To analyse the settlement characteristics of pile-plank structure in soft soil subgrade

the centrifugal model test is used to imitate the pile-plank subgrade with different preloading times about six moth and twen-four month. It is shows that the settlements of pile-plank subgrade mainly happen during construction in which the proportion of settlement will exceed 80% when the preloading time is more than 6 months. Whether the settlement of pile-plank subgrade will rebound or not during unloading time is related to the soil properties and preloading time. Overload preloading can significantly reduce post-construction settlement which can be reduced 70% for twen-four month to 6 nonth of preloading time. During construction of pile-plank structure subgrade

pile foundation exists negative friction and neutral position change is a dynamic process

ratio pile length between 0.47~0.7.