Impact of compression shock loads on buried pipelines

Abstract

Topical issues of interaction of metal pipes with subsoil in the structures of hidden (underground) main pipelines serving for transporting oil or gas are considered. The shock loading of pipes from the subsoil side, caused by seismic earth movements, was investigated. The loading consists of the total compacting pressure and the force local pressure. The calculations were carried out in order to establish a possibility of local buckling of the pipe (pipe wall buckling). The problem was solved in real time, taking into account the bulk of the pipe– subsoil structure and technological deviations. A 3D finite element model of the structure with unilateral constraint along the surface of the pipe-and-subsoil contact has been developed, which is presented in the form of a thick-walled cylinder. The pipe is considered as an elastoplastic body; the subsoil is considered as linearly elastic. The calculations were performed using the LS-DYNA software package in a nonlinear dynamic formulation. Numerical analysis of the stress-strain state of the steel pipe – subsoil structure showed that there were critical loads at which the pipe wall buckles. It is concluded that it is necessary to carry out dynamic calculations of buried pipelines located in seismically active regions.