of post punch-through failure including the infilling soil backflow on top of the spudcan and the formation of sand plug beneath the spudcan. These soil failure modes are key elements in assessing pile performance nearby.