Numerical analysis of passive pile groups in offshore soft deposits

The performance of pile foundations in offshore soft deposits is frequently dominated by passive loading from approach embankments for reclaimed land in Korea. This is mainly because of a Korean offshore soil profile, involving an over 30 m normally consolidated soil, with a strength that varies linearly with depth. This paper presents the results of an investigation on short- and long-term passive loading on the piles using two dimensional elastoplastic-consolidation coupled FEM analyses with large strain mode. This numerical scheme is essentially based on an updated Lagrangian formulation, which is favorably validated in cases of both centrifuge tests and field measurements. Although a parametric study is limited by some of the application, it is shown that passive pile loading is primarily affected by soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. Simultaneously, time-dependent effect of shear transfer at the pile head is explicitly identified and a useful starting point in design is recommended for passive pile loading in construction (short-term) and consolidation (long-term) phases.