Advances in Marine Engineering: Geological Environment and Hazards II

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

Deadline for manuscript submissions: closed (25 April 2024) | Viewed by 19235

Special Issue Editors


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Guest Editor
Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
Interests: marine engineering geology; wave-seabed interactions; submarine sediment gravity flows; seafloor in-situ test and observation
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Guest Editor
Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK
Interests: computational fluid dynamics; coastal hydraulics and environmental fluid mechanics
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK
Interests: marine geotechnical engineering; marine geological disasters; marine engineering geology and environment; deep-sea mining; hydrodynamics; non-Newtonian fluid; two-phase flows; LES; CFD; turbidity current; gravity flow; fluid-structure interaction; sediment plume; pipes and piles
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the continuous advancement of coastal, offshore, and deep-sea engineering construction (marine resource development, offshore wind power projects, etc.), research on marine geological environments and hazards has gradually deepened and many research advances have been achieved. Therefore, this Special Issue has been organized by Prof. Xiaolei Liu, Prof. Thorsten Stoesser, and Dr. Xingsen Guo to document these research advances. The objective of this Special Issue is to collect research papers in the field of marine geological environments and hazards, including geological environments, geological hazards, engineering geology, hydrodynamics, fluid environments, and geotechnical engineering. This Special Issue invites contributions comprising in situ observations, indoor tests, numerical simulations, and theoretical analyses on marine geological environments and hazards. Contributions may also include case studies, review articles, or short communications.

Prof. Dr. Xiaolei Liu
Prof. Dr. Thorsten Stoesser
Dr. Xingsen Guo
Guest Editors

Manuscript Submission Information

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Keywords

  • marine geological environment
  • marine geological hazards
  • marine engineering geology
  • marine hydrodynamics
  • marine environment fluid
  • marine geotechnical engineering

Published Papers (16 papers)

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Research

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25 pages, 7966 KiB  
Article
A Methodology for Susceptibility Assessment of Wave-Induced Seabed Liquefaction in Silt-Dominated Nearshore Environments
by Yueying Wang, Xingsen Guo, Jinkun Liu, Fang Hou, Hong Zhang, Han Gao and Xiaolei Liu
J. Mar. Sci. Eng. 2024, 12(5), 785; https://doi.org/10.3390/jmse12050785 - 8 May 2024
Viewed by 764
Abstract
Wave-induced seabed liquefaction significantly jeopardizes the stability of marine structures and the safety of human life. Susceptibility assessment is key to enabling spatial predictions and establishing a solid foundation for effective risk analysis and management. However, the current research encounters various challenges, involving [...] Read more.
Wave-induced seabed liquefaction significantly jeopardizes the stability of marine structures and the safety of human life. Susceptibility assessment is key to enabling spatial predictions and establishing a solid foundation for effective risk analysis and management. However, the current research encounters various challenges, involving an incomplete evaluation system, poor applicability of methods, and insufficient databases. These issues collectively hinder the accuracy of susceptibility assessments, undermining their utility in engineering projects. To address these challenges, a susceptibility assessment method with the safety factor was developed as the key assessment parameter, allowing for a comprehensive susceptibility assessment across the silt-dominated nearshore environment using Empirical Bayesian Kriging (EBK). The safety factor is determined by combining the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR), which characterize wave loadings and sediment properties in the study area, respectively. This method was applied in the Chengdao region of the Yellow River Estuary, China, a typical silt-dominated nearshore environment where wave-induced liquefaction events have been reported as being responsible for multiple oil platform and pipeline accidents. By collecting the regional wave and seabed sediment data from cores spanning from 1998 to 2017, the safety factors were calculated, and a zonal map depicting the susceptibility assessment of wave-induced seabed liquefaction was created. This study can serve as a valuable reference for the construction and maintenance of marine engineering in liquefaction-prone areas. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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17 pages, 11918 KiB  
Article
Coupling Effects of a Top-Hinged Buoyancy Can on the Vortex-Induced Vibration of a Riser Model in Currents and Waves
by Chi Yu, Sheng Zhang and Cheng Zhang
J. Mar. Sci. Eng. 2024, 12(5), 751; https://doi.org/10.3390/jmse12050751 - 30 Apr 2024
Viewed by 504
Abstract
In order to investigate the effects of the top-end dynamic boundary of risers caused by floater motions on their vortex-induced vibration (VIV) characteristics, a combined model comprising a buoyancy can with a relatively simple structural form and a riser is taken as the [...] Read more.
In order to investigate the effects of the top-end dynamic boundary of risers caused by floater motions on their vortex-induced vibration (VIV) characteristics, a combined model comprising a buoyancy can with a relatively simple structural form and a riser is taken as the research object in the present study. The aspect ratios of the buoyancy can and the riser model are 5.37 and 250, respectively. A set of experimental devices is designed to support the VIV test of the riser with a dynamic boundary stimulating the vortex-induced motion (VIM) of the buoyancy can under different uniform flow and regular wave conditions. Several data processing methods are applied in the model test, i.e., mode superposition, Euler angle conversion, band pass filter, fast Fourier transform, and wavelet transform. Based on the testing results, the effect of low-frequency VIM on the high-frequency VIV of the riser is discussed in relation to a single current, a single wave, and a combined wave and current. It is found that the coupling effect of VIM on the riser VIV presents certain orthogonal features at low current velocities. The effect of the cross-flow VIM component on VIV is far more prominent than that of its counterpart, the in-line VIM, with increasing flow velocity. The VIM in the combined wave–current condition significantly enhances the modulation of vibration amplitude and frequency, resulting in larger fluctuation peaks of vibration response and further increasing the risk of VIV fatigue. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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15 pages, 3538 KiB  
Article
Seafloor Sediment Acoustic Properties on the Continental Slope in the Northwestern South China Sea
by Guanbao Li, Jingqiang Wang, Xiangmei Meng, Qingfeng Hua, Guangming Kan and Chenguang Liu
J. Mar. Sci. Eng. 2024, 12(4), 545; https://doi.org/10.3390/jmse12040545 - 25 Mar 2024
Viewed by 648
Abstract
The acoustic properties of seafloor sediments on continental slopes play a crucial role in underwater acoustic propagation, communication, and detection. To investigate the acoustic characteristics and spatial distribution patterns of sediments on the continental slope, a geoacoustic experiment was conducted in the northwestern [...] Read more.
The acoustic properties of seafloor sediments on continental slopes play a crucial role in underwater acoustic propagation, communication, and detection. To investigate the acoustic characteristics and spatial distribution patterns of sediments on the continental slope, a geoacoustic experiment was conducted in the northwestern South China Sea. The experiment covered two sections: one crossing the shelf and slope in the downslope direction, and the other near the shelf break in the along-slope direction. In situ techniques, sediment sampling, and laboratory measurements were used to acquire data on sediment acoustic properties (such as sound speed and attenuation) and physical properties (including particle composition, density, porosity, and mean grain size). The experimental findings revealed several key points: (1) Acoustic properties of shallow water coarse-grained sediments and deep-sea sediments were higher when measured in the laboratory compared to in situ measurements. (2) Relationships between measured attenuation and physical properties, as well as between sound speed and mean grain size, showed deviations from previous empirical equations. (3) Sediment acoustic and physical properties exhibited significant variations in the downslope direction, while showing gradual variations in the along-slope direction. These variations can be attributed to sedimentary environmental factors such as material sources, hydrodynamic conditions, and water depth. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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18 pages, 3932 KiB  
Article
Centrifuge Modelling of Composite Bucket Foundation Breakwater in Clay under Monotonic and Cyclic Loads
by Minmin Jiang, Zhao Lu, Zhengyin Cai and Guangming Xu
J. Mar. Sci. Eng. 2024, 12(3), 469; https://doi.org/10.3390/jmse12030469 - 9 Mar 2024
Viewed by 800
Abstract
This study investigates the monotonic and cyclic performance of composite bucket foundation breakwater in clay through centrifuge modeling. The application of monotonic loads simulates extreme wave conditions, and cyclic load corresponds to long-term serviceability conditions. In centrifuge tests, three typical soil strengths were [...] Read more.
This study investigates the monotonic and cyclic performance of composite bucket foundation breakwater in clay through centrifuge modeling. The application of monotonic loads simulates extreme wave conditions, and cyclic load corresponds to long-term serviceability conditions. In centrifuge tests, three typical soil strengths were tested, and two load eccentricities were simulated to check the influence of wave force height. Multiple measurements were conducted, including rotation angle, horizontal displacement, vertical settlement, and pore pressure variation. When soil strength increases in monotonic centrifuge tests, the ultimate bearing capacity of the bucket foundation experiences significant growth, and the foundation failure pattern varies. In responding to the monotonic test, the foundation’s rotation center constantly moved downward during the loading process, indicating that the deeper soil would be activated to resist the horizontal loading. In contrast, the rotation center movement in the symmetric centrifuge test was opposed to the non-symmetric test because the deeper soil was required to provide resistance to balance the more severe load under the non-symmetric loading condition. It should be noted that non-symmetric loading does not impact the bucket foundation as seriously as symmetric loading. The utilization of deep-soil resistance in non-symmetric tests is beneficial in controlling deformation. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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20 pages, 8344 KiB  
Article
Propagation Velocity of Excitation Waves Caused by Turbidity Currents
by Guohui Xu, Shiqing Sun, Yupeng Ren, Meng Li and Zhiyuan Chen
J. Mar. Sci. Eng. 2024, 12(1), 132; https://doi.org/10.3390/jmse12010132 - 9 Jan 2024
Viewed by 723
Abstract
Turbidity currents are important carriers for transporting terrestrial sediment into the deep sea, facilitating the transfer of matter and energy between land and the deep sea. Previous studies have suggested that turbidity currents can exhibit high velocities during their movement in submarine canyons. [...] Read more.
Turbidity currents are important carriers for transporting terrestrial sediment into the deep sea, facilitating the transfer of matter and energy between land and the deep sea. Previous studies have suggested that turbidity currents can exhibit high velocities during their movement in submarine canyons. However, the maximum vertical descent velocity of high-concentration turbid water simulating turbidity currents does not exceed 1 m/s, which does not support the understanding that turbidity currents can reach speeds of over twenty meters per second in submarine canyons. During their movement, turbidity currents can compress and push the water ahead, generating propagating waves. These waves, known as excitation waves, exert a force on the seafloor, resuspending bottom sediments and potentially leading to the generation of secondary turbidity currents downstream. Therefore, the propagation distance of excitation waves is not the same as the initial journey of the turbidity currents, and the velocity of excitation waves within this journey has been mistakenly regarded as the velocity of the turbidity currents. Research on the propagation velocity of excitation waves is of great significance for understanding the sediment supply patterns of turbidity currents and the transport patterns of deep-sea sediments. In this study, numerical simulations were conducted to investigate the velocity of excitation waves induced by turbidity currents and to explore the factors that can affect their propagation velocity and amplitude. The relationship between the velocity and amplitude of excitation waves and different influencing factors was determined. The results indicate that the propagation velocity of excitation waves induced by turbidity currents is primarily determined by the water depth, and an expression (v2 = 0.63gh) for the propagation velocity of excitation waves is provided. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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20 pages, 12793 KiB  
Article
Convenient Method for Large-Deformation Finite-Element Simulation of Submarine Landslides Considering Shear Softening and Rate Correlation Effects
by Qiuhong Xie, Qiang Xu, Zongxiang Xiu, Lejun Liu, Xing Du, Jianghui Yang and Hao Liu
J. Mar. Sci. Eng. 2024, 12(1), 81; https://doi.org/10.3390/jmse12010081 - 29 Dec 2023
Viewed by 878
Abstract
Submarine landslides pose a serious threat to the safety of underwater engineering facilities. To evaluate the safety of undersea structures, it is important to estimate and analyze the sliding processes of potential submarine landslides. In this study, a convenient model for simulating submarine [...] Read more.
Submarine landslides pose a serious threat to the safety of underwater engineering facilities. To evaluate the safety of undersea structures, it is important to estimate and analyze the sliding processes of potential submarine landslides. In this study, a convenient model for simulating submarine landslide processes is established by using Abaqus Eulerian large deformation technology with an explicit finite element framework. The VUSDFLD Fortran subroutine is used to consider the strain-softening and rate-dependency characteristics of soil shear strength. The proposed method is validated by comparing its results with experimental data and those of mainstream numerical methods. Then, the results of a dynamic analysis of typical potential submarine landslides in the Shenhu sea area are analyzed using the proposed method. Case studies are carried out under different soil shear strength distributions, and the influence of initial stress is also analyzed. The shear strain-softening and rate-dependency effects are highly involved in the runout process. The simulated landslide’s failure mode is consistent with the geophysical interpretation of existing landslide characteristics. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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17 pages, 4384 KiB  
Article
Prediction Model of the Sound Speed of Seafloor Sediments on the Continental Shelf of the East China Sea Based on Empirical Equations
by Guangming Kan, Junjie Lu, Xiangmei Meng, Jingqiang Wang, Linqing Zhang, Guanbao Li, Baohua Liu, Qingfeng Hua and Mujun Chen
J. Mar. Sci. Eng. 2024, 12(1), 27; https://doi.org/10.3390/jmse12010027 - 21 Dec 2023
Viewed by 904
Abstract
Based on the data of the acoustic and physical properties of seafloor sediments obtained on the continental shelf area of the East China Sea (ECS), prediction equations of the sediment sound speed based on single and dual parameters were established, and the correlation [...] Read more.
Based on the data of the acoustic and physical properties of seafloor sediments obtained on the continental shelf area of the East China Sea (ECS), prediction equations of the sediment sound speed based on single and dual parameters were established, and the correlation of the sound speed with physical parameters was discussed. The results show that the sediment sound speed (c) is strongly correlated with water content (w), density (ρ), void ratio (e), mean grain size (Mz) and median grain size (Md), and the coefficient of determination R2 of the empirical regression equation is generally greater than 0.80, while the empirical regression equation coefficient of determination R2 of the compression coefficient (a) and compression modulus (E) are slightly lower, with 0.79 and 0.73, respectively. The coefficients of determination of the dual parameter regression equations between sediment sound speed with physical property parameters are generally higher than those of the single parameter equations, which are all higher than 0.90 indicating better prediction performance. The sensitivity of the physical parameters to the sound speed was analyzed, and the result shows that the sequence of sensitivity from high to low influence on sediment sound speed is void ratio, density, compressibility coefficient, median grain size and mean grain size. The prediction equations established in this study are a good extension and supplement to marine geoacoustic models and is of great significance for obtaining the acoustic properties of the seafloor sediments on the shelf of the East China Sea. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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21 pages, 8370 KiB  
Article
Determination of Formulae for the Hydrodynamic Performance of a Fixed Box-Type Free Surface Breakwater in the Intermediate Water
by Guoxu Niu, Yaoyong Chen, Jiao Lv, Jing Zhang and Ning Fan
J. Mar. Sci. Eng. 2023, 11(9), 1812; https://doi.org/10.3390/jmse11091812 - 17 Sep 2023
Viewed by 1062
Abstract
A two-dimensional viscous numerical wave tank coded mass source function in a computational fluid dynamics (CFD) software Flow-3D 11.2 is built and validated. The effect of the core influencing factors (draft, breakwater width, wave period, and wave height) on the hydrodynamic performance of [...] Read more.
A two-dimensional viscous numerical wave tank coded mass source function in a computational fluid dynamics (CFD) software Flow-3D 11.2 is built and validated. The effect of the core influencing factors (draft, breakwater width, wave period, and wave height) on the hydrodynamic performance of a fixed box-type free surface breakwater (abbreviated to F-BW in the following texts) are highlighted in the intermediate waters. The results show that four influence factors, except wave period, impede wave transmission; the draft and breakwater width boost wave reflection, and the wave period and wave height are opposite; the draft impedes wave energy dissipation, and the wave height is opposite; the draft and wave height boost the horizontal extreme wave force; four influence factors, except the draft, boost the vertical extreme wave force. Finally, new formulas are provided to determine the transmission, reflection, and dissipation coefficients and extreme wave forces of the F-BW by applying multiple linear regression. The new formulas are verified by comparing with existing literature observation datasets. The results show that it is in good agreement with previous datasets. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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21 pages, 11145 KiB  
Article
Study on the Relationship between Resistivity and the Physical Properties of Seafloor Sediments Based on the Deep Neural Learning Algorithm
by Zhiwen Sun, Zhihan Fan, Chaoqi Zhu, Kai Li, Zhongqiang Sun, Xiaoshuai Song, Liang Xue, Hanlu Liu and Yonggang Jia
J. Mar. Sci. Eng. 2023, 11(5), 937; https://doi.org/10.3390/jmse11050937 - 27 Apr 2023
Cited by 2 | Viewed by 1139
Abstract
The occurrence of deep-sea geohazards is accompanied by dynamic changes in the physical properties of seafloor sediments. Therefore, studying the physical properties is helpful for monitoring and early warnings of deep-sea geohazards. Existing physical property inversion methods have problems regarding the poor inversion [...] Read more.
The occurrence of deep-sea geohazards is accompanied by dynamic changes in the physical properties of seafloor sediments. Therefore, studying the physical properties is helpful for monitoring and early warnings of deep-sea geohazards. Existing physical property inversion methods have problems regarding the poor inversion accuracy and limited application scope. To address these issues, we establish a deep learning model between the resistivity of seafloor sediment and its density, water content, and porosity. Compared with empirical formulas, the deep learning model has the advantages of a more concentrated prediction range and a higher prediction accuracy. This algorithm was applied to invert the spatial distribution characteristics and temporal variation of the seafloor sediment density, water content, and porosity in the South China Sea hydrate test area for 12 days. The study reveals that the dynamic changes in the physical properties of seafloor sediments in the South China Sea hydrate zone exhibit obvious stratification characteristics. The dynamic changes in the physical properties of seafloor sediments are mainly observed at depths of 0–0.9 m below the seafloor, and the sediment properties remain stable at depths of 0.9–1.8 m below the seafloor. This study achieves the monitoring and early warning of dynamic changes in the physical properties of seafloor sediments and provides a guarantee for the safe construction of marine engineering. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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13 pages, 4523 KiB  
Article
Experimental Study on the Bonding Performance of HIRA-Type Material Anchor Solids Considering Time Variation
by Kun Wang, Qingsheng Meng, Yan Zhang, Huadong Peng and Tao Liu
J. Mar. Sci. Eng. 2023, 11(4), 798; https://doi.org/10.3390/jmse11040798 - 7 Apr 2023
Cited by 2 | Viewed by 1011
Abstract
In order to reveal the evolution of bonding performance of HIRA (High Intensity and Rapid Agent) anchor solids with maintenance time, the evolution characteristics of bond strength and stress distribution at the interface between HIRA-based anchor solids and a geotechnical body under different [...] Read more.
In order to reveal the evolution of bonding performance of HIRA (High Intensity and Rapid Agent) anchor solids with maintenance time, the evolution characteristics of bond strength and stress distribution at the interface between HIRA-based anchor solids and a geotechnical body under different maintenance times and the fine damage pattern of anchor solids were studied by an indoor pull-out test of anchor solids. The comparative analysis was performed with 42.5 grade ordinary Portland cement (hereinafter referred to as P.O 42.5). The results show that the early strength and rapid setting characteristics of HIRA type material are obvious, and the difference between its average peak bond strength and that of cement is 10.45 times. The shear stress distribution has obvious stress concentration characteristics, and the peak value will appear and shift with the increase in load, and the peak shift of the HIRA anchor solid occurs earlier than that of cement. Due to different stress levels, the damage of the HIRA anchor solid after being pulled out increases with the increase in maintenance time, while that of cement gradually becomes more severe. The overall damage of the HIRA material is generally lower than that of cement in the same period. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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13 pages, 7675 KiB  
Article
Effect of High Temperature on Mechanical Properties and Microstructure of HSFCM
by Yanbin Li, Qingsheng Meng, Yan Zhang, Huadong Peng and Tao Liu
J. Mar. Sci. Eng. 2023, 11(4), 721; https://doi.org/10.3390/jmse11040721 - 27 Mar 2023
Viewed by 1201
Abstract
A new type of composite cement-based cementing material—high-strength fast cementing material (HSFCM)—will be widely used in marine engineering projects such as submarine tunnels. However, the influence of fire and other high temperature conditions on its material properties have not been explored in previous [...] Read more.
A new type of composite cement-based cementing material—high-strength fast cementing material (HSFCM)—will be widely used in marine engineering projects such as submarine tunnels. However, the influence of fire and other high temperature conditions on its material properties have not been explored in previous studies. Mechanical tests and microstructure observations of HSFCM were carried out, and the strength and deformation characteristics, microstructure and composition evolution of HSFCM after high temperature treatment were discussed. After high temperature treatment, the compressive strength of HSFCM deteriorated. The compressive strength of HSFCM decreased by more than half at 400 °C. The peak strain increased at 200 °C with the increase of temperature, and decreased at 400~600 °C with the increase of temperature. High temperature reduces the stiffness of HSFCM, and the elastic modulus decreases with increasing temperature. The influence of high temperature on the microstructure of HSFCM is mainly shown in the increase and enlargement of pores in three-dimensional space, the development of micro-cracks and the thermal decomposition of cementing material into stable oxides without cementing effect. The microscopic changes of HSFCM are in good agreement with the mechanical test results. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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13 pages, 958 KiB  
Article
Stabilizing and Destabilizing Breaching Flow Slides
by Said Alhaddad, Dave Weij, Cees van Rhee and Geert Keetels
J. Mar. Sci. Eng. 2023, 11(3), 560; https://doi.org/10.3390/jmse11030560 - 6 Mar 2023
Cited by 6 | Viewed by 1287
Abstract
As a result of the dilation of soil matrix, dense submarine sand slopes can temporarily be steeper than the natural angle of repose. These slopes gradually fail by the detachment of individual grains and intermittent collapses of small coherent sand wedges. The key [...] Read more.
As a result of the dilation of soil matrix, dense submarine sand slopes can temporarily be steeper than the natural angle of repose. These slopes gradually fail by the detachment of individual grains and intermittent collapses of small coherent sand wedges. The key question is whether steep disturbances in a submarine slope grow in size (destabilizing breaching) or gradually diminish (stabilizing breaching) and thereby limit the overall slope failure and resulting damage. The ability to predict whether the breaching failure is stabilizing or destabilizing is also crucial for the assessment of safety of submarine infrastructure and hydraulic structures located along rivers, lakes, and coasts. Through a set of large-scale laboratory experiments, we investigate the validity of an existing criterion to determine the failure mode of breaching (i.e., stabilizing or destabilizing). Both modes were observed in these experiments, providing a unique set of data for analysis. It is concluded that the existing method has limited forecasting power. This was quantified using the mean absolute percentage error, which was found to be 92%. The reasons behind this large discrepancy are discussed. Given the complexity of the underlying geotechnical and hydraulic processes, more advanced methodologies are required. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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17 pages, 17182 KiB  
Article
Experimental Investigation on the Cyclic Shear Mechanical Characteristics and Dynamic Response of a Steel–Silt Interface in the Yellow River Delta
by Peng Yu, Jie Dong, Yong Guan, Qing Wang, Shixiang Jia, Meijun Xu, Hongjun Liu and Qi Yang
J. Mar. Sci. Eng. 2023, 11(1), 223; https://doi.org/10.3390/jmse11010223 - 15 Jan 2023
Cited by 3 | Viewed by 1522
Abstract
The shear behavior and dynamic response of a steel–silt interface are significant for the safety and stability of offshore structures in the Yellow River Delta. A series of steel–silt interface cyclic shear tests under constant normal load conditions (CNL) were carried out to [...] Read more.
The shear behavior and dynamic response of a steel–silt interface are significant for the safety and stability of offshore structures in the Yellow River Delta. A series of steel–silt interface cyclic shear tests under constant normal load conditions (CNL) were carried out to explore the effects of normal stress, shear amplitude, roughness, and water content on the interface shear strength, shear stiffness, and damping ratio using a large interface shear apparatus. The preliminary results showed that the amplitude of normal stress and shear amplitude affected the interface’s shear strength, stiffness, and damping ratio in a dominant manner. The roughness and water content were also crucial factors impacting the rule of shear strength, shear stiffness, and damping ratio, changing with the number of cycles. Under various scenarios, the steel–silt interface weakened distinctively, and the energy dissipation tended to be asymptotic with the cyclic shear. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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16 pages, 6458 KiB  
Article
A Case Study Assessing the Liquefaction Hazards of Silt Sediments Based on the Horizontal-to-Vertical Spectral Ratio Method
by Qingsheng Meng, Yang Li, Wenjing Wang, Yuhong Chen and Shilin Wang
J. Mar. Sci. Eng. 2023, 11(1), 104; https://doi.org/10.3390/jmse11010104 - 4 Jan 2023
Cited by 1 | Viewed by 1676
Abstract
Silt liquefaction can occur due to the rapid cyclic loading of sediments. This can result in the loss of the bearing capacity of the underlying sediments and damage to the foundations and infrastructure. Therefore, assessing liquefaction hazards is an important aspect of disaster [...] Read more.
Silt liquefaction can occur due to the rapid cyclic loading of sediments. This can result in the loss of the bearing capacity of the underlying sediments and damage to the foundations and infrastructure. Therefore, assessing liquefaction hazards is an important aspect of disaster prevention and risk assessment in geologically unstable areas. The purpose of this study is to assess the liquefaction hazards of silt sediments by using the horizontal-to-vertical spectral ratio method. Single-station noise recording was carried out in the northern plain of the Yellow River Delta, and a new method was adopted to identify the fundamental frequency. The dynamic parameters of the silt, such as the fundamental frequency, amplification, and vulnerability index, were used as indicators to assess the liquefaction potential. The results show that the silty soils in different areas have different stable ranges of values of the fundamental frequency. Moreover, the distribution of the observations is in good agreement with the geological conditions in the area, which indicates the potential applicability and reliability of the new method for identifying fundamental frequency. The vulnerability index is inversely related to the fundamental frequency, with the southwestern part of the study area having a lower fundamental frequency and a higher vulnerability index, meaning a greater liquefaction risk compared to other areas. The horizontal-to-vertical spectral ratio method has great advantages in characterizing subsurface dynamic parameters and can be applied to liquefaction hazard assessments of silt sediments in large areas, which is critically important in terms of providing information and guidance for urban construction and planning. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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17 pages, 4684 KiB  
Article
Stability Characteristics of Horizontal Wells in the Exploitation of Hydrate-Bearing Clayey-Silt Sediments
by Xiaofeng Sun, Qiaobo Hu, Yanlong Li, Mingtao Chen and Yajuan Zhang
J. Mar. Sci. Eng. 2022, 10(12), 1935; https://doi.org/10.3390/jmse10121935 - 7 Dec 2022
Cited by 4 | Viewed by 1447
Abstract
The mechanical properties of hydrate-bearing strata in clayey-silt sediments are significantly different from those of either conventional reservoirs or hydrate-bearing sandy sediments, which poses great challenges for wellbore stability analyses. The stability characteristics of a deviated borehole during drilling in hydrate-bearing clayey-silt sediments [...] Read more.
The mechanical properties of hydrate-bearing strata in clayey-silt sediments are significantly different from those of either conventional reservoirs or hydrate-bearing sandy sediments, which poses great challenges for wellbore stability analyses. The stability characteristics of a deviated borehole during drilling in hydrate-bearing clayey-silt sediments (HBS-CS) remain to be studied. In this paper, an analysis of the wellbore stability characteristics of a deviated borehole using the Mohr–Coulomb (M-C) criterion and Drucker–Prager (D-P) criterion was carried out based on the elastic stress distribution model of the surrounding strata of the wellbore and the triaxial shear tests of the HBS-CS. The results imply that the collapse pressure and safety density window are symmetrically distributed with deviation angle and azimuth. Considering the effect of hydrate decomposition, the collapse pressure gradient could become higher and the instability risks would be amplified. Considering the combined effects of collapse, fracture pressure gradient, and the safety density window, it is suggested that the borehole be arranged along an azimuth of 60–120°, which could greatly reduce the risk in a drilling operation. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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Review

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27 pages, 8672 KiB  
Review
Seabed Dynamic Responses Induced by Nonlinear Internal Waves: New Insights and Future Directions
by Tian Chen, Zhenghui Li, Hui Nai, Hanlu Liu, Hongxian Shan and Yonggang Jia
J. Mar. Sci. Eng. 2023, 11(2), 395; https://doi.org/10.3390/jmse11020395 - 10 Feb 2023
Cited by 5 | Viewed by 1829
Abstract
Strong nonlinear internal waves generate a significant pressure force on the seafloor and induce a pore-pressure response penetrated in the seabed and are thus an important driver of sediment resuspension and a potential trigger of seabed failure. The following provides an overview of [...] Read more.
Strong nonlinear internal waves generate a significant pressure force on the seafloor and induce a pore-pressure response penetrated in the seabed and are thus an important driver of sediment resuspension and a potential trigger of seabed failure. The following provides an overview of the seabed responses induced by nonlinear internal waves and the theory, models, and limited observations that have provided our present knowledge. The pressure disturbance is generated by the combined effect of interface displacement and near-bottom acceleration by the nonlinear internal waves. Recent observations in the South China Sea have shown that the pressure magnitudes up to 4 kPa, which is the largest known disturbance. Intense pore-pressure changes in roughly the top 1 m of the weakly conductive seabed are expected during the shoaling and breaking of the nonlinear internal waves and lead to 2 cm sediments of the local seabed appearing in transient liquefaction. Since the fluid seepage reduces the specific weight of the bed, results show that the contribution of vertical seepage on sediment resuspension is estimated at 11% for a seabed saturation of 0.97. Finally, in situ observations are needed to confirm theoretical knowledge and to help improve our ability to model the multiscale interaction process between the seabed and internal waves in the future. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards II)
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