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New Advances in Marine Engineering Geology
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New Advances in Marine Engineering Geology

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 (30 April 2020) | Viewed by 48967

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Qing Yang

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Guest Editor
State Key Laboratory of Coastal and Offshore Engineering, School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
Interests: unsaturated soils; marine soil mechanics; offshore geotechnical engineering
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
Prof. Dr. Xiaolei Liu

E-Mail Website
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
Special Issues, Collections and Topics in MDPI journals
Assoc. Prof. Dr. Yin Wang

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Guest Editor
State Key Laboratory of Coastal and Offshore Engineering, School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
Interests: macroscopic and microscopic properties of marine soils; foundations of offshore platforms; discrete element method
Dr. Hendrik Sturm

E-Mail Website
Guest Editor
Norwegian Geotechnical Institute (NGI), PO Box 3930 Ullevaal Stadion, N-0806 Oslo, Norway
Interests: offshore renewables; offshore geotechnical engineering; numerical modelling; constitutive modelling; laboratory and model testing

Special Issue Information

Dear Colleagues,

The ocean is the cradle of life and is rich in natural resources. With the worldwide boom in exploration and application of ocean resources, a dramatically increasing amount of coastal engineering and offshore engineering facilities have been constructed in the last few decades. The rapid development of human economic activities and the global climate change are having a significant impact on the marine environment, resulting in frequent geological disasters. Under this circumstance, there is an urgent demand for a platform for scientists and engineers to share their state-of-art research outcomes in the field of Marine Engineering Geology.

The 2nd International Symposium of Marine Engineering Geology (ISMEG 2019) will be held in Dalian, China, on 18–20 October 2019. The theme of this symposium is “Exploration of Marine Resources and Marine Engineering Geology”. It will provide a great opportunity for scientists and engineers worldwide to discuss recent advances, share their knowledge, and identify future research directions in the field of Marine Engineering Geology. Seven topics will be discussed in the symposium: 1) Engineering Properties of Marine Soils; 2) Marine Geological Hazards and Preventions; 3) In situ Exploration, Monitoring, and Physical Modelling; 4) Hydrodynamics and Environmental Interaction; 5) Exploration of Gas Hydrate; 6) Offshore Foundations; 7) Pipe–Soil–Fluid Interaction.

ISMEG 2019 will invite top researchers worldwide to submit papers, share their research outcomes, and report recent advancements on the key topics mentioned previously. It is expected to receive more than 50 contributions from high-profile senior academic researchers and young researchers, on the basis of previous experience.

The objective of this Special Issue is to publish high-quality papers from ISMEG 2019 participants. The submitted papers will go through JMSE peer-review process, like regular papers. It is believed that this Special Issue will provide a timely overview of marine engineering geology and geotechnics of recent cases, theoretical advances, laboratory and field testing, design methods, and the potential for further development of these disciplines. Moreover, with a timely and well-organized publication, the state-of-the-art data, analyses, and methodologies presented in this Special Issue could be of great interest to all the readers of Journal of Marine Science and Engineering.

Prof. Dr. Qing Yang
Prof. Dr. Dong-Sheng Jeng
Prof. Dr. Xiaolei Liu
Assoc. Prof. Dr. Yin Wang
Dr. Hendrik Sturm
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

  • Engineering Properties of Marine Soils
  • Marine Geological Hazards and Preventions
  • In-situ Exploration, Monitoring, and Physical Modelling
  • Hydrodynamics and Environmental Interaction
  • Exploration of Gas Hydrate
  • Offshore Foundations
  • Pipe–Soil–Fluid Interaction

Published Papers (15 papers)

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Editorial

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4 pages, 175 KiB  
Editorial
New Advances in Marine Engineering Geology
by Xiaolei Liu, Qing Yang, Yin Wang, Dong-Sheng Jeng and Hendrik Sturm
J. Mar. Sci. Eng. 2021, 9(1), 66; https://doi.org/10.3390/jmse9010066 - 11 Jan 2021
Cited by 2 | Viewed by 1999
Abstract
The ocean is the cradle of life and is rich in natural resources [...] Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)

Research

Jump to: Editorial, Review

15 pages, 8597 KiB  
Article
Constitutive Relationship Proposition of Marine Soft Soil in Korea Using Finite Strain Consolidation Theory
by Sang Hyun Jun and Hyuk Jae Kwon
J. Mar. Sci. Eng. 2020, 8(6), 429; https://doi.org/10.3390/jmse8060429 - 11 Jun 2020
Cited by 4 | Viewed by 2011
Abstract
This paper proposes representative constitutive relationship equations of dredging and reclamation soft soil in Korea. The marine soft soils were sampled at 23 dredged-reclaimed construction sites in the Busan, Gwangyang, and Incheon regions in Korea; then, laboratory tests were carried out. The consolidation [...] Read more.
This paper proposes representative constitutive relationship equations of dredging and reclamation soft soil in Korea. The marine soft soils were sampled at 23 dredged-reclaimed construction sites in the Busan, Gwangyang, and Incheon regions in Korea; then, laboratory tests were carried out. The consolidation property was classified as LL = 60% for Busan and Gwangyang marine soft soil and LL = 30% for Incheon marine soft soil by conducting basic physical property tests and consolidation tests. Busan soft soil showed a slightly higher consolidation settlement property than Gwangyang soft soil. Incheon soft soil showed the lowest consolidation settlement property among the three regions. In particular, 77 consolidation simulations were carried out at a high void ratio using the centrifugal experiment to realize high water content and in-field stress conditions. The constitutive relationship equations of each of the 23 specimens were analyzed with regard to the void ratio–effective stress and void ratio–permeability coefficient through the back analysis of finite consolidation theory from the experimental results. The constitutive relationship equation for Korean soft soil was determined to be a reasonable power function equation. The representative constitutive relationships for soft soils in the three regions were estimated using six equations, which were classified by physical and consolidation properties. The representative constitutive equations were compared to those in previous studies on high void ratio conditions of marine soft soil, and the results showed a similar range. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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12 pages, 4313 KiB  
Article
Experimental Investigation on Small-Strain Stiffness of Marine Silty Sand
by Qi Wu, Qingrui Lu, Qizhou Guo, Kai Zhao, Pen Chen and Guoxing Chen
J. Mar. Sci. Eng. 2020, 8(5), 360; https://doi.org/10.3390/jmse8050360 - 21 May 2020
Cited by 10 | Viewed by 2435
Abstract
The significance of small-strain stiffness (Gmax) of saturated composite soils are still of great concern in practice, due to the complex influence of fines on soil fabric. This paper presents an experimental investigation conducted through comprehensive bender element tests on [...] Read more.
The significance of small-strain stiffness (Gmax) of saturated composite soils are still of great concern in practice, due to the complex influence of fines on soil fabric. This paper presents an experimental investigation conducted through comprehensive bender element tests on Gmax of marine silty sand. Special attention is paid to the influence of initial effective confining pressure ( σ c 0 ′ ), global void ratio (e) and fines content (FC) on Gmax of a marine silty sand. The results indicate that under otherwise similar conditions, Gmax decreases with decreasing e or FC, but decreases with increasing FC. In addition, the reduction rate of Gmax with e increasing is not sensitive to σ c 0 ′ , but obviously sensitive to changes in FC. The equivalent skeleton void ratio (e*) is introduced as an alternative state index for silty sand with various FC, based on the concept of binary packing material. Remarkably, the Hardin model is modified with the new state index e*, allowing unified characterization of Gmax values for silty sand with various FC, e, and σ c 0 ′ . Independent test data for different silty sand published in the literature calibrate the applicability of this proposed model. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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15 pages, 6646 KiB  
Article
Numerical Investigation of a Two-Element Wingsail for Ship Auxiliary Propulsion
by Chen Li, Hongming Wang and Peiting Sun
J. Mar. Sci. Eng. 2020, 8(5), 333; https://doi.org/10.3390/jmse8050333 - 09 May 2020
Cited by 18 | Viewed by 2966
Abstract
The rigid wingsail is a new type of propulsion equipment which greatly improves the performance of the sailboat under the conditions of upwind and downwind. However, such sail-assisted devices are not common in large ships because the multi-element wingsail is sensitive to changes [...] Read more.
The rigid wingsail is a new type of propulsion equipment which greatly improves the performance of the sailboat under the conditions of upwind and downwind. However, such sail-assisted devices are not common in large ships because the multi-element wingsail is sensitive to changes in upstream flow, making them difficult to operate. This problem shows the need for aerodynamic study of wingsails. A model of two-element wingsail is established and simulated by the steady and unsteady RANS approach with the k-ω SST turbulence model and compared with the known experimental data to ensure the accuracy of the numerical simulation. Then, some key design and structural parameters (camber, the rotating axis position of the flap, angle of attack, flap thickness) are used to characterize the aerodynamic characteristics of the wingsail. The results show that the position of the rotating shaft of the flap has little influence on the lift coefficient at low camber. When stall occurs, the lift coefficient first increases and then decreases as the flap axis moves backward, which also delays the stall angle at a low camber. At the high camber of AOA = 6°, the lift coefficient always increases with the increase of the rotating axis position of the flap; especially between 85% and 95%, the lift coefficient increases suddenly, which is caused by the disappearance of large-scale flow separation on the suction surface of the flap. It reflects the nonlinear coupling effect between camber of wingsail and the rotating axis position of the flap Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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12 pages, 5153 KiB  
Article
Pressure Sensing Technique for Observing Seabed Deformation Caused by Submarine Sand Wave Migration
by Xiaolei Liu, Xiaoquan Zheng, Zhuangcai Tian, Hong Zhang and Tian Chen
J. Mar. Sci. Eng. 2020, 8(5), 315; https://doi.org/10.3390/jmse8050315 - 30 Apr 2020
Cited by 2 | Viewed by 4509
Abstract
Long-term, continuous in-situ observation of seabed deformation plays an important role in studying the mechanisms of sand wave migration and engineering early warning methods. Research on pressure sensing techniques has examined the possibility of using the temporal characteristics of the vertical deformation of [...] Read more.
Long-term, continuous in-situ observation of seabed deformation plays an important role in studying the mechanisms of sand wave migration and engineering early warning methods. Research on pressure sensing techniques has examined the possibility of using the temporal characteristics of the vertical deformation of the seafloor to identify important factors (e.g., wave height and migration rate) of submarine sand wave migration. Two pressure sensing tools were developed in this study to observe the seabed deformation caused by submarine sand wave migration (a fixed-depth total pressure recorder (TPRFD) and a surface synchronous bottom pressure recorder (BPRSS)), based on the principle that as a sand wave migrates under hydrodynamic forcing, the near-bottom water pressure, bottom pressure and total fixed pressure synchronously change with time. Laboratory flume experiments were performed, using natural sandy sediments taken from the beach of Qingdao, China, to better present and discuss the feasibility and limitations of using these two pressure sensing methods to acquire continuous observations of seabed deformation. The results illustrate that the proposed pressure sensor techniques can be effectively applied in reflecting elevation caused by submarine sand wave migration (the accuracy of the two methods in observing the experimental bed morphology was more than 90%). However, an unexpected step-like process of the change in sand wave height observed by BPRSS is presented to show that the sensor states can be easily disturbed by submarine environments, and thus throw the validity of BPRSS into question. Therefore, the TPRFD technique is more worthy of further study for observing submarine sand wave migration continuously and in real-time. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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16 pages, 7183 KiB  
Article
Comparative Study on Seismic Response of Pile Group Foundation in Coral Sand and Fujian Sand
by Qi Wu, Xuanming Ding, Yanling Zhang and Zhixiong Chen
J. Mar. Sci. Eng. 2020, 8(3), 189; https://doi.org/10.3390/jmse8030189 - 11 Mar 2020
Cited by 19 | Viewed by 2752
Abstract
The physical and mechanical properties of coral sand are quite different from those of common terrestrial sands due to the special marine biogenesis. Shaking table tests of three-story structures with nine-pile foundation in coral sand and Fujian sand were carried out in order [...] Read more.
The physical and mechanical properties of coral sand are quite different from those of common terrestrial sands due to the special marine biogenesis. Shaking table tests of three-story structures with nine-pile foundation in coral sand and Fujian sand were carried out in order to study the dynamic response characteristics of pile-soil-structure system in coral sand under earthquake. The influence of shaking intensity on the dynamic response of the system was taken into consideration. The results indicated that the peak value of the excess pore pressure ratio of coral sand was smaller than that of Fujian sand under two kinds of shaking intensities; moreover, the development speed of excess pore pressure ratio of coral sand was smaller than that of Fujian sand. The liquefaction of coral sand was more difficult than Fujian sand under the same relative density and similar grain-size distribution. The horizontal displacement, settlement, column bending moment, and pile bending moment of coral sand were smaller than those of Fujian sand, respectively. The magnification effect of column bending moment of buildings in coral sand was less than that in Fujian sand with increasing shaking intensity. This study can provide some supports for the seismic design of coral reef projects. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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21 pages, 22011 KiB  
Article
Identifying the Frequency Dependent Interactions between Ocean Waves and the Continental Margin on Seismic Noise Recordings
by Zhen Guo, Yu Huang, Adnan Aydin and Mei Xue
J. Mar. Sci. Eng. 2020, 8(2), 134; https://doi.org/10.3390/jmse8020134 - 19 Feb 2020
Cited by 4 | Viewed by 2896
Abstract
This study presents an exploration into identifying the interactions between ocean waves and the continental margin in the origination of double-frequency (DF, 0.1–0.5 Hz) microseisms recorded at 33 stations across East Coast of USA (ECUSA) during a 10-day period of ordinary ocean wave [...] Read more.
This study presents an exploration into identifying the interactions between ocean waves and the continental margin in the origination of double-frequency (DF, 0.1–0.5 Hz) microseisms recorded at 33 stations across East Coast of USA (ECUSA) during a 10-day period of ordinary ocean wave climate. Daily primary vibration directions are calculated in three frequency bands and projected as great circles passing through each station. In each band, the great circles from all stations exhibit largest spatial density primarily near the continental slope in the western North Atlantic Ocean. Generation mechanisms of three DF microseism events are explored by comparing temporal and spatial variations of the DF microseisms with the migration patterns of ocean wave fronts in Wavewatch III hindcasts. Correlation analyses are conducted by comparing the frequency compositions of and calculating the Pearson correlation coefficients between the DF microseisms and the ocean waves recorded at selected buoys. The observations and analyses lead to a hypothesis that the continental slope causes wave reflection, generating low frequency DF energy and that the continental shelf is where high frequency DF energy is mainly generated in ECUSA. The hypothesis is supported by the primary vibration directions being mainly perpendicular to the strike of the continental slope. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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13 pages, 2246 KiB  
Article
Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process
by Fang Lu, Haoqing Zhang, Yonggang Jia, Wenquan Liu and Hui Wang
J. Mar. Sci. Eng. 2019, 7(12), 449; https://doi.org/10.3390/jmse7120449 - 08 Dec 2019
Cited by 8 | Viewed by 2636
Abstract
Sediments are an important sink for heavy metal pollutants on account of their strong adsorption capacity. Elevated content of Cu was observed in the Chengdao area of the Yellow River Delta, where the surface sediment is mainly silt and is prone to be [...] Read more.
Sediments are an important sink for heavy metal pollutants on account of their strong adsorption capacity. Elevated content of Cu was observed in the Chengdao area of the Yellow River Delta, where the surface sediment is mainly silt and is prone to be liquefied under hydrodynamic forces. The vertical transport of fine particles, along with pore water seepage, during the liquefaction process could promote the migration and diffusion of Cu from the interior of sediment. The present study involved a series of wave flume experiments to simulate the migration and diffusion of Cu from the interior of sediment in the subaqueous Yellow River Delta area under wave actions. The results indicated that sediment liquefaction significantly promoted the release of Cu from internal sediment to overlying water. The variations of Cu concentrations in the overlying water were opposite to the suspended sediment concentrations (SSCs). The sediment liquefaction caused high initial rises of SSCs, but led to a rapid decline of dissolved Cu concentration at the initial period of sediment liquefaction due to the adsorption by fine particles. Afterwards, the SSCs slightly increased and then gradually decreased. Meanwhile, the dissolved Cu concentration generally kept increasing under combined effects of intensively mix of sediment and overlying water, pore water seepage, and desorption. The dissolved Cu concentration in the overlying water during sediment liquefaction phase was 1.5–2.2 times that during the consolidation phase. Sediment liquefaction also caused vertical diffusion of Cu in sediment and the diffusion depth was in accordance with the liquefaction depth. The results of the present study may provide reference for the environmental management in the study area. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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28 pages, 2479 KiB  
Article
Response of a Porous Seabed around an Immersed Tunnel under Wave Loading: Meshfree Model
by Shuang Han, Dong-Sheng Jeng and Chia-Cheng Tsai
J. Mar. Sci. Eng. 2019, 7(10), 369; https://doi.org/10.3390/jmse7100369 - 17 Oct 2019
Cited by 14 | Viewed by 2436
Abstract
Seabed instability surrounding an immersed tunnel is a vital engineering issue regarding the design and maintenance for submarine tunnel projects. In this study, a numerical model based on the local radial basis function collocation method (LRBFCM) is developed to evaluate the seabed behaviour [...] Read more.
Seabed instability surrounding an immersed tunnel is a vital engineering issue regarding the design and maintenance for submarine tunnel projects. In this study, a numerical model based on the local radial basis function collocation method (LRBFCM) is developed to evaluate the seabed behaviour in a marine environment, in which the seabed is treated as the porous medium and governed by Biot’s “ u − p ” approximation. As for the flow field above the seabed, the VARANS equations are used to simulate the fluid motion and properties. The present model is validated with analytical solutions and experimental data which show a good capacity of the integrated model. Both wave and current loading are considered in this study. Parametric studies are carried out to investigate the effects of wave characteristics and soil properties. Based on the numerical results, the maximum liquefaction depth around the immersed tunnel could be deeper under the wave loading with long wave period (T) and large wave height (H). Moreover, a seabed with lower permeability ( K s ) and degree of saturation ( S r ) is more likely to be liquefied. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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10 pages, 4049 KiB  
Article
Wave-Induced Seafloor Instability in the Yellow River Delta: Flume Experiments
by Xiuhai Wang, Chaoqi Zhu and Hongjun Liu
J. Mar. Sci. Eng. 2019, 7(10), 356; https://doi.org/10.3390/jmse7100356 - 06 Oct 2019
Cited by 12 | Viewed by 2540
Abstract
Geological disasters of seabed instability are widely distributed in the Yellow River Delta, posing a serious threat to the safety of offshore oil platforms and submarine pipelines. Waves act as one of the main factors causing the frequent occurrence of instabilities in the [...] Read more.
Geological disasters of seabed instability are widely distributed in the Yellow River Delta, posing a serious threat to the safety of offshore oil platforms and submarine pipelines. Waves act as one of the main factors causing the frequent occurrence of instabilities in the region. In order to explore the soil failure mode and the law for pore pressure response of the subaqueous Yellow River Delta under wave actions, in-lab flume tank experiments were conducted in this paper. In the experiments, wave loads were applied with a duration of 1 hour each day for 7 consecutive days; pore water pressure data of the soil under wave action were acquired, and penetration strength data of the sediments were determined after wave action. The results showed that the fine-grained seabed presented an arc-shaped oscillation failure form under wave action. In addition, the sliding surface firstly became deeper and then shallower with the wave action. Interestingly, the distribution of pores substantially coincided with that of sliding surfaces. For the first time, gas holes were identified along with their positioning and angle with respect to the sediments. The presence of gas may serve as a primer for submarine slope failures. The wave process can lead to an increase in the excess pore pressure, while the anti-liquefaction capacity of the sediments was improved, causing a decrease in the excess pore pressure resulting from the next wave process. Without new depositional sediments, the existing surface sediments can form high-strength formation under wave actions. The test results may provide a reference for numerical simulations and engineering practice. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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21 pages, 6484 KiB  
Article
Accumulation of Pore Pressure in a Soft Clay Seabed around a Suction Anchor Subjected to Cyclic Loads
by Hui Li, Xuguang Chen, Cun Hu, Shuqing Wang and Jinzhong Liu
J. Mar. Sci. Eng. 2019, 7(9), 308; https://doi.org/10.3390/jmse7090308 - 05 Sep 2019
Cited by 2 | Viewed by 3896
Abstract
A suction anchor is an appealing anchoring solution for floating production. However, the possible effects of residual pore pressure can be rarely found any report so far in term of the research and design. In this study, the residual pore pressure distribution characteristics [...] Read more.
A suction anchor is an appealing anchoring solution for floating production. However, the possible effects of residual pore pressure can be rarely found any report so far in term of the research and design. In this study, the residual pore pressure distribution characteristics around the suction anchor subjected to vertical cyclic loads are investigated in a soft clay seabed, and a three-dimensional damage-dependent bounding surface model is also proposed. This model adopts the combined isotropic-kinematic hardening rule to achieve isotropic hardening and kinematic hardening of the boundary surface. The proposed model is validated against triaxial tests on anisotropically consolidated saturated clays and normally consolidated saturated clays. The analytical results show that the excess pore water pressure accumulates primarily on the outside of the suction anchor, whereas negative pore water pressure mainly on the inside. The maximum values of both sides appear in the lower part of the seabed. According to the distribution characteristics of the residual pore pressure, a perforated anchor is proposed to reduce the accumulation of excess pore water pressure. A comparative study generally shows that the perforated anchor can effectively reduce the accumulation of excess pore water pressure. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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19 pages, 6609 KiB  
Article
The Hydrodynamic Dispersion Characteristics of Coral Sands
by Xiang Cui, Changqi Zhu, Mingjian Hu, Xinzhi Wang and Haifeng Liu
J. Mar. Sci. Eng. 2019, 7(9), 291; https://doi.org/10.3390/jmse7090291 - 28 Aug 2019
Cited by 4 | Viewed by 3267
Abstract
Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion [...] Read more.
Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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19 pages, 13388 KiB  
Article
Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints
by Long Yu, Heyue Zhang, Jing Li and Xian Wang
J. Mar. Sci. Eng. 2019, 7(6), 175; https://doi.org/10.3390/jmse7060175 - 03 Jun 2019
Cited by 11 | Viewed by 4515
Abstract
Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the [...] Read more.
Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the coupled Eulerian–Lagrangian (CEL) method. The effects of footprints’ geometry, reinstallation eccentricity (0.25D–2.0D) and the roughness between spudcan and soil on the profiles of the vertical force, horizontal force and bending moment are discussed. The results show that the friction condition of the soil–footing interface has a significant effect on H profile but much less effect on M profile. The eccentricity ratio is a key factor to evaluate the H and M. The results show that the geometry shape of the footing also has certain effects on the V, H, and M profiles. The flat base footing gives the lowest peak value in H but largest in M, and the performances of the fusiform spudcan footing and the skirted footing are similar. From the view of the resultant forces, the skirted footing shows a certain potential in resisting the damage during reinstallation near existing footprints by comparing with commonly used fusiform spudcan footings. The bending moments on the leg–hull connection section of different leg length at certain offset distances are discussed. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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17 pages, 5161 KiB  
Article
Improved Double-Layer Soil Consolidation Theory and Its Application in Marine Soft Soil Engineering
by Deqiang Chen, Junhui Luo, Xianlin Liu, Decai Mi and Longwang Xu
J. Mar. Sci. Eng. 2019, 7(5), 156; https://doi.org/10.3390/jmse7050156 - 18 May 2019
Cited by 9 | Viewed by 3739
Abstract
Marine soft soil foundation is a double-layer foundation structure with a crust layer and soft substratum. Moreover, it is common that there are various forms of drainage. Accordingly, based on Terzaghi’s consolidation theory and the continuous drainage boundary conditions theory of controllable drainage [...] Read more.
Marine soft soil foundation is a double-layer foundation structure with a crust layer and soft substratum. Moreover, it is common that there are various forms of drainage. Accordingly, based on Terzaghi’s consolidation theory and the continuous drainage boundary conditions theory of controllable drainage conditions, an improved double-layer soil consolidation theory considering continuous drainage boundary conditions was proposed. To improve the computational efficiency and accuracy, the Laplace transform and the Stehfest algorithm was used to deduce the numerical solution of the improved double-layer soil consolidation theory considering continuous drainage boundary conditions and to compile a computer program. Subsequently, the theory was validated and analyzed by the degenerated model of the perfectly permeable boundary conditions and the semi-permeable boundary conditions, respectively, which showed that this theory has higher accuracy. Simultaneously, the analysis of double-layer consolidation settlement under continuous drainage boundary conditions for marine soft soil foundation of Guangxi Binhai Highway was carried on. The result showed that the consolidation settlement calculated by the improved double-layer consolidation theory presented is basically consistent with the field measurement results, and that the correlation coefficient between them is higher. Accordingly, the research results can provide useful basic information for marine soft foundation engineering. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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Review

Jump to: Editorial, Research

15 pages, 3105 KiB  
Review
Features of Earthquake-Induced Seabed Liquefaction and Mitigation Strategies of Novel Marine Structures
by Yu Huang and Xu Han
J. Mar. Sci. Eng. 2020, 8(5), 310; https://doi.org/10.3390/jmse8050310 - 29 Apr 2020
Cited by 11 | Viewed by 5192
Abstract
With the accelerated development of marine engineering, a growing number of marine structures are being constructed (e.g., seabed pipelines, drilling platforms, oil platforms, wind turbines). However, seismic field investigations over recent decades have shown that many marine structures were damaged or destroyed due [...] Read more.
With the accelerated development of marine engineering, a growing number of marine structures are being constructed (e.g., seabed pipelines, drilling platforms, oil platforms, wind turbines). However, seismic field investigations over recent decades have shown that many marine structures were damaged or destroyed due to liquefaction. Seismic liquefaction in marine engineering can have huge financial repercussions as well as a devastating effect on the marine environment, which merits our great attention. As the effects of seawater and the gas component in the seabed layers are not negligible, the seabed soil layers are more prone to liquefaction than onshore soil layers, and the liquefied area may be larger than when liquefaction occurs on land. To mitigate the impact of liquefaction events on marine engineering structures, some novel liquefaction-resistant marine structures have been proposed in recent years. This paper reviews the features of earthquake-induced liquefaction and the mitigation strategies for marine structures to meet the future requirements of marine engineering. Full article
(This article belongs to the Special Issue New Advances in Marine Engineering Geology)
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