Abstract: A cloud model for safety evaluation of concrete dam performance based on unit constraint combinatorial weighting is proposed in this paper to tackle the uncertainties of ladder-level index weight, the reasonable weighting of subjective and objective combinatorial weights, and the fuzziness of membership interval in the evaluation. First of all, the system of evaluation indicators is built, and the weights of such indicators are given by optimum weighting under unit constraint condition combining G1 method for subjective weights and entropy method for objective weights. Furthermore, the concept of cloud model was introduced to quantify the randomness of the evaluation indicators and the fuzziness of the membership intervals. The model is applied to evaluate the safety of a practical concrete dam, and the evaluation result is consistent with the actual situation of the dam and the results evaluated by other models, which verifies the effectiveness and feasibility of the model.

Key words: concrete dam, safety evaluation, uncertainty, combinatorial weighting, unit constraint, cloud model