A fractional non-linear creep model for coal considering damage effect and experimental validation |
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Institution: | 1. Department of Mining Engineering, West Virginia University, Morgantown, WV 26506, USA;2. Department of Civil Engineering, University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada;1. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Shijiazhuang Tiedao University, Shijiazhuang 050043, China;4. Hubei Key Laboratory of Geo-Environmental Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China |
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Abstract: | Accurate prediction of coal׳s creep behavior is of great significance to coalbed methane extraction. In this study, taking into account the visco-elastic–plastic characteristics and the damage effect, a fractional non-linear model is proposed to describe the creep behavior of coal. The constitutive and creep equations of the proposed fractional non-linear model are derived via the Boltzmann superposition principle and discrete inverse Laplace transform. Furthermore, uniaxial creep tests under different axial stress conditions were carried out to validate the proposed model. It is found that the present model can describe the experimental data from creep tests with better accuracy than classical models. Particularly, the present model can predict the accelerating creep deformation of coal which classical models fail to reproduce. Finally, the parametric sensitivity analysis is performed to investigate the effects of model parameters on the creep strain. It is verified that the introduction of fractional parameters and damage factor in the present model is essential to accurate prediction of the full creep stage of coal. |
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Keywords: | Fractional derivative Visco-elastic–plastic behavior Accelerating creep deformation Damage effect Coal |
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