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Development of rapidly hardening seal material applicable to steel pipe multistage grouting

강관다단 그라우팅에 적용하는 속경성 실링재 개발

  • Shin, Hyunkang (Infrastructure Solution Group, Infra Division, POSCO E&C) ;
  • Jung, Hyuksang (Dept. of Railway Construction and Safety Engineering, Dongyang University) ;
  • Kim, Donghyun (Dept. of Railway Construction and Safety Engineering, Dongyang University) ;
  • Ryu, Yongsun (Chemius Korea Co., Ltd.) ;
  • Kim, Donghoon (City Planning Team of Jeju Urban Construction Department)
  • 신현강 ((주)포스코건설 인프라사업본부 인프라솔루션그룹) ;
  • 정혁상 (동양대학교 철도건설안전공학과) ;
  • 김동현 (동양대학교 철도건설안전공학과) ;
  • 유용선 ((주)케미우스코리아) ;
  • 김동훈 (제주시 도시건설국 도시계획팀)
  • Received : 2019.02.13
  • Accepted : 2019.03.08
  • Published : 2019.03.31

Abstract

The development of a rapidly hardening seal material applicable to steel pipe multistage grouting is described in this paper. In the multistage technique, seal materials are inserted to prevent the backflow of main grouting material. The grouting material must be inserted only after sufficient time has passed for the seal material to reach a gel state. Otherwise, the fluid seal material mixes with the main grouting material and a backflow of the grouting material occurs, thereby making its in situ insertion difficult. Furthermore, if the seal material remains in the gel state for too long a time, it solidifies; and the main grouting material will not be able to seep into the soil. The gel time, i.e., the time needed for the fluid seal material to turn into a gel state, determines the construction period of steel pipe multistage grouting. The gel time is one of the important factors in this technique, because it impacts the total tunnel construction period significantly. This study develops a rapidly hardening calcium aluminate material, which can reduce the gel time and shorten the construction period while retaining proper sealing function. It also presents a method to determine whether the seal material has reached the gel state as well as the quality standard and bleeding rate testing method for the seal material in the gel state.

본 논문에서는 강관다단 그라우팅에 적용하는 속경성 실링재 개발에 관한 실험적 내용을 다루었다. 강관다단 그라우팅 공법에서 실링재는 본 주입재의 주입시 역류를 방지하기 위해 주입하며 주입 후 일정시간이 지난 다음 겔화 상태에서 본 주입재를 주입해야 한다. 그러나 주입된 실링재가 겔 상태가 되기 이전 유동성이 있을 경우 본 주입재와 함께 혼합됨은 물론, 주입재의 역류가 발생되어 원지반으로 주입이 곤란하며, 반대로 너무 시간이 지나 겔화단계를 넘어 고결되었을 경우 본 주입재가 지반내로 주입되지 못하는 경우가 발생된다. 실링재의 유동성이 없어져 겔화 상태로까지 걸리는 시간에 따라 강관다단 그라우팅의 공사시간이 결정되며, 이는 전체 터널의 공사기간과 밀접한 관련이 있어 중요한 요소 중에 하나이다. 따라서 본 연구에서는 실링재 본연의 역할과 기능을 할 수 있을 뿐 아니라 공사기간을 단축시킬 수 있도록 실링재의 겔화시간을 단축시킬 수 있는 칼슘알루미네이트 재료를 개발하였고, 실링재 겔화 여부를 판단하는 방법에 대해 제시하고, 아울러 실링재의 겔 상태에서 블리딩율에 대해서도 각 품질기준과 시험방법에 대해 제안하였다.

Keywords

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Fig. 1. Role of sealing material and principle of main injection

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Fig. 2. Step-by-step construction sequence for multi-stage grout of steel pipe

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Fig. 3. Separation of materials in sealing materials (Korea Rail Network Authority, 2018a)

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Fig. 4. Structure of clay minerals (Kaolinite) (Storr and Murray, 1986)

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Fig. 5. Crystalline structure of bentonite (Masindi, 2015)

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Fig. 6. Sealing materials mixing

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Fig. 7. Gelled state visually observed when tilted 90°

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Fig. 8. Bleeding observation result

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Fig. 9. Test of Vicat needle penestration and results

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Fig. 10. Injection tube design overview and real picture

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Fig. 11. Model test sequence for sealing materials

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Fig. 12. Test result of Case 1: Grout injection failed into sandy soil and Hardened sealing materials

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Fig. 13. Test result of Case 2: Grout size: Long axis: 43.5 cm, Short axis: 21.75 cm, Width: 17 cm

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Fig. 14. Test result of Case 3: Grout size: Width range: 6.8~12.3 cm, Average length: 20 cm

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Fig. 15. Test result of material separation and viscosity (Korea Railroad Research Institute, 2018)

Table 1. Comparison of sealing material test cases (Ahn, 2018)

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Table 2. Example of compounding ratio (Korea Rail Network Authority, 2018b)

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Table 3. Binding table of sealing material

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Table 4. Test items of sealing material

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Table 5. Chemical composition and physical properties of New sealing Type

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Table 6. Test Result of Vicat needle penestration

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Table 7. Test Cases

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References

  1. Ahn, J.H. (2018), Evaluation of construction management techniques and standards for the umbrella method, Master Thesis, Graduate School of Global Convergence, Korea National University of Transportation, pp. 11-35.
  2. Hong, S., Bae, K., Koo, H., Mun, H., Yoo, Y., Lee, Y., Lee, S. (1994), Development of umbrella arch method for tunneling difficult ground condition, Korea Institute of Construction Technology, pp. 222-225.
  3. Korea Rail Network Authority (2016), Construction specification in Donghae line Pohang-Samcheok railway construction section11, pp. 10-75-154.
  4. Korea Rail Network Authority (2018a), Report on the mixing ratio test results of sealing material and injection material for reinforcement of steel pipe multi-stage grouting, pp. 16-42.
  5. Korea Rail Network Authority (2018b), Small diameter steel pipe multi-stage grouting construction specification (plan), pp. 2-14.
  6. Korea Railroad Research Institute (2018), Study on improvement of steel tube multi-story construction method for rail tunnel reinforcement, pp. 24-38.
  7. Masindi, V. (2015), Remediation of acid mine drainage using magnesite and its bentonite clay composite, Doctor of Philosophy Thesis, Graduate School of Environmental Sciences, University of Venda, pp. 41.
  8. Storr, M., Murray, H. H. (1986), "Well-ordered kaolinite in siderite concretions from the Brazil Formation, western Indiana", Clays and Clay Minerals, Vol. 34, No. 6, pp. 689-691. https://doi.org/10.1346/CCMN.1986.0340612