STUDY OF THE PROBLEM OF STABILITY LOSS OF THE MAIN GAS PIPELINES CROSS-SECTION IN PROTECTIVE CASES UNDER HIGHWAYS AND RAILWAY LINES AS A RESULT OF INCREASE IN THE VOLUME OF FREEZING WATER IN THE INTER-PIPE SPACE

Abstract

The relevance of the study is caused by the need to reduce the risk of accidents at the crossings of trunk gas pipelines laid in protective cases under highways and railway lines – one of the most dangerous and responsible sections. Ice formed in the inter-pipe space in the presence of seasonally freezing and thawing soils or when pumping gas at negative temperature together with poor-quality installation of end sealing cuffs can lead to stability loss of the gas pipeline cross-section, thereby increasing the risk of an accident at this site. The conducted research will allow us to investigate potentially vulnerable sections of crossings in advance using computer modeling and provide for them a set of protective measures. The aim of the research is to assess the possibility of damage to trunk gas pipelines laid in protective cases by ice formed in the inter-pipe space; justify the additional measures and recommendations aimed at ensuring the safe operation of underground crossings of trunk gas pipelines under highways and railway lines. Objects: sections of trunk gas pipelines laid in protective cases under highways and railway lines in seasonally thawing and freezing soil near the protective case or transporting gas at a negative temperature. Methods: mathematical modeling, finite element modeling in the ANSYS software package, methods of structural mechanics and resistance of materials, experiment planning. Results. The possibility of damage to trunk gas pipelines laid in protective cases by ice formed in the inter-pipe space was determined; a mathematical model for determining the pressure arising in the inter-pipe space due to increase in freezing water volume was proposed and its adequacy was verified using the ANSYS software package on the example of a 219×6 mm gas pipeline and a 325×12 mm protective case; recommendations for newly designed gas pipelines and their transitions, as well as for existing ones, were indicated.

Keywords

• trunk gas pipeline
• protective case
• ice
• crossings under highways and railway lines
• stress-strain state