Geoscience Reference
In-Depth Information
The minimum required effective thickness for these geotextile bags is determined
using:
H
085
091
s
Δ
t
103
m
=
=
R
H
11
085
079009
c
079009
.
790
.
790
.
s
Therefore, in terms of the minimum required length of these geotextile bags, the
following relationship applies:
D
k
1. 3
18 43
3. 6m
L
≥
k
=
=
sin
sin.
α
Stability subject to longitudinal water current
To check stability subject to longitudinal water current,
K
s
is first calculated according
to formula (3.15):
2
2
sin.
⎛
⎝
sin
⎞
⎛
⎞
18 43
−
⎛
18 43
20
⎞
α
δ
18
sin
K
s
1
−
⎛
⎛
⎝
⎞
1
⎛
⎝
038
=
=
=
sin
Using a geotextile bag, the equivalent roughness according to Nikuradse is:
k
r
=
D
k
=
0.79 m
The depth parameter
K
h
may be determined using formula (3.13):
02
=
⎛
⎜
⎞
02
−
h
k
=
⎛
⎞
⎞
−
34
079
=
K
⎛
075
⎛
⎝
h
⎝
r
Now, the required thickness can be calculated using formula (3.11):
2
75 15
2
Φ
KK
T
1 520
⋅⋅
u
⋅
Thcr
.
520
.
Δ
D
0 035
0 035
048
.
≥
⋅
48
m
=
⋅
=
t
k
.
0
.
035
Ψ
Kg
s
2
0050
⋅
38 2
981
⋅
.
050
s
048048
091
omplies
480
Δ
.
D
k
053
≥
=
=
⇒
⇒
c
t
