Seismic ground faulting is a severe hazard for continuous buried pipelines. Over the years, researchers have attempted to understand pipeline behavior mostly via numerical models such as the finite element method. The lack of well-documented field case histories of pipeline failure due to faulting along with the costly and complex facilities needed for full-scale experimental simulation make a centrifuge-based method to determine the behavior of pipelines subject to faulting the best method to verify numerical approaches. This paper presents results from four centrifuge tests investigating the behavior of continuous buried steel pipelines that were subjected to reverse faulting. The axial and bending strains induced in a pipeline are presented. Also investigated is the influence of factors such as faulting offset, burial depth, and pipe diameter on the axial and bending strain of pipelines and on the ground soil failure and pipeline deformation pattern. Finally, the initial strain at the wrinkling point of the pipe under reverse faulting is studied and compared with theoretical values. It was found that the pipe deformation mechanism and damage type are significantly altered by variations in pipe diameter, burial depth, and pipe section slenderness ratio (diameter to thickness ratio). Increasing the diameter and burial depth of a pipe changes the deformation mechanism from beam buckling to wrinkling. The wrinkling strains from these tests are in good agreement with the findings of Hall and Newmark.
Azar oil field is located to the east of the city of Mehran, Ilam. The tank of this oil field is shared by Iraq’s oil field whose name is Badra where oil extraction started in 2014, and they have maximized its oil exploration since 2017. Iran started oil exploration in 2017. In this study, we estimated the land surface deformation in Azar oil field using persistent scattering interferometry (PSI) in order to determine the corresponding subsidence source. PSI is a method of time series analysis used to measure various surface deformations. The Stanford Method for Persistent Scatterers (StaMPS) package was employed to process 50 ascending Sentinel-1A satellite images collected between 2016 and 2019, and 50 descending Sentinel-1A satellite images were collected between 2014 and 2019 to extract horizontal and vertical displacement components from the Interferometric Synthetic Aperture Radar (InSAR) LOS (line-of-sight) displacement. The results showed that the maximum displacement rate in the Iran-Iraq joint oil field between 2016 and 2019 was 15 mm in the vertical direction. Moreover, the maximum displacement rate measured in the horizontal direction was 30 mm. The vertical deformation confirms typical patterns of subsidence caused by oil extraction, and the horizontal deformation occurred due to considerable precipitation events after a drought period, as well as the presence of sand layers at different depths of the earth.
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