There is a huge increase in the underground metro projects due to the fact that it causes less disturbance to the public and it addresses the space constraints in congested metro cities. Due to the presence of heterogeneity in ground conditions and nearby structures, the construction of underground tunnels is always a challenging task. Moreover, heritage structures have stringent permissible settlements. Curtain walls in the form of diaphragm walls and contiguous piles have been successively used as intervention scheme to mitigate tunneling-induced settlements in abroad. In this study an attempt is made to assess the effectiveness of contiguous piles as a measure to reduce the tunneling-induced settlement for Indian sub-soil condition. The study is conducted numerically by placing the contiguous pile adjacent to the tunnel prior to tunneling and tunnel construction is carried out sequentially as the actual tunnel excavation. The effect of offset of the piles from the tunnel is studied by varying the offset from 0.75D to 2D from the tunnel axis, where D is the tunnel diameter. It was observed that the settlement of soil near the pile location is reduced by 84 to 35%, but as the distance of the pile from the tunnel axis increases, the settlement above the tunnel axis is also increased. The offset of the contiguous pile could be chosen depending on the location of building to be protected.

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Effect of Contiguous Piles in Minimizing Tunneling-Induced Surface Settlement

  • M. S. Aswathy,
  • Akanksha Tyagi

摘要

There is a huge increase in the underground metro projects due to the fact that it causes less disturbance to the public and it addresses the space constraints in congested metro cities. Due to the presence of heterogeneity in ground conditions and nearby structures, the construction of underground tunnels is always a challenging task. Moreover, heritage structures have stringent permissible settlements. Curtain walls in the form of diaphragm walls and contiguous piles have been successively used as intervention scheme to mitigate tunneling-induced settlements in abroad. In this study an attempt is made to assess the effectiveness of contiguous piles as a measure to reduce the tunneling-induced settlement for Indian sub-soil condition. The study is conducted numerically by placing the contiguous pile adjacent to the tunnel prior to tunneling and tunnel construction is carried out sequentially as the actual tunnel excavation. The effect of offset of the piles from the tunnel is studied by varying the offset from 0.75D to 2D from the tunnel axis, where D is the tunnel diameter. It was observed that the settlement of soil near the pile location is reduced by 84 to 35%, but as the distance of the pile from the tunnel axis increases, the settlement above the tunnel axis is also increased. The offset of the contiguous pile could be chosen depending on the location of building to be protected.