In this paper we describe an experimental study on the inclination-angle of the spillway-crown, which the sediment overflowing a Sabo-Dam are letten fly away maximum distance.
1. It seems to be quite all right to consider that the sediment which leave the spillway-crown, falling in the parabolic motion.
2. In figure-1, the relation of the falling distance (X) and other factors may be formularized following equation:
X=-υ
s2⋅g
-1⋅sinα⋅cosα+υ
s⋅
g-1⋅cosα[υ
s2⋅sin
2α+2⋅g(
Y-S⋅sinα]
1/2+
S⋅cosα
where υ
s is the velocity of the object on the point B,
S is the length of slope (from A to B), α is the angle of slope, g is the acceleration of gravity, Y is the height of Dam. Then, We are able to rewrite this equation as follows:
υs
′=L/[2⋅
g-1⋅cosα(
H⋅cosα-
L⋅sinα)]
1/2,
L=X-S⋅cosα,
H=Y-S⋅sinα
where υ
s′ means the caluclated velocity by the experimental datd.
3. The velocity of the spherical objects which are roll down at the slope on the point B is estimated byfollowing equation:
υ
s=[υ
20+10⋅7
-1⋅
g⋅
S⋅sinα]
1/2where υ
0 is the velosity on the point A and this υs is the theoretical value.
4. Useing several materials and sizes experiments were done and obtained the velocity ratio υ
s′/υ
ssuch as following:
Steel ball: 89-98% average 96%
Porcelain ball and Glass ball: 80-95% average 91%
Cobbles in the river bed: 69-89% average 79%
5. We tryed same experiments which several sizescobbles were throwed into the flow of overflowing the Sabo-Dam in practice and made observation the same phenomena, above-mentioned.
From the results of our experiments, it may be conclude that the optimum angle of inclination for spillway-crown of the Steel-Dam seemes to be suitable for 25-35 degree.
抄録全体を表示