Seismic performance of arch dams on non-homogeneous and discontinuous foundations (a case study: Karun 4 Dam)

Abstract

The present study set out to investigate the nonlinear seismic response of the dam-reservoir-rock foundation system, taking into consideration the effects of change in the material properties of discontinuous foundation. To this end, it is important to provide the proper modeling of truncated boundary conditions at the far-end of rock foundation and reservoir fluid domain and to correctly apply the in situ stresses for rock foundation. The nonlinear seismic response of an arch dam mainly depends on the opening and sliding of the dam body's contraction joints and foundation discontinuities, failure of the jointed rock and concrete materials, etc. In this paper, a time domain dynamic analysis of the 3D dam-reservoir-foundation interaction problem was performed by developing a nonlinear Finite Element program. The results of the analysis of Karun-4 Dam revealed the essential role of modeling discontinuities and boundary conditions of rock foundation under seismic excitation. Keywords Concrete arch dam Á Non-homogeneous and discontinuous foundation Á Nonlinear finite element dynamic analysis Á In situ stress Á Boundary conditions

Nonlinear seismic response of arch dams considering joint opening effects and boundary conditions of discontinuous foundation

“…The main features of this study are considering the effect of contraction joints and choosing a proper boundary condition for far-end which has a direct effect on the accuracy and precision of analytical results. In the analysis and design process of an arch dam, it is necessary to model the following features: 1) Dam reservoir interaction and distribution of hydrodynamic pressure, 2) Reservoir foundation interaction and effects of reservoir bottom sediments, 3) Dam foundation interaction and role of non-homogeneous and discontinuities in bed rock, 4) Nonuniform input of the free-field motions, and 5) Nonlinear behavior of quasi-brittle material of concrete and jointed rock and contact in contraction and peripheral joints of dam body [1,3,4]. Fundamentals and analytical methods of all the above mentioned are outside the scope of this article and just a brief review of the main issues related to research are presented here.…”