Abstract: The main purpose of this paper is to trace a wharf barn built on frictional pile foundation with pile length of 45m and SPT N value of the subsoil ranged from 15 to 25. This structure was seriously damaged due to differential settlement,and a new barn was built at 3m away from the old one. After 3 years, it is found that the cracks of the old one spread increasingly.The preconsolidation stress of each soil layer can only be obtained from the conventional compression test,and the exact amount of settlement is not easy to be calculated.In this study, the methods to judge OCR value of each soil layer from SPT N value and to recover the preconsolidation stress are proposed. Then,the deformation of each soil layer and hence the settlement of the structure could be exactly calculated.