Arabian Journal of Geosciences

, 12:571 | Cite as

Experimental investigation on the mechanical characteristics of gas-bearing coal considering the impact of moisture

  • Ming-yi ChenEmail author
  • Yuan-ping Cheng
  • Jing-chun WangEmail author
  • Hao-ran Li
  • Ning Wang
Original Paper


Water is an inherent component in coal masses. The presence of moisture has a significant impact on the mechanical properties of gas-bearing coal and plays a key role in the development of coal and gas outburst disaster. However, how moisture affects the mechanical behavior of gas-bearing coal is poorly understood. In this research, a series of triaxial compression and acoustic emission (AE) tests were performed on gas-bearing coal under different water treatment conditions. The results show that moisture reduces the change in surface energy of the coal by methane adsorption due to the predominance of water adsorption. Therefore, the influence of moisture is more prominent than that of methane and results in a reduction in strength and enhancement in the gas softening coefficient with increasing moisture content. Simultaneously, AE activity of gas-bearing coal is significantly inhibited by moisture, and two failure types can be determined based on the AE results around peak stress: a sudden rupture type for dry and low-water-bearing coal and a stable rupture type for water-saturated coal. Moreover, a meso-statistical damage model is proposed, which agrees well with the experimental results. An analysis indicates that the moisture in coal can reduce the surface energy and weaken the bonds among coal matrix particles, which not only changes the strength of gas-bearing coal but also restrains the energy release during failure; thus, moisture promotes the development of damage in gas-bearing coal.


Triaxial loading Acoustic emission Meso-statistical damage Gas softening coefficient 


Funding information

This work was supported by the National Natural Science Foundation for Young Scientist of China (Grant No. 51804201), the Young fund project of science and technology research of colleges and universities in Hebei Province (Grant No. QN2019006), and the Key Discipline of Geotechnical Engineering Construction Projects in Hebei Province.


  1. Al-Bazali TM, Al-Mudh’hi S, Chenevert ME (2011) An experimental investigation of the impact of diffusion osmosis and chemical osmosis on the stability of shales. Pet Sci Technol 29(3):312–323CrossRefGoogle Scholar
  2. An FH, Cheng YP, Wu DM, Wang L (2013) The effect of small micropores on methane adsorption of coals from Northern China. Adsorption 19(1):83–90CrossRefGoogle Scholar
  3. Bui BT, Tutuncu AN (2018) Modeling the swelling of shale matrix in unconventional reservoirs. J Pet Sci Eng 165:596–615CrossRefGoogle Scholar
  4. Cao WG, Li X, Zhao H (2007) Damage constitutive model for strain-softening rock based on normal distribution and its parameter determination. J Cent S Univ Technol 14(5):719–724CrossRefGoogle Scholar
  5. Cao WG, Zhao H, Li X, Zhang YJ (2010) Statistical damage model with strain softening and hardening for rocks under the influence of voids and volume changes. Can Geotech J 47(8):857–871CrossRefGoogle Scholar
  6. Chen MY, Cheng YP, Li HR, Wang L, Jin K, Dong J (2018) Impact of inherent moisture on the methane adsorption characteristics of coals with various degrees of metamorphism. J Nat Gas Sci Eng 55:312–320CrossRefGoogle Scholar
  7. Day S, Fry R, Sakurovs R (2011) Swelling of moist coal in carbon dioxide and methane. Int J Coal Geol 86(2):197–203CrossRefGoogle Scholar
  8. Ding YL, Yue ZQ (2018) An experimental investigation of the roles of water content and gas decompression rate for outburst in coal briquettes. Fuel 234:1221–1228CrossRefGoogle Scholar
  9. Du WZ, Zhang YS, Meng XB, Zhang XY, Li WX (2018) Deformation and seepage characteristics of gas-containing coal under true triaxial stress. Arab J Geosci 11(9):190CrossRefGoogle Scholar
  10. Eeckhout EMV (1976) The mechanisms of strength reduction due to moisture in coal mine shales. Int J Rock Mech Min Sci Geomech Abstr 13(2):61–67CrossRefGoogle Scholar
  11. Feng XQ, Yu SW (2002) Damage micromechanics of quasi-brittle materials. Higher Education Press, BeijingGoogle Scholar
  12. Feng D, Li XF, Li J, Wang YH, Yang LF, Zhang T, Li PH, Sun Z (2018) Water adsorption isotherm and its effect on pore size distribution of clay minerals. J China Univ Petroleum 42(2):110–118Google Scholar
  13. Gibbs JW (1921) On the equilibrium of heterogeneous substances. In: The Collected Works of J. Willard Gibbs, vol.1. Yale University Press, New HavenGoogle Scholar
  14. Gupta A, Xu MX, Dehghanpour H, Bearinger D (2017) Experimental investigation for microscale stimulation of shales by water imbibition during the shut-in periods. In: Spe Unconventional Resources ConferenceGoogle Scholar
  15. Houben ME, Barnhoorn A, Peach CJ, Drury MR (2018) Potential permeability enhancement in Early Jurassic shales due to their swelling and shrinkage behavior. Int J Coal Geol 196:115–125CrossRefGoogle Scholar
  16. Hu SB, Wang EY, Li XC, Bai B (2016) Effects of gas adsorption on mechanical properties and erosion mechanism of coal. J Nat Gas Sci Eng 30:531–538CrossRefGoogle Scholar
  17. Jiang WP, Cui YJ, Zhang Q, Li YH (2006) The quantum-chemical study on the coal surface interacting with CH4 and CO2. J China Coal Soc 31(2):237–240Google Scholar
  18. Jiang CB, Yin GZ, Xu J, Peng SJ, Li WP (2014) The effect of original moisture content in coal beds on coal and gas outburst risk level. J Chongqing Univ 37(1):91–95Google Scholar
  19. Jiang CL, Xu LH, Li XW, Tang J, Chen YJ, Tian SX, Liu HH (2015) Identification model and indicator of outburst-prone coal seams. Rock Mech Rock Eng 48(1):409–415CrossRefGoogle Scholar
  20. Jiang CB, Duan MK, Yin GZ, Wu GP, Yu H (2016) Loading-unloading experiments of coal containing gas under the condition of different moisture contents. J China Coal Soc 41(9):2230–2237Google Scholar
  21. Langmuir I (1918) The adsorption of gases on plane surfaces of glass, mica and platinum. J Chem Phys 40(9):1361–1403Google Scholar
  22. Lemaitre J (1996) A course on damage mechanics. Science Press, BeijingCrossRefGoogle Scholar
  23. Li X, Cao WG, Su YH (2012) A statistical damage constitutive model for softening behavior of rocks. Eng Geol 143-144:1–17CrossRefGoogle Scholar
  24. Li J, Li XF, Wu KL, Feng D, Zhang T, Zhang YF (2017) Thickness and stability of water film confined inside nanoslits and nanocapillaries of shale and clay. Int J Coal Geol 179:253–268CrossRefGoogle Scholar
  25. Liu XR, Fu Y, Zheng YR, Liang NH (2012) A review on deterioration of rock caused by water-rock interaction. China J Undergr Space Eng 8(1):77–82+88Google Scholar
  26. Liu XF, Xu G, Zhang C, Kong BA, Qian JF, Zhu D, Wei MY (2017a) Time effect of water injection on the mechanical properties of coal and its application in rockburst prevention in mining. Energies 10(11):1783CrossRefGoogle Scholar
  27. Liu Z, Yang H, Cheng WM, Xin L, Ni GH (2017b) Stress distribution characteristic analysis and control of coal and gas outburst disaster in a pressure-relief boundary area in protective layer mining. Arab J Geosci 10:358CrossRefGoogle Scholar
  28. Liu DQ, Wang Z, Zhang XY, Wang Y, Zhang XL, Li D (2018a) Experimental investigation on the mechanical and acoustic emission characteristics of shale softened by water absorption. J Nat Gas Sci Eng 50:301–308CrossRefGoogle Scholar
  29. Liu JF, Fokker PA, Peach CJ, Spiers CJ (2018b) Applied stress reduces swelling of coal induced by adsorption of water. Geomech Energy Environ 16:45–63CrossRefGoogle Scholar
  30. Liu ZG, Cao AY, Guo XS, Li JX (2018c) Deep-hole water injection technology of strong impact tendency coal seam– a case study in Tangkou coal mine. Arab J Geosci 11:12CrossRefGoogle Scholar
  31. Lu YY, Zhe Z, Ge ZL, Zhang XW, Qian L (2016) Coupling effect of intruding water and inherent gas on coal strength based on the improved (Mohr-Coulomb) failure criterion. Minerals 6(4):118CrossRefGoogle Scholar
  32. Lu SQ, Zhang YL, Sa ZY, Si SF (2019) Evaluation of the effect of adsorbed gas and free gas on mechanical properties of coal. Environ Earth Sci 78(6):218CrossRefGoogle Scholar
  33. Lyu Q, Ranjith PG, Long XP, Kang Y, Huang M (2015) Effects of coring directions on the mechanical properties of Chinese shale. Arab J Geosci 8(12):10289–10299CrossRefGoogle Scholar
  34. Lyu Q, Long XP, Ranjith PG, Tan JQ, Kang Y (2018) Experimental investigation on the mechanical behaviours of a low-clay shale under water-based fluids. Eng Geol 233:124–138CrossRefGoogle Scholar
  35. Makhanov K, Habibi A, Dehghanpour H, Kuru E (2014) Liquid uptake of gas shales: a workflow to estimate water loss during shut-in periods after fracturing operations. J Unconventional Oil Gas Resour 7:22–32CrossRefGoogle Scholar
  36. Meng FB, Ge HK, Yan W, Wang XQ, Wu S, Wang JB (2016) Effect of saturated fluid on the failure mode of brittle gas shale. J Nat Gas Sci Eng 35:624–636CrossRefGoogle Scholar
  37. Pan Z, Connell LD, Camilleri M, Connelly L (2010) Effects of matrix moisture on gas diffusion and flow in coal. Fuel 89(11):3207–3217CrossRefGoogle Scholar
  38. Perera MSA, Ranjith PG, Peter M (2011) Effects of saturation medium and pressure on strength parameters of Latrobe Valley brown coal: carbon dioxide, water and nitrogen saturations. Energy 36(12):6941–6947CrossRefGoogle Scholar
  39. Poulsen BA, Shen B, Williams DJ, Huddlestone-Holmes C, Erarslan N, Qin J (2014) Strength reduction on saturation of coal and coal measures rocks with implications for coal pillar strength. Int J Rock Mech Min Sci 71:41–52CrossRefGoogle Scholar
  40. Qin H, Huang G, Wang WZ (2012) Experimental study of acoustic emission characteristics of coal samples with different moisture contents in process of compression deformation and failure. Chin J Rock Mech Eng 31(6):1115–1120Google Scholar
  41. Skoczylas N, Dutka B, Sobczyk J (2014) Mechanical and gaseous properties of coal briquettes in terms of outburst risk. Fuel 134:45–52CrossRefGoogle Scholar
  42. Song DZ, Wang EY, Li ZH, Zhao EL, Xu WQ (2015) An EMR-based method for evaluating the effect of water jet cutting on pressure relief. Arab J Geosci 8(7):4555–4564CrossRefGoogle Scholar
  43. Su CD, Zhai XX, Wei XZ, Li BF (2014) Influence of saturation period on bursting liability indices for coal seam #2 in Qian-Qiu coal mine. Chin J Rock Mech Eng 33(2):235–242Google Scholar
  44. Sun FR, Yao YD, Li GZ (2018a) Comments on: The flow and heat transfer characteristics of compressed air in high-pressure air injection wells [Arabian Journal of Geosciences (2018) 11: 519]. Arab J Geosci 11(20):631CrossRefGoogle Scholar
  45. Sun FR, Yao YD, Li GZ, Li XF (2018b) Geothermal energy development by circulating CO2 in a U-shaped closed loop geothermal system. Energy Convers Manag 174:971–982CrossRefGoogle Scholar
  46. Sun FR, Yao YD, Li GZ, Li XF (2018c) Performance of geothermal energy extraction in a horizontal well by using CO2 as the working fluid. Energy Convers Manag 171:1529–1539CrossRefGoogle Scholar
  47. Sun FR, Yao YD, Li GZ, Li XF, Li Q, Yang J, Wu JQ (2018d) A coupled model for CO2 & superheated steam flow in full-length concentric dual-tube horizontal wells to predict the thermophysical properties of CO2 & superheated steam mixture considering condensation. J Pet Sci Eng 170:151–165CrossRefGoogle Scholar
  48. Sun FR, Yao YD, Li GZ, Li XF (2019a) A slip-flow model for multi-component shale gas transport in organic nanopores. Arab J Geosci 12(5):143CrossRefGoogle Scholar
  49. Sun FR, Yao YD, Li GZ, Li XF (2019b) Transport zones of oil confined in lipophilic nanopores: a technical note. Arab J Geosci 12:136CrossRefGoogle Scholar
  50. Sun FR, Yao YD, Li GZ, Zhang SK, Xu ZM, Shi Y, Li XF (2019c) A slip-flow model for oil transport in organic nanopores. J Pet Sci Eng 172:139–148CrossRefGoogle Scholar
  51. Švábová M, Weishauptová Z, Přibyl O (2011) Water vapour adsorption on coal. Fuel 90(5):1892–1899CrossRefGoogle Scholar
  52. Viete DR, Ranjith PG (2006) The effect of CO2 on the geomechanical and permeability behaviour of brown coal: Implications for coal seam CO2 sequestration. International Journal of Coal Geology 66:204–216CrossRefGoogle Scholar
  53. Vishal V, Ranjith PG, Singh TN (2015) An experimental investigation on behaviour of coal under fluid saturation, using acoustic emission. J Nat Gas Sci Eng 22:428–436CrossRefGoogle Scholar
  54. Wang L, Chen ET, Liu S, Cheng YP, Cheng LB, Chen MY, Guo HJ (2017) Experimental study on the effect of inherent moisture on hard coal adsorption–desorption characteristics. Adsorption 23(5):723–742CrossRefGoogle Scholar
  55. Wang K, Jiang YF, Xu C (2018a) Mechanical properties and statistical damage model of coal with different moisture content under uniaxial compression. Chin J Rock Mech Eng 37:1070–1079Google Scholar
  56. Wang S, Li HM, Wang W, Li DY (2018b) Experimental study on mechanical behavior and energy dissipation of anthracite coal in natural and forced water-saturation states under triaxial loading. Arab J Geosci 11:668CrossRefGoogle Scholar
  57. Wang XX, Liu YM, Hou JG, Wang DM, Ji L, Sun J, Li YQ, Yan XC (2018c) Impacts of water flooding on pore structure of sandstone reservoirs-case study of Wang Guantun oilfield, Bohai Bay Basin, China. Arab J Geosci 11(19):580CrossRefGoogle Scholar
  58. Xiong DG, Zhao ZM, Su CD, Wang GY (2011) Experimental study of effect of water-saturated state on mechanical properties of rock in coal measure strata. Chin J Rock Mech Eng 30(5):998–1006Google Scholar
  59. Xu J, Geng JB, Peng SJ, Liu D, Nie W (2015) Acoustic emission characteristics of coal and gas outburst under different moisture contents. J China Coal Soc 40(5):1047–1054Google Scholar
  60. Yang YJ, Zhao NN, Ma DP, Zhang FJ (2016) Study on stability of strip coal pillar with different moisture content. J Min Saf Eng 33(1):42–48Google Scholar
  61. Yao QL, Li XH, Zhou J, Ju MH, Chong ZH, Zhao B (2015) Experimental study of strength characteristics of coal specimens after water intrusion. Arab J Geosci 8(9):6779–6789CrossRefGoogle Scholar
  62. Yu YB, Zhou G, Chen LJ, Zhou B, Tian XH (2014) Experimental study on basic mechanical properties of water-saturated coal. Min Saf Environ Prot 41:4–7Google Scholar
  63. Zhang M, Wang F, Yang Q (2013) Statistical damage constitutive model for rocks based on triaxial compression tests. Chin J Geotech Eng 35:1965–1971Google Scholar
  64. Zhang MB, Zhu HQ, Lin MQ, Zhou DH, Li W (2017) Effect of moisture content on damage deformation of coal containing gas under loading and unloading conditions. J Saf Sci Technol 13:90–95Google Scholar
  65. Zhang H, Zhong Y, She JP, Li GF (2018a) Characterization of shale matrix pore structure via experiment and model. Arab J Geosci 11:320CrossRefGoogle Scholar
  66. Zhang XG, Gamage RP, Perera MSA, Ranathunga AS (2018b) Effects of water and brine saturation on mechanical property alterations of brown coal. Energies 11(5):1116CrossRefGoogle Scholar
  67. Zhang YH, Lebedev M, Al-Yaseri A, Yu HY, Xu XM, Sarmadivaleh M, Barifcani A, Iglauer S (2018c) Nanoscale rock mechanical property changes in heterogeneous coal after water adsorption. Fuel 218:23–32CrossRefGoogle Scholar
  68. Zhou Z, Lu YY, Ge ZL, Yang F, Zhang XW (2014) Theoretical and experimental study on strength characteristics of coal under coupling effect of water and gas. J China Coal Soc 39:2418–2424Google Scholar

Copyright information

© Saudi Society for Geosciences 2019

Authors and Affiliations

  1. 1.College of Civil EngineeringShijiazhuang Tiedao UniversityShijiazhuangChina
  2. 2.Key Laboratory of Roads and Railway Engineering Safety Control, Ministry of EducationShijiazhuang Tiedao UniversityShijiazhuangChina
  3. 3.National Engineering Research Center for Coal and Gas ControlChina University of Mining and TechnologyXuzhouChina
  4. 4.Cooperative Innovation Center of Disaster Prevention and Mitigation for Large Infrastructure in Hebei provinceShijiazhuang Tiedao UniversityShijiazhuangChina

Personalised recommendations