Structural analysis of segmented tunnel rings : a combination of transfer relations with an interface law

Abstract

Structural analysis of segmented tunnel rings is challenging, because displacement discontinuities and relative rotation angles develop at segment-to-segment interfaces. To meet this challenge, a hybrid method was recently developed by Zhang et al. (2017). It uses the known external loading and measured interfacial discontinuities as input for structural analysis. The latter is based on analytical transfer relations, representing solutions of the governing equations of the linear theory of slender circular arches. The present contribution goes one step further. In order to enable structural analysis without measured interfacial discontinuities, the transfer relations are combined with an interface law. The latter represents a mathematical relation between the bending moment transmitted across a typical segment-to-segment interface and the resulting relative rotation angle. The proposed approach is applied to linear structural analysis of the first four load steps of a real-scale test on a segmented tunnel ring. Corresponding results are compared with the output of the aforementioned hybrid method. This way, it is shown that the presented method delivers reasonable estimates of the inner forces. However, the displacements are predicted less accurately, because rigid body motions of the segments cannot be quantified by interface laws.