Accurate prediction of the stress-deformation behavior of a concrete-faced rockfill dam (CFRD) under frequent reservoir stage fluctuations is critical to ensuring the safety of the pumped-storage power station. This study develops an improved constitutive model

GP_WHU

in the framework of the generalized plasticity theory

and demonstrates the application of a corresponding user module. We conduct triaxial tests on representative volume elements (RVE)

and use the measurements to validate the model's performance

verifying its capability of effectively capturing the stress-strain response of rockfill materials under triaxial shear

single loading and unloading

and low-frequency multi-cycle loading and unloading conditions. We apply this new model in a case study of an upper reservoir CFRD under construction for a pumped-storage power station in Hezhou

and conduct numerical simulation of dam filling

initial impoundment

and stress-strain response under cyclic reservoir stage fluctuations. Results show the initial impoundment caused significant displacement increment and principal stress direction deviation in the upstream slope area

with the maximum displacement increment occurring at roughly one-third of the dam height from the bottom. And under cyclic hydrodynamic loading

significant cumulative displacement occurred in the dam body near the bottom of the upstream slope in the water level fluctuation zone

and the maximum settlement increment accounted for roughly 3% to 9% of the settlement at the end of construction. As the cycling number increased

both deformation and stress in the dam body and face slabs gradually incresaed but tended to stabilize after around 100 cycles. The study provides key computational support for a full consideration of the effect of frequent reservoir stage fluctuations in the design and operation of CFRD.