Abstract: A reasonable determination of deformation modulus and Poisson ratio of arch dam foundation rock is very necessary for arch-cantilever method in arch stress analysis. Dam foundation is composed of different lithology rock masses, which shows significant mechanical anisotropy, inhomogeneity and discontinuity. Any rock deformation parameter to replace the whole deformation parameters or a simple averaging of all deformation parameters is unreasonable. In the present paper we present a 3-D finite element method for predicting the synthetic deformation modulus and synthetic Poisson ratio of arch dam foundation based on the least squares method. By comparing with theoretical solution, we found this approach is feasible for predicting the synthetic deformation modulus and synthetic Poisson ratio of complex foundation composed of different lithology rock masses, faults and weak interlayers. As an application of this approach, the synthetic deformation modulus and synthetic Poisson ratio of Jinping arch dam foundation are calculated. Results demonstrate that the deformation modulus calculated by this method is reasonable on the premise of considering geological structures and foundation treatments.

Key words: synthetic deformation modulus, Poisson ratio, finite element method, least squares method, Jinping arch dam