Effect of Soil Displacement Rate and Complex Loading on Soil-Pipe Interaction: A Physical Prototype Model

Abstract

Buried pipeline systems may traverse sections in moving soil masses. Large strains may be accumulated in buried pipes under long-term ground movements, and it may affect the performance of the pipes. It is a common practice in that a stress relief procedure is applied to the pipe by removing the soil around the pipe to allow the pipe to spring back to its initial state. Pipeline engineers and designers need to assess the frequency of stress relief to maintain the integrity of the pipeline to prolong its operation. The frequency of applying necessary remediation measures depend on; the rate of soil displacement, soil-pipe interaction, severity of loading, and soil conditions. A physical model has been designed and fabricated to investigate these critical effects on soil-pipe interaction. This model comprises a steel circular soil chamber (1.5 m in diameter and 1.2 m in height) rested on a rail system, and a steel pipe (150–300 mm in diameter) being embedded in a compacted soil inside the chamber. This system has unique features: (i) facilitating the pipe be subjected to relative displacements in complex oblique (combined longitudinal-transverse) loading, (ii) simulating the low soil displacement rates in the field (50 mm per year), and (iii) testing of different soil types. Test results obtained from this research program will be used to evaluate the existing guidelines (e.g., American Lifelines Alliance (ALA) and Pipeline Research Council International (PRCI)).