In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume exper...In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-induced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and ^(210)Pb_(ex) specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in particle size and ^(210)Pb_(ex) specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data.展开更多
A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures wou...A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures would happen, and the following mass movement would present great risk to the submarine pipeline. In view of this, a numerical prediction method based on Eulerian-Eulerian two-phase flow model is introduced to simulate the mass movement of potential submarine landslides. The sliding soil and ambient water are respectively simulated by Herschel-Bulkley rheology model and Newtonian fluid model. The turbulence is simulated using the k-e model. Compared with both the experiment data and Bing result, the two-phase flow model shows a good accuracy, and its result is more close to the actual situation; the dynamic coupling between soil and ambient water can be effectively simulated and the phenomena of hydroplaning and head detachment can be obtained. Finally, the soil movement of a potential submarine landslide is simulated as an example, according to the seismic profile in the canyon area. The result shows that the hydroplaning occurs during the movement process. The runout distance calculated by the two-phase flow model is 877 m, which is 27.1% larger than the Bing result. However, the peak front velocity of soil is relative small, with a maximum value of 8.32 m/s. The Bing program with a simple and rapid process can be used for a preliminary evaluation, while the two-phase flow model is more appropriate for an accurate assessment.展开更多
The safety of submarine pipelines is largely influenced by free spans and corrosions. Previous studies on free spans caused by seabed scours are mainly based on the stable environment, where the background seabed scou...The safety of submarine pipelines is largely influenced by free spans and corrosions. Previous studies on free spans caused by seabed scours are mainly based on the stable environment, where the background seabed scour is in equilibrium and the soil is homogeneous. To study the effects of background erosion on the free span development of subsea pipelines, a submarine pipe- line located at the abandoned Yellow River subaqueous delta lobe was investigated with an integrated surveying system which in- eluded a Multibeam bathymetric system, a dual-frequency side-scan sonar, a high resolution sub-bottom profiler, and a Magnetic Flux Leakage （MFL） sensor. We found that seabed homogeneity has a great influence on the free span development of the pipeline. More specifically, for homogeneous background scours, the morphology of scour hole below the pipeline is quite similar to that without the background scour, whereas for inhomogeneous background scour, the nature of spanning is mainly dependent on the evolution of seabed morphology near the pipeline. Magnetic Flux Leakage （MFL） detection results also reveal the possible connec- tion between long free spans and accelerated corrosion of the pipeline.展开更多
Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to it...Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm2 to 6 A/cm2 in pulsed mode within pulse length 5-20 ms. A 10 cm diameter, 2 m long plasma column with density 10is m-3 to 1019 m3 and electron temperature Te --~ 3-7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.展开更多
This paper investigates the size distribution of submarine landslides on the middle continental slope of the East China Sea (ECS) using the size of the landslide source regions. Geomorphometric mapping is used to iden...This paper investigates the size distribution of submarine landslides on the middle continental slope of the East China Sea (ECS) using the size of the landslide source regions. Geomorphometric mapping is used to identify 102 mass movements from multibeam bathymetric data and to extract morphological information about the head scarps and side walls. These mass movements have areas ranging between 0.06 km2 and 15.51 km2 and volumes between 0.002 km3 and 2 km3. The area vs volume relationship of these failure scarps is approximately linear, suggesting a fairly uniform failure thickness in each event with scarce deep excavating landslides. The cumulative area distribution of the slope failures can be described by an inverse power law. The submarine landslides on the mid-ECS continental slope could be considered as a large-scale self-organizing system because they have the characteristics of a dissipative system in a critical state.展开更多
基金funding for this project was provided by the National Natural Science Foundation of China (No.41976049)。
文摘In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-induced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and ^(210)Pb_(ex) specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in particle size and ^(210)Pb_(ex) specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data.
基金The National Natural Science Foundation of China under contract No.41206058the National Science and Technology Major Project of China under contract No.2011ZX05056-001-02the Scientific Research Fund of the First Institute of Oceanography,State Oceanic Administration under contract No.GY0213G25
文摘A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures would happen, and the following mass movement would present great risk to the submarine pipeline. In view of this, a numerical prediction method based on Eulerian-Eulerian two-phase flow model is introduced to simulate the mass movement of potential submarine landslides. The sliding soil and ambient water are respectively simulated by Herschel-Bulkley rheology model and Newtonian fluid model. The turbulence is simulated using the k-e model. Compared with both the experiment data and Bing result, the two-phase flow model shows a good accuracy, and its result is more close to the actual situation; the dynamic coupling between soil and ambient water can be effectively simulated and the phenomena of hydroplaning and head detachment can be obtained. Finally, the soil movement of a potential submarine landslide is simulated as an example, according to the seismic profile in the canyon area. The result shows that the hydroplaning occurs during the movement process. The runout distance calculated by the two-phase flow model is 877 m, which is 27.1% larger than the Bing result. However, the peak front velocity of soil is relative small, with a maximum value of 8.32 m/s. The Bing program with a simple and rapid process can be used for a preliminary evaluation, while the two-phase flow model is more appropriate for an accurate assessment.
基金financially supported by the National Natural Science Foundation of China(Grant No.41006024)Marine Specific Research for Public‘Forecast and appraisal for geologic hazard of inshore seafloor and study of key technology for protection’(Grant No.201005005)
文摘The safety of submarine pipelines is largely influenced by free spans and corrosions. Previous studies on free spans caused by seabed scours are mainly based on the stable environment, where the background seabed scour is in equilibrium and the soil is homogeneous. To study the effects of background erosion on the free span development of subsea pipelines, a submarine pipe- line located at the abandoned Yellow River subaqueous delta lobe was investigated with an integrated surveying system which in- eluded a Multibeam bathymetric system, a dual-frequency side-scan sonar, a high resolution sub-bottom profiler, and a Magnetic Flux Leakage （MFL） sensor. We found that seabed homogeneity has a great influence on the free span development of the pipeline. More specifically, for homogeneous background scours, the morphology of scour hole below the pipeline is quite similar to that without the background scour, whereas for inhomogeneous background scour, the nature of spanning is mainly dependent on the evolution of seabed morphology near the pipeline. Magnetic Flux Leakage （MFL） detection results also reveal the possible connec- tion between long free spans and accelerated corrosion of the pipeline.
基金supported by National Natural Science Foundation of China(No.11275200)
文摘Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm2 to 6 A/cm2 in pulsed mode within pulse length 5-20 ms. A 10 cm diameter, 2 m long plasma column with density 10is m-3 to 1019 m3 and electron temperature Te --~ 3-7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.
基金funded by the National Science Foundation of China (NSFC) (Nos.40506018, 40576033,40421150011, 40706038 and 40606026)the Ministry of Science and Technology of China (No. 2003cb716706)the Open Research Foundation of State Key Labora-tory of Geohazard Prevention and Geoenvironment Pro-tection (No. GZ2006-01)
文摘This paper investigates the size distribution of submarine landslides on the middle continental slope of the East China Sea (ECS) using the size of the landslide source regions. Geomorphometric mapping is used to identify 102 mass movements from multibeam bathymetric data and to extract morphological information about the head scarps and side walls. These mass movements have areas ranging between 0.06 km2 and 15.51 km2 and volumes between 0.002 km3 and 2 km3. The area vs volume relationship of these failure scarps is approximately linear, suggesting a fairly uniform failure thickness in each event with scarce deep excavating landslides. The cumulative area distribution of the slope failures can be described by an inverse power law. The submarine landslides on the mid-ECS continental slope could be considered as a large-scale self-organizing system because they have the characteristics of a dissipative system in a critical state.
