سال انتشار: ۱۳۸۴
محل انتشار: سمپوزیوم برآورد عدم قطعیت در مهندسی سد
تعداد صفحات: ۱۰
Z. MOHAMMADI – Dept. of Earth sciences, Shiraz University, Shiraz, Iran
E. RAEISI – Dept. of Earth sciences, Shiraz University
Leakage from dam reservoirs has been reported in different karst regions of the world. In most cases tremendous additional grout curtains have been constructed to stop or minimize leakage. The practical solution of leakage is extremely complex and costly. The estimation of leakage is mainly erroneous due to uncertainties in the non-homogenous nature of a karst formation, the method of study, the limited investigation due to time and cost limitations, measurement error, and type of flow model. The qualitative uncertainties in geological features, borehole study, isopotential mapping and dye tracing are discussed based on the direct experiences of the authors with several dams in Iran. The leakageuncertainty was calculated for the diffuse and conduit flow models for two strategies of with or without any grout curtains under the combined effect of input uncertainties such as permeability, hydraulic gradient, conduit cross section and friction factor in one of the dam sites of Iran, The results reveal that there are significant uncertainties in conduit flow systems. A big diameter conduit can convey significant amounts of water under high reservoir pressure heads. The uncertainty may be decreased if a detailedstudy is carried out on the stratigraphical and tectonic settings, karst hydrogeology, geomorphology, speleogenesis, and by performing several dye tracings outside the proposed grout curtain area.