ON-BOTTOM PIPELINE STABILITY IN STEADY WATER CURRENTS

A recommended practice is established for the on-bottom stability design of a pipeline subjected to steady water currents. The analysis leading to the recommended design procedure recognizes that the water velocity decreases as the bottom is approached due to the boundary layer effect and that the magnitude of the hydrodynamic forces on the pipe will be a function of the shape of this velocity profile. The analysis also assumes that the lateral resistance to movement provided by the bottom soil is proportional to the net vertical resultant force acting on the bottom. Equilibrium, or stability, occurs when the lateral resistance is just equal to the forces exerted on the pipeline by the steady current. The resulting design equation for the required pipeline weight contains several parameters whose numerical value depends on the pipe, seawater, and soil properties. A nominal set of these values is chosen and a parametric study is made of their effect on the required pipeline weight. Design curves are generated based on the chosen parameter values, and procedures for their use are recommended. The parametric study demonstrates that the minimum specific gravity required for equilibrium is relatively insensitive to large variations in the value of most of the parameters in the design equation. It also demonstrates that the selection of the design current velocity is the most significant factor in the stability analysis. Hence, further research on stability can most profitably be aimed at developing better methods of determining the design velocity for a particular location in the ocean.

Media Info

  • Features: References;
  • Pagination: p. 763-778

Subject/Index Terms

Filing Info

  • Accession Number: 00138227
  • Record Type: Publication
  • Source Agency: Offshore Technology Conference
  • Report/Paper Numbers: V2, OTC 2598 Proceeding
  • Files: TRIS
  • Created Date: Aug 23 1976 12:00AM