Faculty Publications

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    Hydraulic performance of tandem breakwater with concrete cubes as armour units
    (2009) Rao, M.; Shirlal, K.G.; Rao, S.; Bharadwaj, P.
    Tandem breakwater system consists of a conventional breakwater protected by a seaward submerged reef. The paper discusses physical model study on the hydraulic performance of an isolated as well as tandem breakwater system subjected to varying wave climate and water depths, while keeping a constant crest width of submerged reef. The breakwater in both the cases are armoured with concrete cubes and the submerged reef is constructed with natural stones. It is found that the isolated breakwater is damaged for all waves except those of period 2.5 s. While a submerged reef of crest width (B) 0.40m placed at a seaward spacing(X) of 2.5m transmits only 52% to 81% of the incident wave height and thereby reduces the wave force on the main structure which inturn protects the inner main breakwater completely without causing any damage.
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    Development of concrete armoured protected breakwater structure
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Rao, M.; Rao, S.; Shirlal, K.G.
    The present work involves the physical model study of stability of conventional single breakwater and the reef protected breakwater, constructed with concrete cube as an artificial armour unit. Regular waves of wide ranging heights and periods are used. The tests are carried out for different spacings between the two structures (X/d = 2.5-13.33) and for different relative heights (h/d = 0.625-0.833) and relative widths (B/d = 0.25-1.33) of the reef. It is observed that a reef of width (B/d) of 1.0-1.33 constructed at a seaward distance (X/d) of 6.25-8.33 exhibits a transmission coefficient (Kt) of 0.38-0.708, wave dissipates energy and protect the breakwater optimally. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Damage Analysis of Toe for Wall Type Breakwaters
    (Springer, 2022) Kumaran, V.; Rao, M.; Rao, S.
    This study presents the result obtained from a series of experiments conducted in regular wave flume to assess the stability of toe protection for wall type breakwater. In the present paper, the determination of the size of the toe armour units and its cross-section for the stable design is presented. The applicability of the Brebner and Donnelly (Coast Eng Proc 1: 24, 1962) design curve for depth limited conditions is validated for a certain fixed relative foundation depth (d1/d) and wavelength (L), the significant wave height (Hs). The main aim of the tests is to know the stability of the toe armour units and % damage level for varying wave characteristics. The results are represented in non-dimensional graphs and it is observed that the maximum percentage damage observed for the depth of water 0.35 m is 5.2 %. © 2021, The Institution of Engineers (India).
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    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.
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    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