The Interaction between soil and buried bent pipelines

Abstract

Temperature variation, Poisson's effect of internal pressure, and differential settlement may cause significant longitudinal forces in the buried pipelines. A pipeline bend moves in the transverse direction due to these longitudinal loads. The confining soil resists the transverse movement of the bend. The strength of soil is therefore important to keep a buried pipe bend structurally safe and adequately restrained against excessive deformation.

The classical methods used for the analysis and design of buried pipe bends have proven to be inadequate in modeling the actual field behavior of the pipe-soil system. Numerical methods based on improved modeling techniques are occasionally used, but their appliction is limited for the practical purposes because of the effort reqired in modeling the complex pipe-soil composite system.

The objective of this research is to study the buried pipe bend behavior using the finite element method and then to recommend procedures that may assist in the analysis and design of soil restraint at buried pipe bends. Three-dimensional finite element analyses are carried to investigate the soil strength requirements on the horizontal and vertical buried pipe bends. Tables, graphs and charts are developed using the results of the parametric study. The results are analyzed and the importance of various parameters is discussed.