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2019 Vol.21, Issue 6

Research Paper

A study on the optimal reinforced zone of a small sectional shield TBM tunnel in difficult ground

특수지반 구간의 소단면 쉴드 TBM 터널 굴착 시 최적 보강영역 연구

Byung-Yun Kang1
,
Hyung-Keun Park2*
,
Jae-Hoon Cha3
,
Young-Jin Kim4
강 병윤1
,
박 형근2*
,
차 재훈3
,
김 영진4
1President, Soosung Engineering
2Professor, School of Civil Engineering, Chungbuk National University
3Director, Geotechnical and Tunnel Dept., Soosung Engineering
4Engineer, Geotechnical and Tunnel Dept., Soosung Engineering
1정회원, (주)수성엔지니어링 대표이사
2비회원, 충북대학교 토목공학부 교수
3비회원, (주)수성엔지니어링 지반부 이사
4비회원, (주)수성엔지니어링 지반부 사원
* Corresponding Author
30 November 2019. pp. 735-747
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Abstract

Due to the lack of ground space by urbanization, the demand of utility tunnels for laying social facilities is increasing. During the construction of a utility tunnel in downtown area using a shield TBM, various problems may occur when difficult ground is encountered such as mixed ground and cobbly ground. Thus, in this study, using MIDAS GTS NX (Ver. 280), a numerical analysis was performed on characteristics of difficult ground, reinforced area, depth of cover and groundwater level to analyze the optimal ground reinforced area according to combination of parameters. As a result, it was difficult to secure stability in unconstrained excavation cases on both the mixed ground and the cobbly ground. However, when ground reinforcement grouting as much as 2.0D is applied, convergence occurred within the allowable limit, except for mixed ground with a depth of cover 30 m. In addition, excessive leakage occurred during excavation of both the mixed ground and the cobbly layers. It was able to secure stability after applying waterproof grouting.

Keywords
Shield TBM
Small sectional tunnel
Difficult ground
Grouting
Reinforced zone

도시화에 따른 지상공간 부족으로 인해 사회시설물 매설을 위한 공동구 터널의 수요가 증가하고 있다. 쉴드 TBM 공법을 이용한 도심지에서의 공동구 터널 시공 중 불가피하게 복합지반, 호박돌층과 같은 특수지반 조우 시 여러 가지 트러블이 발생하여 공기 및 공사비가 증가될 수 있다. 따라서 본 연구에서는 MIDAS GTS NX (Ver. 280)을 이용해 특수지반의 특성, 보강영역, 토피고, 수위를 달리하여 수치해석을 수행하여 매개변수 조합에 따른 최적의 지반보강영역을 분석하였다. 그 결과 복합지반과 호박돌층 모두 무보강 지반굴착 시 안정성 확보가 어려웠으나 최대 2.0D 만큼의 지반보강 그라우팅 적용 시 토피고 30 m인 복합지반을 제외하고 내공변위가 허용치 내로 발생하였다. 또한 복합지반 및 호박돌층 모두 굴착 시 과다한 지하수 유출이 발생하여 차수그라우팅 적용 후 안정성을 확보할 수 있었다.

키워드
쉴드 TBM
소단면 터널
특수지반
그라우팅
보강영역
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Information
  • Publisher :Korean Tunneling and Underground Space Association
  • Publisher(Ko) :한국터널지하공간학회
  • Journal Title :Journal of Korean Tunnelling and Underground Space Association
  • Journal Title(Ko) :한국터널지하공간학회 논문집
  • Volume : 21
  • No :6
  • Pages :735-747
  • Received Date : 2019-08-02
  • Revised Date : 2019-08-30
  • Accepted Date : 2019-09-04
  • DOI :https://doi.org/10.9711/KTAJ.2019.21.6.735
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