Abstract: The foundations of infrastructure such as rail transit and roads are typically subjected to cyclic loads from traffic, mechanical vibrations, and other sources. The long-term effects of these cyclic loads on foundation settlement cannot be overlooked. A series of undrained cyclic triaxial tests were performed on soft clay in the Shanghai Yangshan Port area to investigate the long-term settlement of a road subjected to traffic load in Shanghai Yangshan port area. The experimental results indicated that the cumulative deformation increases with the number of cycles. The stable value depended not only on the applied cyclic stress and confined stresses, but also on the void ratio of the soil. Based on the experimental results, an explicit model was proposed to calculate the axial plastic cumulative strain of saturated clay subjected to cyclic loading. Furthermore, the relationship between factors such as void ratio, the applied cyclic stress, confined stresses, and model parameters was further analyzed. The results indicated that the model had a good fitting performance and can effectively predict the undrained cyclic cumulative deformation of soft clay.