PIANC Panama - Agenda

15:30 - 17:00
Room: Track D (Amsterdam - 2nd Floor) - 4:3 Format
Chair/s:
Esteban Biondi
Geotextile Tube and Gabion Armoured Seawall for Coastal Protection - An alternative
Sherlin Prem Nishold, Ranganathan Sundaravadivelu, Nilanjan Saha
Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai - 60036.

The present study deals with a site-specific innovative solution executed in the northeast coastline of Odisha in India. The coastal state of Odisha is almost protected with saline embankment for a length of 475 km along the shoreline, which was constructed with locally sourced soil. A certain stretch of saline embankment has been observed to be regularly eroded during the, storm surge, tides, waves, and flood etc. The damage to the saline embankment was posing a significant threat to the lives and livelihood of the coastal communities. In addition to this, the coastline was also affected by two cyclones, viz. Phailin (2013) and Hud Hud (2014). The coast near the pentha village was subjected to severe erosion for the past 25 years, whereas the tidal ingression is around 500 meter into the land since 1999. The erosion of existing embankment at Pentha ( odisha ) has necessitated the construction of a retarded embankment. The retarded embankment which had been maintained yearly by traditional means of ‘bullah piling’ and sandbags, proved totally ineffective and got washed away for a stretch of 350 meters in 2011, so pertaining to the site condition it is required to design an effective coastal protection system prevailing to a low soil bearing capacity and is continuously exposed to tides and waves. Conventional hard engineered materials for coastal protection are more expensive since they are not readily available near to the site.Moreover, they have not been found suitable for prevailing in in-situ marine environment and soil condition. Geosynthetics are innovative solutions for coastal erosion and protection are cheap, quickly installable when compared to other materials and methods. Therefore, a geotextile tube seawall was designed and built for a length of 505 m as soft coastal protection structure. A scaled model (1:10) study of geotube configurations with and without gabion box was conducted to better understand the hydrodynamic characteristics for such configurations. The scaled model in the mentioned configuration was constructed using woven geotextile fabric as geo tubes. The gabion box was made up of eco-friendly polypropylene tar-coated rope and consists of small rubble stones which increase the porosity when compared to the conventional monolithic rubble mound. In such a configuration, multi-tiered geotextile tube seawall was constructed with three layers of 10 hydraulically filled geotextile tube as the core, while stone filled polypropylene tar coated rope gabion boxes acted as armor layer for the structure. The gabion was placed layer by layer in the form of English bond brickwork technique and perfectly laced together horizontally and vertically. This scaled model was examined for full submerged and emerged water conditions for different wave heights and different wave periods. The geotextile tube with gabion showed good wave energy dissipation characteristics Futhermore, reflection characteristics of this model were also quantified. Thereafter, the design was implemented as a pilot project on Pentha coast with some modifications during construction that involved using double steel sheet pile wall protected by rubble toe to mitigate scour. This case study establishes geo-tube seawall as an alternative to the conventional method of coastal protection. Additionally, this study also highlights the design aspects and challenges encountered in construction.


Reference:
Mo-S3-D - Marinas-4
Session:
Session 3 - Sustainable and resilient marina design - Marinas Working with Nature (best practices and case studies)
Presenter/s:
Sherlin Prem Nishold
Room:
Track D (Amsterdam - 2nd Floor) - 4:3 Format
Chair/s:
Esteban Biondi
Date:
Monday, 7 May
Time:
15:30 - 17:00
Session times:
15:30 - 17:00