Abstract: Based on the original monitoring data of Nanoujiang VII grade CFRD, a joint inversion method of transient-rheological parameters for rockfill dam based on the incremental analysis was proposed. The parameters of the incremental rheological model and E-B model of rockfill were inversed using the immune genetic algorithm. The reliability of the measurement results and the accuracy of the inversion analysis of hydraulic overflow settlement gauge were studied. The results show that: (1) The laboratory test parameters of the rockfill materials obtained according to the current norms are much higher than the parameters of the practical field filling body, and the calculated settlement is 28% less than the measured value of the dam. (2) Due to the fact that the embedding time lags behind the actual filling process of the dam and the existence of the soil arching effect, the measured settlement from the hydraulic overflow settlement gauge is 45% less than the actual settlement of the dam. The measured deformation cannot be directly used for the inversion analysis. (3) According to the embedded condition of the field monitoring instruments, the function relation between the leakage measurement and the ratio of inside soil pressure to outside soil pressure of the trench is established, which can be used to correct the measured value of the hydraulic overflow settlement gauge. (4) The incremental inversion method in different periods can avoid the miss and less measurement value in the measurement process of the hydraulic overflow settlement gauge. The calculated value is in good agreement with the actual deformation, and therefore it is more suitable for the back analysis of mechanical parameters of earth-rockfill dams.

Key words: rockfill dam, deformation monitoring, creep, finite element, back analysis, soil arching effect