Mechanics of Buried Pipelines Loading under Localized Subsidence: A Three-Dimensional Soil-Arching Approach

Abstract

The combined effects of localized subsidence-induced size effects and pipe–soil interaction render conventional load calculation theories inadequate for accurately evaluating pipeline loads after foundation subsidence. To overcome this limitation, the 3D transfer characteristics of vertical loads acting on buried pipelines under localized subsidence are investigated from the perspective of the spatial deflection of 3D principal stresses and the evolution of stress trajectories. On this basis, a 3D soil arching model is established by incorporating the combined contributions of overburden self-weight, lateral passive earth pressure, and boundary friction. Further, a 3D pipe–soil load-transfer framework consisting of the top zone, the up zone, and the gap zone is constructed, through which a unified analytical expression for the vertical load at the pipe crown under localized subsidence is derived. The analytical predictions are validated against data from two laboratory trapdoor tests, which reveal considerable differences in pipeline crown loads between tests and pronounced variations in vertical earth pressure within the same test as trapdoor displacement increases. The results demonstrate that the proposed model provides a more comprehensive representation of stress redistribution in deformation zones induced by pipe–soil interaction under localized subsidence. By explicitly incorporating the geometric configuration and mechanical characteristics of the soil segments within the collapse area, the model offers enhanced explanatory power and predictive accuracy compared with traditional approaches.