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사질토 지반에서 터널체적손실 증가에 따른 군말뚝의 하중변이와 지반거동

Pile Load Transition and Ground Behaviour due to Development of Tunnel Volume Loss under Grouped pile in Sand

  • 오동욱 (서울과학기술대학교 건설시스템공학과) ;
  • 이용주 (서울과학기술대학교 건설시스템공학과)
  • Oh, Dong Wook (Seoul National University of Science and Technology) ;
  • Lee, Yong Joo (Seoul National University of Science and Technology)
  • 투고 : 2016.12.05
  • 심사 : 2017.03.03
  • 발행 : 2017.04.01

초록

지하공간 개발은 인구증가로 인한 도심지의 지상공간 대형화로 발생되는 다양한 문제를 해결하기 위한 유용한 해결책이며, 그 중 터널은 지하공간 개발의 방법 중 가장 많이 사용되고 있는 방법이다. 터널 굴착에 따른 말뚝과 지반의 거동에 대한 연구는 많은 연구자들에 의해 수행되어 왔다. 하지만, 말뚝의 축력 분포에 대한 연구는 아직까지 많이 이루어지지 않은 실정이다. 따라서 본 연구는 느슨한 사질토 지반에서의 군말뚝 기초하부에 터널굴착으로 인한 지반의 거동 뿐만 아니라 각각의 말뚝의 축력분포를 실내모형시험을 통해 관찰하였다. 터널굴착을 모사하기 위해 체적손실율 개념을 적용하였으며, 말뚝과 지반의 파괴 메커니즘을 확인하기 위하여 일반적으로 사용하는 체적손실율(1~2%) 보다 큰 10%까지 단계별로 적용하였다. 실내모형시험 결과 체적손실율 1.5% 적용에 의해 급격한 축력감소가 발생하였으며, 말뚝의 침하량이 인접 지반의 침하량보다 1.2~4.7배 가량 더 큰 것으로 나타났다. 실내모형시험 중 근거리 사진계측 기법을 사용하여 체적손실율 1.5%일 때의 지중 거동을 정량적으로 분석하였으며, 실내모형시험 결과를 수치해석결과와 비교하였다.

A development of underground space is very useful solution to slove problem occurred from ground surface enlargement in urban areas due to the growth of population, tunnelling is the most popular way and widely used. Researches regarding tunneling-induced pile-soil interactive behaviour have been conducted by many researchers. A study on pile axial force distribution due to tunnelling through laboratory model test, however, is being rarely carried out. In this study, therefore, authors investigate ground behaviour due to tunnelling below grouped pile subjected vertical load as well as pile axial force distribution. A concept of volume loss is used to express tunnel excavation, which is normally applied to 1~2% for tunnelling in soft ground. In this study, however, 10% of that applied to investigate failure mechanism. As a result of laboratory model test, a decrease of pile axial force occurs at 1.5% of volume loss, settlement of grouped pile is 1.2~4.7 times greater than the adjacent ground surface one. Ground deformations at 1.5% of volume loss are measured using Close Range Photogrammetry and compared with results from numerical analysis.

키워드

참고문헌

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