Research shows that current methods of calculating the load on underground pipelines during an earthquake are incorrect.
PETER THE GREAT POLYTECHNICAL UNIVERSITY OF SAINT-PETERSBURG
PICTURE: NEW RESEARCH SHOWS CURRENT METHODS OF CALCULATING THE STRESS PRESERVED BY UNDERGROUND PIPELINES DURING AN EARTHQUAKE. show more CREDIT: PETER THE GREAT POLYTECHNICAL UNIVERSITY OF ST.PETERSBURG
Underground pipelines that carry oil and gas are a very important technical communication around the world. Some of these underground connections are built and operated in seismic areas.
The seismic safety or seismic stability of underground pipelines has been studied intensively since the 1950s.
Since then, a number of methods have been proposed for calculating the load placed on an underground pipeline during an earthquake. The purpose of these methods was to make an accurate prediction of the structural load on a pipeline during an earthquake and thus to decide how resilient the pipeline needs to be. It is important to find the right balance between pipeline cost and its structural resilience.
It turned out we were wrong.
New research was carried out by scientists from the Institute of Mechanics and Seismic Stability of Structures of the Academy of Sciences of the Republic of Uzbekistan and Peter the Great St. Petersburg Polytechnic University (SPbPU) in Russia. Research shows that current methods of calculating the load on underground pipelines during an earthquake are incorrect.
“The existing methods do not take into account seismic pressure, ie the stress normal to the outer surface of the pipeline, which results from the propagation of a seismic wave in the ground. This leads to an incorrect determination of the pipeline voltage. The longitudinal stress calculations lead to errors of 100% or more, ”said Nikolai Vatin, professor at the Institute for Civil Engineering SPbPU.
Failure to observe the longitudinal stress means that all underground oil and gas pipelines are more prone to earthquakes than originally expected.
Researchers have developed a new theory of the process of seismic wave propagation in an underground pipeline and in the surrounding soil to address this problem.
The related theoretical material, which explains all the mathematical calculations of the new theory and its advantages compared to the previous method, can be found in the article Wave theory of seismic resistance of underground pipelines.
“It is very admirable indeed that science is moving forward and we get better theories and find our flaws. However, the ominous concern is that all of our current pipelines will remain at risk for some time until they are replaced and modernized, ”said Karim Sultanov of the Institute of Mechanics and Seismic Stability of Structures at the Academy of Sciences of the Republic of Uzbekistan.
The research results in the article.
The research is funded by the Ministry of Science and Higher Education of the Russian Federation under the premier research center program Advanced Digital Technologies (contract number 075-15-2020-934 dated November 17, 2020).