Stability analysis of the middle wall in process of double-arch tunnel construction

Abstract

As the main bearing components of double-arch tunnels, the stability of the middle wall is related to the construction safety of double-arch tunnels during construction and operation. Different construction methods of double-arch tunnel have great influence on the stability of middle wall, especially when the excavation span is large and the buried depth is very shallow. Based on an ultra-shallowly buried double-arch tunnel with extra-large spans in Xiamen, China, the mechanical response and deformation law of the middle wall are obtained. Furthermore, the performance of the CRD method and the double-side-drift method for optimizing the deformation and stress state of the middle wall are compared. The results can serve as initial guidelines for the for the selection of double-arch tunnel construction schemes.