Elastic-plastic-creep behavior of high rockfill dams: a case study on Lianghekou CRFD

Abstract

The instantaneous loading and time-dependent creep deformations occur simultaneously during the lifetime of rockfill dams, but their proportions in monitoring records are still unclear. In previous works, loading and creep were generally simulated independently in turn. This uncoupled method may induce misleading conclusions in interpreting dam behaviors. In this paper, an advanced elastic-plastic-creep model is applied to capture the interaction of loading and creep under complex conditions with varying loading rates based on a benchmark example of 295m-high Lianghekou core wall rockfill dam (CRFD). The instantaneous elastic-plastic parameters of rockfills are calibrated by large-scale triaxial tests (including 300mm and 800mm in diameter) and the time-dependent creep parameters are obtained by back analyses on monitoring records. A series of numerical analyses on the dam are conducted. The loading-creep coupling process of rockfills is successfully captured and the instantaneous and time-dependent creep deformations are explicitly separated. The 800mm-diameter triaxial test weakens the size effect and provides an acceptable representation for the instantaneous behaviors of prototype rockfills. The good agreement between the calculations of the elastic-plastic-creep coupling analysis and measurements indicates creep contributes about 8~15% to total construction deformation. The work provides guides for properly interpreting and evaluating actual dam behaviors.