Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Experimental Evaluation of the Effect of Fine Contents on the Formation of Underground Cavities and Ground Cave-ins by Damaged Sewer Pipes

하수관 손상으로 인한 지하공동 및 지반함몰 발생에 대해 세립분 함량이 미치는 영향의 실험적 평가

  • Kwak, Tae-Young (Dept. of Geotechincal Engrg. Research, Korea Institute of Civil Engrg. and Building Technology) ;
  • Lee, Seung-Hwan (Korea Construction Standard Center, Korea Institute of Civil Engrg. and Building Technology) ;
  • Chung, Choong-Ki (Dept. of Civil & Environmental Engrg., Seoul National Univ.) ;
  • Baek, Sung-Ha (Dept. of Geotechincal Engrg. Research, Korea Institute of Civil Engrg. and Building Technology)
  • 곽태영 (한국건설기술연구원 지반연구본부) ;
  • 이승환 (한국건설기술연구원 국가건설기준센터) ;
  • 정충기 (서울대학교 건설환경공학부) ;
  • 백성하 (한국건설기술연구원 지반연구본부)
  • Received : 2021.10.27
  • Accepted : 2021.11.22
  • Published : 2021.11.30
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Abstract

In this study, we evaluated the effect of soil fine contents on the formation of underground cavities and ground cave-ins induced by damaged sewer pipes. Simulating the domestic rainfall conditions and ground conditions, model tests were performed under three different fine particle contents conditions (7.5%, 15%, and 25%). By repeating the groundwater supply and drainage twice, ground settlement and the amount of discharged soil were obtained. Also, digital images were taken at regular time intervals during the model tests, and internal displacement and deformation were measured using PIV technique. As the cycles were repeated, the soil with high fine content showed greater resistance to the formation of underground cavities. The ground cave-ins, identified by the collapse of the surface, occurred only when the fine particle content was 15%. It is presumed to be due to the suffusion phenomenon; further study was needed to investigate the effect of fine particle contents on the suffusion phenomenon and associated changes of soil strength.

본 연구에서는 매립토의 세립분 함량이 파손된 하수관으로 인해 유발되는 지하 공동 및 지반함몰에 미치는 영향을 평가했다. 국내 강우 조건 및 지반 조건을 모사하였으며, 서로 다른 세 가지 세립분 함량(7.5%, 15%, 25%)을 적용해 지반함몰 모사시험을 수행했다. 모형지반을 조성한 뒤 하수관 손상부를 모사한 부분을 통해 지하수를 유입하고 배출시키는 과정을 두 차례 반복하며, 지표면 침하량 및 배토량을 측정했다. 또한 모형시험 중에 일정 시간 간격으로 디지털 이미지를 촬영하고 이를 PIV 기법을 통해 분석하여 내부 변위 및 변형(지하 공동 형성 과정)을 측정하였다. 시험 결과, 지하수 유입 및 배출 단계가 반복됨에 따라, 세립분 함량이 높을수록 배토량이 적고 지하 공동 형성이 억제되는 것으로 나타났다. 다만, 지표면 붕괴로 확인되는 지반함몰은 세립분 함량이 15%인 경우에만 발생했다. 이는 배토된 흙의 세립분 함량 변화를 통해 서퓨전(suffusion) 현상에 기인한 것으로 분석되어, 세립분 함량이 서퓨전 현상 발현에 미치는 영향과 이에 따른 지반 강도 변화에 대한 추가연구가 필요함을 확인했다.

Keywords

Acknowledgement

본 연구는 한국건설기술연구원 (21주요-대1-임무) 지하공간 정보 정확도 개선 및 매설관 안전관리 기술개발(2/3)의 지원으로 수행되었습니다. 또한 본 연구는 2017년도 정부(미래창조과학부)의 재원으로 한국연구재단의 지원(과제번호 : 2015R1A2A1A01007980)을 받아 수행되었습니다. 이에 감사의 뜻을 표합니다.

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