Effect of fluid presence on the dynamic response of imperfectly bonded buried orthotropic cylindrical shells

Abstract

In this paper the axisymmetric dynamic response of an imperfectly bonded fluid-filled orthotropic cylindrical shell, excited by a plane longitudinal wave, is considered. A thick-shell model including the effects of shear deformation and rotary inertia has been taken. Effects of imperfect bond between the shell/pipe and the surrounding soil have been included by considering a layer of an infinitesimally small thickness between the pipe and the soil. This layer possesses stiffness and damping properties against any axial or radial movement. The linear acoustic equation has been used for wave propagation in the fluid inside the pipe. It is found that under certain conditions the effect of fluid presence can become comparable to the effect of loose contact between the shell and the surrounding soil. Also, it has been found that the presence of fluid inside the pipeline alters the radial displacement of the shell more than its axial displacement, and sometimes its effect is greater on an imperfectly bonded shell than it is on a perfectly bonded shell. In general, however, the fluid effect is not found to be as important as that of the bond imperfection between the shell and the ground.