Journal of Korean Tunnelling and Underground Space Association (한국터널지하공간학회 논문집)

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
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Analysis of hydraulic behavior around tunnel after application of cutoff grouting and proposing a method for estimating grouting range

차수그라우팅 적용에 따른 터널주변 수리학적 거동 분석과 그라우팅 적용범위 산정방법의 제안

  • Joon-Shik Moon (Dept. of Civil Engineering, Kyungpook National University)
  • 문준식 (경북대학교 토목공학과)
  • Received : 2024.01.11
  • Accepted : 2024.01.24
  • Published : 2024.01.31
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Abstract

Excessive inflow of groundwater during tunnel excavation not only affects the stability and constructability of the tunnel, but is also one of the main causes of ground settlement due to groundwater level drawdown. The most commonly applied measure against excessive groundwater inflow during tunnel excavation in soil or fractured zone is to reduce the ground permeability coefficient by injecting grout material. Generally, the grouting area is assumed to be same as the plastic zone that occurs during tunnel excavation, but injecting grout material in the area of plastic zone is appropriate only for reinforcement grouting. In order to determine the thickness of cutoff grouting, the amount of reduction in the water permeability coefficient due to the application of cutoff grouting must be considered. In this study, a method for estimating the range of cutoff grouting considering the reduction in permeability coefficient was mathematically derived and evaluated through computer numerical analysis.

터널굴착 중 지하수의 과다유입은 터널의 안정성 및 시공성에 영향을 줄 뿐만 아니라 지하수위 저하에 따른 상부지반의 침하를 발생시키는 주요 원인 중 하나이다. 지하수위 하부 토사구간과 파쇄구간 내 터널굴착 중 지하수 과다유입에 대한 대책으로 가장 일반적으로 적용되는 방법은 사전 그라우팅을 통한 지반 투수계수의 감소이다. 일반적으로 그라우팅 범위는 터널굴착 중 발생하는 소성구간을 목표구간으로 설정하지만 이는 그라우팅을 통한 강도증진을 목적으로 하는 경우 적절한 범위이다. 차수를 목적으로 하는 사전 그라우팅의 범위를 결정하기 위해서는 원지반의 투수계수와 차수그라우팅의 적용에 따른 투수계수의 감소량을 고려하여야 한다. 본 연구에서는 원지반의 투수계수와 그라우팅의 적용에 따른 투수계수의 감소량을 고려한 차수그라우팅의 범위산정 방법을 수학적으로 유도하고 이를 수치해석을 통해 검토하였다.

Keywords

Acknowledgement

본 연구는 한국연구재단 기초연구사업(NRF-2020R1I1A3071653)의 지원으로 수행되었습니다. 이에 감사드립니다.

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