Three-dimensional simulation of the construction process of the Zipingpu concrete face rockfill dam based on a generalized plasticity model

摘要

Concrete face rockfill dams (CFRDs) are becoming a widely used type of rockflll dam in China. In many cases, the design and construction of CFRDs are based primarily on precedent and engineering judgments. Few numerical or analytical methods have been developed to properly evaluate the deformation of CFRDs, which is important for dam safety and for subsequent evaluation of seismic performance. In this study, a finite element procedure was developed to simulate the construction process of a CFRD, using the Zipingpu CFRD in China as an illustrative example. The Zipingpu dam was subjected to a strong earthquake in 2008, and can be used as a benchmark problem to assess the safety of CFRD. It is thus important to the engineering community to establish the state of stress-strain in the dam prior to the earthquake. A generalized plasticity model was modified to better model the rockfill materials, and the interfaces between face slabs and cushions are modeled using zero-thickness interface elements that follow a hyperbolic stress-strain model in the tangential direction. The model parameters were calibrated by large-scale triaxial tests and direct shear tests performed on materials used in the dam. The step-by-step construction followed by subsequent impounding of the reservoir was simulated in the numerical procedure. The numerical results agree well with in situ monitoring records of dam settlements, indicating that a three-dimensional finite element procedure based on a modified generalized plasticity model and a hyperbolic interface model can be used to evaluate the deformation of CFRDs.