Force properties of longitudinal interaction of the underground pipeline with soil

Abstract

The reliability of underground trunk pipelines, in most cases, is estimated based on their strength. When determining the strength of underground pipelines under seismic effects, it is necessary to take into account the forces of pipe-soil longitudinal interaction (the friction force) in calculations. Currently, linear relationships are used to describe the longitudinal interaction forces, where the interaction force is determined depending on the value of the pipe displacement relative to soil. The dependences of the interaction forces on the seismic stress state of soil are not taken into account at all. The paper shows that the interaction forces on the contact surface of an underground pipeline with soil are complex in nature and depend on the wave parameters in soil and in the pipeline itself. Based on the numerical results of solving one-dimensional unsteady-state coupled wave problems for the interacting system “underground pipeline-soil”, the pattern of changes in interaction forces on the pipeline-soil contact surface are determined. It was found that an account for static and dynamic soil pressure normal to the contact surface leads to quantitatively different results than when only static pressure is considered. It is shown that when solving the reliability problems of underground trunk pipelines under seismic effects, first it is necessary to take into account the dynamic stress-strain state of soil in the vicinity of the pipeline.