Reinforced dunes

By layup and spray-up techniques, large- and short-run reinforced items are fabricated. Examples include boats of all kinds, dune buggies, all-terrain vehicles, custom auto bodies, truck cabs, horse trailers, motor homes, housing modules, conCTete forms, and playground equipment... 

These advances, together with numerous advantages of GSCs as soft rock, have contributed to extend the use of GSCs to permanent coastal defenses, including a wide range of types of structures such as seawalls, revetments, groins, artificial reefs, offshore breakwaters, perched beaches, dune reinforcement, core of rubble mound structures, scour protection, etc. (Fig. 21.1). 

In particular, they are more versatile in application and are used for different class of structmes, including dune reinforcement, seawalls and revetments, detached breakwaters and artificial reefs, groins, etc. (see Fig. 21.5). Comprehensive large-scale model investigations on GSCs used for the scour protection of monopile foundation of offshore wind turbines have also been conducted by Griine et al. The results are described in more detail in a final report by Oumeraci et... 

Revetments, seawalls, and reinforcement of beach-dune system... 

An impressive example of the performance of such a last defense line behind a beach nourishment is the wrapped sand containment needle-punched composite geotextile (woven PP slit film and nonwoven PET) to reinforce a dune on the island of Sylt (North Sea, Germany) is shown in Fig. 21.8. 

Fig. 21.8. Geotextile containment for dune reinforcement, Sylt/Germany (extended and modified from Ref. 26).

Moreover, smaller containers have many advantages over larger containers and tubes (see Sec. 21.1 and Ref. 2). A comparative analysis of containers with V = 0.75 m and containers with a 30 times larger volume for dune reinforcement which confronted the pros and cons of both methods from the client and contractor view point clearly resulted in the selection of the smaller containers. ... 

Fig. 21.9. Beach and dune reinforcement with geotextile sand containers, (a) Beach reinforcement in Australia, (b) Stockton Beach Revetment, and (c) Dune Reinforcement in Wangerooge, North Sea/Germany. ...

Geotextile sand containers (GSCs) represent nowadays a soft and low cost alternative to conventional hard structmes made of rock and concrete. Moreover, GSC-made structures are environmentally more appropriate and more easily reversible as they need essentially sand as construction material which is generally available at any coastal site. As soft rock GSCs can be manufactured at any size and used to build any type of shore protection structure, including scour protection, dune reinforcement, and repair of undermined structures. 

J. Vohlken, H. Lind and J. Witte, Dune reinforcement with geotextile sand containers, HANSA 4, 60-62 (2003) (in German). 

Fig. 20.31(b) shows the constmction of a geotextile tube—reinforced frontal dune. The geotextile mbe is constmcted to the required design height and then covered with sand to form the frontal dune stmcture. To make the stmcmre more resistant to surface erosion resulting from wind, sea grasses can be planted on the sand surface of the reinforced frontal dune stmcmre. 

Figure 20.31 Geotextile tube—reinforced frontal dune structures, (a) Cross section through a geotextile tube reinforced frontal dune structure and (b) construction of geotextile tube reinforced frontal dune.

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