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Numerical Approach to Investigate the Effect of Mud Pressure on the Borehole Stability during Horizontal Directional Drilling

수평굴착 시 점토압력이 굴착공의 안정에 미치는 영향에 관한 수치해석적 연구

  • Kang, Jae Mo (Geotechnical Division, Korea Institute of Construction Technology/Dept. of Civil and Environmental Engrg., Hanyang Univ.) ;
  • Lee, Janggeun (Geotechnical Division, Korea Institute of Construction Technology) ;
  • Bae, Kyu-Jin (Geotechnical Division, Korea Institute of Construction Technology) ;
  • Moon, Changyeul (Dept. of Civil Engrg., Kangwon National Univ.) ;
  • Ban, Hoki (Dept. of Civil Engrg., Kangwon National Univ.)
  • 강재모 (한국건설기술연구원/한양대학교 토목환경공학과) ;
  • 이장근 (한국건설기술연구원) ;
  • 배규진 (한국건설기술연구원) ;
  • 문창열 (강원대학교 사회기반시스템공학과) ;
  • 반호기 (강원대학교 사회기반시스템공학과)
  • Received : 2015.11.11
  • Accepted : 2015.11.20
  • Published : 2015.12.31

Abstract

Recently, people are increasingly interested in horizontal directional drilling (HDD) to construct oil and gas pipeline and utility pipeline in the urban area as one of trenchless methods. One of major issues during the HDD is the collapse of borehole, which may be the potential causes of ground collapse. This study investigated the effect of mud pressure on the borehole stability, using finite element analysis. Since the borehole is being drilled with a certain angle, three dimensional analysis should be performed. The borehole stability was examined by applying two different types of mud pressures, i.e., uniform and non-uniform, to the exterior surface of borehole. The results show that the high mud pressure at the beginning of drilling, i.e., at shallow depth, causes the borehole collapse, whereas the borehole was stable even at high mud pressure as the drilling depth increases. It can be said that the determination of maximum mud pressure is strongly related to the drilling depth.

최근 비개착 공법 중의 하나로 도심지에서 가스관이나 유틸리티관의 건설에서 수평굴착에 대한 관심이 높아지고 있다. 수평굴착에서 가장 문제가 되는 것 중에 하나는 굴착 시 굴착경의 안정성이다. 이러한 굴착경의 불안정은 지반 전체의 붕괴로 이어질 우려가 있기 때문이다. 본 연구에서는 유한요소 해석을 이용하여 굴착경의 보호를 위해 적용하는 점토압이 굴착경의 안전성에 미치는 영향을 살펴보았다. 굴착경 바깥쪽으로 가해지는 점토압이 깊이별로 일정하게 적용되었을 경우와 굴착 깊이가 깊어짐에 따라 큰 점토압이 작용했을 경우로 나누어 그 안전성을 살펴보았다. 유한요소 해석결과 굴착경 입구(앝은깊이)에서의 큰 점토압은 굴착경의 조기 파괴를 가져왔다. 따라서 입구에는 작은 점토압, 굴착 심도가 깊은 곳에서는 큰 점토압이 요구된다. 본 연구를 통해 실제 수평굴착에서 굴착경의 안정성을 확보하기 위한 최대 점토압을 예측하는데 도움이 될 것으로 기대된다.

Keywords

References

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