邻近既有隧道的基坑开挖,由于卸荷作用会使隧道产生变形,超过安全控制值将会对隧道的正常使用和安全运营产生影响,因此对隧道的变形控制至关重要.文中以天津某邻近既有隧道的深大基坑工程实例为依托,验证了考虑土体小应变刚度特性的有限元方法的准确性,并通过大量的二维计算模型分析邻近隧道最大水平位移与基坑开挖深度、隧道距基坑的相对位置、围护结构最大水平位移间的变形规律,提出预测邻近隧道最大水平位移的计算表达式.通过文中提出的方法进行工程预测更加省时简便,且与实测数据对比表明该方法可以较好地预测天津等软土地区基坑开挖引起的邻近隧道最大水平位移.%When excavation is close to existing tunnel,it would lead to tunnel deformation as a result of unloading.Deformation which exceeds the safety control values would have important effect on the normal usage and safe operation of tunnel.So it is important to control the deformation of tunnel.Based on a construction project of deep foundation pit of an adjacent existing tunnel in Tianjin,we verified the accuracy of the finite element method which considering the nonlinear and small strain character of soil.Parametric study was performed with 2D model to obtain the relationship between the maximum horizontal displacement of tunnel and the excavation depth,the relative location of tunnel as well as the maximum horizontal deformation of retaining structures.Finally a simplified calculation formula was proposed to predict the maximum horizontal displacement of the existing tunnel.It would be more time-saving and convenient.The calculated results were compared with the engineering projects.It showed the simplified calculation formula could accurately predict the maximum horizontal displacement of tunnel caused by excavation in Tianjin and other coastal soft soil areas.
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