Abstract: Jack-up rigs are commonly employed for offshore drilling and platform work-overs in various oil and gas fields, and are always operated in close proximity to permanent platforms. The penetration of a spudcan will induce additional lateral loading on the adjacent platform piles due to large soil deformation. However, the effect of spudcan penetration is not considered in the current pile foundation design and becomes a potential safety hazard for permanent platforms. To address this problem, the centrifugal model tests are conducted to investigate the penetration effect on the lateral behaviors of the adjacent piles embedded in clay. Based on the cavity expansion theory and the nonlinear beam model, a two-stage analytical method is established. Based on the three-dimensional CEL models, a large deformation finite element method is established. The two methods are used for evaluating the additional bending moments and deflections of the adjacent piles induced by the spudcan penetration. The bending moments and deflections of the piles predicted by the two methods agree well with the centrifugal test results, which proves the reasonability of the two methods. The additional stresses of the adjacent piles due to the penetration can be up to 51 MPa, indicating the effect of spudcan penetration on adjacent piles cannot be ignored. Finally, some suggestions for the above two methods are provided for practical projects.