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Seismic responses of the Zipingpu concrete face rockfill dam were analyzed using the finite element method. The dynamic behavior of rockfill materials was modeled with a viscoelastic model and an empirical permanent strain model. The relevant parameters were obtained either by back analysis using the field observations or by reference to parameters of similar rockfill materials. The acceleration responses of the dam, the distribution of earthquake-induced settlement, and the gap propagation under the concrete slabs caused by the settlement of the dam were analyzed and compared with site investigations or relevant studies. The mechanism of failure of horizontal construction joints was also analyzed based on numerical results and site observations. Numerical results show that the input accelerations were considerably amplified near the top of the dam, and the strong shaking resulted in considerable settlement of the rockfill materials, with a maximum value exceeding 90 cm at the crest. As a result of the settlement of rockfill materials, the third-stage concrete slabs were separated from the cushion layer. The rotation of the cantilever slabs about the contacting regions, under the combined action of gravity and seismic inertial forces, led to the failure of the construction joints and tensile cracks appeared above the construction joints. The effectiveness and limitations of the so-called equivalent linear method are also discussed.

The Zipingpu concrete-faced rockfill dam (CFRD) experienced strong ground motion from the 2008 Wenchuan earthquake. Separation between concrete face slabs and the cushion layer was observed after the earthquake. The separation voids under the stage III slabs make up 55% of the total area of the stage III slabs. The observed maximum height of the separation voids was nearly 23 cm at the top of the stage III slabs. Separation voids were also observed locally below the top of stage II slabs near the left abutment, with a maximum height of 7 cm. In this study, a static and dynamic elasto-plastic finite element analysis on Zipingpu CFRD was conducted to capture the separation during the Wenchuan earthquake. The rockfill materials were described using a state-dependent elasto-plastic model that considered particle breakage. The model parameters of rockfill materials were obtained from feedback analysis. The numerical results were largely consistent with the field measurements during construction and after the Wenchuan earthquake. A three-dimensional state-dependent elasto-plastic model that can trace the separation and re-contact of a soil-structure interface was employed to investigate the interaction between concrete face slabs and a cushion layer. The analysis showed the distribution of separation voids observed in the Zipingpu CFRD has a close relationship to the water level and slab dislocations at the time of the earthquake. The phenomenon of the separation from the Wenchuan earthquake was successfully captured by the proposed numerical procedure. [ABSTRACT FROM AUTHOR]