软土大直径盾构隧道极端近距离穿越桩基影响规律研究

Study on Influence Rule of Large-diameter Shield Tunneling through Pile Foundation in Extreme Close Distance in Soft Soil

摘要:

以上海轨道交通市域线机场联络线工程为例，研究了软土大直径盾构隧道在极端近距离条件下侧穿桩基的影响规律。基于PLAXIS 3D有限元软件建立了考虑大直径盾构施工过程的数值分析模型，揭示了不同地层损失率对桥台、桥桩变形及桩基附加弯矩的影响规律。结果表明：当地层损失率为2.5‰时，桥台和桥桩的最大变形均小于10 mm，变形控制在允许范围内；通过加固盾构隧道穿越段土体以及桥桩承台区域可有效控制盾构隧道近距离侧穿越桩基的影响。

Abstract:

Taking the Shanghai Urban Rail Transit Airport Link Project as an example, the influence rule of large-diameter shield tunneling through the pile foundation in the extreme close distance in soft soil is studied. Based on PLAXIS 3D finite element software, a numerical analysis model considering the process of large-diameter shield tunneling is established to reveal the influence rules of different ground loss rates on the deformations of bridge abutment and bridge piles, and the additional bending moment of pile foundation. The results indicate that when the ground loss rate is 2.5‰, the maximum deformations of the bridge abutment and bridge piles are both less than 10 mm, and the deformation is controlled in the permitted range. The influence of shield tunneling through pile foundation in the close distance can be effectively controlled by reinforcing the soil in the shield tunneling section and the base slab area of bridge pile.