Effect of pipe installation and external load on buried steel pipe responses: Experimental and numerical investigations

During pipe installation, compacting soil at pipe sides causes an initial pipe deformation which is known as the “peaking” effect. However, in conventional pipe design codes, only pipe deformation caused by vertical overburden is considered while the “peaking” effect is ignored. In this study, a full-scale test was conducted on a Grade X52 steel pipe with a diameter of 600 mm to investigate the impacts of both soil compaction and vertical overburden on pipe deformation. Soil compaction and external load were found to elongate and shorten the vertical pipe diameter, respectively. The “peaking” effect was observed during the installation procedure accompanied by the highest pipe stress measured at the pipe crown. Then, a two-dimensional finite element model was created and validated based on the calculated pipe stresses from the experimental study. A parametric study was performed thereafter to numerically study the impacts of soil water content, pipe wall thickness, compaction pressure, and lift thickness on pipe responses due to soil compaction and external load. An increase in the “peaking” effect is observed with increasing soil water content and compaction pressure, while an increase in pipe wall thickness or lift thickness would cause a decrease in the “peaking” effect.