Anchorage mechanism of inflatable steel pipe rockbolt depending on rock stiffness

팽창형 강관 록볼트의 암반 강성에 따른 정착 거동 특성

  • 김경철 (다산컨설턴트 지반터널부) ;
  • 김호종 (건국대학교 공과대학 인프라시스템공학과) ;
  • 정영훈 (건국대학교 공과대학 인프라시스템공학과) ;
  • 신종호 (건국대학교 공과대학 인프라시스템공학과)
  • Received : 2017.03.14
  • Accepted : 2017.03.27
  • Published : 2017.03.31


The expansion behavior of inflatable steel pipe rockbolt shows geometric nonlinearity due to its ${\Omega}-shaped$ section. Previous studies on the anchoring behavior of inflatable steel pipe rockbolt were mainly performed using theoretical method. However, those studies oversimplified the actual behavior by assuming isotropic expansion of inflatable steel pipe rockbolt. In this study, the anchoring behavior of the inflatable steel pipe rockbolt were investigated by the numerical method considering the irregularity of pipe expansion and other influencing factors. The expansion of inflatable steel pipe rockbolt, the contact stress distribution and the change of the average contact stress and the contact area during installation were analyzed. The contact stresses were developed differently depending on the constitutive behavior of rocks. Small contact stresses occurred in steel pipes installed in elasto-plastic rock compared to steel pipes installed in elastic rock. Also, the anchoring behaviors of the inflatable steel pipe rockbolt were different according to the stiffness of the rock. The steel pipe was completely unfolded in the case of the stiffness smaller than 0.5 GPa, but it was not fully unfolded in the case of the stiffness larger than 0.5 GPa for the given analysis condition. When the steel pipe is completely unfolded, the contact stress increases as the rock stiffness increases. However, the contact stress decreases as the rock stiffness increases when the steel pipe is not fully expanded.


Grant : 고수압 초장대 해저터널 기술자립을 위한 핵심요소 기술개발

Supported by : 건설교통과학기술진흥원, National Research Foundation of Korea


  1. Freeman, T.J. (1978), "The behaviour of fully-bonded rock bolts in the Kielder experimental tunnel", Tunnels & Tunnelling International, Vol. 10, No. 5, pp. 37-40.
  2. Hakansson, U. and Li, C. (1997), "Swellex in weak and soft rock-design guidelines", International symposium on rock support-applied solution for underground structures, Lillehammer, pp. 555-568.
  3. Jeong, Y.Y., Choi, H.J., Kim, B.J., Yu, B.W., Kim, Y.I., Oh, S.J. (2007), "Design on the large section tunnel under shallow overburden", Journal of Korean Tunnelling and Underground Space Association, Vol. 9, No. 2, pp. 171-182.
  4. Kim, K.C. (2017), "A study on the behavior of inflatable pin-holed rockbolt", Master Thesis, Konkok University, Republic of Korea, pp. 1-92.
  5. Kim, Y.I., Yoon, Y.H., Cho, S.K., Yang, J.H., Lee, N.Y. (2002), "A Case study on the construction of a long tunnel in the youngdong railroad(Mt. Dongbeak-Dokye)", Journal of Korean Tunnelling and Underground Space Association, Vol 4, No. 2, pp.155-165.
  6. Li, C.C. (2016), "Analysis of inflatable rock bolts", Rock Mechanics and Rock Engineering, Vol. 49, No. 1, pp. 273-289.
  7. Li, C., Hakansson, U. (1999), "Performance of the Swellex bolt in hard and soft rocks", Rock Support and Reinforcement Practice in Mining, 103.
  8. Li, C., Stillborg, B. (1999), "Analytical models for rock bolts", International Journal of Rock Mechanics and Mining Sciences, Vol. 36, No. 8, pp. 1013-1029.
  9. Park, D.H., Kim, Y.K. (2007), "A study on analysis of tunnel behaviors considering the characteristics of in-situ stress distribution in rock mass", Journal of Korean Tunnelling and Underground Space Association, Vol. 9, No. 3, pp. 275-286.
  10. Son, S.G., You, J.O., You, J.H., Chung, J.M. (2011), "Field Evaluation of the Swelled Steel Tube Rockbolts", 2011 Autumn conference & annual meeting of the Korea Society for railway, Jeju island, Republic of Korea, pp. 1149-1156.
  11. Soni. A. (2000), "Analysis of Swellex bolt performance and a standardized rock volt pull test datasheet and database", Master's thesis, University of Toronto, Canada.
  12. Wijk, G.and Skogberg, B. (1982), "The Swellex rock bolting system", Proc. 14th Canadian Rock Mech. Sympo, 20.