Based on the Duncan E-? constitutive model used for analyzing soil-rock dams

3 parameters creep model used for studying creep deformation of soil-rock dams is developed and programmed. According to the measured deformation data of Three Gorges Project’s 2nd phase cofferdam of early operation period

calculation parameters used for creep analysis are inverse-analyzed using artificial neural networks. The calculated results indicate that the vertical deformation rule of cofferdam versus time and horizontal deformation rule of cofferdam versus time is different from each other. It is also indicated that the stable time needed for vertical creep displacement is about 6 months after the cofferdam is constructed and the stable time needed for horizontal creep displacement is only 3 months. It also shows that the average creep displacement value of the cofferdam structure is 2-3 times of the initial displacement.