Geoscience Reference
In-Depth Information
and the width of the suspended part remains fairly uniform. During this stage
b
0
≤
b
free
(see Figure F.1, stage II).
The tensile load acting in the geotextile at this stage depends on the fill material.
Initially, if we consider the fill material to have zero internal friction (i.e. it is a liquid),
the tensile load is governed by the friction between the geotextile and the sides of the
split barge. The tensile load can be derived from an equilibrium consideration of the
loads acting on the geotextile at the opening of the split barge [22]:
W
L
′
(F.2)
T
05
=⋅
θ
cos
sin
θ
+
μ
where:
μ
=
friction coefficient between the geotextile and the split barge [-].
For design purposes it is sufficient to increase the tensile load calculated using
formula (F.2) by 10% to obtain the maximum tensile load that can occur during the
opening of the split barge (stages I and II).
If the geotextile container is filled with a material that has internal friction (like
sand) the tensile load in the geotextile is determined not only from the friction between
the geotextile and the sides of the split barge but also from the shear stress that the fill
material itself generates on the geotextile. In [22] the following formula is given:
W
L
in
′
⋅
μθ
⋅
θ
cos
s
−
(F.3)
TF
05
F
F
+
⋅
h
θμ
in
θ
+
co
s
⋅
s
where:
2
(F.4)
F
h
Kc hK
2
h
⋅
⋅
h
F
F
h
h
b
c h
γ
a
b
c h
K
γ
a
a
When the geotextile container is filled with sand the second term in formula (F.4)
equals zero because sand has no cohesion (i.e.
c
=
0).
In formula (F.4):
1
45
2
(F.5)
K
=
tan(
2
45
° −
φ
′
/2
=
2
° +
γ
a
a
′
tan(
2
φ
/2
where:
h
=
horizontal load in the axis of the geotextile container [kN/m];
γ
=
unit weight of the geotextile container [kN/m
3
];
b
=
height of the geotextile container (for closed split barge) [m];
K
γ
a
=
coefficient of active earth pressure [-];
φ
′
=
internal friction angle of the sand fill [degrees].
