Fine-grained Sand Behavior in a Dam Reservoir at the Middle Reaches of a River
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Fine-grained Sand Behaviorin a Dam Reservoir at the Middle Reaches of a River
Civil Engineering Research Institute of Hokkaido
〇 Tomonori ShimadaYasuharu Watanabe Hiroyasu Yasuda
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The Saru River ・ Introduction
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Outline
(1) Experiment on soil particle sedimentation Experiment on soil particle entrainment
(2) To produce proposed equation
(3) To confirm the suitability of these equation → Reproduction calculation for the flood
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Experimental setup
(1)① Soil Particle Sedimentation
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) ()=( velocityfallObserved×K+KvelocityFall sb
Influence of Water Tank
(1)① Soil Particle Sedimentation
003.1wasKtheofvalueAverage
2S/r=SWhere
.S.J,McNownS006.1+1=KsurfaceSidewall
erimentexpthisin
considertoneednowasThere
15>ifconsider1S/r=SWhere
H,BrennerS89
+1=KsurfaceBottom
s
s
ss
b
bb
) ( : ・
) (
) ( : ・
S1
S2S2
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Coefficient of resistance to soil particles
(1)① Soil Particle Sedimentation
05.1D
D
Re
18.43=C
2+Re24
=C
Results from the experiment
Reynolds number
Coeffi
cie
nt
of
resis
tan
ce o
f sed
imen
tati
on
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Proposed equations for falling velocity of soil
particles
(1)① Soil Particle Sedimentation
sgdsgd
w
velocityfallforequationsproposed
wCdt
dwmgmM
dt
dwM
motionofEquation
f
D
11.1305.1
21
11
)()38.32
1(
8
1-
2
1-)-(
π
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sgdsgd
ν36
sgd
ν36
3
2w 3
2
3
2
f
sgdν
sgd
32.38
1w
1.1131.05
f
(1)① Soil Particle SedimentationRubey’s Equation and Presented
EquationFall v
elo
cit
y o
f a s
oil p
art
icle
[c
m/s
]
Soil particle diameter [cm]
Rubey’s equationProposed equation
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Experimental Setup
(1)① Soil Particle Entrainment
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Experimental Setup
(1)① Soil Particle Entrainment
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Volume of Entrainment vs. SS Concentration
Time of water flow [min]
Volu
me o
f En
train
men
t [c
m3] C
on
cen
tratio
n o
f su
sp
en
ded
sed
imen
t in
the w
ate
r [mg
/L]
Volume of EntrainmentSS Concentration
(1)① Soil Particle Entrainment
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( )
)wΩu
gdρ
ρραK(=q
Cwqλ-1
1=
tz
f'*s
s*su
bfsu
--
--∂
∂
Proposed of the Entrainment Rate Equation
Proposed coefficient K=0.00027Conventional coefficient K=0.008
(1)① Soil Particle Entrainment
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Calculation Results of the Reproduction
( 3 ) To confirm the suitability of these equation
Reservoir bed
Bed
ele
vati
on
[m
]
Before floodSurveyedProposed equationConventional equation
Volu
me o
f sed
imen
t [
thou
san
d m
3]
Surveyed Proposed Conventional Equation Equation
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• I explained fine grained sand behavior in a Dam reservoir.
• First, I explained the experiment on soil particle sedimentation, and then the experiment on soil particle entrainment.
• Next, I explained the method used to produce proposed equations.
• Finally, in order to confirm the suitability of these equations, I showed the results of a reproduction calculation.
• In conclusion, it is found that estimating the volume of sedimentation in the dam reservoir is possible through use of the equation.
Conclusion
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Check dam
W ater flow
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Cross Section of the Dam Before/After Flood (Downstream of the Check Dam)
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Grain Size of Soil Particles
Grain size [ cm ]
Clay 0.0000 ~ 0.0005
Silt 0.0005 ~ 0.0075
Fine sand 0.0075 ~ 0.0250
Medium-grain sand
0.0250 ~ 0.0850
Coarse sand 0.0850 ~ 0.2000
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Parameters in the entrainment experiment
Case 1 Case 2 Case 3
Discharge [m3/s] 0.10 0.20 0.22
Bed slope 1/5000 1/5000 1/400
Water depth [cm] 75 55 21
Duration of water flow [min.]
30 30 30
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Discharge and Water Level (Calculated)