اهمیت مشخصات هندسی درزه ها در میزان ایمنی تکیه گاه سدهای بتنی قوسی

Abstract:
Concrete arch dams often need sound and strong foundation and abutments due to the usually
large hydrostatic pressure imposed on the abutments. Moreover, it is required to limit the
water leakage through the abutments and foundation. On the other hand, a hard rock mass
often contains joints and discontinuuites, wich are partially created during the thermal and
techtonical activities. Several researches have shown that in most cases, the stability and
permeability of rock masses are governed by the joints. Therefore, it is necessary to consider
the joint roles for preliminary evaluation of a rock mass as abutment and foundation of a
concrete arch dam. In addition, the interaction of hydraulic and mechanical behaviour of
joints causes the saturated rock masses to act more complicated, hence, it must be considered
in the estimation of stability and leakage. In this paper, the effects of geometrical parameters
of joints including joint orientations and initial apertures on the safety of a concrete arch dam
were evaluated using UDEC software. A two-dimentional model including the waterflow
through the joints and a loading from dam and the reservoir was simulated in the analyses. In
this study, the dam stresses imposed on the abutment were applied instead of dam body
modeling. In all analyses, the hydromechanical interaction effects were considered. The
values of maximum sliding, maximum opening and the maximum resulting waterflow along
the discontinuities were adopted as criteria for estimating the dam abutment safety. The
results demonstrate that the joint sets pattern and initial hydraulic aperture of joints dominate
the stability of arch dam abutments.