نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری سازه های آبی، دانشگاه شهید چمران اهواز
2 استاد، عضوهیئت علمی گروه سازه های آبی، دانشگاه شهید چمران اهواز
3 دانش آموخته کارشناسی ارشد مهندسی رودخانه، دانشگاه شهید چمران اهواز
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Channel confluence is a common feature of the most irrigation and drainage channels and river systems, where tributary conflicts the main channel. Due to complex flow patterns - because of variation of magnitude and direction of flow velocity, flow and sediment discharge -bed erosion, shoreline erosion and accumulation of sediment at the downstream of river confluence are common processes. This phenomenon causes damage of the adjacent structures and changes river morphology. A common practice to prevent and control bed erosion at river confluence is to use a cover of stone or riprap. Criterion for design of stone has not been developed in the past, therefore in this study, some stone sizes (D50) with different specific gravity under different hydraulic conditions have been tested to determine the factors that affect the stability of riprap at the threshold and failure conditions. The stability number (SN), which is a decisive factor for riprap stability has been studied for some different stone sizes (D50), specific gravity (Gs) and flow discharge ratio (Qr). It was found that with increasing flow rate, the stability number decreased; also it revealed that the stability number decreased by decreasing particle size of riprap for a constant discharge ratio (Qr). Apart from the effects of the other variables, the stability number (SN) increased, as the specific gravity of stone (Gs) decreased. Finally, a relationship with an acceptable accuracy (R2 = 0.86) was determined to estimate the stability number (SN).
کلیدواژه‌ها [English]
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