دراسة مختبرية للنحر مؤخر هدار مفتاح البيانو نوع C بتغير ارتفاع الهدار وعرض المفاتيح وطول أرضية الحماية

الملخص EN

To find out mechanism scour downstream weirs and study effect changing ratio width of keys Wi / Wo, length of apron solid and studying effect of changing the lateral length b on depth and length of the maximum scour by passing different discharge and using homogeneous soil.

a laboratory study was conducted to measure depth of scour downstream piano key weir type c and to show effect height weir, ratio width of keys and length of apron solid.

three heights of weir (25,30,35) cm, three ratios of width keys (1,1.25,1.5) and two distances were used for apron solid (90,120) by passing four different discharges (15, 22, 29, 36)) l/s in experiments, where number of models used nine models, on which (72) experiments were conducted.

the depth of scour for all experiments that by reducing height weir, maintaining ratio width of the keys and discharge, scour decreases for all experiments.

the results also showed that by increasing length of apron solid by 33.33%, the scour depth will be decreased by a rate ranging between (2.17-28.75)%.

and that by increasing the percentage of the width keys from ratio (1)) to ratio (1.5) scour depth decreases by a rate ranging between (13.04-47.38%) for all experiments, decreasing height of weirs from 35 cm to 25 cm, the percentage decrease scour depth ranged (20-40.2)%.

to arrive at a positional equation in terms of variables and a coefficient of determination of R2 = 0.958.