盾构小夹角下穿运营隧道扰动特性及施工因素敏感性分析

Disturbance Characteristics and Sensitivity to Construction Factors of Shield Tunneling at Small Angles under Operational Tunnel

摘要:

通过建立符合工程特点的FEM模型，研究了大型盾构隧道超小夹角下穿湖底运营隧道的扰动风险及关键工艺因素的敏感性。重点分析了不同地层损失率（0.5%~3.5%）和注浆压力（欠压、等压、超压）对上部隧道竖向位移、应力分布以及桩基承载特性的影响，以及盾构隧道自身结构稳定状态。结果表明，扰动应力场和位移场呈现非对称三维复杂分布状态，随地层损失率的增大，上部隧道竖向位移和Von Mises应力呈线性增大趋势；下部非均匀卸载引发桩基摩阻力和承载模式的区域差异特性，并与地层损失率和注浆压力等施工因素呈现显著的依存关系；随地层损失率增大，桩基承压性能弱化但抗拔性能增强。研究结果对穿越施工设计及其风险防控具有指导意义。

Abstract:

By establishing a FEM model that conforms to the engineering characteristics, the disturbance risk and the sensitivity to key technological factors of a large shield tunneling at a very small angle under a lake-bottom operational tunnel are studied. The influences of different ground loss rates (0.5% to 3.5%) and grouting pressures (under-pressure, equal-pressure and over-pressure) on the vertical displacement and stress distribution of the upper tunnel, the bearing characteristics of the pile foundation, and the stability state of the shield tunnel itself are analyzed in detail. The results show that the disturbance stress field and displacement field present a non-symmetric three-dimensional complex distribution state. With the increase of the ground loss rate, the vertical displacement and Von Mises stress of the upper tunnel show a linear increasing trend. The non-uniform unloading of the lower part causes the regional differences in the frictional resistance and bearing mode of the pile foundation, which show a significant dependence relationship with construction factors such as ground loss rate and grouting pressure. With the increase of the ground loss rate, the pressure-bearing capacity of the pile foundation weakens, but the uplift resistance enhances. The research results have guiding significance for the design and risk control of the shield tunneling.