Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Ground Behavior around Tunnel Using Tunnel-shaped Trapdoor Model Test

터널형상의 Trapdoor 모형실험을 통한 지반 거동에 관한 연구

  • Received : 2013.12.19
  • Accepted : 2014.04.08
  • Published : 2014.04.30
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Abstract

This study conducted Trapdoor tests with actual tunnel shape, investigated the mechanical behavior of ground and loosening load on tunnels, and evaluated the mechanism of progressive failure by numerical simulation. The loosening load sharply decreased initially, but it generally increased and reached the stabilized level exhibiting the arching effect, and loose sand showed relatively higher values than those of dense sand. The shear band started from the tunnel shoulder with $63^{\circ}$ (loose sand) to $69^{\circ}$ (dense sand), and gently curved inward to the ground surface. The widths of shear band formation above the tunnel showed a range from 1.8b to 1.9b (b=Tunnel width), which are similar to those values calculated from existing formular. The vertical height of this shear band for deep tunnel was turned out to be a bit lower than that from existing studies (3.0*Tunnel Height).

본 연구에서는 실제 터널 단면의 형상을 갖는 Trapdoor시험과 수치 해석을 수행하여 주변지반의 거동, 이완하중의 분포 및 점진적인 파괴 현상에 대하여 분석하였다. 지반하중은 Trapdoor의 하강에 따라 급격히 감소 후에 다시 크게 증가하여 일정한 이완하중에 도달하여 아칭효과를 확인 할 수 있었으며, 느슨 모래의 경우가 조밀 모래 보다 상대적으로 큰 값을 나타내었다. 전단대의 형성은 터널 어깨부에서 발생하여 터널 측벽에서 $63^{\circ}$(느슨) 및 $69^{\circ}$(조밀) 방향으로 시작하여 완만한 곡선을 이루며 지표를 향하여 진행하는 형상을 나타내었다. 터널 상부에서의 전단대의 폭원은 1.83b~1.92b(b는 터널폭)로서 기존 제안식으로 구한 값과 유사한 범위를 보였으나, 전단대의 높이는 대심도의 경우 터널고의 1.5~2.0배 정도로서 기존의 제안 값(약 3.0배) 보다 상대적으로 낮은 것으로 나타났다.

Keywords

References

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