Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124406
Kaiwei Xu , Jiaqi Luo , Jiaming Zhao , Danda Shi , Zhiming Chao , Titi Sui
Marine coral clay, a critical fine-grained component in reclaimed island foundations for ocean engineering, is typically mixed with marine coral sand to form composite foundation soil that governs offshore infrastructure stability. To address accurate strength prediction of this soil reinforced by 3D-printed bionic honeycomb polymer grid (BHPG), this study develops a CNN-LSTM model, uses SHapley Additive exPlanations (SHAP) to quantify input parameter importance, and validates it with 1200 triaxial shear tests. Results confirm high accuracy and identify reinforcement type, layers, and confining pressure as key factors, while a derived empirical formula enables rapid engineering use. A user-friendly graphical user interface (GUI) is also developed for ocean engineering practitioners to get real-time strength predictions. This work reduces test costs, advances deep learning-marine engineering integration, and supports BHPG application in reclaimed islands and offshore platforms.
{"title":"Mechanical behavior of marine coral sand - coral clay mixtures reinforced with bionic honeycomb polymer grid: Experimental and artificial intelligence methods","authors":"Kaiwei Xu , Jiaqi Luo , Jiaming Zhao , Danda Shi , Zhiming Chao , Titi Sui","doi":"10.1016/j.oceaneng.2026.124406","DOIUrl":"10.1016/j.oceaneng.2026.124406","url":null,"abstract":"<div><div>Marine coral clay, a critical fine-grained component in reclaimed island foundations for ocean engineering, is typically mixed with marine coral sand to form composite foundation soil that governs offshore infrastructure stability. To address accurate strength prediction of this soil reinforced by 3D-printed bionic honeycomb polymer grid (BHPG), this study develops a CNN-LSTM model, uses SHapley Additive exPlanations (SHAP) to quantify input parameter importance, and validates it with 1200 triaxial shear tests. Results confirm high accuracy and identify reinforcement type, layers, and confining pressure as key factors, while a derived empirical formula enables rapid engineering use. A user-friendly graphical user interface (GUI) is also developed for ocean engineering practitioners to get real-time strength predictions. This work reduces test costs, advances deep learning-marine engineering integration, and supports BHPG application in reclaimed islands and offshore platforms.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124406"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124525
Huipeng Jiang , Qiang Ma
Submarine permafrost occurs in shallow cold-region shelves, where seismic shaking may threaten offshore infrastructure. This study derives an analytical free-field solution for a coupled seawater-frozen seabed-bedrock system subjected to obliquely incident plane SV waves. Seawater is modelled as an inviscid compressible acoustic layer, the frozen seabed as a frozen saturated three-phase porous medium described by LCAM (Linearised Contact-Adhesion Model), and the bedrock as an elastic half-space. Using Helmholtz-decomposed potentials, Snell's law, and the transmission-reflection (T-R) method, closed-form frequency-domain displacements are obtained, capturing P-SV mode conversion within the frozen layer. Dimensionless horizontal and vertical surface-to-base transfer functions are defined, and pulse-excited time histories are reconstructed via inverse FFT. The solution is verified against published benchmark results for coupled seawater-seabed-bedrock systems. Parametric analyses examine temperature, porosity, incident angle, cementation-related Poisson's ratio, ice-skeleton contact condition, and depth. Results show that both the overlying seawater and the incident angle strongly reshape the transfer functions, with the vertical response particularly sensitive to fluid-solid coupling and interference/mode conversion. Lower temperatures reduce displacements and shift dominant peaks to higher frequencies, whereas higher porosity and weaker inter-phase constraint increase amplification. The formulation provides efficient baseline motions for subsequent seawater-frozen seabed-structure interaction analyses at laterally uniform sites.
{"title":"Free-field response of a seawater-frozen seabed system under obliquely incident SV waves","authors":"Huipeng Jiang , Qiang Ma","doi":"10.1016/j.oceaneng.2026.124525","DOIUrl":"10.1016/j.oceaneng.2026.124525","url":null,"abstract":"<div><div>Submarine permafrost occurs in shallow cold-region shelves, where seismic shaking may threaten offshore infrastructure. This study derives an analytical free-field solution for a coupled seawater-frozen seabed-bedrock system subjected to obliquely incident plane SV waves. Seawater is modelled as an inviscid compressible acoustic layer, the frozen seabed as a frozen saturated three-phase porous medium described by LCAM (Linearised Contact-Adhesion Model), and the bedrock as an elastic half-space. Using Helmholtz-decomposed potentials, Snell's law, and the transmission-reflection (T-R) method, closed-form frequency-domain displacements are obtained, capturing P-SV mode conversion within the frozen layer. Dimensionless horizontal and vertical surface-to-base transfer functions are defined, and pulse-excited time histories are reconstructed via inverse FFT. The solution is verified against published benchmark results for coupled seawater-seabed-bedrock systems. Parametric analyses examine temperature, porosity, incident angle, cementation-related Poisson's ratio, ice-skeleton contact condition, and depth. Results show that both the overlying seawater and the incident angle strongly reshape the transfer functions, with the vertical response particularly sensitive to fluid-solid coupling and interference/mode conversion. Lower temperatures reduce displacements and shift dominant peaks to higher frequencies, whereas higher porosity and weaker inter-phase constraint increase amplification. The formulation provides efficient baseline motions for subsequent seawater-frozen seabed-structure interaction analyses at laterally uniform sites.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124525"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124515
Zishun Yao , Hao Hu , Wenlong Lu , Yinuo Chu , Yanhong Wang , Dawei Guan
Jacket foundations, prevalent in offshore wind installations, face local scour threats during service life. While existing studies have experimentally and numerically investigated local scour and flow fields around such foundations, research correlating flow characteristics with local scour under varying attack angles remains scarce. This study employed test conditions and scour bathymetries from previous flume tests, aims to employ numerical modeling to examine flow-structure interactions around jacket foundations subjected to four flow attack angles (0°, 15°, 30°, 45°). Results demonstrate equilibrium scour volumes around jacket foundations increase by 70.8% (15°), 76.8% (30°), and 28.0% (45°) relative to 0° due to varying sheltering effects at different attack angles. The flow intensities at the front piles of the jacket foundation remain consistent across different attack angles, whereas the sheltering effect reduces flow intensity at the rear piles. Equilibrium scour depths at rear piles decrease under 0° and 45° angles owing to sheltering effects, but increase under 15° and 30° angles due to contracted flow, demonstrating a strong correlation between equilibrium scour depth and flow intensity at rear piles. A dimensionless sheltering coefficient () is proposed to correlate with total scour volumes () at the jacket foundation, establishing a strong linear relationship. For engineering practice, alignment with dominant flow direction proves advantageous for scour protection and cost reduction for jacket foundations.
{"title":"Numerical investigation of flow patterns and sheltering effects around jacket foundations under varying attack angles","authors":"Zishun Yao , Hao Hu , Wenlong Lu , Yinuo Chu , Yanhong Wang , Dawei Guan","doi":"10.1016/j.oceaneng.2026.124515","DOIUrl":"10.1016/j.oceaneng.2026.124515","url":null,"abstract":"<div><div>Jacket foundations, prevalent in offshore wind installations, face local scour threats during service life. While existing studies have experimentally and numerically investigated local scour and flow fields around such foundations, research correlating flow characteristics with local scour under varying attack angles remains scarce. This study employed test conditions and scour bathymetries from previous flume tests, aims to employ numerical modeling to examine flow-structure interactions around jacket foundations subjected to four flow attack angles (0°, 15°, 30°, 45°). Results demonstrate equilibrium scour volumes around jacket foundations increase by 70.8% (15°), 76.8% (30°), and 28.0% (45°) relative to 0° due to varying sheltering effects at different attack angles. The flow intensities at the front piles of the jacket foundation remain consistent across different attack angles, whereas the sheltering effect reduces flow intensity at the rear piles. Equilibrium scour depths at rear piles decrease under 0° and 45° angles owing to sheltering effects, but increase under 15° and 30° angles due to contracted flow, demonstrating a strong correlation between equilibrium scour depth and flow intensity at rear piles. A dimensionless sheltering coefficient (<span><math><mrow><msub><mi>C</mi><mrow><mi>s</mi><mi>h</mi></mrow></msub></mrow></math></span>) is proposed to correlate with total scour volumes (<span><math><mrow><msub><mi>V</mi><mi>s</mi></msub><mo>/</mo><msup><mi>D</mi><mn>3</mn></msup></mrow></math></span>) at the jacket foundation, establishing a strong linear relationship. For engineering practice, alignment with dominant flow direction proves advantageous for scour protection and cost reduction for jacket foundations.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124515"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124433
Xiaopeng Yang , Zhi Zong , Zhe Sun , Minghao Guo
To investigate the impact of structural deformation on the interaction between ice and structures, a small-scale indentation test was executed in a low temperature laboratory, utilizing elastic plates and frozen ice. The experiment primarily concentrated on the effect of structural stiffness on the interaction process at various velocities. Three strain rates, corresponding to the ductile and brittle failure modes of ice, were chosen. The compression stiffness ratio of the elastic plates to the ice sample was a critical variable, encompassing the influence of six distinct stiffness scenarios. Test results indicate that structural deformation modifies the relative velocity at which the structure penetrates into the ice and alters the distribution of high-pressure zones on the contact surface. Changes in structural stiffness impact both the location and extent of these high-pressure zones, resulting in shifts in ice failure modes and, subsequently, affecting the magnitude of the load. The nominal peak pressure tends to rise with greater structural stiffness but decreases with faster loading rates. The effect of variations in the relative interaction rates between ice and structure, caused by deformation, on the load magnitude appears to be less pronounced than that resulting from changes in contact position and area induced by deformation.
{"title":"An experimental study of interaction process between sea ice and variable stiffness elastic plates at various speeds","authors":"Xiaopeng Yang , Zhi Zong , Zhe Sun , Minghao Guo","doi":"10.1016/j.oceaneng.2026.124433","DOIUrl":"10.1016/j.oceaneng.2026.124433","url":null,"abstract":"<div><div>To investigate the impact of structural deformation on the interaction between ice and structures, a small-scale indentation test was executed in a low temperature laboratory, utilizing elastic plates and frozen ice. The experiment primarily concentrated on the effect of structural stiffness on the interaction process at various velocities. Three strain rates, corresponding to the ductile and brittle failure modes of ice, were chosen. The compression stiffness ratio of the elastic plates to the ice sample was a critical variable, encompassing the influence of six distinct stiffness scenarios. Test results indicate that structural deformation modifies the relative velocity at which the structure penetrates into the ice and alters the distribution of high-pressure zones on the contact surface. Changes in structural stiffness impact both the location and extent of these high-pressure zones, resulting in shifts in ice failure modes and, subsequently, affecting the magnitude of the load. The nominal peak pressure tends to rise with greater structural stiffness but decreases with faster loading rates. The effect of variations in the relative interaction rates between ice and structure, caused by deformation, on the load magnitude appears to be less pronounced than that resulting from changes in contact position and area induced by deformation.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124433"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124211
S. Oyuela , H.R. Díaz-Ojeda , A.D. Otero , R. Sosa
This study investigates the influence of scale effects on form factor determination for a fishing vessel with a low length-to-beam (L/B) ratio, using a combined Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) approach. The research compares the behavior of the form factor between a fishing vessel and the well-known KCS benchmark hull. Results show that scale effects have a more significant impact on the fishing vessel, particularly due to increased viscous pressure losses in the stern region. While the non-dimensional frictional resistance component remains similar between both hulls, the non-dimensional pressure component differ significantly, highlighting the influence of hull shape on pressure recovery. The comparison with empirical methods reveals that traditional marine formulations may not adequately capture full scale form factor of hulls with very low length to beam ratio. Instead, the form factor obtained using aircraft drag estimation approaches shows better agreement with CFD predictions at full scale. Based on these findings, the adoption of distinct form factor values at model and full scale is recommended for vessels with similar geometric characteristics, in contrast to conventional extrapolation practices that assume a constant form factor. This methodology may improve the accuracy of effective power predictions and support more reliable design evaluations.
{"title":"Combined CFD-EFD methods applied to determining the form factor of vessels with very low length to beam ratio","authors":"S. Oyuela , H.R. Díaz-Ojeda , A.D. Otero , R. Sosa","doi":"10.1016/j.oceaneng.2026.124211","DOIUrl":"10.1016/j.oceaneng.2026.124211","url":null,"abstract":"<div><div>This study investigates the influence of scale effects on form factor determination for a fishing vessel with a low length-to-beam (L/B) ratio, using a combined Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) approach. The research compares the behavior of the form factor between a fishing vessel and the well-known KCS benchmark hull. Results show that scale effects have a more significant impact on the fishing vessel, particularly due to increased viscous pressure losses in the stern region. While the non-dimensional frictional resistance component remains similar between both hulls, the non-dimensional pressure component differ significantly, highlighting the influence of hull shape on pressure recovery. The comparison with empirical methods reveals that traditional marine formulations may not adequately capture full scale form factor of hulls with very low length to beam ratio. Instead, the form factor obtained using aircraft drag estimation approaches shows better agreement with CFD predictions at full scale. Based on these findings, the adoption of distinct form factor values at model and full scale is recommended for vessels with similar geometric characteristics, in contrast to conventional extrapolation practices that assume a constant form factor. This methodology may improve the accuracy of effective power predictions and support more reliable design evaluations.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124211"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124414
Yigang Gong , Hanxu Zheng , Haibo Xu , Jiasong Wang
This study employs a large eddy simulation with a three-dimensional strip-theory-based method on the self-developed platform (HRAPIFS) to investigate vortex-induced vibrations(VIV) of a full-scale (300 m) riser, experiencing both uniform flow () and linear shear flow conditions (from subcritical to supercritical ). The computational model has been rigorously verified through the flow around a fixed cylinder entering the supercritical region and the VIV response of a flexible riser in uniform and linear shear flows. This study provides an in-depth investigation of this practically significant yet rarely studied problem with substantial engineering importance, yielding several new findings. First, traveling wave responses are observed in both flow conditions. VIV response in uniform flow exhibits 8th mode dominance (1.56 Hz) and shows multimodal behavior combining 1st (0.1Hz, corresponding to subcritical St) and 7th modes (1.3 Hz) in linear shear flow. Second, the present study demonstrates that lock-in happens almost along the whole span (with positive excitation force coefficient) in uniform flow, while the low-velocity regions (z < 170 m) in shear flow exhibit negative excitation force coefficients along with clockwise trajectories. The dominant vortex shedding frequency progressively shifts from subcritical () to critical () features before synchronizing with the structural vibration frequency in high-velocity zones. Third, trajectory analysis reveals elliptical patterns in both cases due to identical vibration frequencies in the cross-flow and in-line directions, contrasting with subcritical figure-eight patterns, attributed to the dramatic change in the hydrodynamic responses entering the critical region.
{"title":"Numerical simulation of vortex-induced vibration of a full-scale flexible riser at supercritical Reynolds number in uniform and linear shear flow","authors":"Yigang Gong , Hanxu Zheng , Haibo Xu , Jiasong Wang","doi":"10.1016/j.oceaneng.2026.124414","DOIUrl":"10.1016/j.oceaneng.2026.124414","url":null,"abstract":"<div><div>This study employs a large eddy simulation with a three-dimensional strip-theory-based method on the self-developed platform (HRAPIFS) to investigate vortex-induced vibrations(VIV) of a full-scale (300 m) riser, experiencing both uniform flow (<span><math><mrow><mtext>Re</mtext><mo>=</mo><msup><mn>10</mn><mn>6</mn></msup></mrow></math></span>) and linear shear flow conditions (from subcritical to supercritical <span><math><mrow><mtext>Re</mtext><mo>=</mo><msup><mn>10</mn><mn>5</mn></msup><mo>∼</mo><msup><mn>10</mn><mn>6</mn></msup></mrow></math></span>). The computational model has been rigorously verified through the flow around a fixed cylinder entering the supercritical region and the VIV response of a flexible riser in uniform and linear shear flows. This study provides an in-depth investigation of this practically significant yet rarely studied problem with substantial engineering importance, yielding several new findings. First, traveling wave responses are observed in both flow conditions. VIV response in uniform flow exhibits 8th mode dominance (1.56 Hz) and shows multimodal behavior combining 1st (0.1Hz, corresponding to subcritical St) and 7th modes (1.3 Hz) in linear shear flow. Second, the present study demonstrates that lock-in happens almost along the whole span (with positive excitation force coefficient) in uniform flow, while the low-velocity regions (<em>z</em> < 170 m) in shear flow exhibit negative excitation force coefficients along with clockwise trajectories. The dominant vortex shedding frequency progressively shifts from subcritical (<span><math><mrow><mtext>St</mtext><mo>=</mo><mn>0.2</mn></mrow></math></span>) to critical (<span><math><mrow><mtext>St</mtext><mo>=</mo><mn>0.3</mn></mrow></math></span>) features before synchronizing with the structural vibration frequency in high-velocity zones. Third, trajectory analysis reveals elliptical patterns in both cases due to identical vibration frequencies in the cross-flow and in-line directions, contrasting with subcritical figure-eight patterns, attributed to the dramatic change in the hydrodynamic responses entering the critical region.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124414"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124465
Cong Zhang , Feifei Zhang , Fengjia Peng , Xi Wang , Ke Gao
Accurate identification of lithology with limited measurement-while-drilling data is crucial for improving real-time decision-making in deep-sea drilling. However, achieving high classification accuracy under limited feature conditions remains challenging. This study focuses on vibration signals generated during bit-rock interaction, integrating mechanistic analysis with data-driven modeling to develop an intelligent lithology classification method that uses Tsfresh-based automatic feature extraction. Vibration acceleration data were collected from laboratory drilling tests on granite, limestone, sandstone, and concrete, and were then preprocessed. Time- and frequency-domain characteristics of the different lithologies were analyzed to verify the feasibility of vibration-based lithology identification. Six machine learning models—ANN, CNN, LSTM, GRU, BiLSTM and Transformer—were constructed, and the effects of automatic feature engineering on classification accuracy, training efficiency, and generalization performance were evaluated. The results show that feature engineering significantly improves recognition performance under limited-feature conditions, yielding accuracy gains of more than 30 % for the LSTM, BiLSTM, GRU and Transformer models. The BiLSTM model with automatic feature extraction achieved the best generalization performance, with an identification accuracy of 0.9651 on unseen samples. These findings demonstrate an effective and practical approach to identifying lithology while drilling in deep-water environments with limited feature information.
{"title":"Lithology identification based on drill-bit vibration signals and automated feature extraction for deep-sea drilling","authors":"Cong Zhang , Feifei Zhang , Fengjia Peng , Xi Wang , Ke Gao","doi":"10.1016/j.oceaneng.2026.124465","DOIUrl":"10.1016/j.oceaneng.2026.124465","url":null,"abstract":"<div><div>Accurate identification of lithology with limited measurement-while-drilling data is crucial for improving real-time decision-making in deep-sea drilling. However, achieving high classification accuracy under limited feature conditions remains challenging. This study focuses on vibration signals generated during bit-rock interaction, integrating mechanistic analysis with data-driven modeling to develop an intelligent lithology classification method that uses Tsfresh-based automatic feature extraction. Vibration acceleration data were collected from laboratory drilling tests on granite, limestone, sandstone, and concrete, and were then preprocessed. Time- and frequency-domain characteristics of the different lithologies were analyzed to verify the feasibility of vibration-based lithology identification. Six machine learning models—ANN, CNN, LSTM, GRU, BiLSTM and Transformer—were constructed, and the effects of automatic feature engineering on classification accuracy, training efficiency, and generalization performance were evaluated. The results show that feature engineering significantly improves recognition performance under limited-feature conditions, yielding accuracy gains of more than 30 % for the LSTM, BiLSTM, GRU and Transformer models. The BiLSTM model with automatic feature extraction achieved the best generalization performance, with an identification accuracy of 0.9651 on unseen samples. These findings demonstrate an effective and practical approach to identifying lithology while drilling in deep-water environments with limited feature information.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124465"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124496
Reza Khalili , Naum Shpata , Abhishek Gupta , Saeideh Mohammadi , Chenjie Ruan , Bagus Prasetyo , Maarit Saresma , Joonas J. Virtasalo , Wojciech T. Sołowski
Submarine power cables on soft seabed are prone to damage from fishing gear, anchors, and underwater landslides. To mitigate these risks, the paper investigates the long-term settlement and stability of protective berms using PLAXIS finite element simulations. The paper examines two berm geometries, staged construction, and the influence of backfill pre-consolidation before berm placement. To compute settlements in structured clays, this study developed a novel iterative method within the finite element framework to adjust the modified compression index based on the soil destructuration. The approach identifies the steepest slope of the oedometric curve, indicating maximum clay destructuration, to estimate the critical modified compression index ( Subsequently, vertical stresses are monitored at various soil depths to define a new modified compression index. Finally, the value of the modified compression index is iteratively refined during simulations until reaching convergence. Additionally, for comparison, the paper presents calculations of a single case with the Creep-SCLAY1S model. Simulations calculated cable settlement and long-term stability, giving insights into berm geometry optimisation that can reduce settlement. Results demonstrate that defining the modified compression index according to stress conditions at various depths produces more realistic results than using a single value typically applied to non-structured soils.
{"title":"Submarine power cables on soft structured clay seabed: gravel berm to reduce cable settlements and enhance protection","authors":"Reza Khalili , Naum Shpata , Abhishek Gupta , Saeideh Mohammadi , Chenjie Ruan , Bagus Prasetyo , Maarit Saresma , Joonas J. Virtasalo , Wojciech T. Sołowski","doi":"10.1016/j.oceaneng.2026.124496","DOIUrl":"10.1016/j.oceaneng.2026.124496","url":null,"abstract":"<div><div>Submarine power cables on soft seabed are prone to damage from fishing gear, anchors, and underwater landslides. To mitigate these risks, the paper investigates the long-term settlement and stability of protective berms using PLAXIS finite element simulations. The paper examines two berm geometries, staged construction, and the influence of backfill pre-consolidation before berm placement. To compute settlements in structured clays, this study developed a novel iterative method within the finite element framework to adjust the modified compression index based on the soil destructuration. The approach identifies the steepest slope of the oedometric curve, indicating maximum clay destructuration, to estimate the critical modified compression index (<span><math><mrow><msup><mi>λ</mi><mo>∗</mo></msup><mo>)</mo><mtext>.</mtext></mrow></math></span> Subsequently, vertical stresses are monitored at various soil depths to define a new modified compression index. Finally, the value of the modified compression index is iteratively refined during simulations until reaching convergence. Additionally, for comparison, the paper presents calculations of a single case with the Creep-SCLAY1S model. Simulations calculated cable settlement and long-term stability, giving insights into berm geometry optimisation that can reduce settlement. Results demonstrate that defining the modified compression index according to stress conditions at various depths produces more realistic results than using a single value typically applied to non-structured soils.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"352 ","pages":"Article 124496"},"PeriodicalIF":5.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124454
Chongchong Shen, Liyun Fan, Kui Xu, Chen Chen, Jinwei Sun, Meng Qin, Bo Li
To overcome the limitation of poor training efficiency and real-time optimality in conventional Deep Reinforcement Learning-based Equivalent Consumption Minimization Strategy (DRL-ECMS) for ship hybrid power system, this paper proposes a novel hierarchical framework which integrates offline training and online operation. In the offline triple-layers training framework, first, the dual-state Pontryagin's Minimum Principle (DPMP) is implemented to derive the global optimum as expert knowledge; second, behavior cloning (BC) pre-trains the agent using these expert demonstrations for policy network initialization; third, the adaptive policy entropy (APE) mechanism tunes the policy during agent formal training process by dynamically adjusting the temperature coefficient. In the online operation framework, the feedforward-feedback coordinated control is proposed, comprising the imitation reinforcement learning (IRL) for equivalent factor (EF) feedforward pre-calibration, and the dual-state feedback (DSF) for EF correction. Results confirm the effectiveness of the proposed strategy, showing that compared to traditional DRL, the proposed method achieves a 77.56 % improvement in initial reward and a 51.78 % acceleration in convergence speed. Compared to the single-state feedback (SSF) mechanism, the proposed DSF method reduces the battery degradation rate by 10.75 %, increases the proportion of engine operation in the high-efficiency zone by 19.7 %, and ultimately achieves 96.31 % of the comprehensive performance of the global optimal benchmark. Furthermore, the robustness of the proposed strategy is validated through both cycle adaptability and state of charge (SOC) adaptability analysis.
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Pub Date : 2026-02-05DOI: 10.1016/j.oceaneng.2026.124467
Dominic Lagrois, Clément Chion
Accurate characterization of ship source levels is essential to assess the acoustic footprint of maritime traffic in biologically sensitive regions. This study presents standardized underwater radiated noise (URN) measurements for the N.M. Saaremaa I, a diesel-electric ferry scheduled to operate in the St. Lawrence Estuary, a critical habitat for endangered belugas. Using two seabed-mounted digital hydrophones and a shallow-water measurement protocol adapted from recent standards, we derived monopole source levels (mSLs) across 37 decidecade frequency bands under various operating conditions, including constant-speed transits, acceleration runs, and idle states. Our results show a consistent increase in mSLs with vessel speed, reaching slopes of 2–4 , with strongest correlations above 500 Hz. Acceleration events produced band emissions exceeding 180 dB re 1 µPa2 · m2 at 25 Hz, while mid-to-high frequency levels ( ≳ 1 kHz) were often lower than during steady-speed operation. These findings highlight the dual nature of acceleration noise, potentially degrading acoustic habitat for baleen whales while increasing collision risk for odontocetes near terminals. This work provides one of the first in-situ acoustic profiles of a ferry ahead of service in a high-use marine mammal corridor and offers empirical input for noise modelling, regulatory assessments, and mitigation planning in shallow coastal environments.
船舶源水平的准确表征对于评估生物敏感区域海上交通的声足迹至关重要。这项研究提出了标准的水下辐射噪声（URN）测量，N.M. Saaremaa I是一艘柴油电动渡轮，计划在圣劳伦斯河口运营，这是濒危白鲸的重要栖息地。使用两个安装在海底的数字水听器和采用最新标准的浅水测量协议，我们在各种操作条件下（包括等速传输、加速运行和怠速状态）获得了37个十进制频段的单极子源电平（msl）。我们的研究结果表明，mSLs随着船舶速度的增加而持续增加，达到2-4 dBkn−1的斜率，在500 Hz以上相关性最强。在25 Hz下，加速事件产生的频带辐射超过180 dB re 1µPa2 · m2，而中高频水平（ ￣ 1 kHz）通常低于稳定速度运行时的水平。这些发现强调了加速噪音的双重性质，潜在地降低了须鲸的声学栖息地，同时增加了终端附近齿形鲸的碰撞风险。这项工作提供了在高用途海洋哺乳动物走廊服务前渡轮的第一个原位声学剖面之一，并为浅海海岸环境中的噪声建模、监管评估和缓解规划提供了经验输入。
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