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2020 Vol.36, Issue 12 Preview Page

Research Article

Effect of Overburden Stress on Bulb Shapes of Horizontal Compaction Grout in Loose Sand: 2D-scaled Experimental Study

상부 응력이 수평 압밀 그라우팅 구근 형상에 미치는 영향: 2차원 축소 모형 실험 연구

Hyun-Woo Joo1
,
Seung-Hun Baek1
,
Tae-Hyuk Kwon2†
,
Jin-Tae Han3
,
Ju-Hyung Lee3
,
Wan-Kyu Yoo4
주 현우1
,
백 승훈1
,
권 태혁2†
,
한 진태3
,
이 주형3
,
유 완규4
1Graduate Student, Dept. of Civil and Environmental Engrg., Korea Advanced Institute of Science and Technology
2Member, Associate Prof., Dept. of Civil and Environmental Engrg., KAIST
3Member, Research Fellow, Dept. of Intrastructure Safety Research, Korea Institute of Civil Engrg. and Building Technology
4Senior Researcher, Dept. of Intrastructure Safety Research, Korea Institute of Civil Engrg. and Building Technology
1비회원, 한국과학기술원 건설및환경공학과 박사과정
2정회원, 한국과학기술원 건설및환경공학과 부교수
3정회원, 한국건설기술연구원 인프라안전연구본부 연구위원
4비회원, 한국건설기술연구원 인프라안전연구본부 수석연구원
*t.kwon@kaist.ac.kr
31 December 2020. pp. 107-116
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Abstract

The compaction grouting technique is widely used to improve the liquefaction resistance of loose sands that are liquefaction-prone. Particularly, the horizontal injection of compaction grout is proposed for the liquefiable ground with an overlying structure as it does not allow the vertical compaction grouting. However, there has been limited number of researches on the horizontal compaction grouting. Therefore, this study explores the grout bulb shape and expansion direction in loose sand. A series of scaled two-dimensional experiments on the horizontal compaction grouting was conducted varying the overburden stress. The results show that the grout bulb grows in an elliptical shape though its directivity of major axis changes with the overburden effective stress and relative density. The grout bulb expands faster in a horizontal direction under a low overburden stress with a small relative density. The higher overburden stress and the greater relative density cause the more circular shape with the faster expansion in a vertical direction. The presented finding is expected to contribute to accurate and efficient design of the horizontal compaction grouting method.

Keywords
Gout bulb shape
Horizontal compaction grouting
Loose sand
Low mobility grout
Overburden stress

압밀 그라우팅 공법은 액상화 취약 느슨한 사질토 지반의 보강에 널리 사용되고 있다. 특히 기존에 상부 구조물이 있는 지반의 경우, 압밀 그라우팅 수직 주입이 불가능하여, 수평 주입이 대안으로 제시되고 있는 상황이다. 현재 대부분 이론과 실험은 압밀 그라우팅의 수직 주입 공법을 다루고 있는 반면, 수평 압밀 그라우팅 공법에 대한 연구는 매우 부족하다. 본 연구에서는 수평 압밀 그라우팅 공법에 대한 실내 2차원 실험을 통해 상부 구조물이나 주입 심도를 대변하는 상부 응력에 따른 그라우트 구근 형상과 팽창 방향을 분석하였다. 그 결과 그라우트 구근의 단면은 응력 이방성과 느슨함의 정도에 따라 주로 타원형으로 팽창함을 발견하였다. 특히, 낮은 상부 응력과 낮은 상대 밀도의 조건에 수평축이 긴 타원형으로 수평 방향으로 발달하였고, 상부 응력과 상대 밀도가 증가함에 따라 그 형상이 원형에 가까워지고 수직 방향으로 팽창하였다. 본 연구를 통해 수평 압밀 그라우팅 공법의 구근 팽창에 대한 이해가 높아지고 나아가 보다 정확하고 효율적인 현장 시공 설계가 가능할 것으로 기대된다.

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 36
  • No :12
  • Pages :107-116
  • Received Date : 2020-12-10
  • Revised Date : 2020-12-18
  • Accepted Date : 2020-12-18
  • DOI :https://doi.org/10.7843/kgs.2020.36.12.107
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