Frictional sliding tests on combined coal-rock samples

To research the dynamic response characteristics of cylindrical coal-rock samples under impact loads, the impact of rigid bars on cylindrical coal-rock samples is simulated under different speed conditions, based on LS-DYNA software, and the dynamic distribution characteristics of the stress, strain, and energy of cylindrical coal-rock samples are analyzed. The results demonstrated the following: (1) the cylindrical coal-rock sample failed at the center first, and the damage developed downward along the axial direction. (2) The critical effective stress and strain have an exponential function relationship with the velocity, and the critical time has a linear relationship with the velocity. (3) The energy change law of the cylindrical coal-rock sample is consistent with the destruction morphology. (4) The axial stress peaks in the severe damage part have a linear relationship with the speed, the axial stress attenuates rapidly after passing the stress yield point, and the axial strain does not increase continuously. (5) The peaks stress and strain on the central axis and the radial line obey the power function distribution, the axial stress produces tensile stress in the axial propagation direction, and the axial stress and strain peaks at the same position are larger than those of the radial stress and strain peaks. This research provides a reference for studying coal and rock dynamic disasters.

Download Full-text

An Experimental Apparatus for Monitoring Radon during Compression of Coal/Rock Samples and Its Preliminary Application

Advances in Civil Engineering ◽

10.1155/2021/6655141 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Wei Zhang ◽

Kaidi Xie ◽

Yanchao Zhu ◽

Yandong Zhang ◽

Xu Duan ◽

...

Keyword(s):

Compressive Load ◽

Future Research ◽

Radon Emanation ◽

Compression Tests ◽

Rock Samples ◽

Airtight Container ◽

Experimental Apparatus ◽

Coal Rock ◽

Fractal Characteristics ◽

Mathematical Equations

Based on the radionuclide distributions in sedimentary coal-bearing strata, this study analyzed the microrelease mechanisms of radon in coal-bearing strata. It was found that the microrelease process includes three stages: emanation, migration, and exhalation. Based on this, an experimental apparatus was independently designed for monitoring radon during compression of coal/rock samples from coal-bearing strata, whose major components include an electrohydraulic servocontrolled rock mechanics testing system, an airtight container, coal/rock samples, radon output device, and a continuous emanometer. The developed apparatus was preliminarily utilized for uniaxial compression tests on mudstone samples taken from the #21105 coalface of the Fourth Coal Mine in Yili Coalfield, China. The test results show that before sample failure under the uniaxial compressive load (UCL), the radon concentration is negatively correlated with the applied UCL and the magnitude of imposed elastic deformation. Increasing the applied load shortens the period of stable deformation, gradually decreasing the porosity of the rock, and as a result of declining the concentration of radon emanation from the rock. Finally, suggestions for future research are proposed, including mathematical equations to express the correlations between different experimental parameters and fractal characteristics of radon release from porous media.

Download Full-text

Laboratory technique for measuring anisotropy of rock samples resistivity and permeability

Neftyanoe khozyaystvo - Oil Industry ◽

10.24887/0028-2448-2018-6-84-86 ◽

2018 ◽

pp. 84-86

Author(s):

A.S. Sulima ◽

◽

A.V. Avilov ◽

S.A. Chukhlantsev ◽

V.A. Palaguto ◽

...

Keyword(s):

Laboratory Technique ◽

Rock Samples

Download Full-text

Reinforcement materials for damaged zones in coal–rock mass under mining

MINING INFORMATIONAL AND ANALYTICAL BULLETIN ◽

10.25018/0236-1493-2018-11-0-39-45 ◽

2018 ◽

Vol 11 ◽

pp. 39-45 ◽

Cited By ~ 2

Author(s):

S.N. Reshetnyak ◽

◽

Yu.M. Maksimenko ◽

Keyword(s):

Rock Mass ◽

Coal Rock

Download Full-text

Comparative assessment of morphological mechanisms of maintaining structural liver homeostasis in the dynamics of exposure to coal-rock dust and sodium fluoride on the body

Russian Journal of Occupational Health and Industrial Ecology ◽

10.31089/1026-9428-2020-60-3-189-194 ◽

2020 ◽

pp. 189-194

Author(s):

M. S. Bugaeva ◽

O. I. Bondarev ◽

N. N. Mikhailova ◽

L. G. Gorokhova

Keyword(s):

Sodium Fluoride ◽

Morphological Changes ◽

The Body ◽

System Level ◽

Production Factor ◽

Coal Rock ◽

The Impact ◽

Structural Homeostasis ◽

Rock Dust

Introduction. The impact on the body of such factors of the production environment as coal-rock dust and fluorine compounds leads to certain shift s in strict indicators of homeostasis at the system level. Maintaining the relative constancy of the internal environment of the body is provided by the functional consistency of all organs and systems, the leading of which is the liver. Organ repair plays a crucial role in restoring the structure of genetic material and maintaining normal cell viability. When this mechanism is damaged, the compensatory capabilities of the organ are disrupted, homeostasis is disrupted at the cellular and organizational levels, and the development of the main pathological processes is noted.The aim of the study is to compare the morphological mechanisms of maintaining structural homeostasis of the liver in the dynamics of the impact on the body of coal-rock dust and sodium fluoride.Materials and methods. Experimental studies were conducted on adult white male laboratory rats. Features of morphological mechanisms for maintaining structural homeostasis of the liver in the dynamics of exposure to coal-rock dust and sodium fluoride were studied on experimental models of pneumoconiosis and fluoride intoxication. For histological examination in experimental animals, liver sampling was performed after 1, 3, 6, 9, 12 weeks of the experiment.Results. The specificity of morphological changes in the liver depending on the harmful production factor was revealed. It is shown that chronic exposure to coal-rock dust and sodium fluoride is characterized by the development of similar morphological changes in the liver and its vessels from the predominance of the initial compensatory-adaptive to pronounced violations of the stromal and parenchymal components. Long-term inhalation of coal-rock dust at 1–3 weeks of seeding triggers adaptive mechanisms in the liver in the form of increased functional activity of cells, formation of double-core hepatocytes, activation of immunocompetent cells and endotheliocytes, ensuring the preservation of the parenchyma and the general morphostructure of the organ until the 12th week of the experiment. Exposure to sodium fluoride leads to early disruption of liver compensatory mechanisms and the development of dystrophic changes in the parenchyma with the formation of necrosis foci as early as the 6th week of the experiment.Conclusions. The study of mechanisms for compensating the liver structure in conditions of long-term exposure to coal-rock dust and sodium fluoride, as well as processes that indicate their failure, and the timing of their occurrence, is of theoretical and practical importance for developing recommendations for the timely prevention and correction of pathological conditions developing in employees of the aluminum and coal industry.The authors declare no conflict of interests.

Download Full-text