• Title, Summary, Keyword: Final tunnel arch settlement

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Relations between Initial Displacement Rate and Final Displacement of Arch Settlement and Convergence of a Shallow Tunnel (저심도 터널의 천단침하 및 내공변위의 초기변위속도와 최종변위의 관계)

  • Kim, Cheehwan
    • Tunnel and Underground Space
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    • v.23 no.2
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    • pp.110-119
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    • 2013
  • It is generalized to measure the arch settlement and convergence during tunnel construction for monitoring its mechanical stability. The initial convergence rate a day is defined from the first convergence measurement and the final convergence defined as the convergence measured lastly. The initial and the final tunnel arch settlement are defined like the preceding convergence. In the study, the relations between the initial and final displacements of a shallow tunnel are analyzed. The measurements were performed in the tunnel of subway 906 construction site in Seoul. The overburden is 10-20 m and the tunnel goes through weathered soil/rock. The width and height of the tunnel are about 11.5 m, 10m, respectively. So this is a shallow tunnel in weak rock. The length of tunnel is about 1,820 m and the tunnel was constructed in 2 stages, dividing upper and lower half. The numbers of measurement locations of arch settlement and convergence are 184 and 258, respectively. As a result, the initial displacement rate and the final displacement are comparatively larger in the section of weathered soil.

A Study on the Prediction of Surface Settlement Applying Umbrella Arch Method to Tunnelling (Umbrella arch 공법의 적용에 따른 횡방향 지표침하량 예측에 관한 연구)

  • 김선홍;문현구
    • Tunnel and Underground Space
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    • v.12 no.4
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    • pp.259-267
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    • 2002
  • Recently, Umbrella Arch Method(UAM) is commonly used in order to enhance the stability of tunnel itself and stabilize the adjacent surface structure. But quantitative estimation of reinforcement effect is needed because UAM is designed and constructed only on the basis of empirical experience. By using 3-dimensional finite element method, parametric study is performed for elastic modulus of ground and overburden, and reinforcement effect is analyzed quantitatively. From the results, surface settlement decreases about 9%∼27% in soil tunnel, about 4%∼24% in weathered rock tunnel and 4%∼17% in soft rock tunnel when applied with UAM. The prediction equation for final surface settlement is suggested through regression analysis and the equation is expressed as exponential function which has variable Smax, unknown coefficient i and k.

Forecasting Final Displacement With Displacement Functions Using Deformation Measurements While Constructing a Tunnel (계측치와 변위함수에 의한 시공 중인 터널의 최종변위 예측)

  • Kim, Chee-Hwan
    • Tunnel and Underground Space
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    • v.20 no.6
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    • pp.408-420
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    • 2010
  • It is important to forecast the final deformation of a tunnel during construction for evaluating its mechanical stability. In this study, the final deformation of a tunnel is forecasted by fitting tunnel deformations measured while excavating to a displacement function and exterpolating it. The tunnel for the study was built in two stages divided into an upper and a lower part. During the lower part construction of the tunnel, the displacement function forecasts the final incremental displacement well compared to the increment measured after completion of the tunnel. It is because the critical initial displacement occurred on passing the measurement pins can be adequately measured during excavating the lower part, which can not be measured during the upper part excavation of the tunnel.