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An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law

In order to further explore the relationship between the excavation speed and the damage of surrounding rocks and dynamic manifestation, the stress paths of unloading confining pressure and loading axial pressure were designed based on the changes in the roadway surrounding rock stress in this study...

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Autores principales: Guo, Hongjun, Sun, Zhongguang, Ji, Ming, Wu, Yongfeng, Nian, Lihui
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025814/
https://www.ncbi.nlm.nih.gov/pubmed/35457414
http://dx.doi.org/10.3390/ijerph19084546
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author Guo, Hongjun
Sun, Zhongguang
Ji, Ming
Wu, Yongfeng
Nian, Lihui
author_facet Guo, Hongjun
Sun, Zhongguang
Ji, Ming
Wu, Yongfeng
Nian, Lihui
author_sort Guo, Hongjun
collection PubMed
description In order to further explore the relationship between the excavation speed and the damage of surrounding rocks and dynamic manifestation, the stress paths of unloading confining pressure and loading axial pressure were designed based on the changes in the roadway surrounding rock stress in this study. Additionally, the mechanical properties and energy evolution law of the coal body were investigated under various unloading rates. As the unloading rate increased, the mechanical properties of the coal body including the failure strength, the confining pressure, the axial strain, and horizontal strain tended to decrease at the rupture stage, while the volume strain and the elastic modulus increased, indicating that the rupture form evolved from the ductile failure to brittle failure. Regarding the energy, the axial pressure did positive work while the confining pressure did negative work, with the total work and the stored elastic strain energy decreasing. In addition, with the increase of the dissipation energy, the elastic strain energy conversion rate decreased linearly, indicating that the high unloading rate increased the possibility of dynamic disasters induced by the instantaneous brittle rupture of the coal body. On the other hand, due to the low releasable elastic strain energy stored in the coal body, the strength and probability of subsequent dynamic manifestation of coal body destruction were reduced. Therefore, increasing the excavation speed in a controllable way can benefit the safety of mining.
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spelling pubmed-90258142022-04-23 An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law Guo, Hongjun Sun, Zhongguang Ji, Ming Wu, Yongfeng Nian, Lihui Int J Environ Res Public Health Article In order to further explore the relationship between the excavation speed and the damage of surrounding rocks and dynamic manifestation, the stress paths of unloading confining pressure and loading axial pressure were designed based on the changes in the roadway surrounding rock stress in this study. Additionally, the mechanical properties and energy evolution law of the coal body were investigated under various unloading rates. As the unloading rate increased, the mechanical properties of the coal body including the failure strength, the confining pressure, the axial strain, and horizontal strain tended to decrease at the rupture stage, while the volume strain and the elastic modulus increased, indicating that the rupture form evolved from the ductile failure to brittle failure. Regarding the energy, the axial pressure did positive work while the confining pressure did negative work, with the total work and the stored elastic strain energy decreasing. In addition, with the increase of the dissipation energy, the elastic strain energy conversion rate decreased linearly, indicating that the high unloading rate increased the possibility of dynamic disasters induced by the instantaneous brittle rupture of the coal body. On the other hand, due to the low releasable elastic strain energy stored in the coal body, the strength and probability of subsequent dynamic manifestation of coal body destruction were reduced. Therefore, increasing the excavation speed in a controllable way can benefit the safety of mining. MDPI 2022-04-09 /pmc/articles/PMC9025814/ /pubmed/35457414 http://dx.doi.org/10.3390/ijerph19084546 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Guo, Hongjun
Sun, Zhongguang
Ji, Ming
Wu, Yongfeng
Nian, Lihui
An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title_full An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title_fullStr An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title_full_unstemmed An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title_short An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law
title_sort investigation on the impact of unloading rate on coal mechanical properties and energy evolution law
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9025814/
https://www.ncbi.nlm.nih.gov/pubmed/35457414
http://dx.doi.org/10.3390/ijerph19084546
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