Three-Dimensional Soil-Arching Model for Predicting Earth Pressure on Buried Pipelines under Localized Subsidence

Localized foundation subsidence can lead to catastrophic failure of adjacent buried pipelines, severely compromising their serviceability. As a common cause of municipal pipeline damage, localized subsidence remains insufficiently understood, particularly in terms of the load-transfer mechanisms and stress-redistribution patterns in the surrounding soil and pipeline structure. In pipeline design, the earth pressure within the subsidence zone is a key design parameter. However, the combined influence of size effects and complex pipe-soil interaction makes classical theories inadequate for accurately predicting earth pressure, resulting in considerable discrepancies between theoretical and measured values. To overcome these limitations, this study systematically investigates the stress-redistribution mechanisms induced by localized subsidence through analytical methods. A three-dimensional soil-arching framework incorporating triaxial principal stress states is developed, accompanied by three geometric models—upward-convex, saddle-shaped, and downward-concave—to evaluate loading under different geotechnical conditions. Comparative validation against experimental data demonstrates that the proposed method effectively captures boundary load-transfer characteristics and size effects. The results indicate that the model, by fully accounting for the spatial distribution of the three principal stresses, offers superior predictive capability for load transfer under both plane-strain and three-dimensional conditions. The calculated soil-arching ratios agree well with experimental observations, confirming the validity of the proposed approach and its improvement over traditional methods in analyzing load redistribution caused by localized foundation subsidence.