An approach for the real-time slip deformation coupled with strain softening of a high rockfill dam subjected to pulse-like ground motions

Abstract

The dynamic stability of a dam is a major engineering problem, especially since many high dams have been built or designed in near-fault zones. However, few studies have been focused on the dynamic stability of dams subjected to near-fault pulse-like ground motions. The stability analysis of high rockfill dam subjected to pulse-like ground motions is a meaningful topic. In the traditional computing methods for slope stability, the position of potential sliding surfaces can’t be accurate determined. In order to get more accurate results, the finite element method of sliding calculation is proposed to calculate variation process of the dynamic stress of the element. Meanwhile, the strain softening of rockfill materials under low confining pressure is obvious. Hence, the dam stability considering the strain softening of rockfill materials is an urgent problem that must be investigated. In this study, the peak strength and residual strength were obtained, and the normalized residual strength curve considering strain softening was put forward by analyzing consolidated drained triaxial test data that were derived from real projects. The soil slope stability procedure (FEMSTABLE 3.0) was developed by the first author and used to perform a seismic stability analysis of a core-wall dam in the near-fault area. In addition, the more reasonable approach was proposed to calculate the real-time slip of the dam under pulse-like ground motions, and the method was coupled real-time slip deformation and strain softening. The proposed method of sliding calculation may spend much time on computing safety factors and accumulated displacements of a large number of sliding surfaces, therefore the multicore parallel computing technique was used to improve the calculation speed. Moreover, the sliding displacement responses of the dam subjected to pulse-like and non-pulse ground motions were compared. Furthermore, the effects of pulse-like ground motions on the dynamic stability of 300 m core-wall dam considering strain softening were investigated. The results show that the pulse-like ground motion has a considerable effect on sliding displacement and strain softening of the rockfill, ignoring this factor may lead to inaccurate result.