Geomechanics and Engineering

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Simulation study on effects of loading rate on uniaxial compression failure of composite rock-coal layer

  • Chen, Shao J. (College of Mining and Safety Engineering, Shandong University of Science and Technology) ;
  • Yin, Da W. (College of Mining and Safety Engineering, Shandong University of Science and Technology) ;
  • Jiang, N. (College of Mining and Safety Engineering, Shandong University of Science and Technology) ;
  • Wang, F. (College of Mining and Safety Engineering, Shandong University of Science and Technology) ;
  • Guo, Wei J. (College of Mining and Safety Engineering, Shandong University of Science and Technology)
  • Received : 2018.10.06
  • Accepted : 2019.02.21
  • Published : 2019.03.20
⟨ Previous Next ⟩

Abstract

Geological dynamic hazards during coal mining can be caused by the failure of a composite system consisting of roof rock and coal layers, subject to different loading rates due to different advancing velocities in the working face. In this paper, the uniaxial compression test simulations on the composite rock-coal layers were performed using $PFC^{2D}$ software and especially the effects of loading rate on the stress-strain behavior, strength characteristics and crack nucleation, propagation and coalescence in a composite layer were analyzed. In addition, considering the composite layer, the mechanisms for the advanced bore decompression in coal to prevent the geological dynamic hazards at a rapid advancing velocity of working face were explored. The uniaxial compressive strength and peak strain are found to increase with the increase of loading rate. After post-peak point, the stress-strain curve shows a steep stepped drop at a low loading rate, while the stress-strain curve exhibits a slowly progressive decrease at a high loading rate. The cracking mainly occurs within coal, and no apparent cracking is observed for rock. While at a high loading rate, the rock near the bedding plane is damaged by rapid crack propagation in coal. The cracking pattern is not a single shear zone, but exhibits as two simultaneously propagating shear zones in a "X" shape. Following this, the coal breaks into many pieces and the fragment size and number increase with loading rate. Whereas a low loading rate promotes the development of tensile crack, the failure pattern shows a V-shaped hybrid shear and tensile failure. The shear failure becomes dominant with an increasing loading rate. Meanwhile, with the increase of loading rate, the width of the main shear failure zone increases. Moreover, the advanced bore decompression changes the physical property and energy accumulation conditions of the composite layer, which increases the strain energy dissipation, and the occurrence possibility of geological dynamic hazards is reduced at a rapid advancing velocity of working face.

Keywords

Acknowledgement

Supported by : National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation

References

  1. Blanton, T.L. (1981), "Effect of strain rate from 10-2 to 10 sec-1 in triaxial compression tests on three rocks", Int. J. Rock Mech. Min. Sci., 18(1), 47-62. https://doi.org/10.1016/0148-9062(81)90265-5
  2. Chen, S.J., Qu, X., Yin, D.W., Liu, X.Q., Ma, H.F. and Wang, H.W. (2018), "Investigation lateral deformation and failure characteristics of strip coal pillar in deep mining", Geomech. Eng., 14(5), 421-428. https://doi.org/10.12989/GAE.2018.14.5.421
  3. Chen, S.J., Yin, D.W., Cao, F.W., Liu, Y. and Ren, K.Q. (2016), "An overview of integrated surface subsidence-reducing technology in mining areas of China", Nat. Hazards, 81(2), 1129-1145. https://doi.org/10.1007/s11069-015-2123-x
  4. Chen, S.J., Yin, D.W., Zhang, B.L., Ma, H.F., and Liu, X.Q. (2017), "Study on mechanical characteristics and progressive failure mechanism of roof-coal pillar structure body", Chin. J. Rock Mech. Eng., 37(7), 1588-1598 (in Chinese).
  5. Chong, K.P., Hoyt, P.M., Smith, J.W,, and Paulsen, B.Y. (1980), "Effects of strain rate on oil shale fracturing", Int. J. Rock Mech. Min. Sci., 37(1), 35-43.
  6. Guo, D.M., Zuo, J.P., Zhang, Y. and Yang, R.S. (2011), "Research on strength and failure mechanism of deep coal-rock combination bodies of different inclined angles", Rock Soil Mech., 32(5), 1333-1339 (in Chinese). https://doi.org/10.3969/j.issn.1000-7598.2011.05.009
  7. Guo, W.Y., Tan, Y.L., Yu, F.H., Zhao, T.B., Hu, S.C., Huang, D.M. and Qin, Z. (2018), "Mechanical behavior of rock-coal-rock specimens with different coal thicknesses", Geomech. Eng., 15(4), 1017-1027. https://doi.org/10.12989/GAE.2018.15.4.1017
  8. Hua, Y., Nie, W., Cai, P., Liu, Y.H., Peng, H.T. and Liu, Q. (2018), "Pattern characterization concerning spatial and temporal evolution of dust pollution associated with two typical ventilation methods at fully mechanized excavation faces in rock tunnels", Powder Technol., 334, 117-131. https://doi.org/10.1016/j.powtec.2018.04.059
  9. Huang, B.X. and Liu, J.W. (2013), "The effect of loading rate on the behavior of samples composed of coal and rock", Int. J. Rock Mech. Min. Sci., 61, 23-30. https://doi.org/10.1016/j.ijrmms.2013.02.002
  10. Kulatilake, P.H.S.W., Malama, B. and Wang, J. (2001), "Physical and particle flow modeling of jointed rock block behavior under uniaxial loading", Int. J. Rock Mech. Min. Sci., 38(5), 641-657. https://doi.org/10.1016/S1365-1609(01)00025-9
  11. Lajtai, E.Z., Duncan, E.J.S. and Carter, B.J. (1991), "The effect of strain rate on rock strength", Rock Mech. Rock Eng., 24(2), 99-109. https://doi.org/10.1007/BF01032501
  12. Landriani, G.S. and Taliercio, A. (1987), "A note on failure conditions for layered materials", Meccanica, 22(2), 97-102. https://doi.org/10.1007/BF01556908
  13. Lavrov, A. (2001), "Kaiser effect observation in brittle rock cyclically loaded with different loading rates", Mech. Mater., 33(11), 669-677. https://doi.org/10.1016/S0167-6636(01)00081-3
  14. Lee, H. and Jeon, S. (2011), "An experimental and numerical study of fracture coalescence in pre-cracked specimens under uniaxial compression", Int. J. Solids Struct., 48(6), 979-999. https://doi.org/10.1016/j.ijsolstr.2010.12.001
  15. Liu, J., Wang, E.Y., Song, D.Z., Wang, S.H. and Niu, Y. (2015), "Effect of rock strength on failure mode and mechanical behavior of composite samples", Arab. J. Geosci., 8(7), 4527-4539. https://doi.org/10.1007/s12517-014-1574-9
  16. Liu, J.H., Jiang, F.X., Sun, G.J., Zhang, Z.G. and Tan, W.F. (2014), "Mechanism of intensive venting pulverized coal to prevent coal burst and its application", Chin. J. Rock Mech. Eng., 33(4), 747-754 (in Chinese).
  17. Liu, Q., Nie, W., Hua, Y., Peng, H.T. and Liu, Z.Q. (2018), "The effects of the installation position of a multi-radial swirling aircurtain generator on dust diffusion and pollution rules in a fullymechanized excavation face: A case study", Powder Technol., 329, 371-385. https://doi.org/10.1016/j.powtec.2018.01.064
  18. Lu, C.P., Liu, G.J., Liu, Y., Zhang, N., Xue, J.H. and Zhang, L. (2015), "Microseismic multi-parameter characteristics of rockburst hazard induced by hard roof fall and high stress concentration", Int. J. Rock Mech. Min. Sci., 76, 18-32. https://doi.org/10.1016/j.ijrmms.2015.02.005
  19. Pan, Y.S., Li, Z.H. and Zhang, M.T. (2003), "Distribution, type, mechanism and prevention of rockburst in China", Chin. J. Rock Mech. Eng., 22(11), 1844-1851 (in Chinese). https://doi.org/10.3321/j.issn:1000-6915.2003.11.019
  20. Park, J.W. and Song, J.J. (2009), "Numerical simulation of a direct shear test on a rock joint using a bonded-particle model", Int. J. Rock Mech. Min. Sci., 46(8), 1315-1328. https://doi.org/10.1016/j.ijrmms.2009.03.007
  21. Petukhov, I.M. and Linkov, A.M, (1979), "The theory of postfailure deformations and the problem of stability in rock mechanics" Int. J. Rock Mech. Min. Sci., 16(2), 57-76. https://doi.org/10.1016/0148-9062(79)91444-X
  22. Wang, F., Jiang, B.Y., Chen, S.J. and Ren, M.Z. (2019), "Surface collapse control under thick unconsolidated layers by backfilling strip mining in coal mines", Int. J. Rock Mech. Min. Sci., 113, 268-277. https://doi.org/10.1016/j.ijrmms.2018.11.006
  23. Wang, H., Nie, W., Cheng, W.M., Liu, Q. and Hu, J. (2017), "Effects of air volume ratio parameters on air curtain dust suppression in a rock tunnel's fully-mechanized working face", Adv. Powder Technol., 29(2), 230-244. https://doi.org/10.1016/j.apt.2017.11.007
  24. Xie, G.X., Chang, J.C. and Hua, X.Z. (2007), "Influence of mining velocity on mechanical characteristics of surrounding rock in fully mechanized top-coal caving face", Chin. J. Geotech. Eng., 29(7), 963-967 (in Chinese). https://doi.org/10.3321/j.issn:1000-4548.2007.07.002
  25. Xing, R.J., Meng, X.R. and Wang, P. (2017), "Influence of isolated coal pillar pressure-relieving mining on surrounding rock stability of underlying main roadway", Coal Eng., 49(S1), 82-85 (in Chinese).
  26. Yang, S.L., Wang, Z.H,, Jiang, W. and Yang, J.H. (2016), "Advancing rate effect on rock and coal failure format in highintensity mining face", J. China Coal Soc., 41(3), 586-594 (in Chinese).
  27. Yin, D.W., Chen, S.J., Chen. B., Liu, X.Q. and Ma, H.F. (2018a), "Strength and failure characteristics of the rock-coal combined body with single joint in coal", Geomech. Eng., 15(5), 1113-1124. https://doi.org/10.12989/GAE.2018.15.5.1113
  28. Yin, D.W., Chen, S.J., Liu, X.Q. and Ma, H.F. (2018b), "Effect of joint angle in coal on failure mechanical behavior of rock-coal combined body", Q. J. Eng. Geol. Hydrogeol., 51(2), 202-209. https://doi.org/10.1144/qjegh2017-041
  29. Yin, X.T., Ge, X.R., Li, C.G. and Wang, S.L. (2010). "Influences of loading rates on mechanical behaviors of rock materials", Chin. J. Rock Mech. Eng., 29(S1), 2610-2615 (in Chinese).
  30. Zhang, H.W., Li, Y.P., Chen, Y., Zhu, F. and Shao, L.F. (2017), "Study on safety pushing forward speed of island coal mining face under hard roof and hard seam and hard floor conditions", Coal Sci. Technol., 45(5), 6-11(in Chinese).
  31. Zhang, X.P., Jiang, Y.J., Wang, G., Wang, J.C., Wu, X.Z. and Zhang, Y.Z. (2016), "Numerical experimental on rate-dependent behaviors of granite based on particle discrete element model", Rock Soil Mech., 37(9), 2679-2686 (in Chinese).
  32. Zhao, T.B., Guo, W.Y., Lu, C.P. and Zhao, G.M. (2016), "Failure characteristics of combined coal-rock with different interfacial angles", Geomech. Eng., 11(3), 345-359. https://doi.org/10.12989/gae.2016.11.3.345
  33. Zhao, W.H., Huang, R.Q. and Yan, M. (2015), "Mechanical and fracture behavior of rock mass with parallel concentrated joints with different dip angle and number based on PFC simulation", Geomech. Eng., 8(6), 757-767. https://doi.org/10.12989/gae.2015.8.6.757
  34. Zhao, Z.H., Wang, W.M., Dai, C.Q. and Yan, J.X. (2014), "Failure characteristics of three-body model composed of rock and coal with different strength and stiffness", T. Nonferr. Metal. Soc. China, 24(5), 1538-1546. https://doi.org/10.1016/S1003-6326(14)63223-4
  35. Zuo, J.P., Xie, H.P., Meng, B.B. and Liu, J.F. (2011), "Experimental research on loading-unloading behavior of coalrock combination bodies at different stress levels", Rock Soil Mech., 32(5), 1287-1296 (in Chinese). https://doi.org/10.3969/j.issn.1000-7598.2011.05.002

Cited by

  1. An Experimental Study of the Uniaxial Failure Behaviour of Rock-Coal Composite Samples with Pre-existing Cracks in the Coal vol.2019, 2019, https://doi.org/10.1155/2019/8397598
  2. Parametric Study on the Ground Control Effects of Rock Bolt Parameters under Dynamic and Static Coupling Loads vol.2020, 2020, https://doi.org/10.1155/2020/5247932
  3. Experimental Study on Properties of Rock-Cemented Coal Gangue-Fly Ash Backfill Bimaterials with Different Coal Gangue Particle Sizes vol.2020, 2019, https://doi.org/10.1155/2020/8820330
  4. Crack Initiation Behaviors of Granite Specimens Containing Crossing-Double-Flaws with Different Lengths under Uniaxial Loading vol.2020, 2020, https://doi.org/10.1155/2020/8871335
  5. Research on Deformation Characteristics and Control Technology of Soft Rock Roadway under Dynamic Disturbance vol.2021, 2021, https://doi.org/10.1155/2021/6625233
  6. A Study on the Mechanical Properties and Bursting Liability of Coal-Rock Composites with Seam Partings vol.2021, 2019, https://doi.org/10.1155/2021/9953241
  7. Effects of interface angles on properties of rock-cemented coal gangue-fly ash backfill bi-materials vol.24, pp.1, 2021, https://doi.org/10.12989/gae.2021.24.1.081
  8. Experimental and numerical simulation of loading rate effects on failure and strain energy characteristics of coal-rock composite samples vol.28, pp.10, 2019, https://doi.org/10.1007/s11771-021-4831-6