Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach

Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures (MPFS) of coal is paramount for ensuring the secure extraction of coal resources. This study conducts cyclic loading-unloading and creep experiments o...

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Main Authors: Lei Zhang, Yimeng Wang, Mingzhong Gao, Wenhao Jia, Senlin Xie, Wei Hou, Xiangyu Wang, Hao Zhang
Format: Article
Language:English
Published: Elsevier 2024-10-01
Series:International Journal of Mining Science and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2095268624001356
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author Lei Zhang
Yimeng Wang
Mingzhong Gao
Wenhao Jia
Senlin Xie
Wei Hou
Xiangyu Wang
Hao Zhang
author_facet Lei Zhang
Yimeng Wang
Mingzhong Gao
Wenhao Jia
Senlin Xie
Wei Hou
Xiangyu Wang
Hao Zhang
author_sort Lei Zhang
collection DOAJ
description Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures (MPFS) of coal is paramount for ensuring the secure extraction of coal resources. This study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance (NMR) experimental apparatus which is equipped with mechanical loading units, enabling real-time monitoring the T2 spectrum. The experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal samples. Under identical creep stress conditions, coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep process. After undergoing nearly 35 h of staged creep, the total strains for coal samples CC01, CC02, and CC03 reach 2.160%, 2.261%, and 2.282%, respectively. In the creep stage, the peak area ratio of seepage pores and microfractures (SPM) gradually diminishes. A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal samples. Considering the porosity evolution of SPM during the creep process, this study proposes a novel fractional derivative model for the porosity evolution of SPM. The efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental validation. Furthermore, an analysis of the impact mechanisms on key parameters in the model was carried out.
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spelling doaj-art-4a9ff4358b154d5f8681b73ce329ae3e2025-08-20T01:59:30ZengElsevierInternational Journal of Mining Science and Technology2095-26862024-10-0134101409142510.1016/j.ijmst.2024.09.003Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approachLei Zhang0Yimeng Wang1Mingzhong Gao2Wenhao Jia3Senlin Xie4Wei Hou5Xiangyu Wang6Hao Zhang7College of Safety & Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaSchool of Energy and Mining Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China; Corresponding authors.State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, Shenzhen University, Shenzhen 518060, China; Corresponding authors.School of Mechanics and Civil Engineering, China University of Mining and Technology-Beijing, Beijing 100083, ChinaSchool of Energy and Mining Engineering, China University of Mining and Technology-Beijing, Beijing 100083, ChinaSchool of Energy and Mining Engineering, China University of Mining and Technology-Beijing, Beijing 100083, ChinaSchool of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024, ChinaCollege of Safety & Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaUnderstanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures (MPFS) of coal is paramount for ensuring the secure extraction of coal resources. This study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance (NMR) experimental apparatus which is equipped with mechanical loading units, enabling real-time monitoring the T2 spectrum. The experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal samples. Under identical creep stress conditions, coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep process. After undergoing nearly 35 h of staged creep, the total strains for coal samples CC01, CC02, and CC03 reach 2.160%, 2.261%, and 2.282%, respectively. In the creep stage, the peak area ratio of seepage pores and microfractures (SPM) gradually diminishes. A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal samples. Considering the porosity evolution of SPM during the creep process, this study proposes a novel fractional derivative model for the porosity evolution of SPM. The efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental validation. Furthermore, an analysis of the impact mechanisms on key parameters in the model was carried out.http://www.sciencedirect.com/science/article/pii/S2095268624001356CoalMicroscopic pore and fracture structuresInitial damageCreep behaviorFractional porosity model of seepage pores and microfracturesNuclear magnetic resonance
spellingShingle Lei Zhang
Yimeng Wang
Mingzhong Gao
Wenhao Jia
Senlin Xie
Wei Hou
Xiangyu Wang
Hao Zhang
Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
International Journal of Mining Science and Technology
Coal
Microscopic pore and fracture structures
Initial damage
Creep behavior
Fractional porosity model of seepage pores and microfractures
Nuclear magnetic resonance
title Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
title_full Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
title_fullStr Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
title_full_unstemmed Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
title_short Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior: A real-time NMR-based approach
title_sort spatio temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior a real time nmr based approach
topic Coal
Microscopic pore and fracture structures
Initial damage
Creep behavior
Fractional porosity model of seepage pores and microfractures
Nuclear magnetic resonance
url http://www.sciencedirect.com/science/article/pii/S2095268624001356
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