à Æå¢b4 / I ölibrary.jsce.or.jp/jsce/open/00906/2015/21-0349.pdf1= e ] /¡1= e7 '¨ s º v ö%...
6
ᇶ┙ࡢᆅ┙≉ᛶ࡞␗ࡀἙᕝሐ㜵ࡢ㧗Ỉ ࡢ⥅⥆స⏝₃Ỉࡢࢢ㐍⾜≉ᛶ WATER LEAK - PIPING BEHAVIORS OF RIVER LEVEES WITH DIFFERENT FOUNDATION GROUND PROPERTIES UNDER LONG DURATION OF HIGH WATER LEVEL Hiroshi SAITO, Kenichi MAEDA, Norihiro IZUMI and Zhaoqing LI A river levee of the Yabe River was breached due to piping failure induced by prolonged high water levels following heavy rains in Northern Kyushu in 2012. The piping failure was caused by water infiltration into the highly permeable sand and gravel foundation under the clay levee body. However, some levees with similar foundations were deformed but did not fail. This study used models to investigate the influences of the soil-stratum conditions on the properties of pore water pressure propagation and water leakage and the piping failure behavior. The test results revealed that the piping could not be viewed as a single homogeneous foundation ground with leakage of clean water, according to Darcy's law. Rather, the piping failure progressed with a large water leakage including sand in a two- layer foundation ground consisting of gravel below fine sand, even under a low hydraulic gradient. We propose a new criterion for piping based on the foundation ground strata configuration, average hydraulic gradient, and flow velocity. Key Words : piping, hydraulic gradient, critical velocity ࡌࡣ N ᅗ ᅗ N ᅗ ⢓ᛶᅵ ◁♟㉁ᅵ ◁㉁ᅵ ⢓ᅵ㉁ࢩ ࢺ♟ΰࡌ◁ ࢩࢺ㉁◁ ሐෆഃ ሐእഃ 5.0m T.P+9.4m ㊧T.P+8.3m ィ⏬㧗ỈT.P+7.3m 2.0m 2.0m 1 Ἑᕝᢏ⾡ㄽ㞟, ' 21s , 2015 6 - 349 -
Transcript of à Æå¢b4 / I ölibrary.jsce.or.jp/jsce/open/00906/2015/21-0349.pdf1= e ] /¡1= e7 '¨ s º v ö%...
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WATER LEAK - PIPING BEHAVIORS OF RIVER LEVEES WITH DIFFERENT FOUNDATION GROUND PROPERTIES
UNDER LONG DURATION OF HIGH WATER LEVEL
Hiroshi SAITO, Kenichi MAEDA, Norihiro IZUMI and Zhaoqing LI
A river levee of the Yabe River was breached due to piping failure induced by prolonged high water levels following heavy rains in Northern Kyushu in 2012. The piping failure was caused by water infiltration into the highly permeable sand and gravel foundation under the clay levee body. However, some levees with similar foundations were deformed but did not fail. This study used models to investigate the influences of the soil-stratum conditions on the properties of pore water pressure propagation and water leakage and the piping failure behavior. The test results revealed that the piping could not be viewed as a single homogeneous foundation ground with leakage of clean water, according to Darcy's law. Rather, the piping failure progressed with a large water leakage including sand in a two-layer foundation ground consisting of gravel below fine sand, even under a low hydraulic gradient. We propose a new criterion for piping based on the foundation ground strata configuration, average hydraulic gradient, and flow velocity.
Key Words : piping, hydraulic gradient, critical velocity
5.0mT.P+9.4mT.P+8.3mT.P+7.3m 2.0m
2.0m
, 21 , 2015 6
- 349 -
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[ 7 2 ] [ ]
1.0m45 2700 45 2700
45 2700 45 2700
d=300 (0.300)
Water side
Land side
Fujinomori clay
81
700 (0.700)
70 (0.070)
169Upper sand layer
Lower sand layer
45 (0.045)
45 (0.045)2 3 4 5 6 7
10 11 12 13 14 15
60 (0.060)
h=60 (0.060)
50 (0.050)
Pore water pressure meter
10 (0.010)
Depth 250 (0.250)
Overflow
unit : mm (m)
Scale
045)
0.001 0.01 0.1 1 100
20
40
60
80
100
Fujinomori clay, k=3.0 10-8m/s Silica#7, k=1.4 10-5m/s Silica#4, k=1.6 10-3m/s Silica#2, k=1.8 10-2m/s
Perc
enta
ge p
assin
g by
wei
ght (
%)
Grain size, d(mm) (d 10-3 (m))
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(a)44 37 (2677 )
(b)45 09 (2709 )
(c)45 38 (2738 )
(d)45 42 (2742 )
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Width direction (m)
Wat
er h
ead
, H (m
)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Width direction (m)
Wat
er h
ead
, H (m
)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Width direction (m)
Wat
er h
ead
, H (m
)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Wat
er h
ead
, H (m
)
Width direction (m)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Wat
er h
ead
, H (m
)
Width direction (m)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
0 0.06 0.12 0.18 0.24 0.30 0.36 0.420
0.05
0.10
0.15
0.20
Wat
er h
ead
, H (m
)
Width direction (m)
0(0) 3(180) 30(1800) 35(2100) 41(2460)46(2760) 52(3120) 57(3420) unit : min (sec)
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W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.9-10 No.10-11 No.11-12 No.12-13No.13-14 No.14-15 No.15-16
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
iW.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.9-10 No.10-11 No.11-12 No.12-13No.13-14 No.14-15 No.15-16
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
No.9-10 No.10-11 No.11-12 No.12-13No.13-14 No.14-15 No.15-16
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.1-2 No.2-3 No.3-4 No.4-5No.5-6 No.6-7 No.7-8
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.1-2 No.2-3 No.3-4 No.4-5No.5-6 No.6-7 No.7-8
Duration time , t (min)H
ydra
ulic
gra
dien
t, i
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
No.1-2 No.2-3 No.3-4 No.4-5No.5-6 No.6-7 No.7-8
W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.1-9 No.2-10 No.3-11 No.4-12No.5-13 No.6-14 No.7-15 No.8-16
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
0 10 20 30 40 50 60 70 80-1.0
-0.5
0
0.5
1.0
No.1-9 No.2-10 No.3-11 No.4-12No.5-13 No.6-14 No.7-15 No.8-16
Duration time , t (min)
Hyd
raul
ic g
radi
ent,
i
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
No.1-9 No.2-10 No.3-11 No.4-12No.5-13 No.6-14 No.7-15 No.8-16
30 31 32 33 34 350.02
0.03
0.04
0.05
Wat
er h
ead
, H (m
)
No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8
Duration time , t min (sec)
min(1800) (1860) (1920) (1980) (2040) (2100) sec
33min56sec (2036sec)
↓Dike body33min56sec (2036sec) 67min (4020sec)
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0 10 20 30 40 50 60 70 800
10
20
30
40
50
60
case1-1 case2-1 case2-2
Duration time , t (min)
Dra
inag
e flo
w, q
(cm
3 /s)
W.L.0.06m
W.L.0.11m
W.L.0.16m
W.L.0.21m
W.L.0.26m
(m3 /s
)
( 10-6)
Duration time , t min (sec)
min(0) (600) (1200) (1800) (2400) (3000) (3600) (4200) (4800) sec
Silica 7
case2-2 case2-1case1-1 (m/sec)
(m)
( 10-2 )
( 10-3)
k1
y1 y2 y2 y1y3
k2
k1
k2
k1k2
y1
y2
q
Water side
Land side
Fujinomori clay
yykykk )( 2211112232211 kykykykyky
dk
kk
y
d
0 0.1 0.2 0.30
0.1
0.2
0.3
Measurement permeability, km (m/s)
Theo
ry p
erm
eabi
lity,
kt (
m/s
)
MonolayerBilayer
( 10-2)
( 10-2)
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(B)23360203 24
1)
2)
3)
4)
5)
6)
7)
Piping area
Non-piping area
0 0.05 0.1 0.15 0.20
0.2
0.4
0.6
0.8
1.0
Mean velocity , v (m/s)
Hyd
raul
ic g
radi
ent,
i
case1-1
case1-2
case1-3
case2-1
case2-3case2-4
case2-11
case2-2
case2-9
case2-5
case2-6
case2-7
case2-8case2-10
Monolayer Bilayer
( 10-2)
Uplift pressure
Weight of the soil
Piping hole
Scouring Deposition
Dike body
Dike bodyDike body
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