Determining the Soil Modulus for Use in Soil–Pipe Interaction Modeling

Research and engineering practice for the earthquake, landslide, or tunneling response of underground pipelines has focused on large ground deformation (LGD) effects, recognizing that LGD often causes the most serious local damage in buried pipelines. The adjacent soil reaction that develops as the pipe moves, i.e., soil–pipe interaction, is of key importance in the response of underground pipelines subject to LGD. A finite-element elastoplastic model can be used to analyze the soil–pipe interaction, and the model requires a soil modulus to simulate the force versus displacement behavior. In the simulation of soil–pipe interaction, a secant modulus associated with high stress and strain should be used in the finite-element model rather than an initial tangent modulus. This research provides a strain-compatible secant modulus that can be used in a finite-element analysis (FEA) of soil–pipe interaction for lateral, upward, downward, and oblique pipe movements. The favorable comparison between the experimental data and the FEA using the strain-compatible secant modulus implies that the proposed approach is suitable to predict soil–pipe behavior under large ground deformation.