基坑开挖引起下卧隧道隆起变形的实测数据分析

在上跨隧道的基坑工程中基坑开挖常引起下卧隧道发生结构变形，限制隧道的隆起变形成为基坑施工控制的关键。详细介绍了该类工程的特点，包括交叉形式、隧道变形特点、常见控制措施等，对近期国内发生的39例类似工程进行分类总结，分析了隧道纵向最大隆起变形与各影响因素间的关系，并提出了隧道最大隆起变形的预测模型。结果表明，该类工程中工程地质对隧道的隆起变形影响较大，工程地质条件越差隧道的隆起变形越难控制；开挖深度、基坑面积、基坑形状同样是影响隧道隆起变形的重要因素，基坑开挖面积及深度越大，形状越不规则，隧道的隆起变形越大；在软土地区，当基坑开挖面积及深度较大时设置抗拔桩能显著减小隧道的最大隆起变形。

Measurement data analyses of heave deformation of shield tunnelsdue to overlying pit excavation

Restricting the heave of underlying tunnels is crucial to the construction control of excavations, as pit excavations will cause structure deformation of tunnels in the excavation engineering on existing tunnels. This paper detailedly introduces the characteristics of excavations above existing tunnels, including the crossing directions, tunnel deformation modes, and common controlling measures. 39 similar projects recently constructed in China are categorized and analyzed. Based on the influence of every factor on maximum tunnel heave in longitudinal direction, a model is established to predict the tunnel heave. The results show that the engineering geology conditions have a greater influence on the tunnel deformation in such projects. The worse the engineering geology conditions are, the harder the controlling of tunnel heave will. The other important factors of the tunnel deformation are excavation depth, pit area and shapes of excavations. The tunnel deformation will increase with the excavation depth and pit area. The more irregular of the foundation pit, the harder the controlling of tunnel heave. In soft clay area uplift piles can effectively reduce the maximum deformation of tunnels in the large and deep excavation engineering.