Investigation Depth of Buried Pipeline on Stress

In this study, finite element models of the pipeline and soil are established using the package ABAQUS to carry out stress analysis of buried pipeline caused by static and seismic loads. In order to perform this analysis for a buried gray cast pipeline, it is necessary to accept three basic assumptions as below.
1- The welding between pipeline segments is not considered.
2- The soil is elasto-plastic characterized by Mohr Coulomb theory and the pipeline is isotropic, elastic and perfectly plastic.
3- Pipeline and soil are fully bonded each other and the interface between pipeline and soil is perfect without defects.

Mechanical properties of pipeline

Pipeline dimensions

pipeline

Mechanical properties of soil

Soil

Pipeline dimensions

soil- pipeline boundary condition

Boundary condition:
For this study, assumed infinite length for buried pipeline. It is acceptable to consider roller
as the boundary of the ends of pipeline because the buried pipeline may be moved with soil
relatively.
Additionally, the bottom surface of 3D-FE soil model is proposed to be completely fixed This
is because the bottom boundary is selected at the known location of a bedrock surface.

soil- pipeline element

Displacement of pipeline

There are two type stresses on pipe: inner stress and outer stress. Inner stress is more than
outer stress because of water pressure, so for this study maximum von misses’ stress has
considered.

For compression von misses stress in pipe line, defined four paths in up, down, right and left
corner of pipeline like pervious section.
Von misses stress of these paths compared in below figures for defined paths.

von misses stress for depth 2 m