Keyword: «underground pipeline»

The article considers the spatial altitude of the pipeline affected by interaction with frost heaving. The study shows the results of measuring planned-high-altitude positions (PHAP) of the underground pipeline obtained in different seasons to identify the peculiarities of pipeline deformation from frost heaving. According to the data obtained, the deformations are of a complex shape. The spatial position of the pipeline changes after freezing and thawing of the soil, i.e., twice a year. The level of deformations is beyond the limits of safe operation. An observation of the current state of research on the impact of frost heaving on underground pipelines revealed that the applied mathematical models consider a deformation as a single arch. Our PHAP measurements show a complex picture – specifically, bulges are replaced by concavities.

As a result of seasonal thawing and freezing of the surrounding soil, an underground pipeline, laid in the permafrost area, undergoes vertical displacement changes twice a year. Complex deformations occur in some sections, manifesting as multiple arches transitioning into one another without intervals. This article proposes a methodology for assessing the stresses that occur in the pipeline in such sec-tions. An equation describing the vertical position of the underground pipeline, depending on the weight of the soil above and the reactions of the soil below, has been obtained. There is no need to explicitly specify longitudinal forces in the equation, which greatly simplifies field work in data collection. The soil reactions are determined by using the gradient descent method in solving the equation.