Numerical study of stability of coal pillars under the influence of line of extraction

Vinay, Lingampally Sai; Bhattacharjee, Ram Madhab; Ghosh, Nilabjendu; Budi, Gnananandh; Kumar, Jagapthal Vinod; Kumar, Shankar

doi:10.1080/19475705.2022.2088409

Cited by 13 publications

(4 citation statements)

References 17 publications

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“…A feature of the proposed approach is the introduction of tangential stresses (16) to (21) into consideration with the need to meet boundary conditions along the inclined faces. Simplification of the proposed expressions leads to a complete coincidence of the result with the solutions by other authors [4−6], obtained by the stress method.…”

Section: Discussion Of Using the Complex Variable Function Argument M...mentioning

confidence: 99%

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Solving applied problems of elasticity theory in geomechanics using the method of argument functions of a complex variable

Chigirinsky

Naizabekov

Lezhnev

et al. 2022

EEJET

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When solving many tasks related to mine workings, rock pressure management, development systems, support structures, the issues of strength and stability of rocks become relevant. Limitations and gaps are identified, emphasizing the need for further research and development of new methods for solving applied problems of elasticity theory. It is of theoretical and practical interest to determine the influence of half-space geometry on the stressed state of the medium and to assess whether it would suffice, in this case, to confine oneself to radial stress when characterizing the stressed state. To build a mathematical model of the stressed state of the array, a complex variable function argument method was used. Based on the developed complex variable function argument method, the applied problem of mechanics on loading the wedge with a concentrated force in polar coordinates was solved. A feature of the proposed approach is the introduction of tangential stresses with the need to meet boundary conditions along inclined faces. The introduction to the consideration of tangential stress shows that it cannot be neglected at a certain stage of the search for a solution. First of all, this is due to the half-space geometry, the angle at the apex, and the depth of the array. When changing the angle of the wedge, the interface surface changes fundamentally and can pass from a convex shape to a concave one. Simplification of the proposed expressions leads to a complete coincidence with the solutions by other authors obtained by the stress method, which indicates the reliability of the result reported here. This method may be advanced by complicating the half-space geometry, as well as loading, and by building a mathematical model for assessing the effect of tangent stresses on the strength and stability of soils

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Section: Discussion Of Using the Complex Variable Function Argument M...mentioning

confidence: 99%

“…In the mechanics of the continuous medium, numerical methods for solving problems have become widespread [16,17]. One of them is the method of finite differences and the method based on the variational principles of mechanics, a finite-element method [18][19][20].…”

Section: When Solving Many Tasks Related To Mine Workings Rock Pressu...mentioning

confidence: 99%

Solving applied problems of elasticity theory in geomechanics using the method of argument functions of a complex variable

Chigirinsky

Naizabekov

Lezhnev

et al. 2022

EEJET

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“…The coal pillar area produces stress concentration, especially the irregular shape of the coal pillar, which may be affected by the superposition of stresses in several directions. In addition, these coal pillars are prone to stress concentration when a sudden change in size occurs, so a rock burst is prone to occur near the coal body. − In the past 20 years, about 60% of rock burst risks were caused by coal pillars, resulting in the destruction of working faces and roadways and a large number of casualties. Therefore, coal pillars are a key factor affecting rock burst risks.…”

Section: Rock Burst Risk Assessment Of Continuous Irregular Coal Pill...mentioning

confidence: 99%

Analysis and Prevention of Rock Burst Risk of Working Face under the Influence of Continuous Irregular Triangular Coal Pillar Stress Concentration Area

Chen,

Zhou,

Zhang

et al. 2024

ACS Omega

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Irregular coal pillars inevitably appear in the layout of the current long-wall mining method, which easily forms stress concentrations and becomes a heavy disaster area of rock burst. In order to solve the impact risk of irregular coal pillar working face, it is necessary to study the instability mechanism of the coal pillar and put forward effective prevention and control measures. Based on the research background of 14320 working face of the Dongtan Coal Mine in the Yanzhou mining area of China, this paper studies the prediction and prevention of rock bursts in this kind of coal pillar by means of theoretical calculation, numerical simulation, engineering analogy, and field monitoring. The results show that (1) the absolute stability of coal pillar is that the width of coal pillar B reaches twice the support pressure of 2L, and the possibility of instability from large to small is coal pillars 2, 5, 3, 1, and 4. (2) The ratio of coal pillar strength to its average load determines the stability coefficient of the coal pillar, and it is judged that coal pillars 1 and 4 are in a stable state, coal pillars 3 and 5 are in a limit equilibrium state, and coal pillar 2 is in an unstable state. The numerical simulation shows that the maximum stress value inside the coal pillar during the mining process is basically consistent with the theoretical calculation of the bearing strength of the coal pillar. (3) The new evaluation method is used to evaluate the rock burst risk degree of the working face roadway: 156.75 m is a strong rock burst risk zone, 728.18 m is a medium rock burst risk zone, and 176.88 m is a weak rock burst risk zone. (4) Regional prevention and local prevention measures are proposed for the risk of rock burst in the roadway, which reduces the stress concentration of the coal pillar. It is verified that the pressure relief effect is remarkable, and the safe mining of such an irregular coal pillar working face is completed, which provides a solution for studying and solving such rock burst risk.

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“…In worldwide coal production, India stands 3rd in the row with 13.47 EJ, which increased by 6.9% in 2020. In the worldwide consumption of coal, India ranks 2nd with 20.09 EJ, showing an upsurge of 15.8% in demand compared to the previous year, 2020 (1 Exajoule (EJ) = 40 million tons of hard coal or 95 million tons of lignite and sub-bituminous coal) [51,52].…”

Section: Geological Setting Of the Study Areamentioning

confidence: 99%

Rapid Estimation of Sulfur Content in High-Ash Indian Coal Using Mid-Infrared FTIR Data

et al. 2023

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High-ash Indian coals are primarily used as thermal coal in power plants and industries. Due to the presence of sulfur in thermal coal, flue gas is a major environmental concern. Conventional methods (Ultimate Analysis of Coal) for sulfur content estimation are time-consuming, relatively costly, and destructive. In this study, Fourier-transform infrared (FTIR) spectroscopy has emerged as a promising alternative method for the rapid and nondestructive analysis of the sulfur content in coal. In the present study, the actual sulfur content in the coal samples was determined using Ultimate Analysis (CHNS analyzer). In contrast, mid-infrared FTIR spectroscopic data (4000–400 cm−1) were used to analyze the functional groups related to sulfur or its compounds in the coal samples to predict the sulfur content. A comparison of sulfur estimated using a CHNS analyzer and predicted using mid-infrared spectroscopy (FTIR) data shows that it can accurately predict sulfur content in high-ash Indian coals using the piecewise linear regression method (Quasi-Newton, QN). The proposed FTIR-based sulfur prediction model showed a coefficient of determination (R2) of up to 0.93, where the total no. of samples (Coal + KBr pellets, n) was 126 (using 17:1 split, K-fold cross validation). The root-mean-square error (RMSE, wt.%) is 0.0035, mean bias error (MBE, wt.%) is −0.0003, MBE (%) is 3.31% and mean absolute error (MAE, wt.%) is 0.0020. The two-tailed t-test and F-test for mean and variance indicated no significant difference between the pair of values of observed sulfur (SCHNS, wt.%) using CHNS data and the model predicted sulfur (SFTIR, wt.%) using FTIR data. The prediction model using mid-infrared FTIR spectroscopy data and the Quasi-Newton method with a breakpoint and loss function performs well for coal samples from the Johilla Coalfield, Umaria. Thus, it can be a valuable tool for analyzing sulfur in other ash-rich coals from various basins worldwide.

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Numerical study of stability of coal pillars under the influence of line of extraction

Cited by 13 publications

References 17 publications

Solving applied problems of elasticity theory in geomechanics using the method of argument functions of a complex variable

Solving applied problems of elasticity theory in geomechanics using the method of argument functions of a complex variable

Analysis and Prevention of Rock Burst Risk of Working Face under the Influence of Continuous Irregular Triangular Coal Pillar Stress Concentration Area

Rapid Estimation of Sulfur Content in High-Ash Indian Coal Using Mid-Infrared FTIR Data

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