Numerical simulation of the separation between concrete face slabs and cushion layer of Zipingpu dam during the Wenchuan earthquake

Abstract

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.