Predicting the Earthquake-Induced Permanent Deformation of Concrete Face Rockfill Dams Using the Strain-Potential Concept in the Finite-Element Method

Presented in this paper is a modified strain-potential method for the prediction of earthquake-induced permanent deformation of concrete face rockfill dams (CFRDs). The concept of decomposing the total strain of rockfill materials into a viscoelastic part and a plastic part during dynamic loading was explained based on experimental observations. Use of the strain-decomposition concept in the finite-element method resulted in two residual strain-related terms on the right-hand side of the dynamic equilibrium equation. An approach to predict the equivalent number of loading cycles, which is an independent variable in a residual strain model, was proposed. It was assumed that the energy dissipated in an element during an irregular strain history equals that dissipated in an equivalent regular one. The energy-based approach was proved effective in numerically evaluating the equivalent number of loading cycles by simple column tests considering both compression and shearing. The modified strain-potential method can be easily implemented in an equivalent linear analysis program, and the history of permanent deformation accumulation can be directly obtained without recourse to sophisticated constitutive models. Effectiveness of the method was demonstrated by a successful application in a high CFRD. (C) 2017 American Society of Civil Engineers.