Abstract: The system of evaluation index, methods normalizing index values and assessment methods are the key problems on dam behavior evaluation. The information matter-element system was built to assess dam behavior. Based on the thought of multi-index fusion, fuzzy matter-element model evaluating dam behavior was constructed by matter-element transform. This model can process comprehensively geological data, results of numerical analysis, measurement data, experiential knowledge, and so on. Dam behavior can be described by the qualitative and quantitative manners. According to the development trend of quantitative results, dam behavior can be expressed dynamically with three dimensional pattern. The combined results of weights of matter-element characteristic and weights of characteristic value can be obtained by use of optimization algorithm. As an example, the proposed method was used to assess a concrete dam. The result shows that the global safety can be ranged between normal and basically normal. The numerical example shows that the proposed method is feasible and effective, and the evaluation results are reasonable.

Key words: dam behavior, evaluation model, weight, fuzzy extension theory