Hydrodynamic Performance of Coastal Geotube Embankment with and Without Gabion Boxes

Abstract

Erosion of shoreline is an important coastal phenomenon which takes place due to the movement of sand mass by tides, wave action, and wave induced currents. The often used materials, like artificial armour units or rubble mounds, for coastal protection, are very expensive and time-consuming to install, apart from not being readily available. Therefore Geo-synthetics, like geo textile-tube embankments are, innovative solutions for protection from coastal erosion when compared to other conventional materials and methods. Geo-tube with gabion is an excellent solution for scour protection applications as well as soil with low bearing capacity. It has noted from previous studies, high reflection coefficients of coastal structures can lead to poor performance during rough weather for conventional embankment. This results in increased possibility of scour and failure of coastal sea walls and quays. One way of dealing with this problem is to deploy embankments with high energy dissipation characteristics, using unique geometries of geo-tube embankments. Hence, detailed studies are carried out for a geo-tube embankment with ten geo-tubes in a four layer configuration. These studies involve a scaled model (1:10) with and without gabion boxes to understand the wave energy dissipation for such configurations better. The scaled model in the mentioned configuration of geo-tubes was of woven geotextile fabric. The gabion box is made up of eco-friendly polypropylene tar-coated rope which consists of small rubble stones that increase the porosity when compared to the conventional monolithic rubble mound. Then scaled model was examined for design water level for different wave heights and different wave periods and the results were analysed for various hydrodynamic coefficients. Based on these results, a prototype of this configuration is intended to construct for field trials on the coast of Pentha (Odisha, India).