Geoscience Reference
In-Depth Information
To get an evenly distributed filling, adjacent ports can be opened and closed;
To prevent the geotextile tube rolling away during filling, the tube must (tempo-
rarily) be fixed horizontally. A slight slope in the foundation can cause tilting or
rolling. It must be ensured that the horizontal fixing forms no hindrance to the
change in geotextile tube shape during filling;
The machinery used during construction must be chosen with a view of the scale
of construction. For example, for a small-scale installation with geotextile tubes
a smaller installation set will be required;
The ratio between the filling time and the total construction time (the construc-
tion efficiency factor) can fall to 50% when taking into account changing the
barge, changing the suction dredger/ground compressor, adjusting the cutter suc-
tion dredger or suction dredger, fluctuating weather conditions (wind, wave, cur-
rent), changing the geotextile tube, etc. As a result, the construction time is at
least twice the filling time;
A multilayer tube structure is feasible but must be more broadly set up given the
added space it requires. The gaps between tubes have to be filled up with sand/
fine granular material and it must be ensured that this supplementary fill material
does not wash away when the tube lying above is being filled;
The elements used in a multilayer tube structure must be the same size (insofar as
possible) in view of the standardisation of the construction process.
5.7 CALCULATION EXAMPLE
Given:
The example is a dam composed of stacked geotextile tubes (figure 5.11) in a
lake. The task is to test the stability of the structure.
Parameters
Degree of filling of the geotextile tubes:
f
=
0.7 (70%);
Circumference of the geotextile tubes:
S
=
12.3 m;
Geotextile tube material: woven polypropylene (PP);
Maximum tensile strength of the geotextile:
T
m
=
80 kN/m;
Pore size of the geotextile tube:
O
90
=
250
μ
m;
Figure 5.11
Cross-sectional sketch of the dam structure.
