scholarly journals On some methods of researching the structural, physical and mechanical parameters of granular media as applied to the modeling of rock dumps

2021 ◽  
Vol 303 ◽  
pp. 01030
Author(s):  
Vyacheslav Gogolin ◽  
Yury Lesin ◽  
Ivan Košč
Keyword(s):  
Particle Size ◽  
Granular Media ◽  
Pore Space ◽  
Load Capacity ◽  
Mechanical Parameters ◽  
Mineral Phase ◽  
Mining Operations ◽  
Modern Methods ◽  
Applied Stresses ◽  
Packing Method

The physical properties of the artificial disjointed rock massifs (the filling massifs and arrays of collapsed rocks and dumps) formed during mining operations, are largely determined by the geometry of the structure of pore space and the mineral phase, i.e. particle size, shape and packing method. In this case, the conditions for the arrangement of the particles relative to each other (the distances between the centers of the particles, the orientation, the number of contacts, the angles between the segments connecting the particle centers, etc.) have a decisive influence on the macroscopic characteristics of the rock mass (specific surface, bulk density, load capacity, etc.) and the behavior of such media under the applied stresses. Thus, in order to manage the state of disjointed technogenic rock massifs of bedrock, the question of applying modern methods for modeling bulk media for determining these parameters is considered. The article provides an overview of methods for modeling granular media to determine their structural, physical and mechanical parameters.

scholarly journals Waterfall Algorithm as a tool of investigation the geometrical features of granular porous media

2021 ◽  
Author(s):  
Wojciech Sobieski
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Lattice Boltzmann ◽  
Granular Media ◽  
Density Ratio ◽  
Geometrical Features ◽  
Granular Porous Media ◽  
Collision Density ◽  
Boltzmann Method ◽  
The Impact

AbstractThe paper describes the so-called Waterfall Algorithm, which may be used to calculate a set of parameters characterising the spatial structure of granular porous media, such as shift ratio, collision density ratio, consolidation ratio, path length and minimum tortuosity. The study is performed for 1800 different two-dimensional random pore structures. In each geometry, 100 individual paths are calculated. The impact of porosity and the particle size on the above-mentioned parameters is investigated. It was stated in the paper, that the minimum tortuosity calculated by the Waterfall Algorithm cannot be used directly as a representative tortuosity of pore channels in the Kozeny or the Carman meaning. However, it may be used indirect by making the assumption that a unambiguous relationship between the representative tortuosity and the minimum tortuosity exists. It was also stated, that the new parameters defined in the present study are sensitive on the porosity and the particle size and may be therefore applied as indicators of the geometry structure of granular media. The Waterfall Algorithm is compared with other methods of determining the tortuosity: A-Star Algorithm, Path Searching Algorithm, Random Walk technique, Path Tracking Method and the methodology of calculating the hydraulic tortuosity based on the Lattice Boltzmann Method. A very short calculation time is the main advantage of the Waterfall Algorithm, what meant, that it may be applied in a very large granular porous media.

scholarly journals Influence of Particle and Grain Size on Sand Filtration: Effect on Head Loss and Turbidity

2020 ◽  
Vol 8 (2) ◽  
pp. 36
Author(s):  
Racha Medjda Bouchenak Khelladi ◽  
Abdelghani Chiboub Fellah ◽  
Maxime Pontié ◽  
Fatima Zohra Guellil
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Granular Media ◽  
Particle Concentration ◽  
Head Loss ◽  
Sand Filtration ◽  
Circular Column ◽  
Filter Performance ◽  
Filter Operation ◽  
Suspended Matters

Sand filtration is an eco-friendly method to treat either drinking water or wastewater ; it requires only natural granular media. It is also easy to use and to maintain ; the only problem they face is clogging that affects filter performance, that can be detected when head loss or turbidity increase. The purpose of this work is to see what are the factors that influence the performance of filter operation, for this, we used a pilot consisting on a circular column filled with sand (from South Algeria), where various parameters were tested; pressure, flow rate, sand granulometry, suspended matters and particle concentration of the water which is filtered. After eighteen weeks of operation, we have found that head loss increases by decreasing granulometry and increasing flow rate, pressure, particle size, and concentration. However, turbidity increases by decreasing particle size and increasing granulometry and particle concentration. Turbidity and head loss have different behaviour towards the same parameter; that is why it is necessary to take them into account in order to find a compromise between acceptable head loss / turbidity for a good functioning of the filter.

scholarly journals On the Information Content of Coarse Data with Respect to the Particle Size Distribution of Complex Granular Media: Rationale Approach and Testing

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 601 ◽  
Author(s):  
Carlos García-Gutiérrez ◽  
Miguel Ángel Martín ◽  
Yakov Pachepsky
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Information Content ◽  
Granular Media ◽  
Initial Conditions ◽  
Physical Property ◽  
Conceptual Approach ◽  
Grain Sizes ◽  
Andersen Model

The particle size distribution (PSD) of complex granular media is seen as a mathematical measure supported in the interval of grain sizes. A physical property characterizing granular products used in the Andreasen and Andersen model of 1930 is re-interpreted in Information Entropy terms leading to a differential information equation as a conceptual approach for the PSD. Under this approach, measured data which give a coarse description of the distribution may be seen as initial conditions for the proposed equation. A solution of the equation agrees with a selfsimilar measure directly postulated as a PSD model by Martín and Taguas almost 80 years later, thus both models appear to be linked. A variant of this last model, together with detailed soil PSD data of 70 soils are used to study the information content of limited experimental data formed by triplets and its ability in the PSD reconstruction. Results indicate that the information contained in certain soil triplets is sufficient to rebuild the whole PSD: for each soil sample tested there is always at least a triplet that contains enough information to simulate the whole distribution.

Comparison of the μ(I) and HBP models for simulating granular media

2018 ◽  
Vol 29 (07) ◽  
pp. 1850050 ◽  
Author(s):  
Mehran Kheirkhahan ◽  
Khosrow Hosseini
Keyword(s):  
Friction Coefficient ◽  
Failure Mode ◽  
Granular Flow ◽  
Granular Media ◽  
State Equation ◽  
Dam Break ◽  
Harmonic Mean ◽  
Height Ratio ◽  
Viscoplastic Models ◽  
Applied Stresses

Application of Lagrangian meshless methods in modeling granular flow has been a major concern for researchers due to their particular nature. For modeling granular movement, it is assumed that the particles are continuous. The SPHysics code is developed for modeling the movement of Newtonian fluids in which the pressure is derived from the state equation. In this study, [Formula: see text] and Herschel–Bulkley–Papanastasiou (HBP) viscoplastic models are implemented in the SPHysics code to analyze the movement of grains induced by the applied stresses. In the first model, the movement of granular particles is based on the characteristics such as inertia and friction coefficient, and in the second model, the movement is related to the non-Newtonian viscoplastic behavior of fluids. The accuracy of the models is evaluated by simulating the experimental benchmarks for granular dam break. The effect of length-to-height ratio on the failure mode of dam break phenomenon is also investigated. The performance of the models is increased by introducing the gate removal speed and also the harmonic mean of the viscosity instead of the viscosity proper to each particle. This study shows that the models could capture the behavior of grains in the static and the dynamic parts of the mass body.

Particle Size Effects on the Strength and Fabric of Granular Media

2020 ◽  
Author(s):  
Kevin C. Kuei ◽  
Jason T. DeJong ◽  
Alejandro Martinez
Keyword(s):  
Particle Size ◽  
Size Effects ◽  
Granular Media ◽  
Particle Size Effects

Predicting water retention curves of fine texture soils from particle size distribution

2020 ◽  
Author(s):  
Joseph Pollacco ◽  
Jesús Fernández-Gálvez ◽  
Sam Carrick
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Pore Space ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
Retention Curve ◽  
Soil Particles

<p>Indirect methods for estimating soil hydraulic properties from particle size distribution have been developed due to the difficulty in accurately determining soil hydraulic properties, and the fact that particle size distribution is one piece of basic soil physical information normally available. The similarity of the functions describing the cumulative distribution of particle size and pore size in the soil has been the basis for relating particle size distribution and the water retention function in the soil. Empirical and semi-physical models have been proposed, but these are based on strong assumptions that are not always valid. For example, soil particles are normally assumed to be spherical, with constant density regardless of their size; and the soil pore space has been described by an assembly of capillary tubes, or the pore space in the soil matrix is assumed to be arranged in a similar way regardless of particle size. However, in a natural soil the geometry of the pores may vary with the size of the particles, leading to a variable relation between particle radius and pore radius.</p><p> </p><p>The current work is based on the hypothesis that the geometry of the pore size and the void ratio depends on the size of the soil particles, and that a physically based model can be generalised to predict the water retention curve from particle size distribution. The rearrangement of the soil particles is considered by introducing a mixing function that modulates the cumulative particle size distribution, while the total porosity is constrained by the saturated water content.</p><p> </p><p>The model performance is evaluated by comparing the soil water retention curve derived from laboratory measurements with a mean Nash–Sutcliffe model efficiency a value of 0.92 and a standard deviation of 0.08. The model is valid for all soil types, not just those with a marginal clay fraction.</p>

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