Evaluation of seismic measures for high central core rockfill dam

Abstract

The seismic safety of high core rockfill dams has always been one of the core issues in water conservancy construction, especially in the dam crest area where significant seismic response, known as the “whip effect”, occurs under strong earthquake action. It is necessary to pay special attention to the seismic performance and evolution laws of rockfill dams during construction and long-term operation. This study is grounded in the Lianghekou rockfill dam project, where 2D seismic response simulations were conducted using the HSS (Hardening Soil Small-strain) model in PLAXIS to elucidate the dynamic behavior characteristics of the high central core rockfill dam. Additionally, a reinforced zone model was analyzed for simulation to investigate the seismic performance and mechanical degradation of reinforcement materials under long-term service conditions. The validity of this localized modeling approach was confirmed through comparative analysis of seismic responses between the holistic dam model and the local reinforced zone model. The results indicate that: (1) The maximum displacement along the valley occurs in the middle area on both sides of the dam body, while occurs in the central region of the dam crest vertically; (2) Acceleration responses in both streamwise and vertical directions exhibit height-dependent amplification, with a 2-3 times “Whiplash Effect” at the dam crest; (3) Under seismic excitation, the geogrid-frame beam composite reinforced system demonstrates significant seismic resistance: the maximum tensile forces in reinforcements are significantly lower than their ultimate tensile strength; (4) The cross-sectional dam design has significant influence on the dam mechanical responses; (5) The tensile forces carried by the reinforcements gradually diminish during prolonged service, whereas dam deformations remain essentially stable.