隧道下穿引起地下管线竖向位移的计算方法研究

Calculation Method for Settlement of Underground Pipelines Induced by Shield Undercrossing

为建立盾构隧道正交下穿施工引起的管线变形计算理论,将既有管线视为连续长梁,结合横观各向同性条件下的小孔扩张理论,导出管线在下穿盾构隧道施工作用下的竖向位移计算式。结合工程实例对该计算方法进行算例验证,并在此基础上定量分析管线竖向位移与各向异性参数、隧道外径、净距、管线抗弯刚度等因素的关系。结果表明:1)管线最大竖向位移发生在下穿正交点处;2)各向异性参数越大,对管线竖向位移的影响越显著;3)净距在某一范围内时,管线竖向位移对其变化较敏感,超过此范围后管线竖向位移基本无变化;4)盾构隧道外径、管线抗弯刚度对既有管线竖向位移也有一定的影响。

A theoretical model based on the elastic foundation beam theory and cavity expansion theory is presented,so as to calculate the vertical displacement of existing underground pipelines. And the transverse isotropic characteristics of the soil are taken into consideration. The solution is then degenerated into isotropic results and is verified by a case study. The multiple factor analysis revealed that： 1） The larger the tunnel＇s radius and anisotropic parameters are,the greater the influence on the vertical displacement of the existing pipeline is. 2） The vertical clear distance z0 would have a significant impact on vertical displacement of the underground pipeline when the value of z0 is less than 2. 5D. 3） The external diameter and the bending strength of the shield tunnel affect the vertical displacement of the underground pipeline a little.