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Mechanical properties and permeability evolution of gas-bearing coal under phased variable speed loading and unloading

  • Chengpeng Xin
  • Kai WangEmail author
  • Feng Du
  • Xiang Zhang
  • Gongda Wang
  • Yilei Liu
Original Paper
  • 89 Downloads

Abstract

It is of great significance for the analysis and prediction of coal-gas outburst disasters to understand the mechanical properties and permeability evolution of coal and rock under conditions of stope stress evolution. In this study, mechanical tests were conducted on gas-bearing coal under four stress paths, including conventional triaxial compression (CTC), phased variable speed triaxial compression (PVSTC), unloading confining pressure (UCP), and phased variable speed unloading confining pressure (PVSUCP), simultaneously measuring the permeability in mechanical tests. The mechanical properties and permeability evolutions in gas-bearing coal under four different stress paths were compared. The obtained results show that the deviatoric stress-strain curves of gas-bearing coal under four stress paths could be divided into five stages: compaction, linear elasticity, plastic deformation, stress drop, and residual stress stage. The permeability-strain curves under four stress paths could also be divided into five stages: fast drop, slow decrease, slow increase, sharp increase, and slowed growth. Compared to the CTC conditions, the peak strain and strength of coal under PVSTC conditions increased. Furthermore, the stress drop and energy release under PVSTC were more intense at the moment of instability failure. Compared to both loading paths, the coal was damaged more rapidly under unloading paths and the damage was stronger. Additionally, among both unloading paths, the time required for the failure of coal under PVSUCP was shorter than that under UCP, while the damage under PVSUCP was stronger. The strength characteristics of the gas-bearing coal under PVSTC and PVSUCP still met the Mohr–Coulomb criterion. This preliminary study has guiding significance for the understanding of the co-occurrence mechanisms of coal-gas outburst disasters.

Keywords

Gas-bearing coal Triaxial compression Unloading confining Phased variable speed Mechanical properties Permeability 

Abbreviations

CTC

Conventional triaxial compression

PVSTC

Phased variable speed triaxial compression

UCP

Unloading confining pressure

PVSUCP

Phased variable speed unloading confining pressure

Notes

Acknowledgments

This research is financially supported by the State Key Research Development Program of China (2016YFC0801402, 2016YFC0600708), National Natural Science Foundation of China (51474219, 51604153, 51874314), the Open Funds of Hebei State Key Laboratory of Mine Disaster Prevention (KJZH2017K02), the Joint Fund Project of Guizhou Science and Technology Department and Bijie Science and Technology Bureau and Institute of Circular Economy (LH[2017]7520), the Guizhou Science and Technology Support Program ([2017]2820), and the Yue Qi Distinguished Scholar Project, China University of Mining & Technology, Beijing. Feng Du would like to acknowledge the Fund of China Scholarship Council (CSC) for his study in Department of Civil Engineering and Engineering Mechanics, Columbia University.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

References

  1. Al-Ajmi AM, Zimmerman RW (2005) Relation between the Mogi and the Coulomb failure criteria. Int J Rock Mech Min Sci 42:431–439CrossRefGoogle Scholar
  2. An FH, Cheng YP, Wang L, Li W (2013) A numerical model for outburst including the effect of adsorbed gas on coal deformation and mechanical properties. Comput Geotech 54:222–231CrossRefGoogle Scholar
  3. Aziz NI, Ming-Li W (1999) The effect of sorbed gas on the strength of coal-an experimental study. Geotech Geol Eng 17:387–402CrossRefGoogle Scholar
  4. Beamish BB, Crosdale PJ (1998) Instantaneous outbursts in underground coal mines: an overview and association with coal type. Int J Coal Geol 35:27–55CrossRefGoogle Scholar
  5. Chen HD, Cheng YP, Zhou HX, Li W (2013) Damage and permeability development in coal during unloading. Rock Mech Rock Eng 46:1377–1390CrossRefGoogle Scholar
  6. Chen H, Cheng Y, Ren T, Zhou H, Liu Q (2014) Permeability distribution characteristics of protected coal seams during unloading of the coal body. Int J Rock Mech Min Sci 71:105–116CrossRefGoogle Scholar
  7. Clarkson CR, Bustin RM (1999) The effect of pore structure and gas pressure upon the transport properties of coal: a laboratory and modeling study. 1. Isotherms and pore volume distributions. Fuel 78:1333–1344CrossRefGoogle Scholar
  8. Du F, Wang K, Wang G, Jiang YF, Xin CP, Zhang X (2018) Investigation on acoustic emission characteristics during deformation and failure of gas-bearing coal-rock combined bodies. J Loss Prevent Proc 55:253–266CrossRefGoogle Scholar
  9. Fairhurst CE, Hudson JA (1999) Draft ISRM suggested method for the complete stress-strain curve for intact rock in uniaxial compression. Int J Rock Mech Min Sci 36:281–289Google Scholar
  10. Gentzis T, Deisman N, Chalaturnyk RJ (2007) Geomechanical properties and permeability of coal from the foothills and mountain regions of western Canada. Int J Coal Geol 69:153–164CrossRefGoogle Scholar
  11. George JDS, Barakat MA (2001) The change in effective stress associated with shrinkage from gas desorption in coal. Int J Coal Geol 45:105–113CrossRefGoogle Scholar
  12. Goodman AL, Favors RN, Larsen JW (2006) Argonne coal structure rearrangement caused by sorption of CO2. Energy Fuel 20:2537–2543CrossRefGoogle Scholar
  13. Harpalani S, Chen G (1995) Estimation of changes in fracture porosity of coal with gas emission. Fuel 74:1491–1498CrossRefGoogle Scholar
  14. Hoek E, Brown ET (1982) Empirical strength criterion for rock masses. J Geotech Eng-Div 106:1013–1035Google Scholar
  15. Hoek E, Wood D, Shah S (1992) Modified Hoek-Brown failure criterion for jointed rock masses. Proceedings of the international ISRM symposium on rock characterization. Chester, UKGoogle Scholar
  16. Jaeger JC, Cook NGW (1979) Fundamentals of rock mechanics, third ed. John Wiley & SonsGoogle Scholar
  17. Kasani HA, Chalaturnyk RJ (2017) Influence of high pressure and temperature on the mechanical behavior and permeability of a fractured coal. Energies 10(7):854.  https://doi.org/10.3390/en10070854 CrossRefGoogle Scholar
  18. Kumar H, Elsworth D, Liu J, Pone D, Mathews JP (2012) Optimizing enhanced coalbed methane recovery for unhindered production and CO2, injectivity. Int J Greenh Gas Con 11(6):86–97CrossRefGoogle Scholar
  19. Kumar H, Elsworth D, Liu J, Pone D, Mathews JP (2015) Permeability evolution of propped artificial fractures in coal on injection of CO2. J Pet Sci Eng 133:695–704CrossRefGoogle Scholar
  20. Kumar H, Elsworth D, Mathews JP, Marone C (2016) Permeability evolution in sorbing media: analogies between organic-rich shale and coal. Geofluids 16:43–55CrossRefGoogle Scholar
  21. Labuz JF, Zang A (2012) Mohr-Coulomb failure criterion. Rock Mech Rock Eng 45:975–979CrossRefGoogle Scholar
  22. Lajtai EZ, Duncan EJS, Carter BJ (1991) The effect of strain rate on rock strength. Rock Mech Rock Eng 24:99–109CrossRefGoogle Scholar
  23. Li Z, Wang E, Ou J, Liu Z (2015) Hazard evaluation of coal and gas outbursts in a coal-mine roadway based on logistic regression model. Int J Rock Mech Min Sci 80:185–195CrossRefGoogle Scholar
  24. Liu KD (2017) Mechanical properties of ram coal containing gas under high triaxial stress compression. Chin J Rock Mech Eng 36:380–393Google Scholar
  25. Lu CP, Dou LM, Liu H, Liu HS, Liu B, Du BB (2012) Case study on microseismic effect of coal and gas outburst process. Int J Rock Mech Min Sci 53:101–110CrossRefGoogle Scholar
  26. Masoudian MS, Airey DW, El-Zein A (2014) Experimental investigations on the effect of CO2 on mechanics of coal. Int J Coal Geol 12-23:s128–s129Google Scholar
  27. Palmer I, Mansoori J (1996) How permeability depends on stress and pore pressure in coalbeds: a new model. SPE Reser Eval En 1:539–544Google Scholar
  28. Siriwardane H, Haljasmaa I, Mclendon R, Irdi G, Soong Y, Bromhal G (2009) Influence of carbon dioxide on coal permeability determined by pressure transient methods. Int J Coal Geol 77:109–118CrossRefGoogle Scholar
  29. Somerton WH, Söylemezoḡlu IM, Dudle RC (1975) Effect of stress on permeability of coal. Int J Rock Mech Min Sci 12:129–145CrossRefGoogle Scholar
  30. Viete DR, Ranjith PG (2007) The mechanical behaviour of coal with respect to CO 2 sequestration in deep coal seams. Fuel 86:2667–2671CrossRefGoogle Scholar
  31. Wang S, Elsworth D, Liu J (2011) Permeability evolution in fractured coal: the roles of fracture geometry and water-content. Int J Coal Geol 87:13–25CrossRefGoogle Scholar
  32. Wang K, Du F, Wang G (2017a) Investigation of gas pressure and temperature effects on the permeability and steady-state time of chinese anthracite coal: an experimental study. J Nat Gas Sci Eng 40:179–188CrossRefGoogle Scholar
  33. Wang K, Du F, Wang G (2017b) The influence of methane and CO2 adsorption on the functional groups of coal: insights from a Fourier transform infrared investigation. J Nat Gas Sci Eng 45:358–367CrossRefGoogle Scholar
  34. Wang K, Du F, Zhang X, Wang L, Xin C (2017c) Mechanical properties and permeability evolution in gas-bearing coal–rock combination body under triaxial conditions. Environ Earth Sci 76:815 1–19CrossRefGoogle Scholar
  35. Wold MB, Connell LD, Choi SK (2008) The role of spatial variability in coal seam parameters on gas outburst behaviour during coal mining. Int J Coal Geol 75:1–14CrossRefGoogle Scholar
  36. Xie G, Yin Z, Wang L, Hu Z, Zhu C (2017) Effects of gas pressure on the failure characteristics of coal. Rock Mech Rock Eng 50:1–13CrossRefGoogle Scholar
  37. Xue D, Zhou H, Wang Z, Ren W (2010) Failure mechanism and mining-induced mechanical properties of coal under different loading rates. J China Coal Soc 41:595–602Google Scholar
  38. Xue Y, Ranjith PG, Gao F, Zhang D, Cheng H, Chong Z, Hou P, Xue Y, Ranjith PG, Gao F (2017) Mechanical behaviour and permeability evolution of gas-containing coal from unloading confining pressure tests. J Nat Gas Sci Eng 40:336–346CrossRefGoogle Scholar
  39. Yuan L (2016) Control of coal and gas outbursts in Huainan mines in China: a review. J Rock Mech Geotech Eng 8:559–567CrossRefGoogle Scholar
  40. Yin G, Jiang C, Wang JG, Xu J (2015) Geomechanical and flow properties of coal from loading axial stress and unloading confining pressure tests. Int J Rock Mech Min Sci 76:155–161CrossRefGoogle Scholar
  41. Zhang Q, Fan X, Liang Y, Li M, Li G, Ma T, Nie W (2017) Mechanical behavior and permeability evolution of reconstituted coal samples under various unloading confining pressures-implications for wellbore stability analysis. Energies 10(3):292.  https://doi.org/10.3390/en10030292 CrossRefGoogle Scholar
  42. Zhou X, Qian Q, Yang H (2010) Effect of loading rate on fracture characteristics of rock. J Cent South Univ Techno 17:150–155CrossRefGoogle Scholar

Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  • Chengpeng Xin
    • 1
    • 2
    • 3
  • Kai Wang
    • 1
    • 2
    • 4
    Email author
  • Feng Du
    • 1
    • 2
  • Xiang Zhang
    • 1
    • 2
  • Gongda Wang
    • 5
  • Yilei Liu
    • 3
  1. 1.Beijing Key Laboratory for Precise Mining of Intergrown Energy and ResourcesChina University of Mining and Technology (Beijing)BeijingChina
  2. 2.School of Resource & Safety EngineeringChina University of Mining & Technology (Beijing)BeijingChina
  3. 3.School of Mining EngineeringGuizhou University of Engineering ScienceBijieChina
  4. 4.Hebei State Key Laboratory of Mine Disaster PreventionNorth China Institute of Science and TechnologyBeijingChina
  5. 5.Mine Safety Technology BranchChina Coal Research InstituteBeijingChina

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