考虑盾构隧道轴线倾角的施工地表变形评价

Evaluation of Surface Deformation Considering Inclination Angle of Shield Tunneling Axis

针对盾构掘进过程中地层损失引起的地表变形,目前的理论解析法均假设盾构沿水平线进行掘进,尚未考虑盾构施工角度因素对地表变形的影响效应。基于修正源汇法公式,引入盾构俯仰角、隧道轴线倾角因素,通过离散方法建立考虑隧道轴线倾角的地表变形计算公式。通过基于实际工程参数的数值模拟计算及工程监测数据对提出的方法进行有效性验证,在此基础上深入分析隧道轴线倾角对地表变形的影响规律。分析表明,隧道轴线倾角对地表变形有明显影响:纵断面上,倾角直接影响地表变形曲线的斜率;横断面上,随着倾角增大,地表最大沉降越大,沉降槽越窄,变形曲线越尖锐。提出的考虑盾构隧道轴线倾角的施工地表变形评价方法能够反映实际施工时角度因素对地表变形的影响。

The ground loss in shield tunneling always induces surface settlement.The current theoretical analysis methods assume that the shield machine is driving along a horizontal line,while the influence of shield construction angle on the surface deformation is not considered.As a result,based on the corrected formula of image method,the shield elevation angle and tunnel axis inclination angle are introduced,and the surface deformation calculation formula considering the tunnel axis inclination is established by discrete method.The effectiveness of the proposed method is verified by numerical simulation of the actual engineering parameters and engineering monitoring data.On this basis,the influence of tunnel axis inclination on surface deformation is further analyzed.The analytical results show that the inclination angle of tunnel axis has obvious influence on the surface deformation,which is reflected in two aspects as follows:(1)on the vertical section,the inclination angle directly affects the slope of the surface deformation curve;and(2)on the cross-section,with the increase of the inclination angle,the maximum surface settlement increases,the settlement trough becomes narrower,and the deformation curve becomes sharper.The evaluation method of construction surface deformation considering the inclination angle of shield tunnel axis can reflect the influence of angle factor on surface deformation in actual construction.