Physical Modelling on Buried Pipeline Response in Elasto-Viscoplastic Soils

Buried pipeline systems may traverse sections of unstable soil masses. Long-term ground movement may induce large strains on the pipe over time. To maintain the integrity of the pipeline, pipeline engineers and designers need to assess the frequency of critical ground movements to perform necessary remediation such as a stress relief procedure to prolong pipeline operation. The frequency of applying necessary remediation measures will vary depending on the rate of soil displacement in elasto-viscoplastic soils such as clay. Previous experimental work on simulating soil-pipe interactions was completed extensively on granular soils such as sand. Thus, an experimental program in simulating soil-pipe interaction for buried pipes in elasto-viscoplastic soils is highlighted in this paper. The experimental setup comprises a steel soil chamber (0.9 m in width and height, 2.4 m in length) with a steel pipe (150 mm diameter) being embedded in a compacted clay inside the chamber. The pipe is subjected to relative longitudinal, vertical uplift, and horizontal transverse displacements. The equipment setup has the ability to control and vary the displacement rate of the pipe. Hence, the effect of various displacement rates on the system response or the subgrade reaction can be studied. The system response or the subgrade reaction is recorded in a data acquisition system. In this paper, preliminary results of a vertical uplift test will be compared with existing guidelines from the American Lifelines Alliance (ALA). The ALA guidelines have yet to incorporate the effect of varying soil displacement rates in determining maximum loads subjected onto a pipeline.