Abstract: The safety evaluation of high earth core rockfill dam through deformation and seepage measurement and analysis is one of most important problem in nowdays soil mechanics at present. Due to the influences of construction method, construction quality and management during and after construction, the real parameters of the dam become quite different from the original designing parameters. So it is of great significance to get real parameters and real running state of the dam based on back analysis in order to evaluate the dam stability exactly and comprehensively. To get the real mechanics parameters of the dam soils, the investigation on stress, deformation and seepage behavior by the in-situ measurement in Heihe clay core rockfill dam in Xi ’an are executed based on analysis of the time property and space property. Then the relationship between the deformation and load is built; and a back analysis method for the soil parameters during construction and operation based on the theory of nearly saturated soils using the 3-D finite element simulation is suggested, from which the DUCAN parameters, seepage coefficients and wetting parameters of the core clay of the dam can be determined directly and realistically. And the method proposed is useful for design and back analysis of these type projects.

Key words: clay core rockfill dam, observed data, back analysis, wetting