Different failure modes assessment of bell-spigot jointed ductile iron pipes under abrupt transverse ground movements

Abrupt ground movements induced by earthquake, landslide, tunnelling and excavation, etc., pose significant threats to the safety of underground jointed pipelines. Most previous studies have investigated the response of buried pipelines through experimental tests and numerical simulations, but analytical solutions for the safety evaluation of jointed pipelines are limited. In this study, enhanced analytical solutions of pipe bending moment and joint shear force are derived, in which the effects of different pipe-fault crossing configurations and pipe-soil interactions are considered. Then, the allowable offset distances are investigated using the proposed solutions, respectively, for three different failure modes, i.e., joint shear failure, pipe bending failure, and joint pull-out failure. The results show that the joint pull-out failure governs the pipe safety when the burial depth is relatively shallow, while the pipe bending failure dominates when they are buried deeply. The worst pipe-fault crossing position is not at the pipe joint or the midspan of the pipe segment, but at one tenth of the pipe segment adjacent to the joint. The results offer new insights into buried DI pipe failure mechanism and provide a basis for the protection of buried DI pipes under abrupt transverse ground movement conditions.