Abstract：The evaluation of liquefaction hazard and the seismic design for the pile foundation built in the liquefiable soil is potentially significant. The problem of soil-pile interaction in liquefiable soils is a nonlinear and complicated problem. Now the dynamic centrifuge test is widely used to study the seismic performance of pile foundation. Four cases of 50 g dynamic geotechnical centrifuge model test，dry sine input-wave model 1，saturation sine input-wave model 2，saturation model 3 of level 1 scenario input-wave，and saturation model 4 of level 2 scenario input-wave，are conducted to study the seismic response characteristics such as acceleration，displacement，pore water pressure of pile foundation，and mechanism of soil-pile interaction. A rectangular rigid container with internal dimensions of 150 mm×450 mm×300 mm (W×L×H) was used in the centrifuge tests. The soil profile is comprised of one horizontal layer silica sand of about 10 m thick resting on stiff bedrock at prototype scale. The saturation soil profile is made by de-aired dry sand saturated by de-aired motolose solution of 50 times the viscosity of water that the deposit has the prototype permeability of sand. The model pile foundation consists of structure supported by a 2×2，10 times diameter spacing pile group. Moreover，the results from centrifuge modeling are compared. It is found that displacements of saturation models are larger than those of dry models. Compared with dry model 1，the acceleration value of saturation model 2 descended quickly during shaking. This is may be induced by liquefaction. Sand liquefis at two depths of 2.5 m，5.0 m in prototype scale of model 4 does not liquefy，and the excess pore water pressure dissipated slowly after shaking in model 3. The failure degree，state and mechanism of the site pile foundation in liquefiable soil subjected to the strong motion have been discussed and a good result is achieved. These results are consistent with the one obtained from numerical simulations. This study provides a reliable foundation for the seismic design of the oversize pile foundation.
