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Scale effect stress–strain model of coal containing gas

  • Cuijun Jin
  • Songyong LiuEmail author
  • Panpan Xu
  • Chuwen Guo
Technical Paper
  • 33 Downloads

Abstract

This paper reviews the relationship between mechanical properties and scale effect of coal specimens containing gas in stress condition. Firstly, the scale effect stress–strain model of coal was established based on Weibull theory and modified Terzaghi equation. And then, the scale effect stress–strain model of coal containing gas was proposed considering the effect of interfacial friction and expansion force of gas. Lative parameters of the model were obtained through experiments. The mechanical properties of coal specimens containing gas were analyzed, and the correctness of the theoretical model was validated. The results indicate that the theoretical curve of the coal specimens’ compressive strength varying with height–diameter ratio shows consistency with experimental curve. The theoretical scale effect stress–strain curve of coal containing gas agrees well with the experiment at the pre-peak. With the increase in the height–diameter ratio, the coal specimens’ compressive strength decreases and the elastic modulus increases. The coal specimens’ compressive strength and elastic modulus decrease with the gas pressure.

Keywords

Coal Weibull theory Gas pressure Scale effect Interfacial friction 

Notes

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. U1510113), the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP), and Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

References

  1. 1.
    Weibull W (1939) The phenomenon of rupture of solids. I. V. A. Proc. 153, StockholmGoogle Scholar
  2. 2.
    Hudson JA, Crouch SL, Fairhurst C (1972) Soft, stiff and servo-controlled testing machines: a review with reference to rock failure. Eng Geol 6:155–189Google Scholar
  3. 3.
    Hoek E, Brown ET (1980) Underground excavation in rock. Institution of Mining and Metallurgy, LondonGoogle Scholar
  4. 4.
    Yoshinaka R, Osada M, Park H et al (2008) Practical determination of mechanical design parameters of intact rock considering scale effect. Eng Geol 96:173–186Google Scholar
  5. 5.
    Bažant ZP, Xi Y (1991) Statistical size effect in quasi-brittle structures: II. Nonlocal theory. J Eng Mech 117:2623–2640Google Scholar
  6. 6.
    Bažant ZP, Chen EP (1999) Scaling of structural failure. Adv Mech 50:593–627Google Scholar
  7. 7.
    Planas J, Guinea GV, Elices M (1997) Generalized size effect equation for quasi-brittle materials. Fatigue Fract Eng Mater Struct 20:671–687Google Scholar
  8. 8.
    Carpinter A, Ferro G (1994) Size effects on tensile fracture properties-a unified explanation based on disorder and factuality of concrete microstructure. Mater Struct 27:563–571Google Scholar
  9. 9.
    Odama LE (1998) Method of evaluating the reprehensive elementary volume based on joint on survey of rock mass. Can Geotech J 25:281–287Google Scholar
  10. 10.
    Tang CA, Liu H, Lee PKK et al (2000) Numerical studies of the influence of microstructure on rock failure in uniaxial compression-Part I: effect of heterogeneity. Int J Rock Mech Min Sci 37:555–569Google Scholar
  11. 11.
    Tang CA, Tham LG, Lee PKK et al (2000) Numerical studies of the influence of microstructure on rock failure in uniaxial compression-PartII: constraint, slenderness and size effect. Int J Rock Mech Min Sci 37:571–583Google Scholar
  12. 12.
    Pan PZ, Feng XT, Hudson JA (2009) Study of failure and scale effects in rocks under uniaxial compression using 3D cellular automata. Int J Rock Mech Min Sci 46:674–685Google Scholar
  13. 13.
    Feng XT, Pan PZ, Zhou H (2006) Simulation of the rock microfracturing process under uniaxial compression using an elasto-plastic cellular automaton. Int J Rock Mech Min Sci 43:1091–1108Google Scholar
  14. 14.
    Zhang Q, Zhu H, Zhang L et al (2011) Study of scale effect on intact rock strength using particle flow modeling. Int J Rock Mech Min Sci 48:1320–1328Google Scholar
  15. 15.
    Fakhimi A, Tarokh A (2012) Process zone and size effect in fracture testing of rock. Int J Rock Mech Min Sci 60:95–102Google Scholar
  16. 16.
    Zeng K, Xu J, He P et al (2011) Experimental study on permeability of coal sample subjected to triaxial stresses. Procedia Eng 26:1051–1057Google Scholar
  17. 17.
    AlexeevA D, RevvaV N, AlyshevN A et al (2004) True triaxial loading apparatus and its application to coal outburst prediction. Int J Coal Geol 58:245–250Google Scholar
  18. 18.
    Jiang C, Yin G, Li W et al (2011) Experimental of mechanical properties and gas flow of containing-gas coal under different unloading speeds of confining pressure. Procedia Eng 26:1380–1384Google Scholar
  19. 19.
    Lv Y (2012) Test studies of gas flow in rock and coal surrounding a mined coal seam. Int J Min Sci Technol 22:499–502Google Scholar
  20. 20.
    Zhao H (2012) Experimental study on properties of transverse strain and gas flow of coal containing gas in process of unloading confining pressure. Disaster Adv 5:590–592Google Scholar
  21. 21.
    Terzaghi Karl (1943) Theoretical soil mechanics. Wiley, NewYorkGoogle Scholar
  22. 22.
    Walsh JB (1981) Effect of pore pressure and confining pressure on fracture permeability. Int J Rock Mech Min Sci 18:429–435Google Scholar
  23. 23.
    Brace WF (1978) A note on permeability changes in geologic material due to stress. Pure Appl Geophys 116:627–632Google Scholar
  24. 24.
    Ji S, Wang Q (2011) Interfacial friction-induced pressure and implications for the formation and preservation of intergranular coesite in metamorphic rocks. J Struct Geol 133:107–113Google Scholar
  25. 25.
    Yang SQ, Su CD, Xu WY (2005) Experimental and theoretical study of size effect of rock material. Eng Mech 22:112–118 (in Chinese) Google Scholar
  26. 26.
    Ping LU, Sheng ZW, Zhu GW et al (2001) The effective stress and mechanical deformation and damage characteristics of gas-filled coal. J Univ Sci Technol China 31:686–693 (in Chinese) Google Scholar
  27. 27.
    Adamson AW (1990) Physical chemistry of surfaces. Wiley, New YorkGoogle Scholar

Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2019

Authors and Affiliations

  • Cuijun Jin
    • 1
    • 2
  • Songyong Liu
    • 1
    • 2
    Email author
  • Panpan Xu
    • 1
    • 2
  • Chuwen Guo
    • 1
    • 3
  1. 1.School of Mechatronic EngineeringChina University of Mining and TechnologyXuzhouChina
  2. 2.Jiangsu Collaborative Innovation Center of Intelligent Mining EquipmentChina University of Mining and TechnologyXuzhouChina
  3. 3.School of Electric Power EngineeringChina University of Mining and TechnologyXuzhouChina

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