Analysis Method for the Longitudinal Equivalent Bending Stiffness of Shield Tunnels
(1 The college of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124; 2 BGI Engineering Consultants Ltd., Beijing 100038)
Abstract：
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 considered 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 stiffness 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.
2017, Vol. 54 