Hydraulic Stability of Submerged GSC structures

Abstract

Geotextile Sand Containers (GSCs) are used for the construction of coastal structures as a low cost and softer alternative to expensive and hard structures made of concrete or rubble. However, the hydraulic stability of GSC-structures still needs to be investigated for a better understanding of the processes and the parameters of GSCs, which cause the failure. This study focused on the effect of the geotextile material, the sand fill ratio, and the inclination in GSC placement towards the hydraulic stability of submerged GSC structures. Four sets of specifically designed laboratory model experiments were carried out to study the influence of aforementioned parameters on the GSC stability. A new failure mode of GSCs was identified through the model experiments and named as “uplift and drift”. From the test results (wave and damage analysis), new stability curves were developed and compared with each test scenario. The influencing parameters were quantified and the relative importance of each parameter for the hydraulic stability of submerged GSC structures was assessed. Finally, it was concluded that the sand fill ratio is the key influencing parameter among all considered parameters. For the tested sand fill ratios, the hydraulic stability increases, when the sand fill ratio increases. Furthermore, it was concluded that the stability of inclined GSCs is higher than horizontally placed GSCs. However, stability decrement was concluded for GSC made from the woven geotextile material comparative to the nonwoven GSCs. Hence, the type of the geotextile material and the inclination of GSC placement were found to be two important aspects that need to be considered, when designing GSC-structures.