scholarly journals Improving the method for determining the granular media strength performance by oblique shear test

2020 ◽  
Vol 174 ◽  
pp. 01064
Author(s):  
Sergey Shabaev ◽  
Nikita Martel ◽  
Artemy Shtark ◽  
Elmira Rysbekova
Keyword(s):  
Granular Media ◽  
Shear Resistance ◽  
Coarse Grained ◽  
Open Pit ◽  
Shear Stresses ◽  
Density Structure ◽  
Strength Performance ◽  
Improved Design ◽  
Under Construction ◽  
Shear Area

To ensure the strength performance of the pavement of open pit truck roads, it is necessary that it conforms not only to the designed required deformation (elasticity) modulus, but also to the condition for ensuring the shear resistance of structural layers made from non-cohesive and lowly cohesive granular media. However, today there are no reliable methods for determining the strength performance of coarse-grained materials, therefore, for them there are no designstrength values, and therefore their shear resistance is not evaluated, which is a serious omission. It is proposed to evaluate the strength performance of granular media by the oblique sheartest, for which an improved design of oblique shear apparatus was developed, which made it possible to adjust the granular medium density (structure) to the corresponding density (structure) under construction conditions. An analysis was also made of the influence of the angle of inclination of the shear area on the predicted values of normal and shear stresses arising in the cross section, which made it possible to establish the recommended values of this indicator depending on the prevailing particle size of the test medium.

scholarly journals Substantiation of determination of strength performance of coarse-grained media by the oblique shear method

2021 ◽  
Vol 315 ◽  
pp. 01005
Author(s):  
Sergey Shabaev ◽  
Sergey Ivanov
Keyword(s):  
Particle Size ◽  
Granular Media ◽  
Design Method ◽  
Construction Materials ◽  
Road Construction ◽  
Coarse Grained ◽  
Open Pit ◽  
Strength Performance ◽  
Maximum Particle

The constantly increasing loads of vehicles predetermine the search for ways to improve both design methods, technological processes and the search for ways to improve the quality of road construction materials. The increasing volumes of open-pit coal mining require finding ways to improve the haul roads of open-pit coal mines. Thus, a qualitatively new approach is needed to determine the strength performance of coarse-grained media. In this work, it is proposed to determine the strength performance of granular media by the oblique shear method, since today there is no design method to determine the strength performance of coarse-grained media. The proposed design of the advanced oblique shear apparatus makes it possible to determine the strength performance of pre-compacted coarse-grained media with a particle size of up to 20-30 mm. To avoid the effect of keyways and chaotic results, the optimum clearance between the upper and the lower holders should be 0.3 times the maximum particle size.

scholarly journals Probabilistic Modeling of Slip System-Based Shear Stresses and Fatigue Behavior of Coarse-Grained Ni-Base Superalloy Considering Local Grain Anisotropy and Grain Orientation

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 813 ◽  
Author(s):  
Engel ◽  
Mäde ◽  
Lion ◽  
Moch ◽  
Gottschalk ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Test Data ◽  
Grain Orientation ◽  
Fatigue Behavior ◽  
Coarse Grained ◽  
Shear Stresses ◽  
Grain Sizes ◽  
Crack Initiation Life ◽  
Base Superalloy

New probabilistic lifetime approaches for coarse grained Ni-base superalloys supplement current deterministic gas turbine component design philosophies; in order to reduce safety factors and push design limits. The models are based on statistical distributions of parameters, which determine the fatigue behavior under high temperature conditions. In the following paper, Low Cycle Fatigue (LCF) test data of several material batches of polycrystalline Ni-base superalloy René80 with different grain sizes and orientation distribution (random and textured) is presented and evaluated. The textured batch, i.e., with preferential grain orientation, showed higher LCF life. Three approaches to probabilistic crack initiation life modeling are presented. One is based on Weibull distributed crack initiation life while the other two approaches are based on probabilistic Schmid factors. In order to create a realistic Schmid factor distribution, polycrystalline finite element models of the specimens were generated using Voronoi tessellations and the local mechanical behavior investigated in dependence of different grain sizes and statistically distributed grain orientations. All models were first calibrated with test data of the material with random grain orientation and then used to predict the LCF life of the material with preferential grain orientation. By considering the local multiaxiality and resulting inhomogeneous shear stress distributions, as well as grain interaction through polycrystalline Finite Element Analysis (FEA) simulation, the best consistencies between predicted and observed crack initiation lives could be achieved.

scholarly journals Experimental Study of the Composition and Structure of Granular Media in the Shear Bands Based on the HHC-Granular Model

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Guang-jin Wang ◽  
Xiang-yun Kong ◽  
Chun-he Yang
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Granular Media ◽  
Random Distribution ◽  
Shear Bands ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Coarse Grained ◽  
Composition And Structure ◽  
Coarse Grained Soil

The researchers cannot control the composition and structure of coarse grained soil in the indoor experiment because the granular particles of different size have the characteristics of random distribution and no sorting. Therefore, on the basis of the laboratory tests with the coarse grained soil, the HHC-Granular model, which could simulate the no sorting and random distribution of different size particles in the coarse-grained soil, was developed by use of cellular automata method. Meanwhile, the triaxial numerical simulation experiments of coarse grained soil were finished with the different composition and structure soil, and the variation of shear strength was discussed. The results showed that the internal friction angle was likely to reduce with the increasing of gravel contents in the coarse-grained soil, but the mean internal friction angle significantly increased with the increment of gravel contents. It indicated that the gravel contents of shear bands were the major factor affecting the shear strength.

Study of geodynamic situation cut off parts of the plots using ergonometry with the open method of field development

2020 ◽  
pp. 46-55
Author(s):  
T. Sh. Dalatkazin ◽  
P. I. Zuev
Keyword(s):  
Safety Margin ◽  
Discrete Distribution ◽  
Coarse Grained ◽  
Open Pit ◽  
Carbonate Sediments ◽  
Coal Deposit ◽  
Near Surface ◽  
Field Development ◽  
Deformation Processes ◽  
Geodynamic Activity

Modern methods for calculating the safety factor of the sides of the open pit do not take into account the parameters of the modern geodynamic activity of the instrument array. The article presents the results of the first stage of research on the unique capabilities of radonometry to solve this problem. The studies were carried out in the instrument areas of the Shubarkol coal deposit. Terrigenous-carbonate sediments represented by fine and coarse-grained sandstones, siltstones, mudstones, loamy rocks and coals take part in the geological structure of the deposit. The stress-strain state of the rock massif in the area of the Shubarkulsky coal deposit is very heterogeneous. The nature of the deformation processes of the sides of the section is constant and moderate. Here, a discrete distribution of deformation sections is characteristic. The article presents the methods of radonometric measurements, the processing of measurement results and the results of studies of the near-surface sections of a coal mine, aimed at developing a methodology for quantitatively taking into account the degree of modern geodynamic activity in the design of open pit sides. Based on the results of radonometry, the geodynamic activity indices identified in the study of the deformation zones of the instrumentation areas are determined. An algorithm for further studies of the problem of taking into account the degree of modern geodynamic activity in determining the safety margin of open pit sides is determined.The accumulation and generalization of empirical information about the deformation processes of open pits and the results of studies of the geodynamic situation of dash sites, determined using radonometry, will make it possible to modernize the methodology for calculating the margin of safety margin of the sides.

Granular internal dynamics in a silo discharged with a conveyor belt

2021 ◽  
Vol 925 ◽  
Author(s):  
D. Gella ◽  
D. Maza ◽  
I. Zuriguel
Keyword(s):  
Granular Media ◽  
Vertical Direction ◽  
Conveyor Belt ◽  
Coarse Grained ◽  
Vertical Profiles ◽  
Flow Properties ◽  
Internal Dynamics ◽  
Free Discharge ◽  
Quasistatic Regime ◽  
Two Parameters

The dynamics of granular media within a silo in which the grain velocities are controlled by a conveyor belt has been experimentally investigated. To this end, the building of coarse-grained field maps of different magnitudes has allowed a deep analysis of the flow properties as a function of two parameters: the orifice size and the belt velocity. First, the internal dynamics of the particles within the silo has been fully characterized by the solid fraction, the velocity of the particles and the kinetic stress. Then, the analysis of the vertical profiles of the same magnitude (plus the acceleration) has allowed connection of the internal dynamics with the flow rate. In particular, we show that the gamma parameter – which accounts for the integration of the normalized acceleration along the vertical direction – can successfully discriminate the kind of flow established within the silo (from the quasistatic regime to the free discharge) depending on the outlet size and belt velocity.

scholarly journals PREDICTION OF SHEAR RESISTANCE FACTOR IN FLAT SLABS DESIGN USING CRITICAL PERIMETER OF SUPPORTING COLUMNS

2016 ◽  
Vol 36 (1) ◽  
pp. 1-6
Author(s):  
FO Idagu ◽  
NM Ogarekpe ◽  
TI Ugama
Keyword(s):  
Shear Resistance ◽  
Resistance Factor ◽  
Shear Stresses ◽  
Simplified Approach ◽  
Flat Slabs ◽  
European Code ◽  
Relationship Of ◽  
The Relationship

The distribution of shear stresses at the slab–column connection of flat slabs become non–uniform in the presence of unbalanced moment. The shear resistance (β) factor is used to account for this distribution of shear stresses due to the transfer of unbalanced moment at the slab–column connections. The provisions of the American, Canadian, European and Model codes, regarding the transfer of unbalanced moment at slab–column connections of flat slabs are compared. The relationship of β-factor to the ratio of critical perimeter to the control perimeter of an internal column have been plotted as a simplified approach and additional approximate factors have been found for an internal corner column and various locations of cantilevered edge, corner and internal corner columns encountered in practice by engineers. These additional approximate factors have been proposed for inclusion in European code for situations where adjacent spans do not differ by more than 25%.http://dx.doi.org/10.4314/njt.v36i1.1

scholarly journals Ensuring the shear resistance of asphalt mixtures in the pavement of highways

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Zelgedin Mevlidinov ◽  
Tatiana Levkovich ◽  
Anastasia Bilсko
Keyword(s):  
Carbon Black ◽  
Asphalt Concrete ◽  
Residual Deformation ◽  
Shear Resistance ◽  
The State ◽  
Shear Stresses ◽  
Concrete Mixtures ◽  
Concrete Mix ◽  
Used Car ◽  
The Impact

Studying the state of the issue on the shear resistance of asphalt concrete mixtures in the pavement, the authors reviewed the currently available technical reference literature. The state of the streets of the city of Bryansk and the highways of the Bryansk region by measuring the depth of the tracks and flows was also examined. The asphalt concrete samples were tested in laboratory conditions taking into account the rate of deformation, temperature and stress-strain state using the device manufactured at the Department of «Highways» of the Bryansk state engineering and technological University. As additives in asphalt concrete mix introduced: rubber crumb from used car tyres, wheels automobiles, carbon black (powder form) and definiltely thermoplastics. The conducted researches on samples of asphalt concrete mix with use of divinyl-styrene thermoplastics (DST) showed that at increase in the polymer content from 2 to 5 % there was some increase in durability of asphalt concrete on tension in 1,06…1,16 times at 0 °C (smaller value corresponds to the smaller number of DST). Compressive strength at a temperature of «plus» 50 °C increased by 1.04…1.08 times and the module of residual deformation at «plus» 50 °C increased by 1.18…1.23 times. In General, with an increase in the content of DST from 2 to 5 %, the shear resistance increased almost 1.27 times (with the introduction of 5 % DST over the mass of bitumen). The conducted research allows to conclude that to reduce the impact of shear stresses in asphalt concrete mixtures it is necessary to introduce modifying additives, the properties of asphalt concrete depend on the presence of additives, as well as on the quality of the stone aggregate, bitumen and other materials. With the introduction of certain additives (DST, carbon black, rubber c hips), the shear resistance of asphalt concrete increases.

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