Abstract: Based on the physics of large post-liquefaction deformation of sand, a three-dimensional unified plastic model for the large post-liquefaction deformation of sand is developed. The constitutive model is able to achieve unified description of the behaviour of sand at different states under monotonic and cyclic loadings during both pre- and post-liquefaction regimes. Using the model, a three-dimensional dynamic finite element analysis method for piles in liquefiable ground is established. In the finite element analysis, the soil is modelled through u-p form coupled brick elementss and the pile through brick elements. Centrifuge shaking table tests on a single pile in level liquefiable and lateral spreading grounds are simulated using the proposed finite element analysis method. The results exhibits the effectiveness of the proposed constitutive model and simulation methods in reproducing the dynamic response of both the ground and piles.