Influence of natural climatic conditions on the spatial position of the underwater gas pipelines on the Lena floodplain

Abstract Interaction with complex geotechnical and operational conditions is one of the main factors for the efficiency of trunk gas pipelines, in particular, transitions across the water bodies of Yakutia. The underwater crossing of the trunk gas pipeline across the river Lena was laid in an open-cut way by underwater trenching. This method involves excavation of significant volumes of soil and depends on the climatic conditions. Additional materials are required for ballasting the pipeline and this leads to higher construction costs. The article presents the data of the planned-high-altitude position of the I and II lines of the underwater crossing of the main gas pipeline across the Lena River from the time of their laying. The results of field surveys show that the underwater crossing of the main gas pipeline runs almost parallel to the surface relief and shows the influence of hydromorphological processes on the erosion dynamics of the siphons. During operation, the phenomenon of pipeline erosion in the trench and its sags occurs. The erosion of the soil can change the planned-high-altitude position of the pipeline and create additional stresses in it. The uneven distribution of the planned-high-altitude positions of the I-st and II-nd lines of the main gas pipeline in floodplains from the left bank of the river has been established, which is associated with heaving irregularities, processes of soil thawing and freezing, as well as gas pipeline subsidence and ascent due to inhomogeneous soil composition, distribution of moisture, density, freezing conditions along the pipeline route through the river Lena.