小曲率半径转弯隧道盾构施工扰动实测分析

 受规划及已建结构物的制约，小曲率半径转弯盾构隧道的应用越来越广，小曲率半径转弯隧道盾构施工对紧邻土体扰动有待研究。以广州220 kV犀牛站电缆隧道工程为背景，通过动态监测小曲率半径段转弯盾构施工引起土体分层沉降、水平位移、孔隙水压力的变化，分析小曲率半径转弯隧道盾构掘进对紧邻土体的扰动规律。分析结果表明小曲率半径隧道转弯段盾构掘进过程中，隧道侧边土体沉降及水平位移与直线段隧道有显著不同，且会增加对周边环境的扰动，应引起足够重视。隧道转弯段外侧土体的沉降规律与直线段隧道不同，在盾体挤压作用下竖向离隧道较近的土层不是沉降最大的，甚至可能产生隆起。转弯段土体的深层水平位移由两部分位移的叠加而成：一是盾体通过过程中，由于盾体挤压作用而产生的向外远离隧道的位移；二是由于盾体转弯造成不对称变形，转弯外侧挤压向隧道外位移，转弯内侧卸载向隧道内位移。

Soil disturbance induced by shield advancing through a small radius path

To avoid the disturbing to the existing underground structures，shield advancing along a path with a small radius of curvature is sometimes inevitable. In this paper，the site observation data，the vertical and horizontal deformation and the pore water pressure of soils around the tunnel，were presented and analyzed when a shield advancing through a path with the radius of curvature being 118 m. It was found that the soil deformation mode was very different from those observed in the case of straight path. The soil around the tunnel on the outside of the curve was squeezed and moved upward and the horizontal displacement of soil around the tunnel consists of two parts. One part was induced by the squeezing effect，which was similar to that induced by shield advancing through a straight path，and the other part was from the turning action. The second part is nonsymmetrical. The soil on the outside of the curve moved away from the tunnel and the soil on the inside moved towards the center of the tunnel. The superimposition of the deformation increased the risk and should be paid more attention.