DOI QR코드

DOI QR Code

운영중인 도로터널의 측벽하부 숏크리트 보강에 의한 단면확대

Section enlargement by reinforcement of shotcrete lining on the side wall of operating road tunnel

  • 김동규 (한국건설기술연구원 SOC성능연구소 Geo-인프라연구실) ;
  • 신영완 (하경엔지니어링) ;
  • 신용석 (한국시설안전공단 일반도로팀)
  • 투고 : 2012.11.01
  • 심사 : 2012.11.20
  • 발행 : 2012.11.30

초록

도심지내 기존터널을 단면확대 시공하는 경우, 터널내 교통흐름을 유지하기 위하여 '${\sqcap}$'형태의 프로텍터를 설치한다. 터널내 프로텍터를 설치하면 터널 측벽하부에서 작업공간이 협소하여 록볼트 시공이 불가능해 질 수가 있다. 본 연구는 터널의 측벽하부에서 록볼트를 시공하지 않고 숏크리트만으로 보강하여 터널단면을 확대된 할 경우, 터널구조물의 안정성과 보강되는 최적의 숏크리트 두께를 제시하는데 목적이 있다. 본 연구를 위하여 3차선 NATM 도로터널을 4차선 NATM 도로터널로 확대 시공하는 경우에 대하여 수치해석을 수행하였다. 수치해석결과, 4차선 NATM 도로터널의 측벽하부에서 록볼트를 시공하지 않은 경우의 천단변위와 상반 내공변위는 록볼트를 시공한 경우와 거의 유사하였다. 다만, 하반 내공변위 및 숏크리트 응력은 록볼트를 시공하지 않은 경우가 록볼트를 시공한 경우보다 최대 0.57 mm 및 최대 1,300 kN/$m^2$ 크게 나타났다. 터널 측벽하부에서 록볼트를 시공하지 않아 추가 발생한 하반 내공변위와 숏트리트 응력은 25 cm인 기본 숏크리트 두께의 20%(25 cm${\rightarrow}$30 cm)만 증가시켜도 저감시킬 수 있다.

The protector with the shape of '${\sqcap}$' in cross section can be set up in the tunnel, which can be constructed for enlargement of cross section, to keep traffic flow in the tunnel. It is impossible to install the rockbolt in the side wall of tunnel due to a limited space between the protector and cutting surface of side wall. The objective of this study is to suggest the optimum thickness of shotcrete lining without rockbolt on the side wall and to evaluate the stability of tunnel enlarged. Numerical analysis was performed to evaluate the displacement at the center of tunnel, the convergence of tunnel, and the stress in shotcrete lining in 4-lane NATM road tunnel enlarged from 3-lane NATM road tunnel. The vertical displacement at the center of tunnel and the convergence of crown in the tunnel with rockbolt in the side wall were almost similar to those in the tunnel without rockbolt in the side wall. The convergence of bench/invert and the stress in shotcrete lining without rockbolt on the side wall were greater maximum 0.57 mm and 1,300 kN/$m^2$ than those with rockbolt in the side wall. The increased convergence and the stress in shotcrete lining can be reduced in incerasing of thickness of shotcrete lining about 20% (5 cm) of standard thickness, 25 cm, of shotcrete lining.

키워드

참고문헌

  1. Beak, K.H., Roh, J.R. (2007), "Case study on the widening construction of tunnel under use", 33th Korean Society of Civil Engineers Annual Convention & Civil Expo, pp. 2935-2938.
  2. Hideto Mashimo (2003), "Technological development of section enlargement for existing tunnels", Tunnels and Underground, Vol. 34, No. 9, pp. 41-48.
  3. Hujita Institute of Construction Technology Report (2009), Section Enlargement of existing tunnel on the 7th national road, Vol. 45, pp. 19-24.
  4. Kim, D.G., Jung, H.S. (2007), "Improvement of tunnel performance by cross s section enlargement of existing tunnel", Korean Geotechnical Society Magazine, Vol. 23, No. 3, pp. 14-20.
  5. Kim, W.K., Jin, B.M., Baek, K.H., Seo, K.W. (2011), "The effect of material behavior of blasted muck on the impact force applied on a protector", Journal of Korean Tunnelling and Underground Space Association , Vol. 13, No. 3, pp. 261-275.
  6. Public Works Research Institute (2003), A study of Construction Method of Section Enlargement for Existing Tunnels.
  7. Seo, K.W., Beak, K.H., Kim, W.K. (2008), "Case study on enlargement of existing tunnel in foreign countries(I)", Korean Tunnelling Association Magazine, Vol. 10, No.1, pp. 40-50.
  8. Seo, K.W., Beak, K.H., Kim, W.K. (2008), "Case study on enlargement of existing tunnel in foreign countries(II)", Korean Tunnelling Association Magazine, Vol. 10, No. 2, pp. 71-79.