首页|Pore-pressure and stress-coupled creep behavior in deep coal:Insights from real-time NMR analysis

Pore-pressure and stress-coupled creep behavior in deep coal:Insights from real-time NMR analysis

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Understanding the variations in microscopic pore-fracture structures(MPFS)during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment.In this manu-script,a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance(NMR)detection was conducted.Full-scale quantitative characterization,online real-time detection,and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging(NMRI)techniques.The results revealed that seepage pores and microfractures(SPM)undergo the most significant changes during coal creep,with creep failure gradually expanding from dense primary pore fractures.Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores(AP)to evolve into SPM.Coal enters the accelerated creep stage earlier at lower stress levels,resulting in more pronounced creep deformation.The connection between the micro and macro values was established,demonstrating that increased porosity at different pore pres-sures leads to a negative exponential decay of the viscosity coefficient.The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results,and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed.The model's reasonableness was confirmed using creep experimental data.The damage-state adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics(size and degree of difficulty)of coal.

Real-time monitoringPore pressure-stress couplingMicroscopic pore-fracture structureVariable-order fractional creep modelDeep coal

Wenhao Jia、Hongwei Zhou、Senlin Xie、Yimeng Wang、Xinfeng Hu、Lei Zhang

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School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China

School of Energy and Mining Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China

State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology-Beijing,Beijing 100083,China

College of Safety and Emergency Management Engineering,Taiyuan University of Technology,Taiyuan 030024,China

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National Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaChina Postdoctoral Science Foundation111 ProjectYueqi Outstanding Scholar Program of CUMTB

5212100351827901522041102022M722346B140062017A03

2024

10.1016/j.ijmst.2023.12.001

矿业科学技术学报(英文版)
中国矿业大学

矿业科学技术学报(英文版)

CSTPCDEI
影响因子：1.222
ISSN：2095-2686
年,卷(期)：2024.34(1)
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