Dynamics of an underground pipeline with slipping contact at soil-pipeline interface under seismic excitation: Analytical and numerical investigation of coupled problems

Abstract

As an extension of the previously proposed method of "one-dimensional" elastic deformation of the soil, a new solution of coupled seismic oscillations of underground pipeline and surrounding elastic soil in a non-ideal contact are obtained. Namely, it is assumed that slippage at the interface can occur and when it happens the shear stress is proportional to the relative displacement of the soil and that of the pipeline (dry friction condition). In a case when the incident seismic wave is a longitudinal wave propagating along the pipeline, a closed-form analytical solution of the nonstationary problem is obtained. The dependence between the maximum stresses and the pipe's coefficient of friction is investigated. In a supersonic case, when the wave propagation velocity in the pipe is less than that of the soil, at first sight paradoxical effect was identified. This effect is related to the possibility of resonance while reducing shear stresses at the interface. The effect occurs only if there is a slippage between the pipe and the soil ("seesaw effect").This approximated approach was verified via numerical simulations.