PSI - Issue 20

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Procedia Structural Integrity 20 (2019) 242–247

1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Influence of natural climatic conditions on the spatial position of the underwater gas pipelines on the Lena floodplain 1st International Conference on Integrity and Lifetime in Extreme Environment (ILEE-2019) Influence of natural climatic conditions on the spatial position of the underwater gas pipelines on the Lena floodplain

D.S. Ivanov*, G.S. Ammosov, Z.G. Kornilova V.P. Larionov Institute of the Physical-Technical Problems of the North of the Siberian Branch of the RAS, Oktyabrskaya street 1,Yakutsk 677890, Russia D.S. Ivanov*, G.S. Ammosov, Z.G. Kornilova V.P. Larionov Institu e of the Physical-Technical Problem of the North of the Siberian Branch of the RAS, Oktyabrskaya street 1,Yakutsk 677890, Russia

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. © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers Abstract Interaction with complex geotechnical and operational conditions is one of the main factors for the efficiency of t s pipelines, in particular, transitions across the water bodies of Yakutia. The underwater crossing of the trunk gas pipeline across the riv r Lena w s laid in an open-cut way by u erwater trenchi g. This method involv s excavation of significant volumes of soil and depends on the climatic conditions. Additional materials are required for b llasting the pipeline and this leads t higher construction costs. T article presents the data of the planned high-altitude p sition 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 ru s almost parallel t the surface r lief and shows the i fluence of hydromorphological processes on the erosion dynamics of the siphons. Duri op ration, the p enomenon of pipeline rosion in the t nch and its sags occurs. The erosion of the soil ca change the planned-high-altitude p siti n of the pipeline and create additio al stress s in it. The uneven distribution of the planned-hig - ltitude 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 irr gularities, processes of soil thawi g and freezing, a 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. © 2019 The Autho (s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers

Keywords: Underwater crossing, pipeline, high-rise planning position, pipeline depth, erosion of the soil. Keywords: Underwater crossing, pipeline, high-rise planning position, pipeline depth, erosion of the soil.

* Corresponding author. Tel.: +7-964-419-3419; E-mail address: ivanovds@gmail.com * Correspon ing author. Tel.: +7-964-419-3419; E-mail address: ivanovds@gmail.com

2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers 2452 3216 © 2019 Th Author(s). Publis d by lsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ILEE-2019 organizers 10.1016/j.prostr.2019.12.146