复合地层中超大直径泥水盾构施工开挖面泥水压力确定方法研究

Study of Determination Method for Slurry Pressure on Excavation Face of Super-large Slurry Shield Tunnel in Composite Ground

在超大直径泥水盾构施工中,泥水压力的控制是保证开挖面稳定的关键。依托正在新建的上海北横通道工程,利用三维数值分析方法,总结出适用于软土复合地层超大直径泥水盾构施工的开挖面泥水压力确定方法,并根据北横通道现场实测数据对该方法进行对比分析。研究结果显示:1)超大直径泥水盾构泥水压力最佳平衡计算点位主要与土层厚度比和上下土层有效内摩擦角差值有关;2)在近似均一地层中可以取盾构中心点作为平衡点位,这与以往工程经验相吻合;3)复合地层中可通过理论计算确定最佳平衡计算点位。

The slurry pressure control is the key to excavation face stability during super-large slurry shield tunneling.Based on the Beiheng Tunnel in Shanghai under construction,a determination method for slurry pressure on excavation face of supper-large slurry shield tunnel in composite ground is summarized by three-dimensional numerical analysis method. The results of the method application are compared with the site monitoring data. The study results show that：（ 1） The optimal balance between slurry and pressure is related to the thickness ratio of soil layer and the effective internal friction angle of upper and lower soil layers.（ 2） In the approximate uniform stratum,the shield center point can be selected as the balance point,which is in accordance with engineering experience in practice.（ 3） In the composite ground,the optimal balance point can be determined by theoretical calculation.