Cracking mechanism of coal under high-pressure water jet and its applications for enhanced coalbed methane drainage

  • Jiechao Zhao
  • Deyong Guo
Original Paper


This paper is concerned with the mechanism of coal breakage under high-pressure water jet (HPWJ) and its applications. A model of HPWJ impinging on coal target was established to study the cracking mechanism of coal under impact load. The characteristic and pressure distribution of HPWJ, the propagation characteristics of stress wave in coal, the mechanical properties of different coal particles, and the fracture characteristics of coal under HPWJ erosion were investigated theoretically and numerically. The results show that the shock wave and water wedge pressure are the main factors that cause coal breakage and crack propagation. The damage to the far-field coal particles affected by HPWJ is primarily caused by tensile stress, and the damage to the near-field coal particles affected by HPWJ is caused by the coupled effects of tensile stress and compressive stress. An erosion cavity is formed in the coal model with diameters of 1.25 to 2.5 times that of the jet at different depths. Meanwhile, the strong quasi-static pressure at the crack discontinuities further promotes the propagation of radial cracks around the erosion cavity to form a fracture zone, and the diameter of the fracture zone at different depths is 3.5 to 4.0 times that of the jet. In addition, the results of field application show that there is a significant difference between the methane parameters in the hydraulic flushing borehole and the conventional borehole; the average methane volume fraction and the average methane flow rate in hydraulic flushing boreholes are 3.85 and 3.67 times, respectively, that in conventional boreholes. Indicating hydraulic flushing can effectively promote the initiation and propagation of coal cracks. These results are of great significance to improve coalbed methane drainage technology and prevent gas disaster accidents in coal mines.


High-pressure water jet erosion Coal breakage Crack propagation Coalbed methane 



The authors thank the National Natural Science Foundation of China (No. 41072118 and No. 41430640). Additionally, the authors would like to acknowledge Dr. Pengfei Lv, China University of Mining and Technology Beijing, for his helpful discussion and suggestions. In addition, the authors appreciate the staff of Yi’an Mining Co., Ltd., for their long-term support and help during the field work. The authors also thank the anonymous reviewer for the valuable comments and helpful suggestions.


  1. Chang ZX, Xi BP, Zhao YS, Zhao LM (2008) Mechanical of breaking coal by water jet. J China Coal Soc 33(9):983–987 (In Chinese)Google Scholar
  2. Cook SS (1928) Erosion by water-hammer. Proc R Soc Lond A 119:481–488CrossRefGoogle Scholar
  3. Dehkhoda S, Hood M (2014) The internal failure of rock samples subjected to pulsed water jet impacts. Int J Rock Mech Min Sci 66:91–96CrossRefGoogle Scholar
  4. Engel OG (1955) Waterdrop collision with solid surface. J Res Natl Bur Stand 54(5):281–298CrossRefGoogle Scholar
  5. Field JE (1999) ELSI conference: invited lecture : liquid impact: theory, experiment, applications. Wear 233-235:1–12CrossRefGoogle Scholar
  6. Field JE, Dear JP, Ogren JE (1989) The effects of target compliance on liquid drop impact. J Appl Phys 65:533–540CrossRefGoogle Scholar
  7. Guo DY, Zhao JC, Lv PF, Zhai M (2016) Dynamic effects of deep-hole cumulative blasting in coal seam and its application. Chin J Eng 38(12):1681–1687 (In Chinese)Google Scholar
  8. Guo DY, Zhao JC, Zhang C, Zhu TG (2018) Mechanism of control hole on coal crack initiation and propagation under deep-hole cumulative blasting in coal seam. Chin J Rock Mech Eng 37(4):919–930 (In Chinese)Google Scholar
  9. Hallquist JO (2006) LS-DYNA theory manual. Livermore Software Technology Corporation, LivermoreGoogle Scholar
  10. Heymann FJ (1969) High speed impact between a liquid drop and a solid surface. J Appl Phys 40:5113–5122CrossRefGoogle Scholar
  11. Honegger E (1927) Tests on erosion caused by jets. Brown Boveri Rev 14:95–104Google Scholar
  12. Lesser MB, Field JE (2003) The impact of compressible liquids. Annu Rev Fluid Mech 15:97–122CrossRefGoogle Scholar
  13. Li M, Ni H, Wang G, Wang R (2017) Simulation of thermal stress effects in submerged continuous water jets on the optimal standoff distance during rock breaking. Powder Technol 320:445–456CrossRefGoogle Scholar
  14. Lin BQ, Liu T, Zou QL, Zhu CJ, Yan FZ, Zhang Z (2015) Crack propagation patterns and energy evolution rules of coal within slotting disturbed zone under various lateral pressure coefficients. Arab J Geosci 8:6643–6654CrossRefGoogle Scholar
  15. Liu X, Liu S, Ji H (2015) Numerical research on rock breaking performance of water jet based on SPH. Powder Technol 286:181–192CrossRefGoogle Scholar
  16. Liu Y, Wei JP, Ren T (2016) Analysis of the stress wave effect during rock breakage by pulsating jets. Rock Mech Rock Eng 49:503–514CrossRefGoogle Scholar
  17. Lu ZH (2012) CFD modeling on flow-field structure of high pressure pulse water jet and its hard rock fragmentation mechanism. Dissertation, Chongqing University (In Chinese)Google Scholar
  18. Lu TK, Yu H, Zhou TY, Mao JS, Guo BH (2009) Improvement of methane drainage in high gassy coal seam using waterjet technique. Int J Coal Geol 79:40–48CrossRefGoogle Scholar
  19. Lu YY, Tang JR, Ge ZL, Xia BW, Liu Y (2013) Hard rock drilling technique with abrasive water jet assistance. Int J Rock Mech Min 60:47–56CrossRefGoogle Scholar
  20. Ma L, Bao RH, Guo YM (2008) Waterjet penetration simulation by hybrid code of SPH and FEA. Int J Impact Eng 35:1035–1042CrossRefGoogle Scholar
  21. Mu C, Wang H (2013) Damage mechanism of coal under high pressure water jetting. Rock Soil Mech 34(5):1515–1520 (In Chinese)Google Scholar
  22. Ni HJ, Wang RH, Du YK (2011) Numerical simulation and experimental study on rock breaking under pulse water jet. Electron J Geotech Eng 16:797–810Google Scholar
  23. Oh TM, Cho GC (2014) Characterization of effective parameters in abrasive waterjet rock cutting. Rock Mech Rock Eng 47:745–756CrossRefGoogle Scholar
  24. Szlązak N, Obracaj D, Swolkień J (2014) Methane drainage from roof strata using an overlying drainage gallery. Int J Coal Geol 136:99–115CrossRefGoogle Scholar
  25. Towler B, Firouzi M, Underschultz J, Rifkin W, Garnett A, Schultz H, Esterle J, Tyson S, Witt K (2016) An overview of the coal seam gas developments in Queensland. J Nat Gas Sci Eng 31:249–271CrossRefGoogle Scholar
  26. Wang FX, Wang RH, Zhou WD, Chen GC (2017) Numerical simulation and experimental verification of the rock damage field under particle water jet impacting. Int J Impact Eng 102:169–179CrossRefGoogle Scholar
  27. Xue YZ, Si H, Hu QT (2017) The propagation of stress waves in rock impacted by a pulsed water jet. Powder Technol 320:179–190CrossRefGoogle Scholar
  28. Zhang H, Cheng Y, Liu Q, Yuan L, Dong J, Wang L, Qi Y, Wang W (2017) A novel in-seam borehole hydraulic flushing gas extraction technology in the heading face: enhanced permeability mechanism, gas flow characteristics, and application. J Nat Gas Sci Eng 46:498–514CrossRefGoogle Scholar
  29. Zhou QL, Li N, Chen X, Xu TM, Hui S, Zhang D (2009) Analysis of water drop erosion on turbine blades based on a nonlinear liquid–solid impact model. Int J Impact Eng 36(9):1156–1171CrossRefGoogle Scholar
  30. Zhou H, Dai H, Ge C (2016) Quality and quantity of pre-drainage methane and responding strategies in Chinese outburst coal mines. Arab J Geosci 9(6):445CrossRefGoogle Scholar

Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  1. 1.School of Resource and Safety EngineeringChina University of Mining and Technology (Beijing)BeijingChina
  2. 2.State Key Laboratory of Coal Resources and Ming SafetyChina University of Mining and Technology (Beijing)BeijingChina

Personalised recommendations