On the Mechanics of a Subsea Gas Pipeline Vibration

A well-posed boundary value problem of mathematical physics, governing the vibration characteristics of a deep offshore gas transmission pipeline, as influenced by the mechanics of fluid-structure-mud flow interaction is formulated. For this problem, a segment of a gas transmission pipeline is partially buried in the muddy soil under the ocean-floor, which is idealized as an elastic beam on an elastic foundation, is investigated analytically. By employing integral transforms, closed form analytical results, for the dynamic interaction response and the two natural frequencies associated with each mode of vibration are derived. In particular, the effect of operating variables such as the internal fluid transmission velocity, temperature and pressure variations, compressibility factor, geotechnical properties, debris and mud flow velocities are demonstrated for design analysis and field applications.