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

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
권호 표지

Earth pressures acting on vertical circular shafts considering arching effects in c-$\phi$ soils : II. Lab. Model Tests

c-$\phi$ 지반에서의 아칭현상을 고려한 원형수직터널 토압 : II. 실내 모형실험

  • 김도훈 (고려대학교 건축사회환경공학부) ;
  • 차민혁 (고려대학교 건축사회환경공학부) ;
  • 이대수 (한국전력공사 전력연구원) ;
  • 김경렬 (한국전력공사 전력연구원) ;
  • 이인모 (고려대학교 건축사회환경공학부)
  • Received : 2009.12.24
  • Accepted : 2010.01.18
  • Published : 2010.03.31

Abstract

The earth pressure acting on the vertical shaft is less than that acting on the retaining wall due to three dimensional arching effect. Thus, it might be essential to estimate the earth pressure actually acting on the shaft when designing the vertical shaft. In this paper, large-sized model tests were conducted as Part II of companion papers to verify the newly suggested earth pressure equation proposed by Kim et al. (2009: Part I of companion papers) that can be used when designing the vertical shaft in cohesionless soils as well as in c-$\phi$ soils and multi-layered soils. The newly developed model test apparatus was designed to be able to simulate staged shaft excavation. Model tests were performed by varying the radius of vertical shaft in dry soil. Moreover, tests on c-$\phi$ soils and on multi-layered soils were also performed; in order to induce apparent cohesion to the cohesionless soil, we add some water to the dry soil to make the soil partially-saturated before depositing by raining method. Experimental results showed a load transfer from excavated ground to non-excavated zone below dredging level due to arching effect when simulating staged excavation. It was also found that measured earth pressure was far smaller than estimated if excavation is done at once; the final earth pressure measured after performing staged excavation was larger and matched with that estimated from the newly proposed equation. Measured results in c-$\phi$ soils and in multi-layered soils showed reduction in earth pressures due to apparent cohesion effect and showed good matches with analytical results.

Keywords

File

Download PDF

Acknowledgement

Supported by : 한국전력공사 전력연구원

References

  1. 김도훈, 이대수, 김경렬, 이용희, 이인모 (2009), "c-$\phi$지반에서의 아칭현상을 고려한 원형수직터널 토압: I. 이론", 터널기술, 한국터널공학회 논문집, 제11권, 제2호, pp. 117-129.
  2. 신영완 (2004), "사질토 지반에 설치된 원형수직구의 흙막이벽에 작용하는 토압", 박사학위 논문, 한양대학교.
  3. 이인모, 문홍표, 이대수, 김경렬, 조만섭 (2007), "다층지반에서의 아칭현상에 의한 수직갱 토압", 터널기술, 한국터널공학회 논문집, 제9권, 제1호, pp. 49-62.
  4. 정지희 (2009), "불포화토의 겉보기점착력이 지하구조물 거동에 미치는 영향", 석사학위 논문, 고려대학교.
  5. 천병식, 신영완 (2003), "사질토 지반의 원형수직구에 설치된 흙막이벽에 작용하는 토압", 한국지반공학회 논문집, 제19권, 제5호, pp. 175-187.