On the effect of soil water saturation on buried steel pipe responses under external load

Abstract

Soil water saturation affects soil behavior when subjected to external loads and thus buried pipe deformation. To investigate this effect, full-scale tests were conducted on a buried steel pipe with a diameter of 600 mm. The deformed pipe ring transforms from a “heart” shape into an inclined “heart” shape due to the load redistribution within the soil after increasing soil water saturation. Then, a three-dimensional finite element model was created and validated based on the experimental data. A parametric study was thereafter performed to investigate the impact of factors including soil water saturation, cover depth, and pipe wall-thickness on buried pipe responses when subjected to external loads. Soil might be simply modeled as a linear elastic material at a large cover depth (>0.6 m) or a water saturation < 80%. Soil plasticity should be considered at a relatively low cover depth (≤0.6 m) and a high water saturation (≥80%). The pipe circumferential stress is inversely proportional to the square of pipe wall-thickness when the pipe–soil stiffness ratio is equal to or greater than 0.13.