盾构隧道纵向等效弯曲刚度的分析方法研究

Analysis Method for the Longitudinal Equivalent Bending Stiffness of Shield Tunnels

随着国内外盾构隧道的大量建设和使用,隧道的过量沉降,特别是纵向不均匀沉降引起的问题越来越突出。目前国内外盾构隧道纵向结构性能研究和计算模型理论还不完善,隧道的纵向刚度的确定是其中的重点与难点问题之一。文章通过采用下穿既有隧道的结构变形监测数据反分析隧道纵向弯曲刚度,规避了目前计算分析中难以综合考虑盾构隧道拼装方式、横向刚度、螺栓作用等诸多因素的问题,为盾构隧道纵向弯曲刚度的确定提供了一种新方法。研究发现,盾构隧道在变形过程中纵向刚度并不是不变的,而是会随着隧道的变形而发生变化,呈现非线性特征,并建立了隧道结构纵向刚度有效率与隧道结构最大纵向变形之间的拟合关系。

With more and more shield tunnels being constructed, the problems caused by excessive settlement are increasingly prominent, especially by longitudinal uneven settlement. At the present time, the study of longitudinal structural performance and the theoretical calculation model for shield tunnels are still imperfect, and the determination of the longitudinal stiffness of a tunnel is a key and difficult problem. In this paper, the longitudinal stiffness of a tunnel is back analyzed by the deformation monitoring data of the structure beneath an existing tunnel, providing a new analysis method for the longitudinal bending stiffness calculation of shield tunnels. A variety of factors are con- sidered using this new method, such as the segment erection method, the tunnel＇s transverse stiffness and the bolt function, which is quite different for the present calculation method. The research shows that the longitudinal stiff- ness of a shield tunnel varies with tunnel deformation and is nonlinear. A fitting relationship is established between the efficiency ratio of the longitudinal stiffness and the maximum longitudinal deformation of the tunnel structure.