Geotextile tubes

Geotextile tubes for dewatering dredged spoils until water is removed... 

Three types of geotextile containment units are used in marine engineering, differentiated on the basis of shape and volume geotextile bags, geotextile tubes and geotextile containers (Fig. 20.2). 

Figure 20.2 Types of geotextile containment units used in marine engineering, (a) Geotextile bags, (b) geotextile tubes and (c) geotextile containers.

Empty geotextile tubes are normally described in terms of either theoretical diameter... 

Figure 20.5 Geotextile tube parameters, (a) Empty geotextile tube parameters and (b) filled geotextile tube parameters.

Table 20.1 Approxiniate relationships between empty and filled geotextile tube parameters at maximum fill height...

The volume of fiU contained inside geotextile tubes can be also related to the hjIDj ratio and the theoretical diameter Z>r. Fig. 20.6 shows the fill volume per unit length of geotextile tubes for three different-sized tubes filled at different hilD-Y ratios. 

Figure 20.6 Fill volume per unit length of geotextile tube.

Figure 20.7 Circumferential tensile stresses in geotextile tube skins.

Geotextile tubes are used for a range of marine engineering applications including revetments (Fig. 20.8(a)), offshore breakwaters (Fig. 20.8(b)), protection dykes... 

Geotextile tube sand dike core covering... 

Waves break across breakwater calm water Ocean, waves / Geotextile tube breakwater... 

Geotextile tube Hydraulically dike core placed fill / Permanent protection rock armour... 

Figure 20.8 Marine engineering applications of geotextile tubes, (a) Revetments — exposed and submerged, (b) offshore breakwaters, (c) protection dykes, (d) containment dykes, (e) training walls and (f) groins.

Figure 20.11 Three different revetment structures using geotextiles. (a) Rock revetment utilising geotextile filter, (b) revetment utiUsing geotextile bags and (c) revetment utilising geotextile tubes.

Geotextile tube revetments have much in common with geotextile bag revetments (Section 20.3.3) except that the units are of much greater mass-gravity and are continuous in a longitudinal direction. This makes them considerably more stable even when subjected to extreme weather events. 

Geotextile tube revetments are designed similar to geotextile bag revetments in assessing the possible modes of failure (Fig. 20.14). Bezuijen and Vastenberg (2012) provide relationships for assessing geotextile tube stability when subjected to external water forces. 

Geotextile tubes are used for both exposed and submerged revetments. When the revetment is to be continually exposed, care should be taken to ensure the geotextile tube skin has the required durability. Alternatively, a rock armour layer can be placed over the outer surface of the geotextile tube to ensure long-term performance in exposed conditions. Geotextile tubes are particularly suited for use in submerged... 

Figure 20.15 Single-height geotextile tube revetment.

Figure 20.23 Exposed breakwater with rubble core and equivalent with geotextile tube core, (a) Breakwater with a rubber core and (b) equivalent breakwater structure using geotextile tube core.

Figure 20.24 Different containment dyke configurations using geotextiles, (a) Rubble containment dyke and (b) geotextile tube containment dyke.

Alternative containment dyke structures have been constructed in which mbble fill has proved to be expensive or unsuitable. For example, geotextile mbe containment dyke structures (shown in Fig. 20.24(b)) have become common in which geotextile tube units substitute for the rubble fill. Here, the geotextile tubes can be filled hydraulically with locally available sand fill to construct the containment dyke. Later, the outside of the structure can be covered with rock armour for permanent protection. Fig. 20.26 shows an example of a geotextile mbe containment dyke with rock armour being placed over the exterior for permanent protection. 

Figure 20.26 Geotextile tube containment dyke for land reclamation. Courtesy TenCate Geosynthetics.

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