Experimental Study on the Effects of Internal Erosion on the Physical and Mechanical Properties of Tailings Under Unsteady Seepage

2021 ◽  
Author(s):  
Rong Gui ◽  
Guicheng He
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Shear Strength ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Internal Erosion ◽  
Average Particle ◽  
Sand Column ◽  
Sedimentary Characteristics ◽  
Seepage Erosion

Abstract In this paper, the hydraulic sedimentary model was established to investigate the effects of dry beach slope on the sedimentary characteristics of tailings, and the sand column model was built to investigate the effects of seepage erosion on the physical and mechanical properties of sedimentary tailings under unsteady seepage.The results show that the slope of dry beach have a great effect on the sedimentary characteristics of tailings, the average particle size of tailings decreases along the slope of dry beach, and the larger the slope, the more obvious the stratification of the tailings. The migration of fine-grained tailings caused by seepage erosion increases the permeability of the tailings and reduces the shear strength of the tailings. After seepage erosion,the average particle size of 1#tailings sample, 2#tailings sample and 3#tailings sample increased by 6.4%, 12.0% and 2.4% respectively, the hydraulic conductivity of 1# tailings sample, 2# tailings sample and 3# tailings increased by 27.2%,17.9%, and 15.3% respectively after internal erosion, and the shear strength of 1#tailings sample, 2#tailings sample and 3#tailings sample tailings sample decreased by 20.9 %, 15.1% and 12.4% respectively.

scholarly journals The Effects of Internal Erosion on the Physical and Mechanical Properties of Tailings under Heavy Rainfall Infiltration

2021 ◽  
Vol 11 (20) ◽  
pp. 9496
Author(s):  
Rong Gui ◽  
Guicheng He
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Heavy Rainfall ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Rainfall Infiltration ◽  
Internal Erosion ◽  
Average Particle ◽  
Tailings Dam ◽  
Sand Column

The stability of tailings dam will be affected by the internal erosion under unsteady seepage caused by heavy rainfall infiltration which changes the physical and mechanical properties of tailings. In this paper, the hydraulic sedimentary model was established to investigate the effects of dry beach slope on the sedimentary characteristics of tailings in upstream tailings dam, and the results indicated that the dry beach with a larger slope has a more obvious stratification of tailings. Additionally, the sand column model was built to investigate the effects of internal erosion on the physical and mechanical properties of sedimentary tailings under unsteady seepage, and the results indicated that the migration of fine-grained tailings was caused by internal erosion increases the permeability and reduces the shear strength of the tailings. After internal erosion of tailings under heavy rainfall in 50 years return period for 24 h, the average particle size of downstream tailings (sample DT), midstream tailings (sample MT), and upstream tailings (sample UT) increased by 6.4%, 12.0%, and 2.4%, respectively, the hydraulic conductivity of the samples DT, MT, and UT increased by 27.2%, 17.9%, and 15.3%, respectively, and the shear strength of each samples decreased by 20.9%, 15.1%, and 12.4%, respectively.

Fabrication of A356-based rolled composites reinforced by Ni–P-coated bimodal ceramic particles

2016 ◽  
Vol 232 (10) ◽  
pp. 803-815 ◽  
Author(s):  
R Kheirifard ◽  
N Beigi Khosroshahi ◽  
R Azari Khosroshahi ◽  
R Taherzadeh Mousavian ◽  
D Brabazon
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Average Particle Size ◽  
Microstructural Characterization ◽  
Rolling Process ◽  
Stir Casting ◽  
Ceramic Particle ◽  
Average Particle ◽  
Ceramic Particles ◽  
Sic Particles

Three arrangements of reinforced A356-based composites were fabricated. Samples with 3 wt% Al2O3 (average particle size: 170 µm), 3 wt% SiC (average particle size: 15 µm), and 3 wt% of mixed Al2O3–SiC powders (each reinforcement 1.5 wt%) were fabricated. The novel fabrication process of two-step stir casting followed by rolling was utilized. Analysis of the effect of using bimodal-sized ceramic particles and process parameters on the microstructure and mechanical properties of the composites was examined. Electroless deposition of nickel was used to improve the wettability of the ceramic reinforcements by the molten metal. From microstructural characterization, it was found that fine SiC particles were agglomerated, including when coated with Ni–P. It was also revealed that the rolling process broke the fine silicon platelets within the A356 matrix, which were mostly observed around the Al2O3 particles. The processed microstructure of the composite was altered in comparison to conventionally cast A356 MMC by translocation of the fractured silicon particles, by improving the distribution of fine SiC particles, and by elimination of porosities remaining after casting. A good bonding quality at matrix–ceramic interface was formed during casting and no significant improvement was found in this regard after the rolling process. The mechanical properties of the composites tested showed that the samples, which contained the bimodal ceramic particle distribution of coarse Al2O3 and fine SiC particles produced the highest levels of composite strength and hardness.

scholarly journals 3D Online Submicron Scale Observation of Mixed Metal Powder's Microstructure Evolution in High Temperature and Microwave Compound Fields

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Dan Kang ◽  
Feng Xu ◽  
Xiao-fang Hu ◽  
Bo Dong ◽  
Yu Xiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
High Temperature ◽  
Microstructure Evolution ◽  
Diffusion Mechanism ◽  
Average Particle Size ◽  
Average Particle ◽  
Reconstruction Method ◽  
Neck Size ◽  
Submicron Scale

In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT) technique; the spatial resolution was enhanced to 0.37 μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

scholarly journals Experimental study on mechanical properties of steel - sand interface

2020 ◽  
Vol 143 ◽  
pp. 01030
Author(s):  
Zhaoxiao Fang ◽  
Weijiang Wang ◽  
Zhaoli Fang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Friction Coefficient ◽  
Average Particle Size ◽  
Average Particle ◽  
Shear Tests ◽  
Axial Pressure ◽  
Interface Shear ◽  
Interface Friction ◽  
Sand Particles

The interface between steel and sand can be regard as a steel-sand system, and its mechanical properties have an important role in many geotechnical applications. The mechanical properties of various steel-sand interfaces classified by sand mean particle size D50 were investigated through interface shear tests. The results show that for a given steel-sand interface, the peak strength of the interface increase with increasing axial pressure. As the D50 value increases, the cohesions for steel-sand interfaces decrease, while the friction angles of the interfaces first increase and then decrease. In the process of shearing, the shrinkage of steel-sand interface occurs, mainly due to the broken of sand particles. The decrease in interface friction coefficients due to an increase in axial pressure was observed. Particle size distribution has a significant effect on the interface friction coefficient of steel-sand interface. When the average particle size D50 changes from 0.1 mm to 0.47 mm, the friction coefficient of steel-sand interface increases by 134%-161%.

Preparation and Characterization of Bone Cements Incorporated with Montmorillonite

2007 ◽  
Vol 342-343 ◽  
pp. 753-756
Author(s):  
Sun Yeon Lee ◽  
Sung Soo Kim
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Average Particle Size ◽  
Gel Permeation Chromatography ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Average Particle ◽  
Bone Cements ◽  
Liquid Component ◽  
Powder Component

Bone cements incorporated with montmorillonite (MMT) were prepared in an attempt to improve their mechanical properties. The cements were characterized using particle size analysis, gel permeation chromatography, viscosity measurements, X-ray diffraction, transmission electron microscopy, and mechanical properties. The average particle size and molecular weight of the PMMA powders used were 47 μm and 100,000 g/mol, respectively. The incorporation of MMT led to an increase in viscosity of the bone cement but did not severely affect its setting temperature or the amount of residual monomer. Regardless of the MMT mixing methods used, in this case MMT being mixing in liquid and powder components, sodium MMT (SMMT) was not well dispersed in the bone cements, which was believed to be due to its hydrophilicity. Organophilic MMT (OMMT) was better dispersed in the liquid component than in the powder component. The tensile and compressive strengths of the bone cements with 0.5 wt% OMMT mixed in the liquid component were 35.9 and 119.6 MPa, respectively, which were considerably higher than those of the bone cements with 0.5 wt% OMMT mixed in the powder component (27.9 and 100.5 MPa, respectively).

Modification with boehmite-derived alumina nanoparticles enhances mechanical properties of resin

RSC Advances ◽  
2015 ◽  
Vol 5 (65) ◽  
pp. 52710-52717 ◽  
Author(s):  
Qingxin Guan ◽  
Hui Wang ◽  
Bohan Chai ◽  
Wei Li
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Average Particle Size ◽  
Alumina Nanoparticles ◽  
Average Particle

Nanostructured γ-Al2O3 with an average particle size of 90 nm was synthesized by coated silica in solution.

Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route

2012 ◽  
Vol 05 ◽  
pp. 607-614 ◽  
Author(s):  
Mohammad Amin Baghchesara ◽  
Hossein Abdizadeh ◽  
Hamid Reza Baharvandi
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Powder Metallurgy ◽  
Volume Fraction ◽  
Average Particle Size ◽  
Aluminum Matrix ◽  
Nano Particles ◽  
Aluminum Matrix Composites ◽  
Average Particle ◽  
Powder Metallurgy Method

The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al /nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1μm and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625°C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.

scholarly journals CPT - DR - D50 correlations of sands for liquefaction potential analysis

2020 ◽  
Vol 156 ◽  
pp. 02017
Author(s):  
A Hakam ◽  
S Warzuqni ◽  
BM Adji ◽  
Junaidi ◽  
IF Muharani ◽  
...  
Keyword(s):  
Particle Size ◽  
Relative Density ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Main Stage ◽  
Average Particle ◽  
Liquefaction Potential ◽  
Sand Deposit ◽  
The Relationship ◽  
Cpt Test

Liquefaction assessment is the main stage in determining the potential liquefaction in a certain site. In order to assess the potential liquefaction, the values of physical and mechanical properties of the soil are very important. Two main parameters that are essentially needed to determine the liquefaction potential in a sand deposit; those are relative density and men particle size. In Indonesia, CPT is a testing method that is very practically famous and often conducted in the field. Assessment of Liquefaction Potential will be cheap and valuable by using the results of the CPT test. For this reason, this paper describes the results of conducted research to obtain the values of the relative density and mean particle size based on the outcomes of the CPT test: those are cone resistance (qc) and friction ration (Rf). The relationship between qc-Rf and Dr-D50 is accelerated by conducting a series of tests on soil samples with variations in the value of relative density and average particle size. The test results are plotted in a graph as well as in the terms of mathematical formulations to figure out for the relationship between CPT values and Dr-D50 in detail for sands. This research is very useful to assess the liquefaction potential in a particular area with very satisfying results

scholarly journals Assessment of Bond Integrity, Durability, and Degree of Conversion of a Calcium Fluoride Reinforced Dentin Adhesive

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2418
Author(s):  
Mohammad H. AlRefeai ◽  
Eman M. AlHamdan ◽  
Samar Al-Saleh ◽  
Imran Farooq ◽  
Eisha Abrar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Raman Spectroscopy ◽  
Calcium Fluoride ◽  
Average Particle Size ◽  
Average Particle ◽  
Hybrid Layer ◽  
Edx Analysis ◽  
Micro Raman Spectroscopy ◽  
Heated Air

Our study aimed to synthesize and compare the mechanical properties and dentin interaction of two adhesives; experimental adhesive (EA) and EA containing 5 wt.% calcium fluoride (CaF2) nano-crystals (CaF2 adhesive-CAFA). CaF2 nano-crystals were synthesized by reacting two solutions (containing calcium and fluoride) in a glass chamber using a heated air system. The EA was produced using a mix of monomers, photo-initiators, camphorquinone, and electron initiators. The synthesized CaF2 nano-crystals were centrifuged to guarantee that inside the adhesive there is homogenized dispersion of the filler particles. Their integration in the EA yielded two groups; Gp-1: EA (without CaF2, control) and Gp-2: (5 wt.% CaF2 containing adhesive, CAFA). Sixty teeth were prepared and set to form bonded specimens using the two adhesives. The CaF2 nano-crystals were irregularly shaped with an average particle size of 30–200 nm. The highest μTBS values were obtained for CAFA-non-thermocycled (NTC) samples (32.63 ± 3.15), followed by EA-NTC (31.80 ± 3.75) specimens. On thermocycling (TC), both adhesive groups presented lower μTBS values (CAFA-TC: 29.47 ± 3.33 and EA-TC: 24.04 ± 3.69). Hybrid layer (HL) formation and resin tags of varying depths were perceived for both adhesive groups. The EDX analysis demonstrated the presence of carbon (C), silica (Si), calcium (Ca), and fluoride (F) for CAFA group. Micro-Raman spectroscopy revealed distinct peaks for CaF2 nano-crystals. The CAFA group presented the greatest DC. The addition of CaF2 nano-crystals in the adhesive caused improved bond μTBS and DC. The incorporation also demonstrated suitable dentin interaction, depicted by appropriate HL and resin tag development.

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