Numerical Modeling of Moisture Migration in High-speed...
Transcript of Numerical Modeling of Moisture Migration in High-speed...
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
• Numerical Modeling of Moisture Migration
in High-speed Railway Embankment
Hanlin Wang, Ph.D. Student
Zhejiang University
August 5, 2015
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Outline
Background
Modeling
Material Parameter
Rainy Conditions
Initial and Boundary Conditions
Results and Analysis
Conclusions
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ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Background
Rainwater infiltrates into the embankment through fissures in rainy days.
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Dk
0.4 m
2.3 m
Subgrade
Subsoi l
I nf i l t rat i on of rai nwat er
Sat urat i on Zone
Roadbed
Fi ssure
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Background
Water disease: mud pumping, differential settlement, landslide, etc.
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Dk
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Rainfall precipitation
Model Overview
Modeling on the basis of fissure development at the junction area between concrete base and concrete slab above the roadbed
Fissures Infiltration area
Raining duration
Dk
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Infiltration area
Roadbed
Subgrade
Subsoil
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Material Parameter
Four calculation conditions
Subgrade Category Subgrade
(0.85, 15.4%) Subgrade
(0.90, 15.4%) Subgrade
(0.93, 15.4%) Subgrade
(0.93, 30%)
Compaction Degree 0.85 0.90 0.93 0.93
Fine Particle Content (%) 15.4 15.4 15.4 30.0
100 10 1 0.10
20
40
60
80
100
Per
cen
t F
iner
(%
)
Particle Diameter, d (mm)
China Railway Standard (lower limit)
China Railway Standard (upper limit)
Rahardjo (2008)
Roadbed
100 10 1 0.1 0.01 1E-30
20
40
60
80
100
Perc
en
t F
iner
(%)
Particle Diameter (mm)
Subgrade material
Fine Particle Content=15.4%
Fine Particle Content=30.0%
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Measurement of SWRC and
Permeability of Subgrade Materials
Large-scale infiltration column
TDR5
TDR4
TDR3
TDR2
TDR1
T5
T4
T3
T2
T1
300mm
150mm
100mm
100mm
100mm
100mm
100mm
30mm
Tensiometers
Infiltration
column
TDR 100
TDR
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Material Parameter
SWRC and unsaturated permeability coefficient
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0.01 0.1 1 10 100 10000.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Vo
lum
etr
ic W
ate
r C
on
ten
t
Matric Suction (kPa)
Roadbed
Subsoil
Fissure
Subgrade (0.85,15.4%)
Subgrade (0.90,15.4%)
Subgrade (0.93,15.4%)
Subgrade (0.93,30%)
0.01 0.1 1 10 100 10001E-18
1E-16
1E-14
1E-12
1E-10
1E-8
1E-6
1E-4
0.01
Pe
rmeab
ilit
y C
oeff
icie
nt
(m/s
)
Matric Suction (kPa)
Roadbed
Subsoil
Fissure
Subgrade (0.85,15.4%)
Subgrade (0.90,15.4%)
Subgrade (0.93,15.4%)
Subgrade (0.93,30%)
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
In rainy days, the process of raining is continuous (Zhou, 2005)
Relationship between maximum rainfall
intensity per unit time and daily precipitation
(Zhou, 2005)
Dk
Rainy Conditions
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Relationship between rainfall intensity and raining duration
(Webster 1905)
/ ni S t 1/ nI it S t
i iS a I b
Relationship
between daily
precipitation and
raining duration
0.3622, 6.376, 0.565i ia b n
0 50 100 150 200 2500
2
4
6
8
10
Ra
inin
g D
ura
tio
n t
Daily Precipitation I (mm)
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Parameters Roadbed Subsoil Crack Subgrade
(0.85,
15.4%)
Subgrade
(0.90,
15.4%)
Subgrade
(0.93,
15.4%)
Subgrade
(0.93,
30%) Volumetric
Moisture Content
(%) 10 29.52 10 13.70 13.70 13.70 15.19
Matric Suction
(kPa) 13.2 185.84 389.14 3.75 2.08 15.37 1.46
Dk
Initial and Boundary Conditions
Initial conditions
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Boundary conditions
0.4
m2
.3 m4%
27m
2m
5m4.3m 4.3m
1:1.5 4%
1
2
3
4 56 7
89
10
11
12
13
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Subsoil
Subgrade
Roadbed
Crack
Concrete BaseFree seepage
Impervious
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Results (0.93,15.4%)
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ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Results after 3 Year Cycle
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0.85,15.4% 0.90,15.4%
0.93,15.4% 0.93,30%
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Saturation Zone Comparison
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Compaction degree↑
Saturaion zone↑
slightly
Fine particle content↑
Saturation zone↑
significantly
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content
Variations with Time (Point A)
Roadbed, 0.1 m right below the lower edge of the crack
Not influenced by different subgrade fillings
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0 200 400 600 800 10000.08
0.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.85-15.4%
0.90-15.4%
0.93-15.4%
0.93-30%h=4.6m
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content Variations
with Time (Point B)
Close to the interface of roadbed and subgrade
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0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.85-15.4%
0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.90-15.4%
0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.93-15.4%
0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.93-30%
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content
Variations with Time (Point B)
Water arriving time is the longest for subgrade (0.93,15.4%)
Volumetric Water Content Range after Stabilization: subgrade (0.93,15.4%) and subgrade (0.93,30%) have comparatively low fluctuation.
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Point B Subgrade
(0.85, 15.4%) Subgrade
(0.90, 15.4%) Subgrade
(0.93, 15.4%) Subgrade
(0.93, 30%)
Initial Matric Suction
(kPa) 3.75 2.08 15.37 1.46
Initial Permeability
Coefficient (m/s) 1.24e-9 1.44e-9 2.38e-12 1.88e-10
Water Arriving Time
(day) 48 48 71 59
Volumetric Water
Content Range after
Stabilization 0.13-0.30 0.13-0.25 0.20-0.28 0.15-0.23
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content Variations
with Time (Point C) Middle area of subgrade
High-elevation saturation zone for subgrade (0.93,30%)
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0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.85-15.4%
0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.90-15.4%
0 200 400 600 800 10000.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.93-15.4%
0 200 400 600 800 10000.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.93-30%
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Saturation zone development
Dk
Volumetric Water Content
Variations with Time (Point D)
No long-term saturation zone for subgrade (0.85,15.4%)
Compaction degree↑, water arriving time↑significantly
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0 200 400 600 800 10000.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.85-15.4%
0.90-15.4%
0.93-15.4%
0.93-30%
h=2.9m
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content
Variations with Time (Point C and D)
Longest water arriving time from C to D: subgrade (0.93, 30%)
Point C Subgrade
(0.85, 15.4%) Subgrade
(0.90, 15.4%) Subgrade
(0.93, 15.4%) Subgrade
(0.93, 30%) Water Arriving
Time (day) 60 60 125 89
Volumetric Water
Content Range
after Stabilization 0.15-0.3 0.14-0.25 0.20-0.28
“Saturation zone”
after 496 days
Point D Subgrade
(0.85, 15.4%)
Subgrade
(0.90, 15.4%)
Subgrade
(0.93, 15.4%)
Subgrade
(0.93, 30%) Water Arriving
Time (day) 62 67 133 140
Volumetric Water
Content Range
after Stabilization 0.17-0.30
“Saturation zone”
after 122 days “Saturation zone”
after 158 days “Saturation zone”
after 180 days
From C to D Subgrade
(0.85, 15.4%)
Subgrade
(0.90, 15.4%)
Subgrade
(0.93, 15.4%)
Subgrade
(0.93, 30%) Water Migrating
Time (day) 2 7 8 51
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Volumetric Water Content
Variations with Time (Point E)
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0 200 400 600 800 10000.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
0.32
Vo
lum
etr
ic W
ate
r C
on
ten
t
Time (day)
0.85-15.4%
0.90-15.4%
0.93-15.4%
0.93-30%
h=2.3m
Point E Subgrade
(0.85, 15.4%) Subgrade
(0.90, 15.4%) Subgrade
(0.93, 15.4%) Subgrade
(0.93, 30%) Formation Time of
“Saturation Zone” (day) 71 73 152 160
Water accumulates at the interface of subgrade and subsoil. Infiltration velocity to the subsoil is extremely low.
Compaction degree↑, formation time of saturation zone↑significantly. Fine particle content has little effect.
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Threat to the Embankment with the
Presence of “Saturation Zone”
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Matric suction↓ Shear strength↓
Unsaturated Saturated
instability
Cumulative settlement of Shijiazhuang-
Taiyuan Railway Line reaches 64.2 cm with
infiltration of rainwater and it
causes instability failure.
Stiffness↓ Settlement↑
The running speed of Japanese shinkansen reduces to 110~180
km/h due to settlement caused by
water infiltration
Mud pumping disease
Shanghai-Nanjing Railway
Line
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Dk
Conclusions
After 3 year cycle, “saturation zone” develops for each condition. The size increases with compaction degree (little influence ) and fine particle content.
Subgrade (0.93, 15.4%) has the longest time for water to pass the interface of roadbed and subgrade.
Subgrade (0.93, 15.4%) and (0.93, 30%) have comparatively small fluctuation of volumetric water content.
Subgrade (0.93, 30%) has the largest “saturation zone” and it develops at high elevation.
Formation time of “saturation zone” at the interface of subgrade and subsoil increases significantly with compaction degree. Fine particle content has little effect.
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ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Thank you!
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ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
Q & A
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