scholarly journals The Effect of Particle Size Distribution And Shape On The Microscopic Behaviors of Loess Via DEM

2021 ◽  
Author(s):  
Xi-An Li ◽  
Jianqiang Sun ◽  
Hongyu Ren ◽  
Tuo Lu ◽  
Yongbiao Ren ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Contact Force ◽  
Engineering Properties ◽  
Dry Density ◽  
Normal Contact ◽  
Clay Particles ◽  
Normal Contact Force ◽  
Sand Particles

Abstract Loess has loose metastable structure, which is not difficult to be destroyed under load. As the core and soul of loess structure, it is part of the main research directions of loess engineering properties at present to study its microscopic behaviors and then realize the interpretation and prediction of macroscopic mechanical properties. In this study, based on the analysis of the basic physical properties of loess samples from seven different places, each sample was scanned by X-ray with continuous slice CT, and the three-dimensional microstructure of loess samples was established. According to the computer graphics method, each particle is equivalent to an ellipsoid, and the flattening rate and elongation rate of particles in each sample are quantitatively counted. Taking the particle size distribution (PSD) and shape parameters (flatness and elongation) of each sample as the control factors for generating discrete element method (DEM) samples, a series of triaxial compression simulation tests were carried out, and the microscopic behaviors of each sample were studied within the whole test framework. Comparing the results of seven different samples, it is shown that both PSD and particle shape have effects on stress-strain relationship, dry density and the normal contact force of loess samples. Most of the sand particles (> 0.075mm) are flat particles, while the clay particles (< 0.005mm) are mainly near spheres. When the volume fraction of sand particles is large, the dry density of the sample is the lowest. However, when the content of near spherical clay particles is large and the particle size distribution is good, and the average coordination value is large, which shows that it has strong normal contact force, and thus higher shear strength.

Removal of clay and blue-green algae particles through zeta potential and particle size distribution in the dissolved air flotation process

2006 ◽  
Vol 6 (1) ◽  
pp. 95-103 ◽  
Author(s):  
D.H. Kwak ◽  
S.J. Kim ◽  
H.J. Jung ◽  
C.H. Won ◽  
S.B. Kwon ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Green Algae ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Clay Particles ◽  
Blue Green Algae ◽  
Dissolved Air

The raw water characteristics of a water treatment plant in Korea are mainly dependent on two major factors: the clay particles attributed to rainfall and blue-green algae in reservoirs. In this work, zeta potential and particle size distributions of clay and algae particles, which are the important parameters affecting their removal efficiency, were measured to investigate the behavior and removal characteristics of particles under various conditions. The results showed that the zeta potential of blue-green algae was more sensitive to treatment conditions than clay, and it fluctuated highly with coagulant dosage, suggesting that the control of zeta potential is important for effective removal of algae particles. On the other hand, the range of particle size distribution that remained from the preliminary sedimentation tank was generally smaller than for flotation. However, the zeta potential of the remaining particles was either close to the isoelectric point or positive, and the particles were not so hard to remove for that reason. In the final analysis, for simultaneous removal of clay and algae particles, a sufficient zeta potential difference must be formed not only for algae particles but also for small clay particles from the sedimentation tank in the dissolved air flotation process.

Particle damage observed in ring shear tests on sands

2010 ◽  
Vol 47 (5) ◽  
pp. 497-515 ◽  
Author(s):  
Abouzar Sadrekarimi ◽  
Scott M. Olson
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Normal Stress ◽  
Size Distribution ◽  
Constant Volume ◽  
Engineering Properties ◽  
Shear Tests ◽  
Ring Shear ◽  
Particle Damage ◽  
Ring Shear Tests

In this paper, particle damage of three test sands with different mineralogical compositions is studied using stress–displacement response measured in ring shear tests, particle-size distributions of the original sand prior to shear and from the shear band after shear, and by examining particle shape changes determined by scanning electron microscope. Particle damage during shearing produced a wider particle-size distribution, and damage typically continued until the normal stress was small (about 28 kPa) in constant volume ring shear tests and the internal stresses were distributed among sufficient particle contacts such that damage practically ceased. The dominant damage mechanism (typically either particle abrasion and shearing-off asperities or particle splitting) depended strongly on the soil response (i.e., contraction or dilation), particle hardness, and particle-size distribution, but both mechanisms produced particles that were more angular and rougher than the original sand particles. The magnitude of particle damage observed in the ring shear tests was influenced by the consolidation normal stress, shear displacement, particle mineralogy, particle-size distribution, drainage conditions, and soil fabric (in constant volume tests). Lastly, the influence of particle damage on engineering properties including hydraulic conductivity, liquefaction resistance, stress–strain response, friction angle, and critical state are briefly discussed.

Size Reduction of Clay Particles in Nanometer Dimensions

2002 ◽  
Vol 740 ◽  
Author(s):  
Gopinath Mani ◽  
Qinguo Fan ◽  
Samuel C. Ugbolue ◽  
Isabelle M. Eiff
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Size Distribution ◽  
Research Work ◽  
Particle Size Analysis ◽  
Laser Diffraction ◽  
Size Analysis ◽  
Clay Particles ◽  
Nano Size

ABSTRACTThis research work focuses on combining ball milling and ultrasonication to produce nano-size clay particles. Our work also emphasizes on increasing the specific surface area of montmorillonite clay particles by reducing the particle size to nanometer dimensions. We have characterized the as-received clay particles by using particle size analysis based on laser diffraction and found that the size of the clay particles is not consistent and the particle size distribution is very broad. However, after the unique treatment and processing, the clay particles were obtained in nanometer dimensions with narrowed particle size distribution.

Engineering Properties of Soils as Related to Mineralogy and Particle-Size Distribution

1984 ◽  
Vol 48 (5) ◽  
pp. 978-982 ◽  
Author(s):  
W. G. Harris ◽  
L. W. Zelazny ◽  
J. C. Parker ◽  
J. C. Baker ◽  
R. S. Weber ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Engineering Properties

scholarly journals Characterization of the Relationship between the Loess Moisture and Image Grayscale Value

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7983
Author(s):  
Qingbing Liu ◽  
Jinge Wang ◽  
Hongwei Zheng ◽  
Tie Hu ◽  
Jie Zheng
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Water Content ◽  
Size Distribution ◽  
Dry Density ◽  
Model Parameters ◽  
Light Reflection ◽  
Rate Of Increase ◽  
Three Stages ◽  
The Relationship

This paper presents a model for estimating the moisture of loess from an image grayscale value. A series of well-controlled air-dry tests were performed on saturated Malan loess, and the moisture content of the loess sample during the desiccation process was automatically recorded while the soil images were continually captured using a photogrammetric device equipped with a CMOS image sensor. By converting the red, green, and blue (RGB) image into a grayscale one, the relationship between the water content and grayscale value, referred to as the water content–gray value characteristic curve (WGCC), was obtained; the impacts of dry density, particle size distribution, and illuminance on WGCC were investigated. It is shown that the grayscale value increases as the water content decreases; based on the rate of increase of grayscale value, the WGCC can be segmented into three stages: slow-rise, rapid-rise, and asymptotically stable stages. The influences that dry density and particle size distribution have on WGCC are dependent on light reflection and transmission, and this dependence is closely related to soil water types and their relative proportion. Besides, the WGCC for a given soil sample is unique if normalized with illuminance. The mechanism behind the three stages of WGCC is discussed in terms of visible light reflection. A mathematical model was proposed to describe WGCC, and the physical meaning of the model parameters was interpreted. The proposed model is validated independently using another six different types of loess samples and is shown to match well the experimental data. The results of this study can provide a reference for the development of non-contact soil moisture monitoring methods as well as relevant sensors and instruments.

scholarly journals Functional Relationships Between the Content of Particles Smaller than 0.05 mm. and 0.002 mm. in Size, and the Plasticity Index of Soils

1969 ◽  
Vol 52 (4) ◽  
pp. 343-350
Author(s):  
M. A. Lugo López ◽  
Raúl Pérez Escolar
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Plasticity Index ◽  
Engineering Properties ◽  
Mathematical Approach ◽  
Functional Relationships ◽  
Laborious Work ◽  
Fair Degree

A mathematical approach is presented herein to determine the plasticity index of soils on the basis of the percentage of particles smaller than 0.05 mm in size. The particle-size distribution can be determined easily and quickly, and then, with a few calculations, the plasticity index can be estimated with fair degree of precision. The laboratory determination of plasticity index requires more laborious work. The equation developed is exponential, as follows:Plasticity index = —0.052394 + 3.1538e0.029284X, where e= 2.71828 and X is the percentage of particles smaller than 0.05 mm. in size.The correlation coefficient obtained was on the order of 0.92. On the basis of the percentage of particles smaller than 0.05 mm., about 85 percent of the variability of the plasticity index values was explained. The plasticity index is one of the more useful engineering properties of soils.

scholarly journals Change of physical properties of southern carbonate chernozems at various cultivation systems in Northern Kazakhstan

2016 ◽  
Vol 5 (4) ◽  
pp. 10-13
Author(s):  
Nikolay Ivanovich Vasilchenko ◽  
Grigoriy Aleksandrovich Zvyagin
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Physical Properties ◽  
Size Distribution ◽  
Heavy Particle ◽  
Physical Clay ◽  
Clay Particles ◽  
Cultivation Systems ◽  
Northern Kazakhstan ◽  
Contradictory Data

Contradictory data about impact of the minimum and zero cultivation on physical properties of southern chernozems (Chernozem) of heavy particle size distribution have caused the necessity of their studying on the territory of Akmola region. Researches of physical properties of southern carbonate chernozems were conducted based on comparison of soils physical properties the virgin site with pilot allotments of deep and minimum cultivation of land, direct crops and zero technology. Reduction of content physical clay particles and silt in comparison with the virgin site revealed in the upper layer of 0-10 cm in case of all above-stated handlings. Mechanized conversions cause the activation of profile differentiation with regard to silty fraction. Descending migration from the arable horizon to subarable horizon happens in case of deep cultivation of land. This migration from layer of 0-10 cm to underlying arable layer of 10-26 cm happens in case of minimum and zero cultivation of land. The greatest deterioration in addition density of plougland in a layer of 0-10, 10-20 and 20-30 cm observe in case of the minimum and zero cultivation of land.

Influence of the Sand Particle Shape on Particle Size Distribution Measured by Laser Diffraction Method

2014 ◽  
Vol 28 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Cezary Polakowski ◽  
Agata Sochan ◽  
Andrzej Bieganowski ◽  
Magdalena Ryzak ◽  
Rita Földényi ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Shape ◽  
Diffraction Method ◽  
Laser Diffraction ◽  
Soil Science ◽  
Sand Particle ◽  
Sand Fraction ◽  
Sand Particles

Abstract The aim of this paper was to show how the shape of sand particles affects the results of particle size distribution obtained by the laser diffraction method. On the basis of the results obtained one can conclude: the shape of the investigated particles influences particle size distribution obtained by the laser diffraction method. This phenomenon occurs in the sand fraction, as shown in our investigation. The importance of this effect depends on the type of the measured material and on the aim of the investigations. For most researchers in soil science and sedimentology who investigate sand fractions, this impact can be negligible. Further investigations with other soil and sediment fractions are needed.

scholarly journals Influence of particle grading on the hygromechanical properties of hypercompacted earth

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Alessia Cuccurullo ◽  
Domenico Gallipoli ◽  
Agostino Walter Bruno ◽  
Charles Augarde ◽  
Paul Hughes ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Building Materials ◽  
Dry Density ◽  
Moisture Capacity ◽  
Engineering Research ◽  
Water Durability ◽  
Building Practice ◽  
Energy Efficient Building

AbstractCivil engineering research is increasingly focusing on the development of sustainable and energy-efficient building materials. Among these materials, raw (unfired) earth constitutes a promising option for reducing the environmental impact of buildings over their entire service life from construction to demolition. Raw earth has been used since old times but only recently has acquired prominence in mainstream building practice. This is mainly because of the development of novel methods to enhance the mechanical, hygroscopic and durability properties of compacted earth without increasing carbon and energy footprints. In this context, the present paper studies the dependency of the strength, stiffness, moisture capacity and water durability of compacted earth on particle grading. Results indicate that the particle size distribution is a key variable in defining the hygromechanical characteristics of compacted earth. The effect of the particle size distribution on the hygromechanical properties of compacted earth may be as important as that of dry density or stabilisation. This study suggests that a fine and well-graded earth mix exhibits higher levels of strength, stiffness, moisture capacity and water durability than a coarse and poorly-graded one.

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