بررسي تاثير رفتار هيدرومكانيكي درزه ها در ايمني تكيه گاه سدهاي بتني قوسي

THE EFFECTS OF HYDROMECHANICAL BEHAVIOR OF ROCK JOINTS ON THE STABILITY OF CONCRETE ARCH DAM ABUTMENTS

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 disconti¬nuities 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 inves¬tigate the effects of these weak elements on the stability of the structure. In this paper, the authors present the response of a typ¬ical concrete arch dam abutment under the hydraulic and mechnical interaction of rock joints within abut¬ments, 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 slid¬ing and opening of rock joints and the resulting water flow through these discontinuities are adopted as indica¬tors for an estimation of dam abutment safety. The re¬sults show that the hydromechanical effect is of great im¬portance 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.