Abstract: Based on the settlement monitoring data of two piled rafts under a twin-tower building,the settlement characteristics of piled raft foundation is examined. It is shown that the piled raft settles as a whole underloading, while the settlement of piles under individual plate, which is located outside the tower areas, is sensitive to changing of the adjacent loading and ground water level. By comparing the measurement with the calculated settlement, it is found that the measured settlements are much greater than the calculated values. Then, two influential factors are proposed, bottom sediment in pile and negative skin friction on pile, to revise the settlement calculation equation for piled raft foundation penetrating thick soft soil layers. Finally, the proposed method and the suggested parameters are checked through two real cases.