双线盾构隧道斜交下穿既有机场高速公路的地表沉降预测模型研究*

为指导隧道盾构下穿既有建构筑物施工的变形控制，考虑隧道收敛模式和复合地层主要影响角的影响，以双线圆形盾构隧道斜交下穿既有机场高速公路为例，构建圆形隧道地层主要影响角计算方法，改进传统Peck公式，分析盾构斜交角、盾构坡角和隆起偏角的共同影响，引入地层损失率几何修正系数，并利用叠加原理建立双线盾构隧道斜交下穿既有机场高速公路的地表沉降预测模型，依托实际工程对预测模型的工程适用性进行验证。研究结果表明:本文预测模型的整体精度相比Suwansawat等预测模型提升44.15％，可预测施工影响范围内任意点的地表沉降值，相比现有模型更适用于解决双线盾构隧道斜交下穿施工的地表沉降预测问题，可为类似工程中的地表沉降变形预测及控制提供指导。

Study on prediction model for ground settlement of double-track shield tunnel oblique undercrossing existing airport expressway

In order to guide the deformation control in the construction of tunnel shield undercrossing the existing buildings and structures,considering the influence of the tunnel convergence mode and the main influence angle of composite stratum,taking the double-track circular shield tunneling oblique undercrossing the existing airport expressway as an example,the calculation method of the main influence angle of circular tunnel stratum was constructed,and the traditional Peck formula was improved to analyze the joint influence of the shield skew angle,the shield slope angle and the uplift deflection angle.The geometric correction coefficient of stratum loss rate was introduced,and the prediction model for the ground settlement of double-track shield tunnel oblique undercrossing the existing airport expressway was established by using the superposition principle.The engineering applicability of the prediction model was verified by the actual project.The results showed that the overall accuracy of the prediction model was 44.15% higher than that of the prediction model of Suwansawat et al.,and it could predict the ground settlement value at any point within the scope of construction influence.Compared with the existing models,it was more suitable for solving the ground settlement prediction problem in the oblique undercrossing construction of double-track shield tunnel,and provides the guidance for the prediction and control of ground settlement deformation in similar projects.