Abstract Particle breakage is a significant phenomenon that distinguishes coral sand from other granular materials. This study aims to build an elastoplastic constitutive model which can describe the mechanical behaviour of coral sand at different relative densities and confinement conditions. According to the results of triaxial compression test and isotropic compression test, the expression of the

Abstract Hydrogenetic ferromanganese crusts in the northwestern (NW) Pacific seamounts are considered as potential future sources of strategic metals. The details of their regional and fine-scale variations in composition and structure are currently unknown. We attempted to characterize the variation patterns in a selected area of the NW Pacific seamounts, based on geological and geochemical analyses

Abstract The lateral deformation behaviour of inclined piles in calcareous sand is investigated with model testing and numerical analysis. A model pile is instrumented with quasi-distributed strain sensors and installed in calcareous sand with various inclination angles. The lateral deformation, bending moment and shear force of the pile are analysed by investigating the effect of the inclination angle

Abstract The suction caisson for offshore engineering features fast installation and reuse. When offshore engineering structure supported by a suction caisson is decommissioned, the suction caisson can be extracted by reverse pumping water for reuse and being replaced by a larger one. Model tests were conducted to investigate effects of the installation methods, extraction methods and pumping rate

Abstract The Yellow River Delta is one of the most abundant offshore energy areas in China, and the construction of offshore projects is rapidly developing. In this paper, four typical regions of the Yellow River Delta in different periods were selected as research objects. In-situ cone penetration tests (CPTs), geotechnical testing, electron microscope scanning testing, and soil type indexing (Ic)

Abstract In this study, laboratory experiments are conducted to assess the effects of a set of novel ring-type collars and prevalent spiral threading around a circular pier on scouring in a clear-water flow regime in non-cohesive bed materials. Also, numerical simulations are conducted to reveal the flow field in the scour hole around a pier with spiral threading. Various angles and spacings of the

Abstract This investigation aims to establish a system to test the identification of shoreline changes along the coast of Hurghada. Besides, the Digital Shoreline Analysis System (DSAS) studies the shoreline shift rate analysis. Multi-temporal satellite images have revealed accretion and erosion patterns in the areas of concern. Landsat images with different periods were geometrically and radiometrically

Abstract The seismic rotational stability analysis of waterfront retaining walls can be found in the existing literature, which adopted the limit equilibrium theory and was based on the moment balance of the external force on the wall. However, the application location of the seismic earth pressure still lacks a recognized solution. This paper presented a new methodology for the rotational stability

Abstract Based on the nonlinear Winkler theory, a simplified method for evaluating the lateral bearing capacity of the caisson-pile foundation (CCPF) considering the effect of scour-hole dimensions was proposed. The reliability of this method was verified by the results from a model test. The influences of the scour-hole dimensions on the lateral bearing characteristics of the foundation were discussed

Abstract A preliminary assessment on the economic loss due to 1.0 m sea level rise induced inundation for the Kuwait is carried out. Kuwaiti coast of 500 km is divided into 162 segments and landward slope of the coast was assessed based on field measurements of coastal profiles. The prevailing cost of coastal land for all coastal segments are used for economic impact assessment. It is found that 29%

Abstract The piles of offshore wind turbines are always subjected to multidirectional loads. The vertical and lateral behaviours of piles are designed separately in practice. However, many studies have shown that the vertical load has a substantial influence on the lateral behaviours of piles. The influence of the vertical load on the lateral behaviours of monopiles can be divided into three aspects:

Abstract The shear wave characteristics of shallow seafloor sediment are vital to marine acoustic study and ocean engineering exploration. We analyzed the shear wave speed and the physical properties of the southern Yellow Sea sediment based on the Grain-Shearing (GS) model. The results show that: (1) The shear wave speed of the high-porosity sediment is lower than that of the low-porosity sediment;

Abstract Fifteen constant rate of strain consolidation tests were performed on Wenzhou clay specimens under various strain rates and initial water contents using an advanced oedometer to investigate the remolded yield stress during compression. The results for different initial water contents indicated that the remolded clay compression curves could be expressed by a unique trend line using the void

Abstract The dynamic shear modulus and damping ratio, as important parameters of soil dynamics, are indispensable for the evaluation of seismic safety and analysis of soil layer seismic response. Due to the limited existing research into marine soil’s dynamic shear modulus and damping ratio, there is a failure to get the reference values, along with the reference values for relevant parameters of soil

Abstract Analysis and design with simple correlations are always of interest to engineers. Predicting the bearing capacity of a spudcan in a multi-layered clay soil is one of the challenges facing jack-up designers and the installation process. In this paper, simple correlations are presented for the prediction of the bearing capacity–penetration curve of the spudcan using numerical modeling results

Abstract An improved method, i.e., flocculation–solidification combined method (FSCM), has been developed for building a working platform more efficiently at the surface of newly reclaimed ground filled with hydraulically dredged mud slurry at extra high water content (EHW-MS). Previous experimental results have demonstrated the significant superiority of FSCM over conventional pure cement solidification

Abstract The performance of a double-core prefabricated vertical drain (PVD), which could reduce the well resistance via its large cross-sectional area and structural stability, was investigated experimentally and numerically. The double-core and the conventional single-core PVD, which has been widely adopted in reclaimed ground improvement, were compared in this study. In the experimental investigation

Abstract To examine the coral reef limestone–concrete shear failure characteristics, we conducted large-scale direct shear tests to study five types of interfaces: planar, sloped, arc shaped, stepped, and triangular. Furthermore, the shear failure characteristics and shear strength variations were examined under three interface connection types: smooth, mud filled, and cemented. The results show that

Abstract Accurate determination of scour depth (ds) around bridge piers is a major concern and an essential criterion in the safe and economical design of bridge pier foundation. The estimation of ds by the conventional empirical methods is difficult due to the very complex mechanism of the 3D flow around the bridge piers. This paper proposes the Sequential Minimal Optimization Regression (SMOREG)

Abstract River morphological processes are among the most complex and least understood phenomenon in nature. Recent research indicates that the braiding of marine waterways of the estuary zone occurs at an aspect ratio similar to the alluvial braided river. The instability of complex sporadic fluvial processes at river-sea interface is responsible for bar formation in alluvial as well as in marine

Abstract The insufficiency of research on the calculation of the sidewall friction of large and deep-water caissons lies in that the longitudinal and lateral distribution of the sidewall friction is not clear. In this paper, a large-scale (1:70) model test was conducted based on the caisson foundation of the main pier at the Shanghai-Suzhou-Nantong Yangtze River Bridge to explore the longitudinal and

Abstract Ferromanganese (FeMn) crusts with oxides ranging from a thin coating to a maximum of 5 cm thickness were recovered from the South West Indian Ridge (SWIR) and Central Indian Ridge (CIR) segments. The substrate for the oxides are altered mafic, ultramafic, and serpentinite rocks. Twenty FeMn crusts were studied to determine their mineralogical compositions, microstructures, and chemical compositions

Abstract Lake Urmia is located in the northwest of Iran and shared between the provinces of West Azarbaijan and East Azarbaijan. In the last two decades, there has been a considerable decline in the lake’s water level. Satellite altimetry (SA) together with the advanced precise orbital positioning system has reached a high accuracy in the measurement of the water level height, but increasing the accuracy

Abstract Internal solitary waves bring great challenges to the safety of deep-sea mining pipeline deployment operations. The three-dimensional finite element model of deep-sea mining pipeline system under the action of internal solitary waves is established and solved. The shape, tension, stress, upper rotation, offset, and transient response of the pipe string during the deployment process of the

Abstract Soil restraints associated with relative soil-pipe movements is an important consideration for stability assessment of buried pipelines. This paper investigates the effects of pipe surface roughness, inclination angle within the horizontal-vertical plane and embedment ratio on the development of soil restraint on shallow pipes in sand. In total, 24 model tests were performed, using an image-based

Abstract The classification of seabed soil in the Yellow River Subaquatic Delta can be obtained more accurately by cone penetration test (CPT). The Soil behavior type index (Ic), over-consolidation ratio (OCR), sensitivity (St) and the relationship between them were clarified. The cyclic stress ratio (CSR) of seabed soil in the Yellow River Delta was calculated based on the wave elements in the 5-year

Abstract MgCl2 is widely used on roads for controlling dust and humidity, reducing the scattering of coarse particles, anti-icing, and improving the geotechnical properties of “problematic soils” by chemical stabilization. In this study, we initially induced the MgCl2 solution to electrokinetic stabilization. Six electrokinetic experiments were conducted on marine clayey soil, collected from Zhuhai

Abstract Soil anchors are among the most widely used reinforcements to stabilize unstable soil mass or stabilize and anchor structures built in onshore and offshore regions. Anchors are generally installed in soil and rocky environments by penetration and embedment methods. These methods are classified into two main groups of grouted and mechanical anchors. In the present study, Expandable Mechanical

Abstract Flocculation by chemicals can adequately reduce the clogging effect, and the bending effect of prefabricated vertical drains can be eliminated by laying a prefabricated drain in the horizontal direction. Various settling column tests with different contents of chemicals, polyacrylamide (PAM) and hydrated lime (Ca(OH)2), were initially conducted to find the optimum dose for the fastest settling

Abstract Ground treatment via the vacuum preloading technique has been extensively used in coastal belts worldwide in the field of civil engineering. However, due to the poor effect of traditional ground treatment, a new technology of combined air-booster and straight-line vacuum preloading without sand was proposed. Field tests were conducted in this study to illustrate the treatment effect. Based

Abstract The design and construction of coastal structures such as breakwaters, at great water depths is rapidly increasing as a result of the increasing draught of large vessels and off-shore land reclamations. Vertical caisson breakwaters may be the best alternative compared to ordinary rubble mound breakwaters in larger water depths, in terms of performance, total costs, environmental aspects, construction

Abstract Port development results in production of large quantities of dredged marine sediments. Once dredged, sediments often have high water contents and are pumped to near-shore or in-water bunded marine impoundments for port expansion. However, dredged material disposal to freshwater onshore or empty impoundments typically changes sedimentation conditions that may change the effective grain-size

Abstract In this study, the ultimate undrained bearing capacity of a laterally loaded pile, embedded in heterogeneous marine deposits exhibiting linear and bi-linear undrained shear strength profiles was calculated by putting into practice the three-dimensional finite element lower bound limit analysis in conjunction with the second-order cone programming method. The lower bound finite element bearing

Abstract The deep-sea sediments are usually heterogeneous due to overburden pressure. Excessive deformation of deep-sea sediments caused by mining collector vibration can decrease the stability and reduce the efficiency of the mining system. This study analyzed the dynamic response of the heterogeneous deep-sea sediments under mining collector vibration. First, experiments were conducted to confirm

Abstract Skirted spudcan foundations can effectively provide a considerable bearing capacity and moment fixity to withstand the complex combined vertical, horizontal, and moment loadings encountered in offshore engineering practices. The failure envelope is a general solution that characterizes the bearing capacities of offshore foundations under combined loading conditions. In this study, a series

Abstract In the present study, the uplift capacity of the under-reamed piles (also referred to as belled piles) in the sand was determined by following a finite element analysis. In this regard, the soil was assumed to obey Mohr-Coulomb's failure criteria, together with a non-associated flow rule. The pile geometry, soil, and pile properties were selected by following relevant literature. The friction

Abstract A series of undrained cyclic axial-torsional shear tests on saturated coral sand and quartz sand under linear, circular, and heart stress paths are performed. The test results show significant differences in liquefaction characteristics for coral sand and quartz sand. A unique relationship between deviatoric strain amplitude and excess pore water pressure ratio (R u) can be established regardless

Abstract Suction caisson is one of the important forms of marine foundation. It is worthwhile to study scour effects on the vertical bearing capacity of suction caissons, which can provide a reference for the design of multi-caisson foundations. This paper investigated the influence of scour depth, stress history, and aspect ratio on the vertical bearing capacity of suction caissons. The capacity decreases

Abstract Suction caisson is one of the important forms of marine foundation. It is worthwhile to study scour effects on the vertical bearing capacity of suction caissons, which can provide a reference for the design of multi-caisson foundations. This paper investigated the influence of scour depth, stress history, and aspect ratio on the vertical bearing capacity of suction caissons. The capacity decreases

Abstract Electroosmotic consolidation effect of electrode configuration and fracture grouting with sodium hydroxide were investigated. In this study, a series of laboratory tests were performed by using a homemade electroosmotic cell. Results indicate that electroosmotic consolidation that uses fracture grouting with sodium hydroxide effectively improved the mechanical properties of dredged clay sediment

Abstract Based on the soil behavior type (SBT) and its parameters (I c) obtained by cone penetration tests (CPTs) in the Yellow River Delta, the standardized shear wave velocity (Vs1), permeability coefficient (k), and fine-grained soil content (FC) were calculated. The fine-grained soil content offshore is higher than that near the coast. The shear wave velocity is primarily distributed in the range

Abstract In this paper, the engineering application of microbial self-healing concrete in ship lock engineering was studied. Researches including the design and batch preparation of microbial self-healing agent, and laboratory tests of microbial self-healing concrete were carried out. A class of self-healing agents containing microbial spores and calcium sources was designed and batch-produced by spray

Abstract The coral reef pores are the main reservoir space of oil and gas resources. Through determining the structural form and distribution characteristics of pores, it can be helpful for scientific and reasonable stratigraphic division and reservoir evaluation, and provide basic data for the efficient development of using coral reefs as oil and gas reservoir sites. The core difficulty of interpretation

Abstract Hydrate reservoirs present numerous challenges due to their occurrence in ultra-deep regions, presence of mud-layers, unconfined boundaries, and complex morphological heterogeneities. Individual effect of some of these reservoir settings on overall production is known, however, a systematic assessment of their mutual impact on gas production and land subsidence is essential from production

Abstract The effect of the initial deviatoric stress direction and magnitude of deviatoric stress q on the strain components and non-coaxial behavior of soft marine clay during principal stress rotation was experimentally examined. The strain components and pore water pressure depended considerably on the deviatoric stress direction and q. Through polar diagrams, a notable non-coaxiality was observed

Abstract This study presents finite element analysis (FEA) results of suction buckets subjected to vertical sustained uplift loads, focusing on the suction pressure and the displacement responses. The accumulative seepage of water and the heave of the soil in the bucket are the key components of the displacement. The accumulative seepage of water is modelled using a layer of soft elastic material (water

Abstract The large-diameter monopile, as one of the most used foundations of offshore wind turbines, is subjected to severe sea conditions, such as the cyclic lateral loads induced by wind and waves, as well as the scour induced by the flushing currents. The combined cyclic lateral loads and scour introduces additional complexity and is encountered in offshore wind turbines as well as other offshore

Abstract Chennai is a major metropolitan city along the southeast coast of India and is popular for its world’s second longest sandy beach called as Marina beach the shoreline of which has been gradually advancing towards the Bay of Bengal over a century. The advance of the shoreline is due to the construction of breakwaters for the formation of the harbor of Chennai port, one of the 12 major ports

Abstract Stick of the deep-sea sediment on the surface of the mining machine can deteriorate its working efficiency. To resolve this issue, this study aims to reduce the adhesion force along the soil-metal interface by adjusting the roughness of the metal surface. During the experimental study, six types of Titanium samples with different surface roughness were first prepared through surface polishing

Abstract During remote monitoring of the Persian Gulf to detect oil spills, conducted from 2017 to 2019, leaking oil on the sea surface was observed at an offshore site. The site was located 26 km west of the Sir Abu Nuyar Island in the waters of the United Arab Emirates. A more detailed analysis was conducted using remote sensing data, particularly synthetic aperture radar and optical images from

Abstract Offshore wind turbines (OWT) subjected to long-term complex marine loads are prone to foundation damages, affecting their regular operation. However, the failure mode of the large-diameter monopile foundation under complex marine loads is not well understood. Hence, failure modes of monopile foundation for OWT in soft-soil seabed under unidirectional and multidirectional loads are investigated

Abstract Recently, many of the world’s major river deltas have been sinking, making them increasingly vulnerable to floods and storm surges, salinization and permanent inundation. For the Yellow River delta, annual subsidence rates of several to dozens of centimeters have been reported in the past few years. The extraction of a considerable amount of groundwater due to continuous pumping is suggested

Abstract The dynamic cone penetration test (DCPT) is a common method for assessing the physical and mechanical properties of cohesionless soils. However, current formulas might not be suitable for carbonate granular soil because of its unique engineering properties. In this study, a series of DCPTs were conducted on carbonate granular soil in the field and laboratory using a light dynamic penetrometer

Abstract Embankment is vulnerable to scouring and erosion during heavy rainfall events in most coastal areas in China. In this study, microbially induced calcium carbonate precipitation (MICP) technique was applied for sand embankments for scouring/erosion control. Three small-scale MICP treated sand embankments and one untreated embankment were first prepared using the injection method. Then, a series

Abstract The mechanical properties of calcareous sands are very different from those of terrestrial sands as the particle crushing occurs under low confining pressure. If the calcareous sand is used as the foundation materials, engineering problems such as the uneven settlement of the foundation are prone to occur. In this paper, the Polyurethane foam adhesive (PFA) is used to improve the calcareous

Abstract Pile foundations are one of the significant marine substructure systems for a variety of offshore and onshore facilities. Thus, optimum and reliable design during their lifetime and under inherent uncertainties is noteworthy. Among various methods for predicting axial pile bearing capacity, cone penetration test (CPT)-based methods enhance geotechnical design to a more satisfying level due

Abstract Taut or semi-taut mooring lines are often used in deep-sea area to connect the floating structures to the anchors in the seabed. In previous studies, the quasi-static analysis method was adopted to assess the load transfer of the mooring line. However, the inertia effect of mooring line and chain–seabed dynamic interaction cannot be neglected in practice. In this paper, the soil strain rate

Abstract This study investigates the effect of combined operational and seismic loads on the dynamic fore-aft, and the side-side response of monopile supported OWT in liquefiable soil under operational and parked conditions. A two dimensional (2 D) coupled soil-pile-structure interaction model is formulated in OpenSees, where the monopile and tower are modeled as Euler-Bernoulli beam elements, the

Abstract This paper performs finite element (FE) analysis to investigate the behaviour of a large geotextile mat offshore dike on clay-overlaying-sand soil deposits, which is reinforced by a new type of non-uniform thick geotextiles technique. A FE model is generated and validated against laboratory centrifuge testing data. A comprehensive parametric study is then conducted to examine the influences

Abstract An experimental investigation was conducted to understand the impact of salinity on the microstructure, phase composition, and shear strength of cement-treated Champlain Sea clay. Based on a scanning electronic microscopy (SEM) analysis, Champlain Sea clay exhibits an open structure fabric with flocculated particles. Leaching results in de-flocculation of the aggregates and leads to an increase