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Feature Papers in Ocean Engineering
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Feature Papers in Ocean Engineering

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Ocean Engineering".

Deadline for manuscript submissions: closed (15 April 2024) | Viewed by 25769

Special Issue Editor

Prof. Dr. Dong-Sheng Jeng

E-Mail Website
Guest Editor
School of Engineering and Built Environment, Griffith University, Gold Coast Campus, Southport, QLD 4222, Australia
Interests: offshore geotechnics; ocean engineering; coastal groundwater hydraulics; offshore wind energy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are pleased to announce the launch of a new Special Issue on “Feature Papers in Ocean Engineering”, with the aim of contributing to the publication of high-quality research on all the main aspects of Ocean Engineering—from ocean wave modelling aspects (ocean wave motion, fluid–structure interactions and tsunamis, etc.) to seabed mechanics and sediment transport, marine geotechnics and geohazards, ocean energy (offshore wind, wave energy, tidal current and combined marine energy) and field studies in ocean or marine environments. Submissions of original and high-quality research on all the abovementioned branches of ocean engineering are encouraged.

Prof. Dr. Dong-Sheng Jeng
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • marine geohazard
  • ocean energy
  • fluid–structure (–seabed) interactions
  • marine sediment
  • seabed mechanics
  • ocean field study
  • wave motion

Published Papers (16 papers)

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Research

30 pages, 15864 KiB  
Article
Research on Ship Automatic Berthing Algorithm Based on Flow Matching and Velocity Matching
by Yi Zhang, Hengchao Zhao, Zheng Zhang and Hongbo Wang
J. Mar. Sci. Eng. 2024, 12(3), 511; https://doi.org/10.3390/jmse12030511 - 19 Mar 2024
Viewed by 618
Abstract
Addressing the automatic berthing task for vessels, this study introduces the Flow Matching Double Section Bezier Berth Method (FM-DSB) for handling downstream and upstream berthing instructions. By considering the orientation relationship between the direction of water flow and the berth, combined with berthing [...] Read more.
Addressing the automatic berthing task for vessels, this study introduces the Flow Matching Double Section Bezier Berth Method (FM-DSB) for handling downstream and upstream berthing instructions. By considering the orientation relationship between the direction of water flow and the berth, combined with berthing modes, the algorithm determines the vessel’s entry angle into the berth and plans the berthing path using double-section Bezier curves. Effective control of vessel speed post-path determination is essential. Therefore, based on the response of vessels to propeller inputs, this study introduces the Berthing Path Velocity Matching Method (BPVM). The BPVM ensures speed matching along the berthing path through analysis of vessel acceleration and deceleration capabilities. Subsequently, simulation experiments are conducted to validate the planning algorithm for both long-distance and short-distance berthing. Furthermore, the feasibility and effectiveness of the berthing path are verified using a dual-loop path tracker based on the planned results. Experimental outcomes illustrate the adaptability of the proposed algorithm in planning berthing paths that align with vessel motion characteristics, effectively guiding vessels into berths through the designed dual-loop control system. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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17 pages, 3987 KiB  
Article
Design and Optimization of PV Power Supply System for Marine Buoys
by Chunjie Wang, Xiaodong Song, Qiang Fu, Lin Cui and Peng Chen
J. Mar. Sci. Eng. 2023, 11(9), 1808; https://doi.org/10.3390/jmse11091808 - 16 Sep 2023
Viewed by 1040
Abstract
Marine buoys need to operate in high sea areas far from land for a long time. Therefore, how to provide a long-term power supply for the buoy system is critical to be addressed. Photovoltaic (PV) power supply systems are the most commonly used [...] Read more.
Marine buoys need to operate in high sea areas far from land for a long time. Therefore, how to provide a long-term power supply for the buoy system is critical to be addressed. Photovoltaic (PV) power supply systems are the most commonly used power supply method for marine buoys. Due to the limitations of the buoy structure and considering the rotation of the buoy in the ocean, most of the PV modules are placed in a four-sided enclosure. The output performance of the PV power supply system in this placement is affected by the tilt angle produced by waves. However, there are few relevant studies on the actual power generation performance of PV power supply systems for marine buoys, and there is a lack of methods for power generation performance analysis. In order to meet the power requirements of the marine buoy, a large design margin must be left. It increases the cost of marine buoys. In this paper, second-order Stokes waves are used to simulate waves of different levels by varying the wave height and frequency. The motion characteristics of the marine buoy are analyzed using ANSYS-AQWA under calm-rippled, smooth, slight, and moderate conditions. Combined with the tilted surface irradiance calculation model to get the variation law of solar radiation of PV modules under dynamic conditions, the effect of different tilt angle PV modules on the output of PV system under dynamic conditions was also studied. The experiments show that for every 5° increase in the tilt angle of the PV modules the output power of the system decreases by 3% on average. As the tilt angle of the PV modules increases, the impact on the system output performance is more pronounced. The output power decreased by 69.5% when the PV modules were tilted at an angle of 90°, and the PV system electrical parameters were similarly affected. By comparing the influence of different tilt angles on the power supply performance of PV modules, we optimize the design of the PV power supply system of the buoy. This enables the designers to maximize the use of limited area and space while reducing the cost and extending the power supply time and service life of the buoy. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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15 pages, 2457 KiB  
Article
Underwater Wireless Sensor Network-Based Localization Method under Mixed Line-of-Sight/Non-Line-of-Sight Conditions
by Ying Liu, Yingmin Wang, Cheng Chen and Chenxi Liu
J. Mar. Sci. Eng. 2023, 11(9), 1642; https://doi.org/10.3390/jmse11091642 - 23 Aug 2023
Cited by 1 | Viewed by 806
Abstract
Source localization in underwater sensor networks (UWSNs) presents complex challenges due to sensor nodes drift caused by ocean currents, non-line-of-sight (NLOS) propagation resulting from underwater multipath effects, and environmental noise. This paper proposes a practical and innovative algebraic solution based on the time [...] Read more.
Source localization in underwater sensor networks (UWSNs) presents complex challenges due to sensor nodes drift caused by ocean currents, non-line-of-sight (NLOS) propagation resulting from underwater multipath effects, and environmental noise. This paper proposes a practical and innovative algebraic solution based on the time difference of arrival (TDOA) for source localization in shallow seas. The proposed solution effectively addresses the issues arising from sensor position errors and multipath effects by incorporating the sea-surface reflection non-line-of-sight (SNLOS) link and optimizing the algorithm, thereby significantly improving positioning accuracy. The core concept of the method involves utilizing the weighted least squares algorithm to obtain an initial estimate of the source position, followed by direct estimation of the bias and subsequent refinement of the solution. In contrast to traditional closed-form solutions, this method avoids the introduction of intermediate parameters and directly handles the estimated bias from the previous step. Even when only considering the line-of-sight (LOS) link, the proposed solution achieves precise localization with a minimal number of sensors. Theoretical analysis demonstrates that the solution can achieve the Cramér–Rao lower bound (CRLB) accuracy under low noise conditions, and simulation results validate the superior performance of the proposed solution. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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19 pages, 7955 KiB  
Article
Study on the Accessibility Impact of Anti-Rolling Tank on the Offshore Wind O&M Gangway
by Songtao Zhang, Peng Zhao, Chenyang Li, Ziqi Song and Lihua Liang
J. Mar. Sci. Eng. 2023, 11(4), 848; https://doi.org/10.3390/jmse11040848 - 17 Apr 2023
Cited by 3 | Viewed by 1242
Abstract
In order to improve the accessibility of offshore wind O&M gangway in complex sea conditions, a control method for the controllable anti-rolling tank based on wavelet neural network period prediction is proposed in this paper. Firstly, a model of ship motion with a [...] Read more.
In order to improve the accessibility of offshore wind O&M gangway in complex sea conditions, a control method for the controllable anti-rolling tank based on wavelet neural network period prediction is proposed in this paper. Firstly, a model of ship motion with a controllable passive anti-rolling tank was established. Then, the inverse kinematics of the gangway were carried out. In order to analyze the influence of the anti-rolling tank on the accessibility of the on-board gangway, an accessibility simulation of the gangway under different sea conditions was completed. Finally, a hardware-in-the-loop simulation of the active compensation gangway system was carried out. The simulation and test results show that the anti-rolling tank can effectively restrain the rolling motion of the ship and significantly improve the accessibility of the on-board gangway. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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18 pages, 4475 KiB  
Article
Numerical Simulation of Wave Overtopping of an Ecologically Honeycomb-Type Revetment with Rigid Vegetation
by Jinfeng Zhang, Na Zhang, Qinghe Zhang, Fangqian Jiao, Lingling Xu and Jiarui Qi
J. Mar. Sci. Eng. 2022, 10(11), 1615; https://doi.org/10.3390/jmse10111615 - 01 Nov 2022
Viewed by 1518
Abstract
Traditional concrete revetments can destroy the ecological environment and the water landscape. An increasing number of ecological revetment structures have been applied in coastal, lake, and river regulation projects. It has been found that honeycomb-type revetments display a better performance in the attenuation [...] Read more.
Traditional concrete revetments can destroy the ecological environment and the water landscape. An increasing number of ecological revetment structures have been applied in coastal, lake, and river regulation projects. It has been found that honeycomb-type revetments display a better performance in the attenuation of wave overtopping when compared to experimental data collected using the Eurotop and Muttray’s formula; recording a 40% decrease in the wave run-up in comparison to the latter. To further investigate the wave run-up and overtopping of the ecologically vegetated honeycomb-type revetment, based on OpenFOAM, an open source computational fluid dynamics software, a three-dimensional numerical wave tank was established. The Discrete Particle Method (DPM) was used to simulate gravel movement, and the flexible plant move boundary model was developed to simulate vegetation. The results of wave run-up calculated by the numerical model and those obtained by the experiments were in good agreement, with errors less than 20%. The modeled results of wave overtopping were within the same order of magnitude as those from the experiments; however, critical limitations were noticed due to effects of plant generalization and grid restrictions imposed by DPM methods. The results showed that wave overtopping increased with increasing wave period and wave height. However, with an increase in the wave overtopping, the influence of the wave period on wave overtopping decreased. The increase in vegetation density effectively reduced wave overtopping. Furthermore, an empirical formula for wave overtopping, considering the effects of vegetation density, was proposed. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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28 pages, 11820 KiB  
Article
Effect of the Dry-Wet Cycle on the Performance of Marine Waste Silt Solidified by Calcium Carbide Residue and Plant Ash
by Hao Yang, Jianfeng Zhu, Yanli Tao, Zhengqing Wang and Qiqi Zheng
J. Mar. Sci. Eng. 2022, 10(10), 1442; https://doi.org/10.3390/jmse10101442 - 07 Oct 2022
Cited by 2 | Viewed by 1524
Abstract
This research aims to investigate the potential of engineering waste marine silt stabilized by a self-developed stabilizing chemical additive called PZ-1 as a subgrade filler. PZ-1 is composed of calcium carbide residue (CCR) and plant ash (PA) under an optimal composition ratio determined [...] Read more.
This research aims to investigate the potential of engineering waste marine silt stabilized by a self-developed stabilizing chemical additive called PZ-1 as a subgrade filler. PZ-1 is composed of calcium carbide residue (CCR) and plant ash (PA) under an optimal composition ratio determined by coupling particle swarm optimization with a support vector machine (PSO-SVM). The effect of curing agent dosage (wg), temperature (wT), number of dry-wet cycles (Ndw), and organic matter content (wo) on the micro-macro behavior of the stabilized silt were investigated via the unconfined compressive strength (UCS) test, the scanning electron microscope (SEM) test, and the X-ray diffraction (XRD) test. The experimental results demonstrate a significant positive effect of PZ-1 on the unconfined compressive strength (qu) of marine engineering waste silt with curing agent contents of 0~8%. It was also found that strength improvement of the stabilized silt can be attributed to the formation of gelling substances such as C-S-H and calcite. The water resistance of the stabilized silt can be enhanced by increasing the dosage of the curing agent. Moreover, the organic matter content and ambient temperature have significant effects on the dry-wet cycle tolerance of solidified soil, among which temperature exhibits a more obvious impact. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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20 pages, 8158 KiB  
Article
Experimental Study of the Effect of Backfill Conditions on Soil Responses around a Pipeline under Wave–Current Load
by Hao Chen, Yakun Guo, Shiqi Yu, Jisheng Zhang and Sheng Liu
J. Mar. Sci. Eng. 2022, 10(10), 1384; https://doi.org/10.3390/jmse10101384 - 27 Sep 2022
Cited by 5 | Viewed by 1455
Abstract
Waves and currents coexist widely in the ocean, and the interaction of waves and currents plays an important role in the instability of submarine pipelines. So far, most studies have concentrated on discussing the dynamic reaction within the seabed around a pipeline under [...] Read more.
Waves and currents coexist widely in the ocean, and the interaction of waves and currents plays an important role in the instability of submarine pipelines. So far, most studies have concentrated on discussing the dynamic reaction within the seabed around a pipeline under pure wave action, monotypic sediment, and an exposed or fully buried condition. In this study, the effect of current characteristics (e.g., current velocity and propagation direction) and backfilling conditions (e.g., backfill depth and sand property) on the dynamic response around the submarine pipeline is investigated by conducting laboratory experiments. Pipeline was buried in the excavated trench using three types of sand with the median size of 0.150 mm, 0.300 mm and 0.045 mm, respectively. Five relative backfilled depths, with the ratios of backfill depth over the pipeline diameter being 0, 1/2, 1, 3/2 and 2, were tested. The excess pore pressure was measured simultaneously by using the pore pressure sensors installed around the pipeline surface and beneath the pipeline. Results show that both the pore pressure amplitude and its descent rate gradually decrease with an increasing backfill depth, which decreases the soil liquefaction potential. Under the co-current actions, the decrease rate of the pore pressure along the vertical direction increases with an increasing current velocity. However, the increased current velocity leads to a decrease of the attenuation rate under the counter-current actions compared with the pure wave actions, and the counter-current effect on the pore pressure within the seabed is greater than the co-current. The results indicate that the dynamic response around the pipeline in coarse sand is close to that without the backfill scenario, even if the backfill depth reaches up to two times that of the pipeline diameter. It is found that the larger the median particle size of backfill sand, the smaller the impact on pore pressure within the seabed beneath the pipeline. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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26 pages, 11272 KiB  
Article
Improved Fractional-Order PID Controller of a PMSM-Based Wave Compensation System for Offshore Ship Cranes
by Hao Chen, Xin Wang, Mohamed Benbouzid, Jean-Frédéric Charpentier, Nadia Aϊt-Ahmed and Jingang Han
J. Mar. Sci. Eng. 2022, 10(9), 1238; https://doi.org/10.3390/jmse10091238 - 03 Sep 2022
Cited by 7 | Viewed by 1845
Abstract
Wave compensation technology is crucial to the safety of the ship operation and the accurate placement of load. Its compensation efficiency and the gentle change of the rope tension are particularly important. In this paper, we adopt permanent magnet synchronous machine (PMSM) as [...] Read more.
Wave compensation technology is crucial to the safety of the ship operation and the accurate placement of load. Its compensation efficiency and the gentle change of the rope tension are particularly important. In this paper, we adopt permanent magnet synchronous machine (PMSM) as the actuator to construct the basic wave compensation system. Firstly, the motion model of ship and load under wave action is established, and the fractional-order PID (FOPID) controller for the position loop of the PMSM is introduced. Then, the parameters of FOPID are optimized by genetic algorithm-particle swarm optimization (GAPSO) algorithm, which is based on genetic algorithms (GA) and particle swarm optimization (PSO) algorithms for better compensation performance. The wave synchronization strategy is used to simulate the load, when it needs to be taken into the water. The non-linear dynamic equations of the rope are solved by Lagrange mechanics and the heave displacement is obtained by time series prediction algorithm. Finally, the effect of wave compensation and wave synchronization strategy are verified on MATLAB/Simulink. The results show that after the compensation, the crane load can follow the set height value very well, the compensation efficiency can reach more than 94%, and the wave synchronization strategy significantly reduces the change of the rope tension. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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14 pages, 14253 KiB  
Article
Optimization of the Hydrodynamic Performance of a Double-Vane Otter Board Based on Orthogonal Experiments
by Lei Wang, Xun Zhang, Rong Wan, Qingchang Xu and Guangrui Qi
J. Mar. Sci. Eng. 2022, 10(9), 1177; https://doi.org/10.3390/jmse10091177 - 24 Aug 2022
Cited by 3 | Viewed by 1267
Abstract
An orthogonal experiment was conducted to study the effects of the aspect ratio, camber of the fore wing, and gap ratio of front and rear wing panels on the hydrodynamic performance of double-vane otter boards. The design of the orthogonal experiment comprised three [...] Read more.
An orthogonal experiment was conducted to study the effects of the aspect ratio, camber of the fore wing, and gap ratio of front and rear wing panels on the hydrodynamic performance of double-vane otter boards. The design of the orthogonal experiment comprised three factors (each having three levels), namely the aspect ratio (1.0, 1.5, and 2.0), camber (0.12, 0.14, and 0.16), and gap ratio (0.25, 0.30, and 0.35), the drag coefficient Cx and the lift coefficient Cy of nine otter board models obtained in a wind tunnel experiment, and the lift–drag ratio K obtained by calculation. The lift–drag ratio for a working angle of attack of 30° was selected as the inspection index, and the experimental data were analyzed in an orthogonal design-direct analysis. Analysis of each factor revealed that the optimal level combination of factors was A3B3C3 and that the decreasing order of the effects of the factors was A (aspect ratio) > B (gap ratio) > C (camber). The orthogonal experiment thus obtained an optimal otter board in terms of the aspect ratio (2.0), fore wing camber (0.16), and gap ratio (0.35), with the aspect ratio having the greatest effect on performance. The hydrodynamic performances of the otter board with the optimized structure and another otter board model were compared in numerical simulation, which verified the correctness of the analysis results. The experimental results provide a reference for the optimal design of the double-vane otter board. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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17 pages, 9685 KiB  
Article
Numerical Investigation on Higher-Order Harmonic Waves Induced by a Submerged Inclined Plate
by Zhimin Zhou, Yawei Sun, Lifen Chen, Dezhi Ning and Sulisz Wojciech
J. Mar. Sci. Eng. 2022, 10(8), 1115; https://doi.org/10.3390/jmse10081115 - 13 Aug 2022
Viewed by 1264
Abstract
In this paper, a two-dimensional time-domain numerical flume has been established to model and investigate nonlinear interactions between nonlinear surface waves and a submerged inclined thin plate. The model solves the Laplace equation and the fully nonlinear free surface boundary conditions within the [...] Read more.
In this paper, a two-dimensional time-domain numerical flume has been established to model and investigate nonlinear interactions between nonlinear surface waves and a submerged inclined thin plate. The model solves the Laplace equation and the fully nonlinear free surface boundary conditions within the framework of potential flow theory based on the high-order boundary element method. The mixed Euler–Lagrangian method is applied to update the water surface at each time step, and the fourth-order Runge–Kutta method for time stepping. A so-called four-point method was employed to separate the second-order harmonic free and bounded wave that has the same wave frequency but different wave celerity in front of and behind the submerged plate. It is found that the amplitude of the second-order harmonic free wave increases with the inclination angle of the submerged plate, and the level/amount of the increase is larger for a larger wave steepness. In addition, the amplitudes of both the second-order reflected and transmitted waves are found to increase with the wave steepness, and their empirical relationships are derived for potential use in practical engineering. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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12 pages, 4097 KiB  
Article
Field Investigation on the Coastal Erosion and Progradation Evolution of the Binzhou Shelly Chenier in China: Comparisons between Normal and Typhoon Hydrodynamics
by Mingzheng Wen, Huaibo Zhang, Shoujun Wang, Zhiwen Shang, Shaotong Zhang, Peng Yang and Hong Wang
J. Mar. Sci. Eng. 2022, 10(6), 752; https://doi.org/10.3390/jmse10060752 - 30 May 2022
Viewed by 1443
Abstract
The shelly chenier is a dike-like accumulation formed by waves, currents, and other hydrodynamic forces pushing the shells and their debris in the intertidal zone to the high tide line. It is a special type of coastal dike. The shelly chenier located in [...] Read more.
The shelly chenier is a dike-like accumulation formed by waves, currents, and other hydrodynamic forces pushing the shells and their debris in the intertidal zone to the high tide line. It is a special type of coastal dike. The shelly chenier located in Wangzi Island of northern Shandong Province is the last well-preserved chenier of the Bohai Bay with natural attributes exposed on the surface. It has unique and irreplaceable attributes among the shell beaches of China. Based on remote sensing interpretation, field investigation, and GPS-RTK (Real-Time Kinematic) measurement, this paper investigates the coastal erosion and progradation evolution of the Binzhou Shelly Chenier in China usingcomparisons between normal and typhoon hydrodynamics. The results show that: (1) There are two kinds of shelly chenier in the study area, the first is “the tidal channel shelly chenier” which is significantly affected by the tidal current, and the second is “the open shelly chenier”, which is significantly affected by direct scouring and silting of waves. The open shelly chenier is continuously eroding under the normal hydrodynamics and the shell beach is supplied by a large number of shells and their debris under the typhoon hydrodynamics, while the tidal channel shelly chenier is gradually developed due to the action of alongshore currents and in–out flows. (2) The energy of waves and currents under normal hydrodynamics is insufficient to transport the shells and their debris in the intertidal zone to the shell-beach. On the contrary, the continuous action of waves makes the shells and their debris on the open-shell beach finer and transports the shells and their debris to the sea causing erosion and retreat of the shelly chenier. (3) The action of typhoons and other strong winds and waves results in the original accumulation on the open shell-beach being further transported to the land and provides a large amount of shells and debris from the intertidal zone to the shelly chenier. Based on GPS-RTK monitoring data from 2020–2021, it was found that the transport volume of shells and debris caused by a typhoon storm surge is equivalent to the annual transport volume under normal ocean dynamics. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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12 pages, 4837 KiB  
Article
Study on the Electro-Osmosis-Combined-Preloading Method in Strengthening Reclaimed Sludge from the Macroscopic and Microscopic Views
by Yanli Tao, Jianfeng Zhu, Jian Zhou, Zeyi Yu and Jia Lu
J. Mar. Sci. Eng. 2022, 10(5), 646; https://doi.org/10.3390/jmse10050646 - 09 May 2022
Viewed by 1762
Abstract
The electro-osmosis-combined-preloading method is considered very promising in soft soil improvement, while the uncertainty in the function mechanism has hindered its practical application. To explore the mechanism of the combined method, experiments concerning the single electro-osmosis method and the combined method were carried [...] Read more.
The electro-osmosis-combined-preloading method is considered very promising in soft soil improvement, while the uncertainty in the function mechanism has hindered its practical application. To explore the mechanism of the combined method, experiments concerning the single electro-osmosis method and the combined method were carried out using reclaimed sludge. Macroscopic and microscopic properties of the soil were explored and compared. Drainage, soil settlement, soil water content and soil pore structure were detected during the experiments. The total drainage and average settlement of the combined method were, respectively, 20.8% and 34.5% greater than that of the single electro-osmosis method. The average void ratio of soils treated by the combined method was 13.8% lower than that by the electro-osmosis method. Moreover, reduction rates of the soil water content are found higher than that of the apparent void ratio for each method. It can be concluded that the combined method had better performances, both from the macroscopic and microscopic views. Furthermore, a theoretical analysis demonstrated that soil was desaturated and the soil shrinkage volume was lower than the drained water volume during electro-osmosis. This is derived from the essence of electro-osmosis, which determines that considerable pores formerly occupied by drained water cannot be effectively compressed. The combined method can fully use the advantages of the single methods by active drainage through electro-osmosis and further compression of the soil skeleton through preloading. Therefore, the electro-osmosis-combined-preloading method was strongly recommended for reclaimed sludge strengthening. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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18 pages, 37687 KiB  
Article
Experimental Study on Silty Seabed Liquefaction and Its Impact on Sediment Resuspension by Random Waves
by Jiangfeng Dong, Jishang Xu, Guangxue Li, Anlong Li, Shaotong Zhang, Jianwei Niu, Xingyu Xu and Lindong Wu
J. Mar. Sci. Eng. 2022, 10(3), 437; https://doi.org/10.3390/jmse10030437 - 17 Mar 2022
Cited by 5 | Viewed by 2282
Abstract
Seabed liquefaction and sediment resuspension under wave loading are key issues in marine engineering, but are usually regarded as independent processes (instead of coexisting and interacting processes). Here, we analyzed random wave-induced seabed liquefaction and its impact on sediment resuspension using flume experiments. [...] Read more.
Seabed liquefaction and sediment resuspension under wave loading are key issues in marine engineering, but are usually regarded as independent processes (instead of coexisting and interacting processes). Here, we analyzed random wave-induced seabed liquefaction and its impact on sediment resuspension using flume experiments. Results show that in a nonliquefaction scenario, excess pore pressure in the seabed oscillates with wave fluctuations, but pressure accumulation is low, while a consistent upward pressure gradient promotes sediment suspension. Wave-induced shear stress was the key driver of sediment resuspension in a nonliquefaction scenario. In the liquefied state, waves with different amplitudes differently responded to excess pore pressure; small-amplitude waves accumulated pressure, while large-amplitude waves dissipated it. Liquefied soil formed mud waves, creating elliptical motion along with random waves. Seabed liquefaction accelerated sediment resuspension in the following ways: reducing soil critical shear stress; forming seepage channels inside the seabed; forming mud waves, resulting in increased turbulent kinetic energy; dissipating excess pore pressure and releasing porewater, expelling fine-grained sediment from the liquefied soil. Our study reveals the variation in excess pore pressure in silty seabed under random waves and its effect on sediment resuspension, which is significant for understanding soil liquefaction and sediment movement of silt. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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27 pages, 6556 KiB  
Article
Wave Forces on a Partially Reflecting Wall by Oblique Bragg Scattering with Porous Breakwaters over Uneven Bottoms
by Jen-Yi Chang and Chia-Cheng Tsai
J. Mar. Sci. Eng. 2022, 10(3), 409; https://doi.org/10.3390/jmse10030409 - 11 Mar 2022
Cited by 5 | Viewed by 1841
Abstract
In this study, the scattering of oblique water waves by multiple variable porous breakwaters near a partially reflecting wall over uneven bottoms are investigated using the eigenfunction matching method (EMM). In the solution procedure, the variable breakwaters and bottom profiles are sliced into [...] Read more.
In this study, the scattering of oblique water waves by multiple variable porous breakwaters near a partially reflecting wall over uneven bottoms are investigated using the eigenfunction matching method (EMM). In the solution procedure, the variable breakwaters and bottom profiles are sliced into shelves separated steps and the solutions on the shelves are composed of eigenfunctions with unknown coefficients representing the wave amplitudes. Using the conservations of mass and momentum as well as the condition for the partially reflecting sidewall, a system of linear equations is resulted that can be solved by a sparse-matrix solver. The proposed EMM is validated by comparing its results with those in the literature. Then, the EMM is applied for studying oblique Bragg scattering by periodic porous breakwaters near a partially reflecting wall over uneven bottoms. The constructive and destructive Bragg scattering are discussed. Numerical results suggest that the partially reflecting wall should be separated from the last breakwater by half wavelength of the periodic breakwaters to migrate the wave force on the vertical wall. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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21 pages, 4186 KiB  
Article
Predicting the Instability Trajectory of an Obliquely Loaded Pipeline on a Clayey Seabed
by Ning Wang, Wengang Qi and Fuping Gao
J. Mar. Sci. Eng. 2022, 10(2), 299; https://doi.org/10.3390/jmse10020299 - 21 Feb 2022
Cited by 4 | Viewed by 1554
Abstract
Predicting the instability trajectory of an obliquely loaded pipeline on the seabed is vital for the global buckling assessment. To numerically investigate the obliquely loaded pipe–soil interactions, a plane strain elastoplastic finite element model incorporating the adaptive meshing technique and the contact-pair algorithm [...] Read more.
Predicting the instability trajectory of an obliquely loaded pipeline on the seabed is vital for the global buckling assessment. To numerically investigate the obliquely loaded pipe–soil interactions, a plane strain elastoplastic finite element model incorporating the adaptive meshing technique and the contact-pair algorithm is employed and verified with the existing experimental data and the analytical predictions. The evolution of slip mechanisms within the underlying soil is simulated, indicating the instability direction of the pipe, and the corresponding ultimate soil resistance is closely correlated. It is also indicated that the ultimate load angle is in the positive correlation with the movement angle, the dimensionless embedment of the pipe and the roughness coefficient of the pipe–soil interface. On the basis of numerous simulations, a force-resultant plasticity model including the bearing capacity envelope and the flow rule is proposed for predicting the behavior of a partially embedded pipeline on the clayey seabed. Finally, an explicit expression with respect to the critical submerged weight of the pipe is derived for distinguishing the lateral instability of a pipe between the ‘light’ and the ‘heavy’ mode. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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16 pages, 5220 KiB  
Article
Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents
by Zhiyong Zhang, Yakun Guo, Yuanping Yang, Bing Shi and Xiuguang Wu
J. Mar. Sci. Eng. 2021, 9(12), 1421; https://doi.org/10.3390/jmse9121421 - 12 Dec 2021
Cited by 5 | Viewed by 2298
Abstract
In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the [...] Read more.
In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the situation of bidirectional tidal currents. To deeply understand scour characteristics and produce a more accurate prediction method in bidirectional tidal currents for engineering application, a series of laboratory scale experiments were conducted in a bidirectional current flume. The experiments were carried out at a length scale of 1:20 and the tidal currents were scaled with field measurements from Cezhen pipeline in Hangzhou Bay, China. The experimental results showed that under bidirectional tidal currents, the scour depth increased significantly during the first half of the tidal cycle and it only increased slightly when the flow of the tidal velocity was near maximum flood or ebb in the following tidal cycle. Compared with scour under a unidirectional steady current, the scour profile under a bidirectional tidal current was more symmetrical, and the scour depth in a bidirectional tidal current was on average 80% of that under a unidirectional, steady current based on maximum peak velocity. Based on previous research and the present experimental data, a more accurate fitted equation to predict the tidally induced live-bed scour depth around submarine pipelines was proposed and has been verified using field data from the Cezhen pipeline. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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