Abstract: Compatible deformation between a dam body and its bank slopes is a crucial engineering issue of clay core dams, and the bank slope ratio is a major influencing factor of the deformation compatibility. To optimize the design of this factor, this paper examines the influence of different bank slope ratios on the compatible deformation, using finite element calculations in a case study of the Qianping clay core dam. We conclude that, (1) three indexes are crucial to analysis of the deformation, namely, compatible deformation evaluation indexes for a dam body and its bank slopes－a deformation index for the maximum settlement and deformation gradient of the dam body, a stress index for the degree of stress deterioration under the arch effect on dam stress, and a strength index for the stress level of the dam body; (2) If the stability and reliability index of bank slopes is used as a safety control index and the earthwork volume of slope cutting as an economic control index, we can determine separately the upper and lower limits of the bank slope ratio, which give an optimization interval for multi-objective optimization analysis; (3) In addition to the three indexes above, a safety control index is added to the evaluation system, so that we can realize a multi-objective optimization design of bank slope ratios, through combing the weights of the functions for all the indexes and minimizing the objective function. In the Qianping dam case, optimization based on the compatible deformation control gives an optimal slope ratio (slope angle) of 58o. This result meets all the three requirements of safety, economic efficiency, and dam-bank slope compatible deformation, thus indicating our bank slope ratio optimization method is effective and practical for dam design.

Key words: clay core dam, compatible deformation, bank slope ratio, optimization method, multi-objective