scholarly journals Vacuum Preconsolidation Settlement Characteristics and Microstructural Evolution of Marine Dredger-Filled Silt

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Keping Chen ◽  
Xinkai Ren ◽  
Yong He ◽  
Muyuan Gan ◽  
Danwei Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Levels ◽  
Equivalent Diameter ◽  
Vacuum Preloading ◽  
Element Analysis ◽  
Scanning Electron

The method of vacuum preloading for foundation treatments is used in the construction of the Fangchenggang coastal area in Guangxi province, China. The thick marine dredger-filled silt has a considerable impact on the treatment effort. In this study, the mineral composition and grain size distribution of these silts were analyzed to investigate their consolidation settlement property and microstructures. The scanning electron microscope and finite element method were adopted. The results reveal that the dredger-filled silt in this area is composed mainly of sand with particle size mostly smaller than 0.075 mm. To replicate the construction process, the process of drainage by the vacuum preloading method was simulated by setting different water levels in the finite element analysis. The displacement and the dissipation of the pore water pressure obtained by simulations were reasonably consistent with the field monitoring data. In addition, the results obtained using the scanning electron microscope indicate that the equivalent diameter of the structural unit and that of the pore unit decrease with the silt depth. However, the value of the structural abundance approaches one, whereas the pore abundance is significantly different from one.

Design and fabrication of a scanning electron microscope using a finite element analysis for electron optical system

2008 ◽  
Vol 22 (9) ◽  
pp. 1734-1746 ◽  
Author(s):  
Man-Jin Park ◽  
Dong Hwan Kim ◽  
Keun Park ◽  
Dong Young Jang ◽  
Dong-Chul Han
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Optical System ◽  
Electron Optical System ◽  
Element Analysis ◽  
Scanning Electron

A Study on the Effects of Covered Stents on Tissue Prolapse

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Jason D. Weaver ◽  
D. N. Ku
Keyword(s):  
Finite Element ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Wall Stress ◽  
Environmental Scanning Electron Microscope ◽  
Environmental Scanning ◽  
Covered Stents ◽  
Artery Wall ◽  
Element Analysis ◽  
Scanning Electron

Polyvinyl alcohol (PVA) cryogel covered stents may reduce complications from thrombosis and restenosis by decreasing tissue prolapse. Finite element analysis was employed to evaluate the effects of PVA cryogel layers of varying thickness on tissue prolapse and artery wall stress for two common stent geometries and two vessel diameters. Additionally, several PVA cryogel covered stents were fabricated and imaged with an environmental scanning electron microscope. Finite element results showed that covered stents reduced tissue prolapse up to 13% and artery wall stress up to 29% with the size of the reduction depending on the stent geometry, vessel diameter, and PVA cryogel layer thickness. Environmental scanning electron microscope images of expanded covered stents showed the PVA cryogel to completely cover the area between struts without gaps or tears. Overall, this work provides both computational and experimental evidence for the use of PVA cryogels in covered stents.

Otospongiosis: Morphologic and Microchemical Investigation after Naf-Treatment

1981 ◽  
Vol 89 (4) ◽  
pp. 646-650 ◽  
Author(s):  
Paul Bretlau ◽  
Hans Jørgen Hansen ◽  
Jean Causse ◽  
Jean-Bernard Causse
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sodium Fluoride ◽  
Energy Dispersive ◽  
Blind Study ◽  
Element Analysis ◽  
X Ray ◽  
Scanning Electron

Element analysis of microareas of otospongiotic specimens is described. A total of 36 otospongiotic stapes are ultrasectioned without decalcification and examined using a transmission and a scanning electron microscope (STEM-mode). The latter was equipped with an energy dispersive x-ray analyzer. Twenty of the stapes came from patients who have had sodium fluoride (NaF) treatment (15 to 45 mg/day) for a minimum of 12 months. The otospongiotic stapes are classified as spongiotic and sclerotic according to their pathologic characteristics and state of mineralization. Using the Ca/P ratio as criterion—measured by the characteristic x-ray fluorescence—it was shown in a blind study that the NaF-treated otospongiotic stapes had a statistically higher Ca/P ratio, indicating that the fluoride may stabilize otospongiotic lesions, particularly the spongiotic type with unstable mineralization.

Finite-element analysis of deep excavation in layered sandy and clayey soil deposits

1994 ◽  
Vol 31 (2) ◽  
pp. 204-214 ◽  
Author(s):  
Chang-Yu Ou ◽  
Ching-Her Lai
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Clayey Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Deep Excavation ◽  
Element Analysis ◽  
Modified Cam Clay ◽  
Soil Deposits ◽  
Cam Clay

This paper presents an application of finite-element analysis to deep excavation in layered sandy and clayey soil deposits using a combination of the hyperbolic and the Modified Cam-clay models. In the analysis, the drained behavior of cohesionless soil and the undrained behavior of cohesive soil were simulated using the hyperbolic and Modified Cam-clay models, respectively. A rational procedure for determining soil parameters for each of the models was established. A simulation of the dewatering process during excavation was proposed. The analytical procedure was confirmed through an analysis of three actual excavation cases. Finally, analyses considering pore-water pressure dissipation during the actual elapsed time for each construction phase were carried out. The results indicate that the calculated displacement of a retaining wall during excavation is smaller than that given by undrained analysis. It was thought that some degree of pore-water pressure dissipation actually occurs during the intermediate excavation stages. This results in a decrease in the final deformation of the wall and ground.-surface settlement than would be predicted by undrained analysis. Key words : finite-element analysis, deep excavation, hyperbolic model, Cam-clay model.

The Finite-Element Analysis of Characteristics of Soil Slope Seepage Field Change in Rainstorm Condition

2012 ◽  
Vol 204-208 ◽  
pp. 50-53
Author(s):  
Zhong Ming He ◽  
Wei Wu ◽  
Ling Zeng ◽  
Zhong Xin Cai
Keyword(s):  
Finite Element ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Element Analysis ◽  
Finite Element Software ◽  
The Finite Element Analysis ◽  
Pressure Region ◽  
Pressure Area ◽  
Depth Of Infiltration

A numerical model was built by Finite Element software,discussed the effect of rainfall on slope pore water pressure、volatile water content and depth of infiltration in rainstorm condition. The results indicated that: (1)the variation of slope surface pore water pressure is more significant and the depth of infiltration is larger with the increase of rainfall intensity on the condition of fixed rainfall duration;(2)The slope section appears three pore water pressure divisions: transient saturated zone、negative pressure region and hydrostatic pressure area after the rainfall.

The Finite-Element Analysis of Characteristics of Soil Slopeseepage Field Change in Continuous Rain Condition

2012 ◽  
Vol 238 ◽  
pp. 451-454
Author(s):  
Zhong Ming He ◽  
Wei Wu ◽  
Ling Zeng ◽  
Zhong Xin Cai
Keyword(s):  
Finite Element ◽  
Ground Water ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Element Analysis ◽  
Finite Element Software ◽  
The Finite Element Analysis ◽  
Pressure Area ◽  
Depth Of Infiltration

A numerical model is built by Finite Element Software, discussed the effect of rainfall on slope pore water pressure, volatile water content and depth of infiltration in continuous rain condition. The result indicated that when the rainfall intensity and rainfall duration reach a certain condition, the ground water table rises slowly, and mostly, the spill points of ground water locate in the foot of slope. The slope section appears three pore water pressure divisions: transient saturated zone, negative pressure region and hydrostatic pressure area after the rain.

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