Effect of deformations on the hydraulic stability of coastal structures made of geotextile sand containers

The hydraulic stability of geotextile sand containers (GSCs) for dune reinforcement, seawalls, revetments and artificial reefs for shore protection against storm waves has been studied within an ongoing extensive research program at Leichtweiß Institute. Although the effect of the deformation of the sand containers on the hydraulic stability is significant, no stability formula is available to account for this effect and the associated processes which have led to the observed failures. To achieve a better understanding of these processes and to analyze the influence of the deformations on the stability of coastal structures made of GSCs, different types of scale model tests have been performed. Results from a variety of scale model tests on: (i) wave-induced forces on the sand containers, (ii) internal movement of sand in the containers and (iii) underlying processes leading to the deformations and displacement of the containers have clarified many of the hydrodynamic processes involved, showing that indeed the deformations of the geotextile sand containers substantially affect their stability.