Element analysis of consolidation of soil under surcharge and vacuum preloading

2012 ◽  
pp. 531-535
Author(s):  
Xiaowu Shu ◽  
Bingchuan Guo ◽  
Xiaoxian Song
Keyword(s):  
Vacuum Preloading ◽  
Element Analysis

scholarly journals Analytical and numerical solutions for a single vertical drain including the effects of vacuum preloading

2005 ◽  
Vol 42 (4) ◽  
pp. 994-1014 ◽  
Author(s):  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn ◽  
Iyathurai Sathananthan
Keyword(s):  
Finite Element ◽  
Plane Strain ◽  
Numerical Solutions ◽  
Soft Clay ◽  
Vacuum Pressure ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Vacuum Preloading ◽  
Element Analysis ◽  
Vertical Drains

A system of vertical drains combined with vacuum preloading is an effective method to accelerate soil consolidation by promoting radial flow. This study presents the analytical modeling of vertical drains incorporating vacuum preloading in both axisymmetric and plane strain conditions. The effectiveness of the applied vacuum pressure along the drain length is considered. The exact solutions applied on the basis of the unit cell theory are supported by finite element analysis using ABAQUS software. Subsequently, the details of an appropriate matching procedure by transforming permeability and vacuum pressure between axisymmetric and equivalent plane strain conditions are described through analytical and numerical schemes. The effects of the magnitude and distribution of vacuum pressure on soft clay consolidation are examined through average excess pore pressure, consolidation settlement, and time analyses. Lastly, the practical implications of this study are discussed.Key words: consolidation, finite element method, soft clay, vacuum preloading, vertical drains.

Effect of Variable Permeability Coefficient on Consolidation of Ultra-Soft Ground under Vacuum Preloading

2014 ◽  
Vol 580-583 ◽  
pp. 56-60
Author(s):  
Bin Bin Xu ◽  
Ai Hua Liang ◽  
Ming Ying Li
Keyword(s):  
Finite Element Analysis ◽  
Permeability Coefficient ◽  
Soft Ground ◽  
Vacuum Preloading ◽  
Element Analysis ◽  
Variable Permeability ◽  
Significant Acceleration ◽  
Good Accordance ◽  
Macro Element ◽  
Cam Clay

In this paper, a soil-water coupled finite element analysis incorporated the macro-element method is carried out to investigate the effect of variable permeability coefficient on the consolidation of the ultra-soft ground using vacuum preloading. Sys cam-clay model is employed as the constitutive model of the ultra-soft soils. When the drain space becomes from 60cm to 40cm, there is significant acceleration in the numerical settlement of the ground using the constant permeability coefficient, which is quite different from the observational results. When the variable permeability coefficient where a liner relationship between the void and the logarithmic value of permeability coefficient is adopted is employed, there is a good accordance between the numerical and observational settlements. According to the distribution of variation in the void, the largest variation in the void occurs at the top several layers and therefore the predominant settlement can be attributed to the volumetric compression of the top several layers.

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.

Computer programs for the calculation of x-ray intensities emitted by elements in multi-layer structures

1990 ◽  
Vol 48 (2) ◽  
pp. 216-217
Author(s):  
G.F. Bastin ◽  
H.J.M. Heijligers ◽  
J.M. Dijkstra
Keyword(s):  
Software Package ◽  
Light Element ◽  
Matrix Correction ◽  
Excellent Performance ◽  
Element Analysis ◽  
X Ray ◽  
Know How ◽  
Accurate Knowledge ◽  
Layer Structures ◽  
Bulk Matrix

For the calculation of X-ray intensities emitted by elements present in multi-layer systems it is vital to have an accurate knowledge of the x-ray ionization vs. mass-depth (ϕ(ρz)) curves as a function of accelerating voltage and atomic number of films and substrate. Once this knowledge is available the way is open to the analysis of thin films in which both the thicknesses as well as the compositions can usually be determined simultaneously.Our bulk matrix correction “PROZA” with its proven excellent performance for a wide variety of applications (e.g., ultra-light element analysis, extremes in accelerating voltage) has been used as the basis for the development of the software package discussed here. The PROZA program is based on our own modifications of the surface-centred Gaussian ϕ(ρz) model, originally introduced by Packwood and Brown. For its extension towards thin film applications it is required to know how the 4 Gaussian parameters α, β, γ and ϕ(o) for each element in each of the films are affected by the film thickness and the presence of other layers and the substrate.

An improved interference correction for trace element analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1646-1647
Author(s):  
John J. Donovan ◽  
Donald A. Snyder ◽  
Mark L. Rivers
Keyword(s):  
Trace Element Analysis ◽  
Accurate Estimate ◽  
Simple Expression ◽  
Standard Reference Materials ◽  
Characteristic Line ◽  
Analytical Line ◽  
Element Analysis ◽  
Electron Probe Analysis ◽  
Calculated Concentration ◽  
X Ray

We present a simple expression for the quantitative treatment of interference corrections in x-ray analysis. WDS electron probe analysis of standard reference materials illustrate the success of the technique.For the analytical line of wavelength λ of any element A which lies near or on any characteristic line of another element B, the observed x-ray counts at We use to denote x-ray counts excited by element i in matrix j (u=unknown; s=analytical standard; ŝ=interference standard) at the wavelength of the analytical line of A, λA (Fig. 1). Quantitative analysis of A requires an accurate estimate of These counts can be estimated from the ZAF calculated concentration of B in the unknown C,Bu measured counts at λA in an interference standard of known concentration of B (and containing no A), and ZAF correction parameters for the matrices of both the unknown and the interference standard at It can be shown that:

The Influence of Specimen Thickness in Quantitative Electron Energy Loss Spectroscopy

1980 ◽  
Vol 38 ◽  
pp. 112-113
Author(s):  
Nestor J. Zaluzec
Keyword(s):  
Quantitative Analysis ◽  
Adverse Effects ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Light Element ◽  
Specimen Thickness ◽  
Element Analysis ◽  
Electron Energy Loss

The application of electron energy loss spectroscopy (EELS) to light element analysis is rapidly becoming an important aspect of the microcharacterization of solids in materials science, however relatively stringent requirements exist on the specimen thickness under which one can obtain EELS data due to the adverse effects of multiple inelastic scattering.1,2 This study was initiated to determine the limitations on quantitative analysis of EELS data due to specimen thickness.

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