Determination of dynamic material properties of concrete face rockfill dams based on earthquake-induced settlements and investigating their coherence with the design parameters

The safe and economical design of dams depends on their performance and behavior under static and dynamic loading conditions. In this study, the determination of the dynamic parameters of the rockfill material, which acts elastoplastic under the effect of seismic loads in concrete face rockfill dams (CFRDs), and the coherence of these parameters with the design parameters were investigated. Numerical analyses were carried out in the example of the Kürtün dam, constructed as a CFRD and simulated in the ANSYS software using the finite element method. Duncan-Chang (D-C) hyperbolic (HB) material model was used for the non-linear stress-strain relationship of the rockfill. Static analyses were performed with a non-linear isotropic hardening soil model for the end of construction (EoC), reservoir first impoundment (RFI), and operational cases (OpC) of the dam under 2-dimensional plane strain conditions. The calculated results provided a convergence of 94.42% for EoC, 86.36% for RFI, and 80% for OpC to the measured values. Calibrated elasticity and shear modulus parameters were also used in dynamic analyses. Dynamic analyses were performed for two scenarios using the direct excitation of the 1992 Erzincan earthquake acceleration to the dam foundation in the time domain and the acceleration attenuation relationships. Modal and nonlinear time-dependent (transient) analyses were carried out with the kinematic hardening soil model. Hydrodynamic analyses were made with the Westergaard approach. By using the calculated viscous damping parameters in the modal analyses, displacements and the amplification values of the acceleration from the base to the crest were computed. Peak ground acceleration increased 1.83 times in EoC and 1.96 times in OpC for Scenario I at the crest. For Scenario II, it increased by 2.32 times in EoC and 2.23 times in OpC. The values obtained by the dynamic analyses were considered reasonable and compatible with the literature. So, dynamic material parameters were determined depending on the measured settlement values by static and dynamic analyses carried out in the Kürtün dam example. Keywords: ANSYS, Non-linear analysis, Hyperbolic model, Concrete face rockfill dam, Finite element method, Dynamic analysis