Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Effect of Groundwater Flow on the Behavior of Circular Vertical Shaft

지하수 유동을 고려한 원형수직구 거동분석

  • Park, Heejin (Railroad Business Dept., CHEIL Engineering Co., Ltd.) ;
  • Park, Jongjeon (Dept. of Civil and Environment Engrg., Yonsei Univ.) ;
  • Jeong, Sang-Seom (Dept. of Civil and Environment Engrg., Yonsei Univ.)
  • 박희진 ((주)제일엔지니어링종합건축사무소 철도사업부) ;
  • 박종전 (연세대학교 토목환경공학과) ;
  • 정상섬 (연세대학교 토목환경공학과)
  • Received : 2022.02.24
  • Accepted : 2022.05.12
  • Published : 2022.06.30
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Abstract

This study investigates the behavior of a circular vertical shaft wall in the absence and presence of a groundwater table. The effects of wall deflection, backfill settlement, and earth pressure distribution around the circular vertical shaft caused by sequential excavations were quantified. The vertical shaft was numerically simulated for different excavation depths of the bearing layer (weathered soil, weathered rock, soft rock) and transient and steady-state flows in the absence of a groundwater table. The backfill settlements and influential area were much larger under transient flow conditions than in steady-state flow. On the contrary, the horizontal wall deflection was much larger in steady state than in the transient state. Moreover, less settlement was induced as the excavation depth increased from weathered soil to weathered rock to the soft rock layer. Finally, the horizontal stresses under steady- and transient-state flow conditions were found to exceed Rankine's earth pressure. This effect was stronger in the deeper rock layers than in the shallow soil layers.

도심지 원형 수직구 굴착 시 주변 지반의 침하는 포장 하부에 설치된 인프라시설의 안정성 뿐만 아니라 상부구조의 안정성에 큰 영향을 미친다. 배면지반의 침하량을 예측하는 방법은 지반조건, 벽체 변위, 해석 방법 등에 따라 달라지므로 근접시공 설계자는 합리적으로 침하량을 예측해야한다. 본 연구에서는 3차원 유한요소해석을 활용하여 굴착심도별로 지하수의 침투에 따른 영향을 고려하기 위해 비정상류, 정상류, 지하수를 고려하지 않은 조건으로 배면지반의 침하와 벽체의 변위 그리고 토압분포를 검토하였다. 수치해석결과, 배면지반의 침하량과 침하영향범위는 비정상류 상태가 정상류 상태보다 크게 발생하였으나 벽체의 수평변위는 반대로 정상류 상태가 비정상류 상태보다 크게 나타났다. 침하량의 크기는 굴착 깊이에 따라 다르게 나타났으며 굴착 깊이 별로 토사층에서 가장 크고 풍화암층, 연암층 순으로 감소하였다. 또한 수압을 포함한 수평응력값을 기존의 Rankine 토압식과 비교했을 때 토사지반에서는 유사한 경향을 보이나 암반층에서는 수치해석 결과보다 작은 토압형태가 나타남을 확인 할 수 있었다.

Keywords

Acknowledgement

본 연구는 정부(교육부)의 재원으로 '한국연구재단의 기초연구사업(2018R1A6A1A08025348)'의 지원을 받아 수행되었으며, 이에 감사드립니다.

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