Faculty Publications

Now showing 1 - 4 of 4

Coastal Protection Using Geosynthetic Containment Systemsâ€”An Indian Timeline
(Springer Science and Business Media Deutschland GmbH, 2021) Elias, T.; Shirlal, K.G.
Maritime countries like India face serious coastal erosion issues. Over 1200Â km of Indian coastline is identified as eroding. Unavailability and high cost of natural rocks remain as a major hindrance for construction of conventional hard options like breakwaters, seawalls and groynes. This has forced coastal engineers to find nature friendly and economical alternatives. Experiences from Australia, Germany and United States prove the efficacy of geotextile containment systems in coastal protection. This chapter aims at reviewing Indian examples of protection works using geosynthetic and geotextile containment systems from early 1980s. Geosynthetic protection structures include groynes, submerged reefs, seawalls and breakwaters. Benefits and difficulties in implementation of protection works are identified by reviewing prominent works conducted in the east and west coast of India. Experiences at Hamla, Dahanu and Pentha helped in replacing conventional structures with geotubes. Equilibrium beach profile is attained using near-shore geotube reef system at Hamla and Dahanu, Maharashtra, whereas reef constructed using geotextiles at Candolim, Goa suffered serious damage due to vandalism and toe scour. Geosynthetic systems along with gabions and rock armours improve the stability, wave dissipation and reflection characteristics as seen in Pentha, Odisha and Uppada, Andhra Pradesh. Lack of proper design criteria and deliberate destruction by vandals remains as the major threat. Countering these challenges, geosynthetic containment systems offer a cost-effective alternative to conventional coastal protection methods in India. Â© 2021, Springer Nature Singapore Pte Ltd.
Physical model studies on damage and stability analysis of breakwaters armoured with geotextile sand containers
(Elsevier Ltd, 2021) Elias, T.; Shirlal, K.G.; E.v, K.
Harnessing the advantages of geotextile sand containers (GSCs), numerous submerged breakwaters and shoreline protection structures have been constructed worldwide. But an emerged breakwater structure with geotextile armour units, capable of replacing the conventional structures, is rarely discussed. A 1:30 scaled physical experimentation is chosen as a preliminary investigation to test the feasibility of using GSCs as breakwater armour units. Structural design is evolved based on a comprehensive literature survey. The paper focuses on the stability parameters and damage characteristics of the proposed structure. Four different configurations are subjected to waves, confining to Mangaluru's wave parameters. Effect of armour unit size and sand fill ratio on the stability of the structure is analysed and it is concluded that changing sand fill ratio from 80% to 100% shot up the structural stability to a maximum of 14%. Increasing bag size also resulted in the increased stability up to 8%. Experiments revealed that the best performing configuration could withstand wave heights up to 2.7 m. Stability curves for all tested configurations are discussed and can serve as an effective guideline for designing GSC breakwaters. © 2020 Elsevier Ltd
Experimental Investigation of the Hydraulic Performance of Breakwater Structures with Geotextile Armor Units
(American Society of Civil Engineers (ASCE), 2022) Elias, T.; Shirlal, K.G.
Geotextile sand containers (GSCs) gained popularity recently as a modern age coastal protection measure. Its usability as an ecofriendly alternative for traditional breakwaters overcomes issues such as scarcity and quarrying prohibition of natural rocks. The current work involves a 1:30 scaled physical experimentation on the hydraulic performance of an emerged, nonovertopping breakwater model with GSCs. Four configurations of GSC structures are analyzed for their runup, rundown, and reflection characteristics confining to wave parameters of Mangaluru. The study revealed that the reflection coefficient (Kr) for GSC structures could range from 0.26 to 0.69. In addition, reducing GSC fill percentage from 100 to 80 is found to be more effective (up to 64%) in reducing reflection, runup, and rundown rates, than altering GSC size. These results can serve as a practical guideline for designing GSC breakwaters. © 2022 American Society of Civil Engineers.
Effect of armour unit layers and placement mode in the determination of stability of geotextile sand container (GSC) breakwaters
(Elsevier Ltd, 2022) Elias, T.; Geetha, T.; Shirlal, K.G.
Geosynthetic Sand Containers (GSCs) are increasingly harnessed for their coastal protection capabilities. Recent studies point to its efficacy to be used even as armour units of breakwaters. The current investigation aims at understanding the effect of armour unit layers and placement modes in altering the stability of GSC breakwaters. Single-layered and double-layered GSC structures with slope parallel and perpendicular placement are tested for stability against wave conditions of the Mangaluru coast. A 1:30 scaled monochromatic wave flume model study is adopted to detail the damage levels and stability of various GSC breakwaters. It is observed that the stability of structure increased by up to 17% when supplemented with double layers. Structure tends to be stable with increasing armour units size and fill percentage. Larger bags stacked to double layers is found to be the most stable configuration. 80% filled, slope parallel placement exhibited the least stability. The paper dealt with all factors affecting structure stability and deduced stability nomograms helpful for coastal engineers to design GSC breakwaters. © 2022

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