Mechanical response estimation of jointed rigid pipes under normal fault rupture

The integrity of rigid pipes is significantly affected by differential ground settlements, which can inevitably induce excessive stress in the pipeline and even cause structural failure. The mechanical responses of bell-spigot jointed rigid pipes, e.g., joint shearing and barrel bending, can change remarkably, when the shear band induced by normal fault offsets passes the pipeline through a pipe joint or the midspan of a pipe segment. A systematic analytical evaluation on mechanical response of bell-spigot jointed vitrified clay (VC) pipes to ground subsidence was conducted in this study. Firstly, based on the results of laboratory full-scale test and three-dimensional finite element analysis, the development of soil resistance and bending curvature along the VC pipeline during the offset process was analyzed. Then simplified analytical solutions were proposed for estimating the maximum longitudinal bending curvature and the joint shear force in the most unfavorable pipe segment. Parametric studies were conducted to evaluate the sensitivity of burial depth and soil properties to the pipe response. Results show that the estimations using the proposed solutions agreed with the experimental measurements and numerical simulations well. The maximum allowable offset distance for pipe safety reduced significantly with the increment of burial depth, and increased gently when pipes were buried in less compacted soils. Finally, the most vulnerable portions in the VC pipeline subjected ground subsidence were discussed.