Geotextile tubes containment dyke

Offshore wetlands developments are usually located in sheltered marine locations and serve as habitats for local and migrating birds. Fig. 20.29(a) shows a cross section of a typical offshore wetlands development area in which dredged spoil has been used as the hydraulic fill to construct the wetlands habitat. The wetlands development is contained within geotextile tube containment dykes which also can be filled with the dredged spoil material, which thus makes full use of the dredged spoil. If the... 

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 20.24 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.

Alternative spoil containment dyke structures have been used where hydrauhc conditions permit and where cost savings are important. For example. Fig. 20.28(b) shows the use of geotextile tubes as a dredged spoil containment dyke. The advantage of this solution is that the dredged spoil itself may be used as the fill inside the geotextile mbes, which increases the effective spoil capacity of the containment facility. This... 

Wetlands development using geotextile tube containment dykes... 

Figure 20.29 Offshore wetlands development, (a) Cross section through typical offshore wetlands development area and (b) construction of combined spoil containment and wetlands development area utilising geotextile tube containment dykes.

Fig. 20.29(b) shows the constmction of an offshore wetlands habitat area using spoil excavated from a nearby mnnel construction. The spoil, which consisted of fine, uniform sand, was also used to fill the geotextile tube containment dyke surrounding the wetlands development area. For permanent protection, a rock armour layer was placed over the outer surface of the geotextile mbe containment dyke. 

Geotextile tube Planted vegetation containment dyke... 

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