Geoscience Reference
In-Depth Information
Table 6.1 Relation between the size of a split barge and the placed dimensions of a geotextile container
for a geotextile container with a degree of filling of 40% that fills 80% of the barge bin. The
width given is an indication since the width changes with the height. This table is a revised
version of the table from [14, in Dutch].
Split barge
Geotextile container dimensions after placement
Hold contents
(80% filled)
[m 3 ]
Height [m]
deviation
± 25%
Hold length
[m]
Filling
[m 3 ]
Circumference
[m]
width
[m]
A (V/l)
[m 2 ]
200
23.4
160
14.5
6.7
6.8
1.25
250
25.2
200
15.7
7.2
7.9
1.40
300
26.8
240
16.6
7.6
9.0
1.50
350
28.2
280
17.5
8.0
9.9
1.55
400
29.5
320
18.3
8.4
10.8
1.60
450
30.7
360
19.0
8.7
11.7
1.65
500
31.7
400
19.7
9.0
12.6
1.75
550
32.8
440
20.4
9.3
13.4
1.80
600
33.7
480
21.0
9.6
14.2
1.85
In some cases, the height of the dropped geotextile container is important, for
example where a dam is built from these elements and where a distinction has to
be made between containers dropped in shallow water (less than 8 m depth) and
in deep water (more than 8 m depth). The cross-sectional shape of a geotextile
container dropped in deep water can be assumed, as a first approximation, to form
a rectangle. For the filled cross-sectional area of the bin this is equal to the filling
volume ( V ) divided by the bin length ( l ). By dividing this filled cross-sectional area
by the width ( b ) of the geotextile container a more realistic height is found when
dropping in deep water. The method for calculating the height is generally not very
accurate since the height realised depends on many factors (drop procedure, sand
grain diameter and sand saturation). So, this must be checked and the procedure
adjusted where necessary (for example, if possible a higher degree of filling if the
height is too low). Due to these aspects it is difficult to determine the final shape
of the geotextile container when dropped in shallow water. The geometry of the
installed geotextile container could be determined by using a (multi-beam) echo
sounder after installation. It is recommended to determine the shape after every
container dropped. In this way it is possible to monitor the shape and position of
every individual container.
If a certain cross-sectional area has to be filled with geotextile containers in a
hydraulic structure, the values shown in Table 6.1 cannot be used to calculate the
filled cross-sectional area of an individual geotextile container. The geotextile con-
tainers will take on such a shape during the construction phase that the whole cross-
sectional area will be filled. In order to estimate the required number of geotextile
containers the filled cross-sectional area per geotextile container has to be calculated.
This is determined by dividing the filling volume ( V ) by the bin length ( l ). The (mini-
mum) required number of geotextile containers can be determined from the cross-
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