Environmental Engineering Reference
In-Depth Information
Table 5.2
(
Continued
)
Reference
Equation
Description
1
van Genuchten (1980)-
Burdine (1953)
n
=
(a
v
b
ψ)
n
v
b
]
m
v
b
[1
+
where
2
n
v
b
m
v
b
=
1
−
exp
a
m
1
−
ψ
McKee and Bumb (1984)
(Boltzmann distribution)
n
=
a
m
1
=
curve-fitting parameter
n
m
1
n
m
1
=
curve-fitting parameter
where
w
(ψ)
−
w
r
n
=
w
s
−
w
r
1
McKee and Bumb (1987)
(Fermi distribution)
n
=
a
m
2
=
curve-fitting parameter
1
+
exp[
(ψ
−
a
m
2
)/n
m
2
]
n
m
2
=
curve-fitting parameter
where
w
(ψ)
−
w
r
n
=
w
s
−
w
r
w
s
Fredlund and Xing (1994)
w
(ψ)
=
C(ψ)
ln
e
(ψ/a
f
)
n
f
m
f
a
f
fitting parameter which is
primarily a function of air-entry
value of soil
n
f
=
+
where
fitting parameter which is
primarily a function of rate of
water extraction from soil once
air-entry value has been exceeded
m
f
=
ln
(
1
+
ψ/ψ
r
)
C(ψ)
=
1
−
ln[1
+
(
10
6
/ψ
r
)
]
w
(ψ)
w
s
d
=
fitting parameter which is
primarily a function of residual
water content
C(ψ)
=
correction factor which is
primarily a function of suction
corresponding to residual water
content.
=
w
s
−
w
r
Pereira and Fredlund
(2000)
w
(ψ)
=
w
r
+
a
p
=
fitting parameter which is
primarily a function of air-entry
value of soil
n
p
=
1
+
ψ/a
p
n
p
m
p
fitting parameter which is
primarily a function of rate of
water extraction from soil, once
air-entry value has been exceeded
m
p
=
fitting parameter which is
primarily a function of residual
water content
⎧
⎨
Pham and Fredlund
(2005)
S
1
,S
2
,S
3
=
slope of straight line
portions of SWCC within each of
three zones
w
u
=
w
1
(ψ)
=
w
u
−
S
1
log
(ψ)
1
≤
ψ<ψ
aev
S
2
log
ψ
ψ
aev
w
2
(ψ)
=
w
aev
−
ψ
aev
≤
ψ<ψ
r
S
3
log
10
6
ψ
⎩
water content at 1 kPa
w
aev
=
ψ<
10
6
kPa
w
3
(ψ)
=
ψ
r
≤
water content at air-entry
value
w
1
,
w
2
,
w
3
=
water content in line
segments 1, 2, and 3, respectively.
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