Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Has files: NoSubject: search.filters.subject.Rubble mound breakwaters

Search Results

Now showing 1 - 10 of 15
  • No Thumbnail Available
    Item
    Review of Literature on Design of Rubble Mound Breakwaters
    (Springer Science and Business Media Deutschland GmbH, 2023) Akarsh, P.K.; Chaudhary, B.
    Breakwaters are offshore structures constructed to protect the coastal and port structures from uncertain and extreme wave conditions. It creates tranquility in and around the harbor side for smooth transactions of ships. Depending upon the availability of rocks, depth of water, geotechnical nature of the sea bed, and its functional requirement, breakwaters are classified as rubble mound breakwaters, caisson type, and composite breakwaters. Rubble mound is a flexible, heterogeneous, trapezoidal structure consisting of quarried rocks in the core and artificial armor as a protection cover. Armor units at the outer layer absorb most of the energy and under-layers prevent transmission of the wave energy. The main advantage of the rubble mound is its failure is not immediate and can be repaired by adding the stones in the flushed-out part. More than 50% of breakwaters constructed around the world are of rubble mounds. Looking at its importance for coastal structures, this paper gives an overview of the basic aspects of rubble mound breakwaters, design considerations, and its failure conditions. The design of rubble mound breakwaters include hydraulic stability of it against wave actions, structural components design, and geotechnical considerations. The common modes of rubble mound failure are hydraulic damage, erosion of subsoil, slope failures, toe erosion, overtopping, liquefaction of subsoil, crest erosion, and leeside damage. The failure of rubble mound breakwater at Ergil fishery port, Turkey due to Kocaeli earthquake of 1999 has been explained to support this part. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
  • No Thumbnail Available
    Item
    Seismic Responses of Rubble Mound Breakwater: Numerical Analyses
    (Springer Science and Business Media Deutschland GmbH, 2024) Akarsh, P.K.; Chaudhary, B.; Sajan, M.K.; Kumar, S.
    Rubble mound breakwater is a coastal structure, which is constructed to provide tranquil conditions in and around the port areas. Generally, the rubble mound structures are subjected to vigilant waves throughout the year. After the earthquakes of Kobe (1995), Kocaeli (1999), Tohoku (2011) etc. it is observed that the breakwaters can collapse due to failure of foundation and by seismic activity. Hence, in order to assess this problem, the current investigation deals with the study of rubble mound breakwaters and it is behavior against the seismic forces using numerical analysis. A finite element software PLAXIS is used for the numerical simulations. For study, a prototype has been selected and numerical model developed is a conventional rubble mound breakwater. In countermeasure model, the sheet piles in the foundation soil on extreme side of mound were considered. The numerical analyses have been done for constant seismic loading and soil properties. The parameters like vertical settlement and horizontal displacement were determined at different nodes. The vertical settlement was observed to be predominant in the crest region and it was reduced by 38% in countermeasure model. The displacement contours were significantly seen in core and armor units. The horizontal displacement of mound was seen by lateral movement of outer layers and it was 23% lesser for sheet pile reinforced model. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
  • No Thumbnail Available
    Item
    Dynamic Analysis on the Seismic Resilience of Rubble Mound Breakwaters
    (Springer Science and Business Media Deutschland GmbH, 2025) Sajan, M.K.; Chaudhary, B.; Akarsh, P.K.; Sah, B.
    In the aftermath of past earthquakes causing damage to rubble mound (RM) and exposing coastal infrastructure to potential tsunami waves, this paper presents an in-depth investigation into the seismic performance of these critical coastal defenses. Employing advanced finite element analysis software, the study utilizes sinusoidal input ground motions with varying accelerations to simulate the seismic response of RM breakwaters. The research methodology entails meticulous finite element modeling of conventional breakwaters and the strategic integration of reinforcements, such as sheet piles and geogrids. A detailed analysis of displacement profiles and changes in pore pressures within the seabed soil beneath the RM breakwater is conducted, offering crucial insights into its seismic behavior. The investigation explores diverse combinations of reinforcements to assess their efficacy in fortifying the breakwater against seismic loading. Seismic response is simulated by imposing sinusoidal input waves as displacements at the bottom boundary of the soil layer, with free-field boundaries at either end to eliminate reflective effects. This research significantly contributes to the optimization of RM breakwater designs, providing practical strategies for enhancing their seismic performance in coastal engineering applications. The use of finite element analysis facilitates a nuanced understanding of dynamic interactions, allowing for the development of robust and resilient coastal structures to withstand seismic challenges and mitigate potential damages to coastal infrastructure and life. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
  • No Thumbnail Available
    Item
    On numerical modelling of waves, currents and sediment movement around Gurupur-Netravathi river mouth
    (2010) Radheshyam, B.; Rao, S.; Shirlal, K.G.
    This paper presents an overview of the investigations that were carried out to understand the coastal process along Bengre and Ullal at the Gurupur-Netravathi River mouth in the west coast of India. This river inlet was facing problems of migration and siltation since several decades and therefore two rubble mound breakwaters were constructed during the year 1994 as an intervention to maintain the inlet mouth. After the construction of these river training jetties, the inlet was stabilized, but severe erosion has been taking place along the Ullal spit on the south side of southern breakwater, since 1996 and heavy accretion on the North of Northern Breakwater along Bengre spit, which is now almost stabilized. This study has been undertaken to understand the hydrodynamics along the beaches adjoining the river mouth. For the present study, various field data was collected for the post monsoon season of 2006. The hydrodynamic (HD), Parabolic mild slope (PMS) and Sediment transport (ST) modules of MIKE-21 software were used to understand the hydrodynamics of the study area. Before the model was made use, it was first validated by using field data to understand the hydrodynamics of the area. Since the field data is of limited duration, data collected from the NMPT wave buoy for an entire year was used for the model simulation. From the studies it was confirmed that current direction and sediment movement follow a similar pattern in monsoon and pre-monsoon and a different pattern during post-monsoon. It is observed that the main cause of erosion is due to direct action of waves on the adjoining beaches of the coast and the beaches in the study area are generally in dynamic equilibrium with a small amount of erosion at Ullal. © 2010 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
  • No Thumbnail Available
    Item
    Study on performance of Savonius rotor type wave energy converter used in conjunction conventional rubble mound breakwater
    (Elsevier Ltd, 2014) Bikas, G.S.; Ramesh, H.; Hindasageri, V.
    In the present study the performance characteristics of a wave energy converter used in conjunction with conventional rubble mound breakwater is investigated using physical model studies. Savonius rotor type converter is used in the present study. The rotor is placed in front of the breakwater towards seaward side can cause substantial wave attenuation and thereby reduce the impact on the breakwaters apart from generating electricity. Regular waves of wide ranging heights and periods are considered in the present study. Tests are carried out for different spacing between the breakwater and the wave energy converter (X/d=10 to 40) and for two depth cases viz. shaft of the rotor at SWL (z=0) and rotor fully submerged case (z=-55 mm). The dead weight loading (shaft power) capacity for the rotor is also optimised in the present study. From the experimental study, it is observed that at a distance of X/d=22.5 to 30 and for submerged case (z=-55 mm) the rotor is found to be most efficient. It results in a wave height attenuation of 15-33%. © 2014 Elsevier Ltd.
  • No Thumbnail Available
    Item
    Prediction of wave transmission over submerged reef of tandem breakwater using PSO-SVM and PSO-ANN techniques
    (Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Kuntoji, G.; Rao, M.; Rao, S.
    Protection of the damaged breakwater from the high-intensity wave action has become inevitable. Submerged reef can act as a protective structure in reducing the wave action. Further, placed the reef structures on the sea side of a conventional rubble mound breakwater will reduce the effects of wave action. The conventional breakwater and reef structure combination is a tandem breakwater. Keeping in mind the end goal to decrease the complexities associated in model scaling, time constraints and cost in conducting the experiments, an attempt is made to apply soft computing techniques such as an Artificial Neural Network (ANN) and Support Vector Machine (SVM) to model various problems of real case scenario, where mathematical modelling is also difficult. In the present study, Particle Swarm Optimization (PSO) optimizes various parameters of ANN and SVM model in predicting the wave transmission over a submerged reef of the tandem breakwater. The performance of proposed hybrid models such as PSO-ANN and PSO-SVM is evaluated using statistical indices. The results show that PSO-SVM tool performs better in predicting the wave transmission compared to PSO-ANN. © 2018, © 2018 Indian Society for Hydraulics.
  • No Thumbnail Available
    Item
    Assessment of dynamic pressure and wave forces on vertical-caisson type breakwater
    (Taylor and Francis Ltd., 2022) Kumaran, V.; Rao, M.; Rao, S.
    The design and construction of coastal structures such as breakwaters, at great water depths is rapidly increasing as a result of the increasing draught of large vessels and off-shore land reclamations. Vertical caisson breakwaters may be the best alternative compared to ordinary rubble mound breakwaters in larger water depths, in terms of performance, total costs, environmental aspects, construction time and maintenance. To fulfilling the functional utility and impact of the structure on the sea environment, it is necessary to study the hydraulic performance. This can be found by field investigation, numerical simulations and by physical modelling. Scale modelling techniques are used to study various coastal engineering problems. This article presents the results obtained by conducting series of experiments in two-dimensional wave flume to assess the hydrodynamic performance of vertical-caisson breakwater, which is made of concrete, with the protection of toe. The dynamic pressure distribution, wave runup, wave reflection, wave forces and stability parameter on the vertical caisson breakwater are discussed. The maximum wave force on the wall breakwater is calculated from measured pressure values and is compared with the forces calculated by Goda’s and Sainflou wave theories. © 2021 Informa UK Limited, trading as Taylor & Francis Group.
  • No Thumbnail Available
    Item
    Hydrodynamic analysis of floating tunnel with submerged rubble mound breakwater
    (Elsevier Ltd, 2022) Patil, S.B.; Karmakar, D.
    The wave interaction with a Submerged Floating Tunnel (SFT) of two different shapes (rectangular and circular) in the presence of a submerged rubble mound breakwater (SRMB) is analyzed using Multi-Domain Boundary Element Method (MDBEM). Furthermore, three typical SFT cross-sections (rectangular, trapezoidal, and circular) of equal area and structural height in the presence of SRMB under similar operating conditions are investigated as comparative study to analyse the influence of SFT shape on hydrodynamic performance. The performance of the tunnel configurations is analyzed as a (a) measurement in terms of hydrodynamic efficiency and (b) criterion for tunnel structure safety. In both shallow and intermediate water depth regions, the critical wave number and the critical angle of incidence followed by resonant wave reflection are identified, and suitable structural parameters of SRMB such as structural porosity in the armour layer, relative crest width, relative gap width between the SFT and the SRMB, structural width and position (relative draft of tunnel structure measured from the free water surface) of SFT are investigated. The present parametric investigation of SFT with SRMB reveals an improved wave transformation properties for a specific range of water depth. The coupling of SRMB has resulted not only in a reduction of wave-induced force acting on SFTs, but also in improved performance in wave transformation characteristics as a coastal protection structure, which is substantially determined by SRMB structural properties. Due to the presence of SRMB, the SFT's safety is improved, which may also add stability to the SFT. A comparative study of different distinct cross-sections of SFTs indicates that, due to its shape, the circular SFT has a reduced reflection capability and lower wave-induced force with nearly the same wave transmission as the rectangular and trapezoidal SFT. The study performed on the coupled SFT and rubble mound breakwater may be useful in determining the suitability of breakwaters not only for maintaining shore dynamics but also for protecting important floating structures for underwater transit. © 2022 Elsevier Ltd
  • No Thumbnail Available
    Item
    Hydrodynamic performance of submerged breakwater in tandem with thin-walled as submerged reef structure
    (SAGE Publications Ltd, 2023) Patil, S.B.; Karmakar, D.
    The interaction of gravity waves with submerged tandem breakwater of different structural configurations is analysed in finite water depth using the Multi-Domain Boundary Element Method (MDBEM). The wave transformation characteristics, wave forces and wave energy dissipation are analysed considering the presence of impermeable type thin-walled as reef structure in front of the primary submerged breakwater. The comparative study is performed for the submerged structures of various shapes (trapezoidal, triangular, rectangular and thin-walled) and types (rubble mound, permeable, impermeable) that are designed to function together as a tandem breakwater. The effect of varying angle of incidence, relative submergence depth, and relative gap between the reef structure and primary breakwater on wave reflection and transmission are derived for the suggested tandem breakwater models. Among all the impermeable-type models, the thin-walled as reef structure designed at a distance in front of thin-walled as a primary submerged breakwater as a tandem is observed to perform efficiently in terms of energy dissipation and also offers an optimum wave transmission for both short and long wave conditions. Further, the permeable and rubble mound type trapezoidal tandem breakwater offers higher energy dissipation in comparison with all other breakwaters. In view of the design considerations and structural stability of submerged breakwaters, the addition of a reef structure acts as a defence system for the primary breakwater and also creates an energy dissipation zone that allows the shore dynamics to be preserved, making tandem models more effective in the harbour region. © IMechE 2022.
  • No Thumbnail Available
    Item
    Geosynthetic reinforced rubble mound breakwater for mitigation of tsunami-induced damage
    (Elsevier Ltd, 2024) Sajan, M.; Chaudhary, B.; Akarsh, P.K.; Kumar, S.
    Several rubble mound breakwaters (RMB) were damaged and even collapsed during the past tsunamis. The main reasons for the failure of the breakwaters occurred due to the combined effects of seepage and scouring. Limited articles are available dealing with the behaviour of RMB during the tsunami. Furthermore, few available articles are related to developing countermeasures for the RMB against tsunamis. Therefore, an attempt has been made in the study to determine the exact behaviour of the RMB under the action of the tsunami. In addition, the main aim of the present study is to develop countermeasures to make the breakwater tsunami resilient. The present study proposes a novel geosynthetics-reinforced RMB to mitigate tsunami-induced breakwater damage. Based on the available information, this is the first time geosynthetics have been used in the RMB to mitigate tsunami-induced damage. Geogrid layers, geobags, sheet piles and crown walls (with shear keys) are adopted as countermeasure elements against the tsunami. Since the height of a tsunami can exceed its design tsunami height, tsunami waves were allowed to overflow the breakwater in physical model tests. Comparative analyses between the reinforced and unreinforced RMB were performed by conducting physical model tests, analytical tools, and numerical simulations. © 2023 Elsevier Ltd