Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
Browse
9 results
Search Results
Item Hydraulic performance of perforated enlarged pile head breakwaters through laboratory investigation(Elsevier Ltd, 2021) Suvarna, P.S.; Hunasanahally Sathyanarayana, A.H.; Umesh, P.; Shirlal, K.G.An economical, ecofriendly and efficient breakwater system is vital for coastal protection and harbour tranquility. In this regard, various researchers are working to develop the appropriate solutions to encounter site-specific challenges. With this viewpoint, concept of enlarged pile head breakwater is developed. The study focuses on improving the hydraulic efficiency of pile breakwater by enlarging the structure near the free surface and providing it with perforations. Effect of percentage distribution of perforations, size of perforations and percentage of perforations on wave transmission, reflection and dissipation characteristics of the structure is investigated. The physical experiments are conducted in a two-dimensional wave flume under varying monochromatic wave climates. Results indicate that the pore size highly dominants the wave attenuation than considering the increasing percentage of perforations with the small size of the pore. Perforations effectively reduce the Kt of about 10%–18% to that of non-perforated pile head breakwater. Hydraulic efficiency of enlarged pile head breakwater is optimum when D/Hmax = 0.6, Y/Hmax = 1.0, b/D = 0.2, S = 0.25D, pa = 75% and P = 22.5 at 0.3 m water depth. A hybrid theoretical solution is developed based on the current set of experimental data for the quick estimate of hydraulic coefficients. The proposed hybrid equation for the perforated pile breakwater predicts more desirable values of Kt, Kr and Kd. The proposed concept of breakwater gives a reasonably enhanced hydraulic efficiency than the compared type of breakwaters. © 2021 Elsevier LtdItem Lateral Resistance of Finned-Piles in c– ϕ Soils: Experimental Investigations and Numerical Studies(Springer, 2023) Bariker, P.; Kolathayar, S.; Chandrasekaran, S.S.Finned pile foundation systems are advantageous at resisting lateral loads, particularly for offshore foundations. They can replace large-dimension monopiles. This paper evaluates the lateral load resistance of finned piles for onshore foundation applications. The dimensionless factor fin-efficiency is used to quantify the improvements in the resistance caused by the fins. This study performed a series of small-scale model experiments for long piles embedded in c– ϕ soil. The numerical studies were performed with finite element approach. The paper presents the influence of fin-factors such as fin-position, width, length, orientation, embedment in pile cap, and eccentric loading on lateral resistance of finned pile. This study also suggests the optimum fin parameters that help increase the lateral resistance to the maximum possible. The study on effect of fin-embedment in pile cap shows that finned piles with fin embedded in pile cap (FP-FEPC) perform better than those without fin embedment (FP-WFE). The material cost-benefit study supported the economy of the construction with the finned pile, utilizing only 55% of the material used by the regular pile. © 2023, The Author(s), under exclusive licence to Indian Geotechnical Society.Item Hydrodynamic analysis of an H-shaped pile-restrained floating breakwater combined with a pair of vertical barriers(Elsevier Ltd, 2024) Panda, A.; Karmakar, D.; Rao, M.The present study analyses the performance of a composite breakwater consisting of an H-shaped breakwater attached with vertical/inclined barriers held from both sides using the Multi-Domain Boundary Element Method (MDBEM). The study is performed to analyse the wave transformation characteristics (reflection and transmission), wave energy dissipation and horizontal wave forces due to the gravity wave-structure interaction. The hydrodynamic performance of the integrated breakwater is performed due to the effect of changing various structural properties such as porosity, width and depth of structural elements, relative spacing between breakwater and barrier, angle of incidence and the inclination of the barriers. The boundary conditions and the corresponding edge conditions are incorporated for each surface and interface and correlated with Green's function to solve the boundary value problem. The detailed study proposes the suitable dimensions of the structural elements of the breakwater for optimal performance. The application of inclined barriers over the vertical barrier in certain conditions for maximising wave reflection is presented and analysed to understand the effectiveness of the barrier inclination. The favourable barrier dimensions and the suitable relative spacing for deep water regions are discussed, and the effect of rigidity and porosity of the barriers are analysed to maximise breakwater performance in wave attenuation. On considering the suitable design parameters and structural stability, the composition of vertical/inclined barriers with an H-shaped pile-restrained floating breakwater serves as a protective component by encountering maximum wave force and dissipating considerable wave energy to provide an efficient solution in harbour protection. © 2024 Elsevier LtdItem Oblique wave interaction with pile-restrained dual H-shaped breakwater(National Institute of Science Communication and Policy Research, 2024) Panda, A.; Karmakar, D.; Rao, M.The hydrodynamic performance of pile-restrained dual H-shaped floating breakwater is investigated using the small amplitude wave theory considering oblique wave incidence. The research on a single H-shaped floating structure supported by the piles has demonstrated effective wave reflection and wave trapping due to its distinctive configuration, composed of a vertical member called a web and a horizontal member called a flange. Thus, the dual H-shaped breakwater is proposed to enhance the breakwater’s efficiency and to provide additional support to the leeside structure. The present analysis is performed by varying the structural parameters such as the width and submergence draft of the web, flange width of the dual H-shaped breakwaters and the corresponding effect on the hydrodynamic coefficients along with the wave-induced force acting horizontally on the breakwater using Multi-Domain Boundary Element Method (MDBEM). Based on the study, the leeside structure experiences a greater wave force than the primary H-shaped structure placed seaside for the critical angle of incidence. The dual H-shaped breakwater is noted as a highly effective harbour defence solution based on the structural and design specifications. The dual H-shaped pile-restrained floating breakwaters provide protection by absorbing the highest wave force and releasing a significant quantity of wave energy. © 2024, National Institute of Science Communication and Policy Research. All rights reserved.Item Investigating the wave attenuation capabilities of rectangular pile head breakwater: A physical modelling approach(Elsevier Ltd, 2024) Hunasanahally Sathyanarayana, A.H.; Suvarna, P.S.; Banagani, V.K.Y.; Umesh, P.; Shirlal, K.G.The study provides a comprehensive examination of single row Rectangular Pile Head Breakwaters (RPHB), encompassing both non-perforated and perforated variations. In the non-perforated RPHB category, the investigation delves into the effects of pile head height and width, and wave climate. For perforated RPHB structures, the study analyses the influence of percentage of perforations, perforation size, and depth of water. Further, the research includes a comparative assessment between non-perforated and perforated RPHB structures. Additionally, the research conducts a comparative analysis with similar structures. In the case of non-perforated RPHB, the configuration with relative pile head diameter (D/d) of 2.4 and relative pile head height (Y/Hmax) of 1.5 stood out as the most effective model. Similarly, the perforated RPHB demonstrated its maximum wave attenuation potential with percentage of perforations (P) of 24% with relative size of perforations (S/D) of 0.25. This optimal configuration achieved a minimal wave transmission coefficient (Kt) of 0.53, reflection coefficient (Kr) of 0.33, and energy dissipation coefficient (Kd) of 0.79 at a relative water depth (h/H) 0.865. Notably, the introduction of perforations on the RPHB structure led to an improvement in wave attenuation performance by 4–8%, resulting in lower reflection and higher energy dissipation. Comparatively, the RPHB structure outperformed the Enlarged (cylindrical) Pile Head Breakwater (EPHB) and Conical Pile Head Breakwater (CPHB) structures in terms of wave attenuation, exhibiting higher reflection and superior energy dissipation characteristics. The consistent outcome of these investigations reveals that the RPHB exhibits superior hydrodynamic performance characteristics and design suitability, making it a promising choice for breakwater applications. © 2024 Elsevier LtdItem Novel technique to mitigate the earthquake-induced damage of rubble mound breakwater(Elsevier Ltd, 2024) Akarsh, P.K.; Chaudhary, B.; Sajan, M.; Sah, B.; Kumar, S.In past, the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake had caused collapse of many breakwaters due to failure of their foundations. The seismic behaviour of rubble mound (RM) breakwater is not well understood may be due to limited number of research works done in the area. Therefore, in the present study, a series of shaking table tests were conducted for RM breakwater in order to determine the exact reasons and mechanisms of failure of the breakwater during an earthquake. In addition, a novel countermeasure technique was developed to mitigate the earthquake-induced damage of RM breakwater. The countermeasure model dealt with geobags as armour units on the both sides instead of conventional armours to increase the stability. The developed model has geogrid and sheet piles in seabed foundation soils of the breakwater. The effectiveness of countermeasure model was examined by comparing with conventional RM breakwater model considering parameters like settlement, horizontal displacement, acceleration-time histories, excess pore water pressure and deformation patterns. Numerical analyses were done to elucidate the failure mechanisms. Overall, the developed model was found to be resilient breakwater against the earthquakes; and the technique could be adopted in practical use on the real ground. © 2023 Elsevier LtdItem An Appraisal of the Mechanism and Research Development Status of Anti-slide Piles as Effective Technique for Landslide Risk Reduction(Springer, 2024) Jose, D.; Kolathayar, S.; Nayak, S.The increased frequency of landslides and associated devastations necessitates developing sustainable mitigation measures. The present paper aims to appraise the research developments in enhancing slope stability using anti-slide piles for landslide mitigation. The previous researchers made an immense effort to identify the soil–structure interaction of the anti-slide pile. The soil arching between the piles was identified as the soil–pile interaction mechanism. A detailed review of the soil arching between the piles is performed, and the observations are presented in detail. Recently, different sustainable methods for the analysis and design of anti-slide piles have been developed. An attempt was made to carry out a comprehensive review of the analysis methods and their critical features, and the observations are provided. The parameters affecting the performance of the anti-slide piles were identified, and the influence of those parameters on the behavior of piles is also discussed. Finally, the novel designs developed by researchers to overcome the limitations of conventional anti-slide piles and the utilization of sustainable materials as anti-slide piles were appreciated. The authors like to highlight that anti-slide piles are an effective solution for landslide risk reduction, and there is further scope for research in this field. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.Item 3D Finite Element Analysis of Anti-slide Pile Performance for Slope Stabilization(Springer Science and Business Media Deutschland GmbH, 2025) Jose, D.; Kolathayar, S.; Nayak, S.The stability of the slope plays a significant role in the formation and development of landslides. Among numerous slope stabilizing techniques, the reinforcement using anti-slide piles is an efficacious method for mitigating slope failures. These piles are usually installed in a row with uniform spacing, which will anchor the unstable zone to the deeper stable strata, thus maintaining the stability of the slope. In this study numerical analysis of the pile reinforced was carried out using the finite element software PLAXIS 3D to appraise the performance of anti-slide piles for controlling landslides. The variation of the factor of safety with the pile position, pile spacing, pile length, and shape of the pile was identified based on the safety analysis using the strength reduction method. The anti-slide pile effectively stabilized the slope and enhanced the safety factor by 1.4 times. The fixity of the pile head influences the performance of anti-slide piles, and fixed-head piles excels than free-head piles. The optimum position for placing the pile was observed as the middle of the slope for fixed head piles and near the toe of the slope for free head piles. The optimum spacing between the piles is recommended to be five times the diameter of the pile. A critical pile length of 0.8 times the height of the slope is suggested for attaining the maximum factor of safety and effective anchoring, and square-shaped piles are recommended. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Influence of Separation Layer Properties on Seismic Response of Modified Piled Raft Foundations(Springer, 2025) Amalu, P.A.; Jayalekshmi, B.R.Conventional piled raft foundations, with the raft and piles interconnected, severely restrict lateral movement, especially during seismic events. These constraints result in substantial stresses at the connection, posing a risk of potential breakage. Therefore, in seismic-prone areas, where transient lateral loadings of larger magnitudes are expected, conventional piled raft foundations are not feasible. Providing a separation layer between the raft and pile foundations is a viable solution to improve the performance of conventional piled raft foundations. The performance of such a modified piled raft system depends largely on the properties of the separation layer introduced. However, limited studies have been conducted to evaluate the seismic performance of these separation layers by considering the effect of soil–structure interactions. The present study thus aims to investigate the performance of modified piled raft systems by comparing them with their conventional counterpart. The existing conventional piled raft foundation of the Treptower building has been chosen as the prototype and is numerically analysed for static and dynamic loading conditions. Further, a separation layer has been introduced between the pile and raft, and the performance of the modified piled raft foundation is analysed under similar loadings. The results of these analyses are comprehensively compared to ascertain the performance of modified piled rafts under seismic excitation. It is found that the modified piled raft foundation with PE foam in the separation layer is advantageous in damping the propagation of seismic waves to the superstructure, reducing settlement and lateral displacements, and thereby decreasing the potential risk of failure of superstructures in seismic-prone areas. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.