A modified soil reaction model for laterally-loaded piles considering the effects of spudcan penetration

Large-diameter spudcan needs to be penetrated into seabed to provide bearing capacity for the jack-up rigs operating adjacent to existing jacket platforms. The platform piles are subjected to severe additional stresses induced by large volume of soil displaced during spudcan penetration, meanwhile the pile head is also subjected to horizontal loads transmitted from the platform. Therefore, it is necessary for the adjacent piles to evaluate the combined effect of spudcan penetration and pile head loads. The Coupled Eulerian-Lagrangian (CEL) method is adopted to investigate the effects of spudcan penetration on the soil reaction behavior of piles, and is firstly validated by available centrifuge model tests. Further, the p-y curves of the adjacent piles under three pile head loading conditions are analyzed, and the loading direction respect to spudcan penetration is observed to give different p-y responses. A modified soil reaction model is in turn proposed by modifying the API formula of ultimate lateral pressure to consider the effects of loading direction, as well as the overall softened soil reaction due to spudcan penetration. Finally, a pair of model tests are conducted to validate the proposed p-y curves of adjacent piles subjected to combined spudcan penetration and pile head loads.