Table 2 Properties of Rock Foundation
Roller Compacted Concrete
c
Maximum Modulus of Elasticity, E
24.4 GPa
(t)*
c
Modulus with time, E
)
exp(
b
c
t
a
E
Poisson’s Ratio
0.2
Density
3
2540 kg/m
Coeff. of Thermal Expansion
8.1 E-6 / ˚C
Specific Heat
˚C
920 J/kg
Thermal Conductivity
˚C
2.15 J/s m
Film (convection) Coefficient (air)
˚C
2
10 J/s m
Heat Generation of RCC
320J/g at 28 days
Placement Temperature
Different for each layer
Average Placement Temperature
20 ˚C
Rock Foundation
Modules of Elasticity
20 GPa
Poisson’s Ratio
0.3
Density
3
/m
2600 kg
Coeff. of Thermal Expansion
6.0 E-6 / ˚C
Specific Heat
900 J/kg ˚C
Thermal Conductivity
2.6 J/s m ˚C
Foundation Rock Temperature
23 ˚C
20
Figure 1 Mujib Dam near Compilation
21
Figure 2 Detailed schematics for Mujib dam with the installation of fiber optics
(Conrad et al., 2002)
DFOT SECTIONS
22
Figure 3 Fiber cable impacts due to on-site equipment (Conrad et al., 2002)
Figure 4 cable type chosen for Mujib Dam (Conrad et al., 2002)
23
Figure 5 Forced stress in young concrete under restrained deformation (Aufleger et
al., 2000)
T
0
A
B
C
D
E
B
H
G
F
(A)
Concrete temperature
(B)
Time
(C)
Concrete stresses
(D)
Zero-stress Temperature
(E)
Cracking temperature
(F)
Compressive prestressing
(G)
Tensile stresses
(H)
Tensile strength
24
0
5
10
15
20
25
30
35
40
0
10
20
30
40
50
60
Time (days)
T
e
mp
e
ra
tu
re
(
d
e
g
C
)
Figure 6 Heat of hydration as ramp input
Figure 7 Adiabatic temperature rises
25
Foundation
RCC
UY=0.0
UX=0.0
UX = 0.0
Boundary Conditions for 2D Structural Analysis
Boundary Conditions for 3D Structural Analysis
Figure 8 Boundary conditions (2D and 3D) for structural modeling
26
0
2
4
6
8
10
12
14
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
Strain [-]
S
tr
e
s
s
[
M
P
a
]
1
3
7
28
91
182
365
Con
cr
e
te
A
g
e
[
d
]
Figure 9 Stress-strain curves for different RCC ages (Conrad et al., 2003)
27
Figure 10 Two-dimensional mesh with gallery and CVC for conventional model
Figure 11 Three-dimension mesh with gallery and facing (conventional model)
28
0
5
10
15
20
25
30
35
40
0
50
100
150
200
250
300
350
400
Time (days)
T
e
m
p
e
ra
tu
re
(
d
e
g
C)
Point at distance 1.15m from upstream
Point at distance 22.6m from upstream
Figure 12 Predicted temperature history at different nodal points from up stream face
at 9m from base of dam (conventional approach)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
0
50
100
150
200
250
300
350
Time (days)
Cr
o
ss va
lle
y st
re
ss (
z-
d
ir
e
ctio
n
,
M
P
a
)
Point at distance 1.15m from upstream
Point at distance 22.6m from upstream
Figure 13 Cross valley stress (z-direction) at different nodal points from up stream
face at 9m from base of dam
29
0
10
20
30
40
50
-1
0
1
2
3
Stress in x-direction, MPa
El
e
va
ti
o
n
,
m
At end of palcement
At end of heat of hydration
After two year
Figure 14 Stress distributions (x-direction) at vertical section at the center of dam
from conventional model
Figure 15 Temperature contour at the Figure 16 Temperature contour
end of casting after two years
30
0
5
10
15
20
25
30
35
0
50
100
150
200
250
300
350
400
Time (days)
T
e
mp
e
ra
tu
re
(
d
e
g
C
)
2D conventional approach
3D conventional approach
Figure 17 Predicted temperature distributions at 25.15 m from u/s of the dam 1.5 m
from foundation
-5
-4
-3
-2
-1
0
1
2
3
0
50
100
150
200
250
300
350
Time, days
C
ro
s
s
v
a
lle
y
s
tr
e
s
s
(
z
-d
ir
e
c
tion
,
M
P
a
)
0
5
10
15
20
25
30
35
3D Conventional approach, constant (E)
3D Conventional approach, time dependent (E)
Temperature
T
e
m
p
e
ra
tu
re
(
d
e
g
C)
Figure 18 Temperature distribution and the effect of change of modulus of elasticity
on Cross valley stresses (z-direction) at 2.6 from US of dam and 1.5 m from
foundation (one reaches tensile stresses although temperature difference at the end
effectively zero ?)
31
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
0
50
100
150
200
250
300
350
Time, days
C
ro
s
s
v
a
lle
y
s
tr
e
s
s
(
z
-d
ir
e
c
tion
,
M
P
a
)
0
5
10
15
20
25
30
35
40
3D Conventional approach, constant (E)
3D Conventional approach, time dependent (E)
Temperature
T
e
m
p
e
ra
tu
re
(
d
e
g
C)
Figure 19 Temperature distribution and the effect of change Modulus of Elasticity on
Cross valley stresses (z-direction) at 2 m from upstream, 15 m from foundation (same
comment as Fig. 18)
-1.5
-1
-0.5
0
0.5
1
0
50
100
150
200
250
300
350
Time, days
C
ro
s
s
v
a
lle
y
s
tr
e
s
s
(
z
-d
ir
e
c
tion
,
M
P
a
)
0
5
10
15
20
25
30
35
3D Conventional approach, constant (E)
3D Conventional approach, time dependent (E)
Temperature
T
e
m
p
e
ra
tu
re
(
d
e
g
C)
Figure 20 Temperature distribution and the effect of change Modulus of Elasticity on
cross valley stresses (z-direction) at center of dam at, 15 m from the foundation at end
32
of RCC placement (for the shown temperature-history really strange stress-histories
come up)
0
5
10
15
20
25
30
35
01
/0
1/0
1
12
/0
2/0
1
26
/0
3/0
1
07
/0
5/0
1
18
/0
6/0
1
30
/0
7/0
1
10
/0
9/0
1
22
/1
0/0
1
03
/1
2/0
1
14
/0
1/0
2
Date
Te
m
p
e
ratu
re d
e
g
(C
)]
average daily temperature
trend
Figure 21 Average daily temperatures Mujib 2001
Chia sẻ với bạn bè của bạn: |