Geoscience Reference
In-Depth Information
The strength of the geotextile is mainly governed by the loads to which the
geotextile tube is subjected during filling. The geotextile must meet the following
overall requirements:
Be sufficiently permeable;
Be sufficiently sand-tight;
Be resistant to pressures in the geotextile tube (during filling);
Be resistant to localised loads (tearing, vandalism);
Be resistant to UV radiation.
In addition to the choice of geotextile, the stability of the whole structure must be
evaluated. Experience has shown that the construction of a geotextile tube structure
with several layers can be difficult. It is preferable to design a single-layer structure uti-
lizing geotextile tubes with a relatively large diameter. A multilayer structure is possible
but it has to be more broadly erected, which takes up additional space (see figure 5.5).
To make an assessment of the number of geotextile tubes required to achieve a par-
ticular design profile, or the tensile loads acting in the geotextile, information must be
acquired on the dimensions of the geotextile tube after filling. There are various methods
of calculation available (see Appendices D and E) that give an approximation of the (ulti-
mate) shape of the filled geotextile tube and the tensile loads acting in the geotextile.
At a certain degree of filling a minimum height and maximum width can be
determined (see Figure 5.6).
An initial estimation of the dimensions and filled shape can be calculated using
the design formulae below. Experiments in the Delta flume of Deltares [38] show
that the best estimation of the initial shape (without compaction) are found using
the Timoshenko method (see Appendix E and [44]). Computer programs such as
GeoCoPS [21] also use this method.
Figure 5.5
Principle of multilayer stacking.
Figure 5.6
Initial estimation of filled geotextile tube dimensions.
