Method Evaluating Axial Response of Vertically-Loaded Piles During Spudcan Penetration

Large soil deformation can be induced during spudcan penetration into stratum near an existing piled foundation of a fixed offshore platform, and some research has been done on the effects of spudcan penetration on the lateral response of an adjacent pile. However, available centrifuge model tests found that the maximum vertical soil displacements are manifested in the same magnitude compared with those in the lateral direction, leading to large negative friction along the pile shaft. Also, the combined loading effects of transmitted loads from the upper structure should be taken into account in axial analysis during spudcan penetration, which has been proved important in prediction of axial pile response due to soil movement. This paper investigates a method to quantitatively evaluate the effect of spudcan penetration on vertical response of an adjacent pile. The vertical soil displacement is found by first simulating a free field spudcan penetration by Coupled Eulerian-Lagrange (CEL) method. The flow field is then analyzed to calculate the displacement components at specific pile location. Then the predicted vertical soil displacement profile is input into the nonlinear foundation pile model to determine the axial response of an adjacent pile subjected to spudcan penetration-induced axial and pile head loads. The proposed method is adopted to analyze centrifuge model tests in sand and clay, and predicted results prove to be basically in agreement with measured ones.