Pipe-Soil Interaction Model Incorporating Large Lateral Displacements in Calcareous Sand

Abstract

The use of the plasticity theory offers an attractive framework to encapsulate the behavior of a pipe and the underlying soil in terminology consistent with pipeline structural analysis. Models that express the pipe-soil behavior purely in terms of the loads on a segment of pipe and the corresponding displacements have been suggested, although verification with geotechnical centrifuge experiments has been limited to relatively small lateral displacements (i.e., less than two pipe diameters). Over larger movements, the berms that build up alongside the pipe affect the load-displacement behavior, with existing strain-hardening plasticity models incapable of simulating this transition. This technical note provides experimental evidence of pipe-soil behavior for lateral displacements for up to five diameters. It further presents observations from 20 centrifuge experiments of a prototype 1-m-diameter pipe in calcareous sand. The results are used to validate the modification of a pipe-soil model to include the horizontal displacement hardening of the yield surface. Retrospective numerical simulations of the centrifuge experiments verify the modified model’s performances for lateral displacements of up to five diameters which was also the extent of the centrifuge experiments. This incorporation of large lateral displacements has significant application in on-bottom stability analysis as displacement-based design becomes more prevalent.