This study analyzes the impact of the number of ground motions on the seismic fragility of a high earth-rockfill dam and the estimation of reasonable fragility parameters based on a sufficient number of earthquake records. In this paper, the vertical deformation is obtained using the three-dimensional finite element program DYNE3WAC combined with the Pastor–Zienkiewicz–Chan model and Biot dynamic consolidation theory. The relative seismic settlement rate is considered the damage index for the seismic fragility analysis of the dam. The fragility curves of the high earth-rockfill dam are determined by the multiple stripe analysis (MSA) method. A set of seismic waves is chosen based on the spectrum in the Chinese hydraulic structure seismic code. With an increasing number of earthquake records, the coefficients of variation (COV) of the mean and standard deviation (STD) of the relative seismic settlement rate decrease and tend to stabilize when the number of earthquake records reaches 34. The estimated fragility parameters θ and β are constant when the number of earthquake records exceeds 34. The requisite number of earthquake records for an accurate fragility estimation is determined by analyzing the lower and upper confidence intervals for the estimated θ and β. The 95% and 90% confidence interval can accurately estimate the fragility of a high earth-rockfill dam when the number of ground motion records reaches 36 and 32, respectively. The results of the fragility analysis demonstrate that the DYNE3WAC program and MSA method can provide an effective basis for determining fragility curves. Furthermore, the sensitivity analysis of earthquake records is essential for assessing the seismic fragility of high earth-rockfill dams.

Abstract. The Pastor-Zienkiewicz-Chan model based on the generalized plasticity theory can simulate the main materials of the earth-rockfill quite well. The three-dimensional modeling of a typical earth-rockfill dam was modeled by HYPERMESH and was implemented into the three-dimensional elasto-plastic program DYNE3WAC through the development of the interface based on FORTRAN. Therefore, the DYNE3WAC can analysized the typical earth-rockfill dam in the impoundingt period and reasonable analysis the dam displacement along the river and settlement and the pore water pressure which can satisfy the dam static development rules. The results show that displacement and pore water pressure are in accordance with the general rule of the earth-rockfill dam and can prepare for the next dynamic analysis.