Faculty Publications
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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.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.Item Comprehensive Analysis of Gabion Configurations for Modelling Tsunami-Resilient Rubble Mound Breakwaters(Springer, 2025) Sajan, M.K.; Sah, B.; Kumar, S.; Chaudhary, B.Coastal communities face significant threats from tsunamis, which cause extensive damage to infrastructure and endanger human lives. Rubble mound breakwaters, widely adopted structures in ports and harbours globally, serve as the first line of defense against tsunami waves. However, their failures in past tsunamis highlight the need for enhanced resilience. The performance of rubble mound breakwaters under tsunami conditions has received limited research attention, and few studies have explored effective countermeasures to mitigate tsunami-induced damages. This study addresses this research gap by performing a comprehensive evaluation through physical model tests, analytical studies and numerical simulations, focusing on the behaviour of rubble mound breakwaters under tsunami overflow. Observations from the responses of conventional models during overflow tests informed the proposal of a reinforcing technique utilizing gabions as a countermeasure to enhance tsunami resilience. Measurements of crest displacements and excess pore water pressure developed in both the foundation soils and the breakwater during tsunami overflow were ascertained to comparatively analyse the performance of the proposed reinforced models. An in-depth analysis was conducted on the placement and positioning of gabions to identify the most effective configuration for transforming a conventional rubble mound breakwater into a tsunami-resilient structure. Among the various gabion placement configurations studied, the stepped configuration demonstrated a remarkable 97.8% reduction in settlement during tsunami overflow. Further analytical and numerical studies were performed to assess the performance of the proposed gabion-reinforced model under tsunami overflow conditions. This proposed technique presents significant potential for protecting a wide range of coastlines by enhancing the resilience of rubble mound breakwaters against tsunamis. © The Author(s), under exclusive licence to Indian Geotechnical Society 2025.Item Developing Tsunami-Resilient Rubble Mound Breakwater: Novel Gabion-Based Technique(American Society of Civil Engineers (ASCE), 2025) Sajan, M.K.; Chaudhary, B.; Akarsh, A.P.; Sah, B.The rubble mound (RM) breakwater, which is a prevalent coastal structure worldwide, often faces the significant challenge of tsunami-induced damage. Coastal regions which are characterized by high population density necessitate robust breakwaters to withstand the destructive forces of tsunamis. The most devastating natural hazard that a breakwater could encounter during its lifespan is the tsunami. Past occurrences have revealed vulnerabilities in conventional RM breakwaters leading to failures attributed to the scouring of rubble and seabed caused by excessive seepage during tsunami overflow events. This study presents novel countermeasures aimed at mitigating the potential failure mechanisms induced by tsunamis on RM breakwaters. The proposed countermeasure elements include gabions, crown walls equipped with shear keys, and sheet piles. To assess the efficacy of these innovations, a series of tsunami overflow tests was conducted on small-scale models. The results demonstrated a marked improvement in the stability and resilience of RM breakwaters against tsunamis with the incorporation of these countermeasures. Additionally, numerical simulations were performed to determine the precise mechanisms influencing the behavior of the breakwater during tsunamis. © 2024 American Society of Civil Engineers.