Document Type : Original Article

Author

• Sahar Jalili

Assistant Professor, Department of Civil Engineering, Faculty of Engineering, Islamic Azad University, Kermanshah Branch, Kermanshah, Iran

Abstract

Pipeline systems are the most important means for transporting gas and other liquid fuels. Most of these pipelines are buried underground and are highly susceptible to sudden ground movements caused by earthquakes and landslides. Severe damages inflicted on pipelines during such events can lead to joint failures and consequently significant economic losses. With each ground movement, the pipeline is subjected to one or all types of axial, bending, and shear loads. These loads may result in large compressive stresses, which can lead to local or global buckling. In this study, the interaction between the pipeline and the surrounding soil due to sudden ground movement is investigated using a coupling model between the pipeline and soil, incorporating nonlinear soil response, nonlinear material behavior, and nonlinear geometry. The most critical parameter for determining the performance level and extent of damage in buried pipelines during an earthquake is the maximum strain. Vital infrastructure codes (such as ALA and APA) also evaluate the seismic behavior of buried pipelines by examining the maximum strain. Using code-based relationships, stress and strain values were derived and compared with results obtained from Abaqus software.
The most influential factor identified in this study is the pipe thickness. As the pipe thickness increases, the strain and stress values decrease, and the deformation mode also changes. The burial depth of the pipeline does not significantly affect the applied stress values but does influence the strain values. At shallow burial depths, the strain is not highly sensitive to the pipe diameter. However, as the burial depth increases, the strain values become more sensitive to increases in pipe diameter. Additionally, for larger thicknesses, an increase in pipe diameter leads to a noticeable rise in strain values. For several model cases, stress and strain values were calculated using code-based relationships. Comparing these results with those obtained from finite element analysis, it can be concluded that both stress and strain values are overestimated in the codes.

Keywords

• Pipelines
• Earthquake
• Reverse Fault
• Buried Depth
• code Relationships

Main Subjects

• Geotechnics