DETERMINATION OF THE PIPELINE AXIS CURVATION BY THE METHOD OF NUMERICAL DIFFERENTIATION AND SMOOTHING OF THE PLANNED AND HEIGHT MEASUREMENT DATA BASED ON THEIR REPEATED AVERAGING

Abstract

The most important practical value for ensuring the operational reliability and industrial safety of trunk pipelines (TP), especially those operating in special climatic zones, in mountainous or geocryological conditions that cause TP bending, is adequate assessment of their actual stress-strain state (SSS) in order to identify potentially hazardous areas (PHA) and estimate their technical condition. It is convenient and sufficient to consider pipeline axis curvature as a controlled parameter characterizing the SSS level of TP pipe-sections during operation. Therefore, the problem of determining the actual true pipeline axis curvature and the locations of the maximum values of curvature along the TP route is one of the topical urgent methodological problems. The experience of using the «Instructions for determining, according to geodetic survey data, the actual stress-strain state of sections of gas pipelines located in areas with dangerous geodynamic processes and assessing their operability», a regulatory document in force PJSC Gazprom shows that estimates of pipeline axis curvature, based on the approximation of the data of the plan and height measurements of the position of the axis by interpolation polynomials of the fourth order, are very sensitive to the data of measurements chosen for to approximate the pipeline section, its length, etc. These circumstances necessitate the development of adequate methods for determining the pipeline axis curvature, in which the true shape of the axis is not specified in advance. The method of numerical differentiation and smoothing of the data of planned and height measurements of the pipeline axis position, proposed in the article, makes it possible to efficiently obtain reliable distributions of the pipeline axis curvature in areas of great length when available significant errors in these measurements and, accordingly, adequately identify the PHA and evaluate the technical condition of the pipeline by SSS level. An example of the implementation of this method for monitoring the SSS of a section of the main gas pipeline located on a landslide hazardous hillside is given. The results obtained by this method can be used to verify calculated estimates of the distribution of pipeline axis curvature, obtained by other methods, for example, methods that directly approximate the plan and elevation measurements of the position of the axis of the decomposition by orthogonal systems feature topics.