Investigating the Effective Factors on Reducing the Vulnerability of Urban Gas Pipelines Against Explosive Threats.

Buried pipelines, which are used to distribute water, gas, oil, etc., are considered as one of the important arteries. Experiences from past wars confirm that the attacking country devotes its attention to bombing and destroying vital and sensitive centers. Gas pipelines, as one of the important transmission arteries during war, can cause a lot of human and financial losses if damaged. In this article, the degree of vulnerability of buried city gas steel pipes due to explosion has been determined and the methods of reducing the vulnerability of pipelines have been investigated. For this purpose, while preparing a three-dimensional model of the pipe-soil system in ABAQUS software, to study the effect of effective factors on pipe behavior, including pipe diameter, diameter-to-thickness ratio, soil internal friction angle, soil type, explosives consumption, pipe burial depth, distance Blasting up to the pipe burial site, the deformation capacity of the pipe has been investigated according to the ALA regulations. Soil was modeled using 3D Solid elements and pipe with Shell element. For parametric studies, analyzes were performed using the finite element method. Studies for diameters of 4 and 12 inches, ratio of diameter to thickness of 26, 21 and 35, burial depth of 1, 2, 3 and 4 meters, the amount of explosion charge of 15, 30, 45, 60 and 200 kg of TNT and for hard sandy soil, Softening was done. The results showed that proper burial depth has the most effect in order to reduce the vulnerability of pipelines against explosive threats. By increasing the thickness of the pipe and increasing the diameter and using soft sandy soil around the pipe, a better behavior of the pipe during the explosion was observed.