Abstract Submarine telecommunication cables, which carry about 99% of international telecommunications, are usually buried shallowly beneath seabed and vulnerable to seabed movements. In recent years, many submarine cable damages have been observed when significant lateral seabed movements occur due to geohazards, e.g., offsets of strike-slip faults and submarine landslides. However, research on the

Abstract Sub-bottom profiling traditionally uses low-frequency signals (less than 20 kHz) to examine layered structures of the bottom sediment in large depth, but it has some limitations in deep-sea surveying. The surficial sediment within several meters under the water–sediment boundary in the deep sea cannot be distinguished clearly. In this study, a high-frequency sub-bottom profiler (HFSBP) was

Abstract This research aims to study the effect of pile arrangement and inclination on the bending moment of piles as well as the horizontal acceleration of the cap under explosion loadings. Data was obtained from five centrifuge tests, which were performed on a 2 × 2 pile group with various arrangements of vertical and batter piles. The results showed that among all the tested models, the pile group

Abstract In seafloor mining environments, ultrasonic detection is often used for underwater target recognition, and a large number of suspended particles reduce the recognition rate of single-classifier cobalt-rich crusts. In this paper, we propose a recognition method based on multi-classifier fusion (MCF). First, the kernel Fisher discriminant analysis (KFDA) method is used to reduce the multi-class

Abstract A closure on the recent discussion regarding the review on the behavior of helical piles as a potential offshore foundation system by the Authors is presented. Installation torque, uplift capacity, installation effects, model pile, installation speed and results proposed by Discussers are commented.

Abstract Monopiles are popular solutions as the foundation to support offshore wind turbines (OWTs), which suffer from various amplitudes of continuous lateral cyclic wind and wave loading. The accumulation of tilt and change of the natural frequency of OWTs under cyclic loading have become crucial issues for OWT design. Hence the monopile-tower-soil system was established at the small-scale level

Abstract Geosynthetic-encased stone column (GESC) has been proved as an effective alternative to reinforcing soft marine clay soils with low undrained shear strength. In this paper, three-dimensional (3-D) coupled mechanical and hydraulic modeling based on centrifugal model test was carried out to investigate the performance of GESC-supported embankment over soft clay with two different stiffness of

Abstract Marine sandy soils may liquefy under wave loading and/or seismic loading. Current research shows that the presence of fines can significantly affect the liquefaction potential of sandy soils. Thus, a quantitative evaluation of the effect of fines on the undrained behavior of sandy soils can provide useful information on soil liquefaction that can advance the design of foundations of coastal

Abstract Soil liquefaction can be induced by natural events that entail complicated loading directions and magnitudes. To investigate the liquefaction behaviour of granular material under complex loading conditions, a series of strain-controlled cyclic simple shear tests are conducted on the uniform-sized glass beads. These tests include uni-directional and multi-directional loading paths. An energy-based

The degradation of rock mechanical behavior after cyclic wetting and drying could affect the stability of rock slope, embankment, and tunnel significantly. A series of tests were first conducted on sandstone collected from a reservoir bank slope. The results showed that the mechanical parameters (including tensile strength, uniaxial compressive strength, elastic modulus, and internal friction angle)

Aiming at the problems of soil column forming near the plastic vertical drains and soil cracking during electro-osmosis stage in the treatment of dredged slurry by vacuum pre-loading combined with electro-osmosis method, this paper proposed a new method, i.e. vacuum pre-loading combined with electro-osmosis and with dynamic compaction method. Through the laboratory model tests in self-made glass bucket

Under seismic loading, marine soil experiences horizontal shearing in two directions with different shear directions and amplitudes. It is therefore of considerable practical relevance to study the deformation behavior of marine cement soil under bidirectional shear loading. In this study, a series of cyclic simple shear tests were carried out to investigate the undrained deformation behavior of marine

Stabilization/solidification (S/S) has been examined as an effective way to strengthen soft soils. However, the presence of organic matter (OM) in dredged marine silt can substantially weaken the reinforcement effect of S/S. To treat organic silt that is difficult to strengthen by S/S, a new combined application of S/S and electroosmosis (EO) treatments was adopted in this paper to increase the strength

This study investigated effects of initial deviatoric stress state and the orientation of their major principal stresses on the strain components and shear strength of soft marine clay. Hollow cylinder test results demonstrated that the axial and circumferential strain component magnitudes substantially depended on the initial deviatoric stress and the principal stress direction. The octahedral shear

This paper presents a case study on the improvement of thick marine deposits. A new method that combines vacuum pressure and surcharge load with no need for a sand cushion is proposed and evaluated. The main features of this method are as follows: (1) each integrated prefabricated vertical drain (PVD) is connected directly to a branch pipe, which is in turn connected to a main pipe with a T-shaped

Knowledge of the processes governing salt intrusion in estuaries is important since it influences the eco-environment of estuaries as well as its water resource potential in many ways. The aim of this paper is to test the effectiveness of the new 1-D thermodynamic salt intrusion equation proposed by Zhang and Savenije (i.e., is an extreme power theory for the mixing of saline sea water and fresh river

Impulse waves generated by landslides lead to serious secondary disasters. To investigate the effects of impulse waves on a bank slope, a three-dimensional physical model test was conducted considering multiple factors, such as the width, thickness, and volume of the landslide body, inclination angle of the landslide, and bank slope angle. The results show that the wave did not break upon the first

In NGI-type simple shear apparatus, including recently developed NGI-type bi-directional simple shear apparatus, the complete stress state is unknown which limited the interpretation of test results. This study compares the stress state of NGI-type simple shear test obtained by two methods, the stress state determined by an empirical method using test data, and stress state determined by measured values

Investigation of gas migration in saturated soil is of great theoretical and practical significance in marine science and engineering. The transport of gas bubbles in soil and its effects on soil physical and mechanical properties can be further studied. Gas injection and permeability tests were conducted using a self-developed oedometer with gas injection and water infiltration. Before the gas injection

A closure on the recent discussion regarding the review on the behavior of helical piles as a potential offshore foundation system by the Authors is presented. Installation torque, uplift capacity, installation effects, model pile, installation speed and results proposed by Discussers are commented.

The use of complex piers to build bridges has become widespread. In this study the experimental data was obtained to determine scour hole's dimension and its changes versus pile cap elevation. Five models with different geometry were used in experiments under clear water condition and thresholds velocity. The models were made with an appropriate scale from real piers of bridges. A 3D illustration of

Model tests accompanying numerical analyses on the modified suction caissons (MSCs) in saturated marine sand subjected to inclined loading were conducted to investigate the bearing behavior and earth pressure distribution along the embedded depth. Influences of external structure sizes, inclined loading angles and loading point position on the inclined bearing behavior were discussed. Results show

Cement treatment is a promising and effective method to enhance strength of calcareous sand in regions where offshore foundations and coastal facilities are localized. In treatment, the added cement content and curing period influence the strength of cemented calcareous sand. In order to regulate the loading resistance of cemented calcareous sand, effects of cement content and curing period on strength

Monopiles are widely used to support the upper structures of wind turbines in offshore engineering. Due to harsh environmental conditions, they are subjected to long-term lateral cyclic loading from waves and winds during the design life. A robust beam on the Winkler foundation model is presented to analyze the responses of monopile foundation under long-term lateral cyclic load, incorporating cyclic

Submarine pipelines are likely to be impacted by frequently catastrophic landslides, resulting in broken pipelines and causing irreversible economic losses; however, because pipelines located in deep-sea environments are simply laid atop the seabed, effective protective measures have not yet been proposed. In this paper, a pipeline with a uniform distribution of honeycomb holes on the surface, namely

This paper studies a novel CTD sensor (SZQ1-1) which is developed for underwater glider to meet the requirement of autonomous acquisition of high-quality profile hydrodynamic oceanography data. An independently developed electromagnetic induction type conductivity sensor, a quick response thermistor and a high-precision pressure sensor is used to integrate the CTD sensor. Several designs of compact

The hydrodynamic characteristics (wave transmission, reflection, and dissipation) of nine different scrap-tire floating breakwater configurations are studied in a wave flume for a wide range of input wave conditions. The breakwater has 3 different configurations: a) four and b) eight rows of tires as well as c) four rows in two levels. The effect of these configurations is assessed on the hydrodynamic

Cement stabilized clay (CSC) from dredged sediment or sludge is receiving increasing attention for its use as construction material. In this paper, seven CSC mixture samples were tested to investigate the effect of constituent proportion parameters and curing time (T) on strength characteristics. Results illustrate that clay-water/cement ratio (W/C) is significantly related to the unconfined compression

Abstract Helical piles have emerged as an attractive foundation system for offshore applications with renewed interest from the offshore community. Significant research gap currently exists in transferring this technology offshore and this paper discusses how existing and emerging knowledge can be successfully used to bridge some of the gaps. We focus on the Coupled Eulerian Lagrangian (CEL) large

The organic matter within clay soil is one of the important factors affecting its engineering characteristics. In this study, the influence of organic matter on the strength evolution of cement-stabilized marine soft clay is evaluated by scanning electron microscopy (SEM) and unconfined compressive strength (UCS) testing. The experimental results show that the after-curing clay water content of the

Flow liquefaction is a catastrophic failure phenomenon of loose sand when subjected to wave or seismic load, and an instability state can be regarded as the onset of flow liquefaction. Most of the previous studies focused mainly on the static instability state, while the investigations on cyclic instability state (CIS) are very limited and unsystematic. The characteristics of CIS are complex and there

The accurate knowledge of the location and movement of the sand bars is important for the coastal manager to establish correctly the coastal defence elements. This work applies a numerical model of finite elements based on Galerkin's formulation for predicting the location of the start, crest and end of the outer bar. The model that shows the best results is the one that combines the variables wave

Fragile angular-shaped granular materials, such as calcareous sand, rockfill material, and ballast, show complex stress–strain–volumetric relationships due to the effects of particle breakage. This paper presents a proposed constitutive model to simulate the effects of particle breakage on the mechanical response of calcareous sand and rockfill materials in drained triaxial tests previously conducted

The dredged clay (DC) could not be directly reutilized for its extra-high water content. So, the dewatering is needed before further improvement. At present, the commonly used self-weight sedimentation and natural air-drying are often difficult to meet the engineering requirements and time-consuming, thus chemical flocculants are used to improve the dewatering process for their excellent flocculation

The Orange Basin situated offshore South Africa has been subject to various studies as it is gas prone, but limited literature exists on the determination of fluid contacts. The availability of well logs, repeat formation tests (RFT), and drill stem test (DST) results make the Orange Basin an ideal example to carry out studies on the integration of these data to understand the fluid contacts in the

In recent years, bucket foundations have continuously been developed for offshore wind turbine, and the diameter of the bucket foundation has also increased with an increase in the load subjected to wind and waves. However, the bucket foundation can experience minor inclination during the installation process owing to soil anisotropy, which can largely increase the installation resistance. First, two

The use of vacuum preloading combined with electro-osmosis (VP-EO) to treat dredger fill from seabed has been studied extensively. However, there remain some drawbacks to this method, such as clogging outside of the prefabricated vertical drains (PVDs) and the inhomogeneous consolidation of soil. A novel method for stepped vacuum preloading combined with stepped voltage electro-osmosis (SVP-SVEO) was

This study proposes a methodology to prevent excessive and misuse of polymers in dewatering applications. In this study, to determine the optimum conditions some measurement were performed such as zeta potential measurements to arrange the pH of the slurry, flocculation tests to reduce turbidity and settlement time, particle size distribution analysis to enhance floc size, and Fourier-Transform Infrared

Offshore engineering is facing the challenges of modeling large deformation problems combined with the complexity of spatial variability of soils. This complex large deformation problem has not been extensively investigated, where one reason is believed due to limited practical approaches available. In this paper, the complex problem has been addressed through the in-house developed approach by implementing

Accreting soil system with horizontal drainage layers (HDLs) widely exists in engineering practices. With the existence of HDLs, each soil layer undergoes two stages: layer formation stage and surcharge loading stage. The methods proposed by Gibson and Zheng et al. are adopted to derive the analytical solution for the layer formation stage, while the separation of variables method and Duhamel’s principle

This study examines the effect of the initial fabric on the coefficient of the lateral earth pressure at rest K0, the undrained monotonic loading strength and the liquefaction resistance of a calcareous sand from a reclamation land in Persian Gulf. K0 consolidation, undrained compression and extension and cyclic undrained loading triaxial tests are performed on laboratory samples reconstituted by air

An innovative plate anchor, increasing its bearing section area during uplift is introduced in this paper. In this experimental study, the influence of the embedment ratio (depth of embedment/anchor width) of the plate anchor and anchor width (120, 150, 180, 250 mm) on the anchor pullout capacity and anchor displacement during an uplift test is investigated. Particle Image Velocimetry (PIV) is used

This paper proposes a coupled fluid half-space - strip foundation - poroelastic half-space vibration model to study how dynamic water pressure caused by strip vibration affects foundations operating offshore. Both vertical and rocking vibrations are considered. The governing equations of the problem are obtained using the Biot’s theory and proper boundary conditions at the seawater - seabed interface

A 2 D cross-shore transect model with variable density and saturation was established in FEFLOW to investigate the groundwater dynamics and solute transport under the influences of three tidal conditions. This study resulted in four major conclusions. The phreatic aquifer acted as a low-pass filter accompanied by a longer period in groundwater fluctuations. More obvious stability was observed in the

Piled raft is the most desirable foundation option in the recent era for offshore and onshore structures which are often exposed to combined vertical and lateral (V-L) loads. Due to the scarcity of literature, this study aims to comprehend the response of the piled raft foundation (PRF) under combined vertical and lateral loads. A series of laboratory experiments and finite element analysis has been

The present research investigates the undrained behavior of calcareous sand of Qeshm island in the south of Iran. The study was performed through undrained cyclic and monotonic stain-controlled triaxial tests on two relative densities (40 and 70%) and different effective confining pressures. Five different amplitudes of strains including 0.01, 0.07, 0.14, 0.7, and 1% were applied for cyclic triaxial

Submarine groundwater discharge is the main way to transfer land-based sources to the ocean. To verify the in situ monitoring capability of the multichannel electrical resistivity method for groundwater discharge in the coastal zone during tidal processes, in situ monitoring was carried out in different aquifers of Shilaoren Bay in September 2015 and May 2017. The electrodes were placed on the seabed

A series of oedometer tests were conducted on slurries with three additives (NaCl, CaCl2, and FeCl3) of different concentrations in pore water (0.1–1.0 mol/L) to investigate the effect of the valency of cations and their concentration on the consolidation–compression behavior of slurries. Further laboratory model tests on the vacuum consolidation of a prefabricated vertical drain (PVD) unit cell were

Millions of cubic meter of sediments are dredged annually to open channels for navigation of ships in ports and harbors. Beneficial reuse of these dredgings is typically possible upon their stabilization with calcium-rich amendments. A series of long-term laboratory column leaching tests and contaminant transport models were employed to study metal leaching behavior of bottom-sea dredged material (DM)

Engineering vessels play an important role in offshore engineering operations, and the control of their motion under the effects of sea environments is crucial for the safety and efficiency of the operation. In this study, a real-time monitoring system for vessel motion and sea environment with synchronization function designed at the Harbin Engineering University is introduced. The system consists

Based on limit equilibrium analysis, this paper presents a general pseudo-dynamic solution for the seismic active earth pressure considering anisotropic seepage conditions. The proposed method is applied to a vertical waterfront wall retaining fully submerged backfill with a drainage system along the soil-structure interface. To simplify the calculation, a steady state hydraulic head field satisfying

Aiming at the problem of serious soil cracking during electro-osmosis stage in the treatment of dredged slurry by vacuum pre-loading in combination with electro-osmosis method, this study proposes a new vacuum pre-loading method in combination with electro-osmosis and with dynamic compaction to overcome these drawbacks. Meanwhile, different current ratios are used to characterise the different activation

Based on an analysis of current research regarding dune migration and deformation monitoring methods, high-precision ground-based synthetic aperture radar (GB-InSAR) interferometry was used for continuous dynamic monitoring of the migration and deformation of dunes in Changli Gold Coast in Hebei Province, China, a typical area of coastal dunes. Methods for interpretation and key data processing were

Submarine pipeline was widely used to transport oil and gas in offshore petroleum exploitation. In practice, deep-water pipeline experiences several times of maintenance every year. This periodic open-up and shut-down operation causes cyclic rise and fall in the temperature of a pipeline, resulting in the periodic expansion and contraction of the pipeline. Due to the characteristics of heating-up operation

Sludge contains a little organic matter. Due to the action of microorganisms, organic matter was decomposed, and released humic acid. It can also affect lime or cement solidified sludge. Three categories of pH solution (pH = 4.0, 7.0, and 9.0) were prepared to soaking sludge. The organic matter and pH were observed for 78 days. The results showed that both acidic and alkaline buffer solutions can accelerate

This paper presents an experimental investigation of the impact of leaching on the geotechnical properties of Champlain Sea clay. Champlain Sea clay has a high salinity level in its pore fluid. A leaching apparatus was developed to leach a series of 15-cm diameter undisturbed Champlain Sea clay samples to different salinity levels. A series of geotechnical tests were conducted on leached samples. The

The mechanical characteristics of calcareous silt interlayers play an important role in the stability of island-reef foundations. Direct shear and consolidation tests were performed to study the relationship between the mechanical properties and the physical parameters of calcareous silt. Based on the consolidation test results and analysis of the settling examples, different calculation methods for

Several hundred million cubic meters of sediment are dredged from various U.S. ports, harbors, and waterways annually to maintain and improve the nation’s navigation system for commercial, national defense, and recreational purposes. The United States Environmental Protection Agency mandated containment of dredged sediments in designated containment facilities. The current study aims to explore the

Pile foundations in calcareous sand are often applied to bear vertical cyclic loads. Model tests of a single pile bearing vertical cyclic loads were performed in calcareous sand, and the accumulated settlement and bearing capacity were measured via sensors using a self-designed experimental device. The influences of the dynamic load and number of cycles on the accumulated settlement and bearing capacity

Rock drilling is a significant activity widely used in the exploration of marine mineral resources and offshore civil engineering such as marine mining, petroleum and deep-water drilling. The characteristics of size and shape of particles produced during rock drilling influence drilling efficiency and energy consumption. We report a series of drilling experiments on sandstone, limestone and shale to