Response of Clay-Pile System under Earthquake Loading

The response of pile foundations during past earthquakes have shown that piles in firm soils generally perform well, while the performance of piles in soft or liquefied ground can raise some questions. Pile foundations are very frequently used in soft clay to achieve the required bearing in stiff stratum. This paper presents the results of dynamic centrifuge model tests carried out at the National University of Singapore to physically model dynamic soil-pile response in soft clay. The experimental results strongly suggest that there are significant effects arising from stiffness degradation due to imposed inertial loading of surrounding soil on piles with repetitive shaking during earthquake, and corresponding changes in time period and amplification of ground motion. The study also examined the influence of different relative stiffness of the clay-pile system, and different superstructural inertial loads. The centrifuge tests were back-analyzed via 3-D finite element modeling using the general purpose code ABAQUS. The analyses show that the use of simple non-linear hypoelastic soil models can provide reasonable agreement with the experimental observations.