Showing papers in "Marine Georesources & Geotechnology in 2018"
TL;DR: Group method of data handling (GMDH) as a one of the self-organized approaches is utilized to predict three-dimensional free span expansion rates around pipeline due to waves to perceive influences of different input parameters on the three- dimensional scour rates.
Abstract: In this research, group method of data handling (GMDH) as a one of the self-organized approaches is utilized to predict three-dimensional free span expansion rates around pipeline due to waves. The...
68 citations
TL;DR: In this paper, the long-term strength and deformation behavior of marine sediments solidified with cement, lime, and fly ash was analyzed by analyzing the unconfined compressive tests.
Abstract: Most of the previous studies concerning solidification of marine sediments focus mainly on the mechanical properties within the curing time of 90 days, but the long-term (e.g., 360 days) behavior has not been fully appreciated. The current study attempts to address this issue by analyzing the long-term strength and deformation behavior of sediments solidified with cement, lime, and fly ash. A series of unconfined compressive tests were conducted, and the effect of binder amount and binder type is discussed on 360-day cured specimens. It can be found that the increasing amount of cement/lime enhances the mechanical performance of sediments. The fly ash addition plays different roles in cement- and lime-solidified sediments. Fly ash improves the strength and modulus of lime-solidified sediments but weakens the mechanical characteristics of cement-solidified sediments. The test results demonstrate that the lime–fly ash binder is capable of replacing lime and cement–fly ash binder for sediment solidif...
38 citations
TL;DR: Vacuum preloading is often used to improve the geotechnical properties of dredged slurry as discussed by the authors, and although the performance of this method has improved with rapidly developing technology, soil columns usual...
Abstract: Vacuum preloading is often used to improve the geotechnical properties of dredged slurry. Although the performance of this method has improved with rapidly developing technology, soil columns usual...
32 citations
TL;DR: In this paper, the authors describe the bed shear stress in channel contraction, which occurs due to the flow concentration within them inducing excessive bed-shear stress, and describe a complex process that is difficult to describe through a gen...
Abstract: Scouring in the channel contractions occurs due to the flow concentration within them inducing excessive bed shear stress. This is a complex process, so it is difficult to describe it through a gen...
30 citations
TL;DR: To reduce the settlement induced by long-term traffic loads, the surcharge preloading method is widely used to improve the characteristics of marine soft clay subgrade as mentioned in this paper, but its effectiveness n...
Abstract: To reduce the settlement induced by long-term traffic loads, the surcharge preloading method is widely used to improve the characteristics of marine soft clay subgrade. However, its effectiveness n...
25 citations
TL;DR: Due to a few limitations through laboratory testing for determining soil shear strength parameters, cone penetration test (CPT) has been realized as a multipurpose apparatus with an acceptable performance as discussed by the authors.
Abstract: Due to a few limitations through laboratory testing for determining soil shear strength parameters, cone penetration test (CPT) has been realized as a multipurpose apparatus with an acceptable perf...
24 citations
TL;DR: The electroosmosis method is regarded especially suitable for the disposal of dredged clay sediment, but its excessive power consumption and electrode corrosion has limited its widespread applicati... as discussed by the authors,.
Abstract: The electroosmosis method is regarded especially suitable for the disposal of dredged clay sediment, but its excessive power consumption and electrode corrosion has limited its widespread applicati...
23 citations
TL;DR: Vacuum preloading is a soft ground improvement method that has been successfully used by geotechnical engineers and specialists to accelerate the rate of consolidation as mentioned in this paper, however, consolidation effic...
Abstract: Vacuum preloading is a soft ground improvement method that has been successfully used by geotechnical engineers and specialists to accelerate the rate of consolidation. However, consolidation effic...
20 citations
TL;DR: In this article, a specially designed platform was used to perform model tests with different loading angles and cyclic parameters and the experimental results showed that when the loading angle decreases from 50.2° to 32.0°, the failure mode changes to a combined mode consisting vertical motion, horizontal motion, and anticlockwise rotation, and its corresponding capacity noticeably increases.
Abstract: In addition to the loading angle at the pad eye, the types of applied forces will affect the failure mode and the capacity of suction caisson in a soft clay seabed. In this study, a specially designed platform was used to perform model tests with different loading angles and cyclic parameters. First, the short-term static capacities and the failure modes for the typical inclined loading angles were studied, and then the influences of cyclic amplitude, number of cycles and cyclic period on the subsequent failure mode, and caisson capacity were investigated by applying a series of one-way cyclic loadings. The experimental results showed that when the loading angle decreases from 50.2° to 32.0°, the model caisson’s failure mode changes to a combined mode consisting vertical motion, horizontal motion, and anticlockwise rotation, and its corresponding capacity noticeably increases. However, the increases in amplitude, number, and frequency of the previous cyclic loadings would turn this combined failur...
18 citations
TL;DR: In this article, the analysis of wave-induced liquefaction of seabeds is of profound importance for offshore structures such as wind turbines and oil platforms, and the seabed around pile foundations is subjected to two different wave phases.
Abstract: The analysis of wave-induced liquefaction of seabeds is of profound importance for offshore structures such as wind turbines and oil platforms. The seabed around pile foundations is subjected to tw...
18 citations
TL;DR: The Yellow River Delta has experienced varying degrees of land subsidence since the late 1970s as mentioned in this paper, and although recent studies have identified the natural consignments, they did not identify the natural causes of the subsidence.
Abstract: The Yellow River Delta, which is the second-largest delta in China, has experienced varying degrees of land subsidence since the late 1970s. Although recent studies have identified the natural cons...
TL;DR: In this paper, the effects of metakaolin content and different ions on the mechanical properties of salt-rich soil-cement were explored, and it was found that the strength of salt rich soil-cement increased with an increase in metakolin content, and then no further increase in strength was found when the metakalin content exceeds a certain value.
Abstract: The corrosive ions in salt-rich soft soil have negative effects on soil–cement when the soft soil ground is reinforced by cement. To improve the strength of salt-rich soil–cement, a series of laboratory tests on metakaolin were performed, and the effects of metakaolin content and different ions on the mechanical characteristic of salt-rich soil–cement were explored as well. It was found that the strength of salt-rich soil–cement increased with an increase in metakaolin content, and then no further increase in strength was found when the metakaolin content exceeds a certain value. Therefore, salt-rich soil–cements with different ions have its optimal metakaolin content. Orthogonal test results show that three ions Cl−, Mg2+, and have different effects on the strength of salt-rich soil–cement improved by metakaolin, Cl− has the most important influence on the strength but is minor. Metakaolin has the characteristics of accelerating hydration reaction of salt-rich soil–cement, filling effect, and vol...
TL;DR: 1g model tests indicate that the OMNI-Max anchor can dive both in homogeneous and lightly overconsolidated clays under certain conditions and can be improved with small uplift angles at the mudline and with thick anchor flukes.
Abstract: The OMNI-Max anchors are newly developed dynamically installed anchors for deep water mooring systems. After installation, the anchor is keyed to a new orientation and position by tensing the attac...
TL;DR: In ocean engineering, storm-wave loading imposes irregular cycles in the magnitudes acting on the coastal or seabed cohesionless soils, giving rise to more complex consequences on the their liquefa...
Abstract: In ocean engineering, storm-wave loading imposes irregular cycles in the magnitudes acting on the coastal or seabed cohesionless soils, giving rise to more complex consequences on the their liquefa...
TL;DR: In this article, the experimental data collected from an actual project were first analyzed to identify the statistical characteristics of the engineering properties of in situ Cement-Stabilized Marine Clay (CSMC) embankments.
Abstract: Cement-stabilized marine clay (CSMC), usually used as filling material of coastal facilities such as land reclamation embankments, shows very high spatial variability in engineering properties. This high spatial variability produces substantial influence on the stability of CSMC embankments. In this study, the experimental data collected from an actual project were first analyzed to identify the statistical characteristics of the engineering properties of in situ CSMC. It is shown that the strength of the in situ CSMC follows a lognormal distribution, and the coefficient of variation (COV) is higher than the value (0.35) assumed in the conventional deterministic design method (CDDM). Both deterministic and random numerical analyses were then performed for a typical CSMC embankment. Special attention was paid to evaluate the effects of COV and the mean value of strength on the embankment stability. Results show that the effect of spatial variability is significant but not reasonably accounted for i...
TL;DR: In this paper, a superposed saw-tooth model of suspended sediment concentration disturbed by waves and currents was developed, which explained how episodic waves were responsible for the big sawtooth shape and how currents accounted for the small saw tooth shape.
Abstract: Sediment suspended in the Yellow River delta provides significant physical, geological, and biogeochemical information. A time series of waves, currents, turbidities, temperatures, and tide levels were measured over a 134-d period using a submarine deployed tripod. A static model (multiple linear regression) and a dynamic model (superposed saw-tooth model) were constructed to express the interactions among wave height, current velocity, and suspended sediment concentration. The results documented a high suspended sediment concentration in this area with a mean of 2.24 g/L. A superposed saw-tooth model of suspended sediment concentration disturbed by waves and currents was developed. The shear stress results explained how episodic waves were responsible for the big saw-tooth shape and how currents accounted for the small saw-tooth shape.
TL;DR: In this article, the authors performed 25 types of sedimentation tests on the clay suspensions with different liquid limits, initial water contents, and initial heights using different sizes of sediment columns.
Abstract: Dredging activities in China produce a great deal of clay suspensions which are generally pumped into yards as filling materials to form reclaimed lands. Understanding the settlement behavior of clay suspensions during settling process is essential in engineering practice for meeting the design requirement on the storage capacity of reclaimed yards. To this end, this study performed 25 types of sedimentation tests on the clay suspensions with different liquid limits, initial water contents, and initial heights using different sizes of sediment columns. The experimental results indicate that the settlement–time curves of clay suspensions can be classified into three stages. It is found that the first stage can be ignored, and the sedimentation can be attributed to the second stage termed as settling stage in practice. Hyperbolic model is proposed for describing the settlement–time relationship during the settling stage, and a quantitative method of determining the settlement at the end of the settl...
TL;DR: In this paper, a series of mini-drum centrifuge experiments on motion of submarine debris flow, which are able to correctly reproduce the self-weight stresses and gravity-dependent processes, are presented.
Abstract: In this paper, a series of mini-drum centrifuge experiments on motion of submarine debris flow, which are able to correctly reproduce the self-weight stresses and gravity-dependent processes, are p...
TL;DR: The sand compaction pile (SCP) method can be applied to soft marine clay ground that is a reinforcement of composite ground consisting of compacted sand piles and surrounding clay.
Abstract: The sand compaction pile (SCP) method can be applied to soft marine clay ground that is a reinforcement of composite ground consisting of compacted sand piles and surrounding clay. The application ...
TL;DR: In this article, oil and its derivatives contaminate many soils and not only affect their chemical and biological properties but also their geotechnical properties, as oil contamination may deteriorate the function of the soil.
Abstract: Oil and its derivatives contaminate many soils and not only affect their chemical and biological properties but also their geotechnical properties. As oil contamination may deteriorate the function...
TL;DR: In this article, a semi-empirical scheme is adopted to involve a mechanical constitutive model to extract stress and strains at the first cycle and polynomial-type strain accumulation functions to track the progressive plastic deformation.
Abstract: This paper analyzes the long-term monopile foundation that undergoes numerous mechanical cycles. The semiempirical scheme is adopted to involve a mechanical constitutive model to extract stress and strains at the first cycle and polynomial-type strain accumulation functions to track the progressive plastic deformation. In particular, the strain function contains the fundamental features that require simulating the long-term response of geomaterials: volumetric strain (terminal void ratio) and shear strain (shakedown or ratcheting), the strain accumulation rate, and stress obliquity. The numerical simulation shows evolution of displacements, pile rotation, and stress redistribution along the embedded pile as the number of load cycles increases. The analysis highlights that the pile rigidity affects the pattern of horizontal stress and displacement. The repetitive lateral load enhances the lateral load resistance due to soil densification along the pile.
TL;DR: In this article, a laboratory investigation on undrained cyclic behavior of natural organic clay is presented and conducted by cyclic triaxial apparatus to simulate the loading conditions induced by passing vehicles in actual engineering.
Abstract: One-way cyclic loading is more typical for traffic loading and cyclic triaxial test has been recognized as a useful method for solving many engineering problems. Under traffic loading, the influence of variable confining pressure on cyclic behavior of natural organic clay subjected to cyclic traffic loading is rarely reported in the literature. In this study, a laboratory investigation on undrained cyclic behavior of natural organic clay is presented and conducted by cyclic triaxial apparatus. Tests are conducted by both constant confining pressure and variable confining pressure, to simulate the loading conditions induced by passing vehicles in actual engineering. Different stress levels are also considered in this study. By comparing between the results of constant confining pressure tests and variable confining pressure tests, it shows that the one-way cyclic behavior of organic clay is influenced significantly by variation of confining pressure, in terms of pore water pressure, permanent axial...
TL;DR: In this article, a field EO test using a type of new patented electrically conductive wick drain (ECWD) and a specially designed automated power supply (APS) on a hydraulically filled sludge ground in Jiangsu Province, China is presented.
Abstract: Electro-osmosis (EO) methods have not been widely used for the drainage consolidation of soft clay soils in practice because of two key problems; (i) metallic electrode corrosion, and (ii) high electric energy consumption. With recent advancements of conductive plastics, there has been interest in using conductive plastic electrodes instead of metallic electrodes to accelerate drainage of soft clay soils. This paper presents the details of a field EO test using a type of new patented electrically conductive wick drain (ECWD) and a specially designed automated power supply (APS) on a hydraulically filled sludge ground in Jiangsu Province, China. The in-situ investigations and laboratory tests were conducted to evaluate the improvement effectiveness after performing EO treatment for a period of 36 days (including a continuing intermittence of 16 days). The results suggest that the EO technique using the ECWD combined with the APS (i) decreased the average moisture content of the sludge from 62 to 39...
TL;DR: In this paper, a heave compensation system combined with a vibration absorber and accumulator is proposed for poly-metallic nodule mining at an ocean depth of 6,000m in Ch...
Abstract: A heave compensation system combined with a vibration absorber and accumulator is proposed, with regard to the requirement for poly-metallic nodule mining systems at an ocean depth of 6,000 m in Ch...
TL;DR: The development of the Yantai West Port was implemented on a large scale that had an impact on the dynamic environment of the surrounding sea area as discussed by the authors, and investigations of the tides, tidal currents, wate...
Abstract: The development of the Yantai West Port was implemented on a large scale that had an impact on the dynamic environment of the surrounding sea area. Investigations of the tides, tidal currents, wate...
TL;DR: In this paper, a series of model tests were conducted on Perspex-made suction caissons in saturated dense marine sand to study the sand plug formation during sand extraction.
Abstract: A series of model tests were conducted on Perspex-made suction caissons in saturated dense marine sand to study the sand plug formation during extraction. Suction caissons were extracted by pullout...
TL;DR: The elastic mechanical response of porous materials under a heat source has many applications in civil engineering and has received considerable attention in the geotechnical literature as mentioned in this paper, where the elastic response has been investigated in a number of applications.
Abstract: The elastic mechanical response of porous materials under a heat source has many applications in civil engineering and has received considerable attention in the geotechnical literature. In...
TL;DR: The deformation of cement-consolidated soil under external load occurs because of the accumulation of its internal damage, which was studied from the aspect of the microstructure pore behavior as mentioned in this paper.
Abstract: The deformation of cement-consolidated soil under external load occurs because of the accumulation of its internal damage, which was studied from the aspect of the microstructure pore behav...
TL;DR: In this article, the authors propose to use the lateral response of rigid shafts for energy infrastructure, such as electric transmission towers, offshore platforms, or wind turbines, which are usually rigid and close to the lateral responses of rigid shavings.
Abstract: Pile foundations for energy infrastructure, such as electric transmission towers, offshore platforms, or wind turbines, are usually rigid and close to the lateral response of rigid shafts. This pap...
TL;DR: In this paper, the effects of organic content and the frequency of cyclic shear straining on the cyclic degradation and the normalized pore water pressure in 27 fibrous marine organic soil specimens were investigated with the two-way cyclic strain-controlled dynamic triaxial testing system.
Abstract: The effects of organic content and the frequency of cyclic shear straining on the cyclic degradation and the normalized pore water pressure in 27 fibrous marine organic soil specimens were investigated with the two-way cyclic strain-controlled dynamic triaxial testing system. The testing program included three cyclic shear strain amplitudes, γc = 0.25, 0.5, and 1%, three ranges of the organic contents, OC = 13.3–18.4%, 23.3–27.9%, and 36.9–45.3%, and three loading frequencies, f = 0.05, 0.25, and 1 Hz. The results clearly exhibit that the degradation parameter, t, which means the rate of the cyclic degradation with the number of loading cycles, N, decreases with the OC and increases with the f. At the γc = 0.25–1%, if the OC decreases from 40.8 to 13.3%, the degradation parameter t may increase by 82.9–221.1%. If f is increased 20 times, from 0.05 to 1 Hz, then t may increases by 34.7–117.9%. The cyclic pore water pressure normalized by the effective consolidation pressure, , increases with the OC...