عنوان مقاله [English]
Due to extensive loading commonly applied in concrete arch dams, the rocky sites selected as their foundation and abutments must be of high strength and degree of stiffness. However, hard rock usually contains discontinuities arising from its brittle behaviour under different natural loadings. Thus, the foundations of arch dams often consist of discontinuities in the forms of joints, bedding planes and faults. It is, then, necessary to investigate the effects of these weak elements on the stability of the structure.In this paper, the authors present the response of a typical concrete arch dam abutment under the hydraulic and mechnical interaction of rock joints within abutments, using UDEC software. Two different approaches of increasing hydrostatic water pressure and reduction in the strength of rock joints have been utilized to discover abutment stability. In this study, the values of the sliding and opening of rock joints and the resulting water flow through these discontinuities are adopted as indicators for an estimation of dam abutment safety. The results show that the hydromechanical effect is of great importance to the stability of abutments and hence, must be considered in the modelling of arch dams. Otherwise, the failure mechanisms and the level of safety obtained from the analyses may lead to an unsafe design.