Advances in Offshore Geotechnics

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 (31 July 2023) | Viewed by 16936

Special Issue Editors

Department of Geotechnical Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
Interests: offshore pile foundation; geotechnical earthquake engineering; soft soil engineering; deep-water foundation; scour and erosion
Special Issues, Collections and Topics in MDPI journals
Department of Civil Engineering, Case Western Reserve University, 2104 Adelbert Road, Bingham Building-Room 206, Cleveland, OH 44106-7201, USA
Interests: geotechnical engineering; resilient, sustainable, and intelligent infrastructure, infrastructure/city informatics; efficient design, operation, and management of infrastructure systems; multiscale and multiphysics modeling and characterization of engineering materials and systems
Special Issues, Collections and Topics in MDPI journals
Department of Geotechnical Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
Interests: marine geotechnical engineering; scour and erosion; deep-water foundation; disaster prevention and resilience; intelligent infrastructure; underground space
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Coastal areas house a major portion of the global population, also providing an important engine for economic activities. Offshore geotechnics play a crucial role in the development and expansion of coastal infrastructure for the effective utilization of natural resources from the ocean and lakes. The increasing natural hazard risks associated with climate change (i.e., shoreline erosion, hurricanes, wave surges, tides, coastal floods, etc.) present novel challenges for geotechnical engineering. This Special Issue entitled "Advances in Offshore Geotechnics" solicits papers concerning recent progress in geotechnical theory and applications in this important domain. Topics include, but are not limited to:

  • The characterization of engineering behaviors of offshore sediments;
  • Offshore site characterization;
  • Shoreline erosion, including the Arctic region;
  • Offshore geohazards and risk assessment;
  • Offshore geostructure design;
  • Offshore land reclamation;
  • Offshore landslides;
  • Effects of waves on sediment liquefaction;
  • Geotechnical engineering design for coastal natural hazards prevention and mitigation;
  • Geotechnical adaptation for climate change;
  • Geotechnical engineering for coastal infrastructure (coastal roads and bridges, pipelines, wind turbines, ports, maritime transportation, etc.).

Prof. Dr. Fayun Liang
Prof. Dr. Xiong (Bill) Yu
Dr. Chen Wang
Guest Editors

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

  • offshore geotechnics
  • sediments
  • shoreline erosion
  • coastal hazards
  • coastal flooding
  • arctic coastal line
  • geo-risk

Published Papers (11 papers)

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Research

21 pages, 5619 KiB  
Article
Proportioning Test on the Similar Materials of the Rock Mass Physical Model Test Considering Seepage and Dynamic Characteristics
by Wanpeng Shi, Jianwei Zhang, Chunlei Xin, Danqing Song, Nan Hu and Bowei Li
J. Mar. Sci. Eng. 2023, 11(9), 1815; https://doi.org/10.3390/jmse11091815 - 18 Sep 2023
Viewed by 720
Abstract
With the development of infrastructure construction, an increasing number of projects are faced with the problem of hydraulic and dynamic coupling. However, traditional physical model materials mainly consider the single factor influence and lack comprehensive research on the hydraulic and dynamic parameters of [...] Read more.
With the development of infrastructure construction, an increasing number of projects are faced with the problem of hydraulic and dynamic coupling. However, traditional physical model materials mainly consider the single factor influence and lack comprehensive research on the hydraulic and dynamic parameters of similar materials. Based on the dimensionless criterion and Buckingham π theorem, the dimension and similarity relation of physical model tests of rock masses under seepage and dynamic coupling are derived. A new type of similar material considering hydraulic and dynamic properties was developed by using quartz sand, barite powder, cement, water glass, rosin, and glycerol as raw materials through a large number of orthogonal tests. Meanwhile, the sensitivity analysis of the physical and mechanical properties of similar materials was carried out and the influence of each component factor on the physical properties was revealed. A material preparation scheme was developed to meet the physical and hydraulic characteristics of different rock and soil physical models. An empirical matching formula considering each parameter is proposed. This work can provide an important reference for physical model tests of similar rock masses. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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16 pages, 5951 KiB  
Article
Study on the Micro-Mechanical Mechanism of Fine-Grained Marine Sediments Subjected to Shallow Gas Invasion
by Yehuan Wang, Yong Wang, Yanli Wang, Cheng Chen, Lingwei Kong and Mengbing Xu
J. Mar. Sci. Eng. 2023, 11(4), 822; https://doi.org/10.3390/jmse11040822 - 13 Apr 2023
Viewed by 934
Abstract
Marine sediment is an important channel for methane leakage from the earth interior to the atmosphere. The investigation of gas invasion in fine-grained marine sediments is of great theoretical and practical significance in marine science and engineering. To study the mechanical mechanisms of [...] Read more.
Marine sediment is an important channel for methane leakage from the earth interior to the atmosphere. The investigation of gas invasion in fine-grained marine sediments is of great theoretical and practical significance in marine science and engineering. To study the mechanical mechanisms of fine-grained marine sediments subjected to shallow gas invasion, a gas injection test with a self-developed experimental apparatus was performed, and the gas invasion behavior was investigated. The results showed that the behavior of gas invasion in fine-grained sediments can be divided into different phases; the fracturing direction β gradually changes from vertical to horizontal, and finally fractures along the roof. Based on the 2D undrained elliptical cavity model and the tensile strength of sediments, considering both tensile and shear failure modes, a discrimination criteria of gas invasion was proposed. It revealed that gas invasion gradually changes from shear failure to tensile failure, and the fracturing angle θ predicted by the criteria is consistent with the experimental phenomenon. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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11 pages, 2155 KiB  
Article
A State-Dependent Hypoplastic Bounding Surface Model for Gassy Sand
by Mingyuan Wang, Jizhu Sun and Yong Wang
J. Mar. Sci. Eng. 2023, 11(3), 658; https://doi.org/10.3390/jmse11030658 - 21 Mar 2023
Viewed by 1084
Abstract
As a kind of partially saturated soil often containing dissolved gas with a high degree of saturation (S > 85%), gassy sand sediment widely exists in the marine environment all over the world. Due to the effect of gas dissolution and exsolution on [...] Read more.
As a kind of partially saturated soil often containing dissolved gas with a high degree of saturation (S > 85%), gassy sand sediment widely exists in the marine environment all over the world. Due to the effect of gas dissolution and exsolution on the pore fluid compressibility, its stress–strain and pore pressure responses are quite different from those of common saturated and unsaturated soils when subjected to undrained loading. Since almost all the gas bubbles are occluded in the pore water of offshore gassy sand, the matric suction may be neglected, and an undrained constitutive model for gassy sand is developed based on the existing hypoplastic bounding surface model for saturated sand. Both Boyle’s and Henry’s laws are employed in the model to characterize the equilibrium behavior of the gas compressibility and solubility, and then the equivalent compressibility coefficient of the pore fluid is obtained. To avoid unrealistic volumetric expansion, the concepts of the critical state and state-dependent dilatancy stress ratio are incorporated to describe its ultimate shear strength and dilatancy characteristics, respectively. Finally, the triaxial undrained test results on gas-charged sand from Hangzhou Bay are analyzed at three initial saturation degrees of 85%, 90%, and 100%, and two effective confining pressures of 50 kPa and 200 kPa. Moreover, carbon dioxide (CO2) was selected in the test, and the samples were loose with a relative density of 30%. It is noted that a good agreement is achieved between the simulation results and the experimental data, including the influence of gas content and confining pressure on the shear dilatancy and the mean effective stress increase at the beginning of the effective stress path, among others. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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16 pages, 3304 KiB  
Article
Experimental Study on Poisson’s Ratio of Silty-Fine Sand with Saturation
by Kai Yan, Yong Wang, Xianghua Lai, Yanli Wang and Zhiyong Yang
J. Mar. Sci. Eng. 2023, 11(2), 427; https://doi.org/10.3390/jmse11020427 - 16 Feb 2023
Viewed by 1494
Abstract
The influence of saturation on the Poisson’s ratio v of reservoir sediments has an engineering significance in the field of oil and nature gas exploration. Based on a self-developed combined (BE-EE-RC) test system, under the dehydration path, the Poisson’s ratio variation of reservoir [...] Read more.
The influence of saturation on the Poisson’s ratio v of reservoir sediments has an engineering significance in the field of oil and nature gas exploration. Based on a self-developed combined (BE-EE-RC) test system, under the dehydration path, the Poisson’s ratio variation of reservoir silty-fine sand in Hangzhou Bay, China, was investigated. Results show that the P- and S-wave velocities vary non-monotonically with decreasing saturation at different net stresses, and reach a maximum at the optimum saturation Sr(opt); Biot’s theory with respect to variation in Vp with Sr matches well with the measured e data. With a small amount of gas intrusion, Poisson’s ratio of saturated sand shows a sudden drop and gradually stabilizes; then, it attenuates slowly and reaches the minimum value at Sr(opt). Once the saturation degree decreases to the level lower than Sr(opt), it rapidly increases. Based on the soil–water characteristic curve (SWCC) and mesoscopic evolution of internal pore water morphology, the variation in Poisson’s ratio v can be divided into four segments of saturation: the boundary effect stage, the primary transition stage, the secondary transition stage, and the unsaturated residual stage. Ultimately, a prediction model for Poisson ratio’s v of the silty-fine sand was proposed to consider the saturation variation. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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29 pages, 10093 KiB  
Article
Field Measurement and Numerical Study on the Effects of Under-Excavation and Over-Excavation on Ultra-Deep Foundation Pit in Coastal Area
by Jifei Cui, Zhenkun Yang and Rafig Azzam
J. Mar. Sci. Eng. 2023, 11(1), 219; https://doi.org/10.3390/jmse11010219 - 14 Jan 2023
Cited by 14 | Viewed by 2189
Abstract
An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through [...] Read more.
An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through the measured data and 3D numerical simulation. The results show that the exceptional performance of the current project is due to the combination of under-excavation and over-excavation during construction. The under-excavation procedure restrained the wall deflections at the middle part of the diaphragm wall, making the corner effects at the corresponding side inapparent. Both the under-excavation and over-excavation procedure can only influence the performance of the excavation in close proximity, while having negligible impacts on the normally excavated areas. Based on the results of this study, practical suggestions are given to improve the performance of similar excavations in the future. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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15 pages, 4206 KiB  
Article
Effect of Relative Stiffness of Pile and Soil on Pile Group Effect
by Bo Liu, Xiaomin Wang, Chunhui Liu and Jingchang Kong
J. Mar. Sci. Eng. 2023, 11(1), 192; https://doi.org/10.3390/jmse11010192 - 12 Jan 2023
Cited by 1 | Viewed by 2441
Abstract
Pile groups are designed to sustain complex loads in various engineering. During the design of a pile group, the obvious pile group effect should be considered for closely spaced pile groups. However, the group effect considered by different scholars varies, which makes it [...] Read more.
Pile groups are designed to sustain complex loads in various engineering. During the design of a pile group, the obvious pile group effect should be considered for closely spaced pile groups. However, the group effect considered by different scholars varies, which makes it hard for engineers to consider the pile group effect for the design of a pile group. In this study, the finite element (FE) method is proposed to advance our understanding of the variations of pile group effects developed by different researchers, based on the concept of soil–pile relative stiffness. The relationship between soil–pile relative stiffness and normalized lateral load–displacement curves and bending moment profile response of the pile group is investigated. The results show that the pile group effect increases with the increase in soil–pile relative stiffness; the pile group effect increases with the decrease in pile spacing, increases with the increase in of number of piles in the group, and is significantly affected by pile group arrangement as well. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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13 pages, 4384 KiB  
Article
Numerical Investigation on Behavior of Compressive Piles in Coastal Tidal Flat with Fill
by Kanmin Shen, Kuanjun Wang, Juntian Yao and Jian Yu
J. Mar. Sci. Eng. 2022, 10(11), 1742; https://doi.org/10.3390/jmse10111742 - 13 Nov 2022
Cited by 1 | Viewed by 1175
Abstract
The control centers of wind power plants are usually located in coastal tidal flat areas. A thick fill should be placed at the original ground level to ensure that the design elevation of the control centers is maintained above the water table. However, [...] Read more.
The control centers of wind power plants are usually located in coastal tidal flat areas. A thick fill should be placed at the original ground level to ensure that the design elevation of the control centers is maintained above the water table. However, the filling would cause a long-term ground settlement and further lead to the development of the negative skin friction (NSF) of the pile foundations for the control centers. The CPTU tests were conducted to calibrate the soil properties, of which the rationalities were verified by comparisons of the pile-bearing capacities between the full-scale axial compressive tests and β-method. The numerical analysis method was then established to investigate the influence of additional ground pressures on the pile axial bearing behavior over time and the influence of NSF caused by consolidation on pile-bearing capacity. Finally, a simple procedure was further employed to investigate the evolution of the long-term pile-bearing behavior. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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19 pages, 5273 KiB  
Article
Effects of Strain-Softening and Strain-Rate Dependence on the Anchor Dragging Simulation of Clay through Large Deformation Finite Element Analysis
by Mun-Beom Shin, Dong-Su Park and Young-Kyo Seo
J. Mar. Sci. Eng. 2022, 10(11), 1734; https://doi.org/10.3390/jmse10111734 - 11 Nov 2022
Cited by 1 | Viewed by 1742
Abstract
Large-deformation finite element (LDFE) analysis with the coupled Eulerian–Lagrangian (CEL) technique for large-deformation soil functions without twisting or distorting the mesh. However, the model does not consider the strain-softening and strain-rate dependence of clay-based soils. The undrained shear strength of clay is sensitive [...] Read more.
Large-deformation finite element (LDFE) analysis with the coupled Eulerian–Lagrangian (CEL) technique for large-deformation soil functions without twisting or distorting the mesh. However, the model does not consider the strain-softening and strain-rate dependence of clay-based soils. The undrained shear strength of clay is sensitive to the strain rate. In addition, the strain-softening effect of soil strength reduction accompanied by large-scale shear deformation should be considered. In this study, anchor dragging simulations were performed for large-deformation analysis considering strain-softening and strain-rate dependence. Furthermore, a shear strength equation expressing the strain-softening and strain-rate dependence of the Tresca constitutive model was developed based on VUMAT, an ABAQUS/Explicit subroutine. The equation was designed so that it could be linked to the LDFE/CEL model. The model was verified by performing comparative analysis with the Mohr–Coulomb (M–C) perfect-plasticity model. The newly constructed Tresca base strain-softening and strain-rate-dependence VUMAT algorithm in the LDFE/CEL model analysis confirmed the effects of strain-softening and strain-rate dependence. The proposed model enabled a highly realistic simulation of the actual phenomenon than the M–C model. Finally, a parametric study on strain-softening and strain-rate dependence was conducted, and the behavior of clay due to the anchor drag phenomenon was revealed. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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15 pages, 6310 KiB  
Article
One-Dimensional Solar Energy Thermal Consolidation Model Testing and Analytical Calculation for Marine Soft Clays
by Changqing Xia, Yuebao Deng, Min Zhu, Jiajun Niu, Liangke Zheng and Xiangsheng Chen
J. Mar. Sci. Eng. 2022, 10(11), 1634; https://doi.org/10.3390/jmse10111634 - 02 Nov 2022
Cited by 5 | Viewed by 1001
Abstract
There are significant energy and financial expenditures associated with the current thermal drainage consolidation approach used to treat the marine soft clay foundation. Especially for some reclaimed lands in remote areas where a large amount of stable electricity is not readily available. In [...] Read more.
There are significant energy and financial expenditures associated with the current thermal drainage consolidation approach used to treat the marine soft clay foundation. Especially for some reclaimed lands in remote areas where a large amount of stable electricity is not readily available. In view of the problem, this paper aims to investigate a novel treatment method by using solar energy thermal consolidation. The model testing was conducted to assess the treatment effect of the foundation. Results from two groups of one-dimensional surcharge preloading consolidation model experiments, conducted under conditions of both solar heating and ambient temperature, were presented. The advantage of the solar heating approach was demonstrated by a comparison of the two tests. An analytical calculation method was proposed for predicting the consolidation behavior on the basis of the temperature variation caused by solar energy in the marine soft clays, and good agreement was observed. The outcomes reveal that solar heating can improve the consolidation effect of soil deep in the foundation. The foundation temperature can be raised by 15 °C in winter, and the variation range can exceed 10 °C. The settlement increases by 16% compared with the ambient temperature group. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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15 pages, 3443 KiB  
Article
A Simplified Calculation Method for Cyclic Response of Laterally Loaded Piles Based on Strain Wedge Model in Soft Clay
by Xin Liu, Zhongyuan Yao, Wenbo Zhu, Yu Zhang, Shu Yan, Xiaojiang Guo and Guoliang Dai
J. Mar. Sci. Eng. 2022, 10(11), 1632; https://doi.org/10.3390/jmse10111632 - 02 Nov 2022
Cited by 2 | Viewed by 1552
Abstract
This paper proposed a simplified calculation method to analyze the cyclic response of large-diameter single piles based on the modified strain wedge model. Firstly, the pile–soft clay interaction above the pile-rotating point is represented by a p–y curve, and the pile–soft clay interaction [...] Read more.
This paper proposed a simplified calculation method to analyze the cyclic response of large-diameter single piles based on the modified strain wedge model. Firstly, the pile–soft clay interaction above the pile-rotating point is represented by a p–y curve, and the pile–soft clay interaction below the rotating point is represented by an equivalent rotation spring. At the same time, a stiffness attenuation model is proposed to describe the cyclic p–y curve for analyzing the cyclic bearing characteristics of soft clay. Finally, the simplified calculation method is verified by two case studies. The results from the proposed method agree reasonably well with the measured results. This can provide a new method for analyzing the horizontal cyclic bearing characteristics of piles. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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22 pages, 6692 KiB  
Article
An Investigation of the Effect of Utilizing Solidified Soil as Scour Protection for Offshore Wind Turbine Foundations via a Simplified Scour Resistance Test
by Jing Wang, Jinbo Xie, Yingjie Wu, Chen Wang and Fayun Liang
J. Mar. Sci. Eng. 2022, 10(9), 1317; https://doi.org/10.3390/jmse10091317 - 17 Sep 2022
Cited by 2 | Viewed by 1548
Abstract
Offshore wind power is rapidly developing as a source of clean energy. However, as local scour of the foundation of an offshore wind turbine can create serious safety risks to the normal operation of the turbine, it is necessary to protect the foundation [...] Read more.
Offshore wind power is rapidly developing as a source of clean energy. However, as local scour of the foundation of an offshore wind turbine can create serious safety risks to the normal operation of the turbine, it is necessary to protect the foundation from scour. In this paper, a new scour protection countermeasure using solidified soil has been investigated via an updated apparatus for a simplified scour resistance test (SSRT). Two types of tests were carried out: an unconfined compressive test to determine geotechnical parameters and an SSRT test to reflect the scour resistance of the soil samples. The results show that unconfined strength is approximately related to the critical flow velocity of the scour resistance as a power function. Soil samples having an unconfined compressive strength of 300 kPa can resist erosion under flow conditions above 3.14 m/s after solidification. In addition, the solidification state of the solidified soil has a great impact on the scour resistance of the soil sample, and the critical scour velocity of the final solidified soil is increased by 80–150% as compared to an initial solidified soil having the same final unconfined strength. These results suggest that attention should be paid to the state of the solidified soil during the construction process. The engineers should control the ratio of cement, water, and soil of the solidified soil according to the hydraulic parameters at the time of construction so that no great loss of solidified soil will occur during the construction process. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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