The China-Russia oil pipeline can't avoid crossing large permafrost zone in northeast China. Permafrost is extremely sensitive to changes in temperature. The hot oil will lead to the increase of soil temperature around the pipeline, and the formation of thaw bulb will lead to soil settlement. The differential thawing settlement displacement loading may cause pipeline failure, by producing a large axial strain due to bending and geometric deformation. With the increase of oil temperature, Permafrost thawing settlement has become a major threat to the safe operation of buried pipeline in permafrost region. In this paper, considering the case of parallel laying of double pipes in the China-Russia crude oil pipeline route from Mo’he to Daqing, northeastern China, the numerical simulation model of buried pipeline in permafrost zone is established by using ABAQUS finite element software. The calculation of temperature field of soil around the pipeline was conducted, considering the ice-water phase change. Then, the permafrost thawing settlement based on moisture-heat-stress coupled will be used for stress-strain analysis of X65 steel pipeline, by considering pipe-soil interaction. The failure analysis of pipe by using the strain-based design criterion, and the maximum differential thawing settlement displacement allowed for the safe operation of the pipeline is given. Parameter sensitivity analysis will be conducted. The effects of oil temperature, internal pressure, the geometric size of pipe and the distribution of soil on the safe operation of the pipeline are studied. The numerical simulation method used in this paper can well reflect the real process of permafrost thawing settlement. Compared with soil spring model, 3D solid model may describe pipe-soil interaction and predict strain of pipeline accurately. The research results have a certain reference value for the optimization of design parameters of buried pipeline in permafrost region and the safety maintenance of in-service pipeline route from Mo'he to Daqing.

Key words: permafrost , thawing settlement, coupled method, X65 pipeline, pipe-soil interaction, strain-based design


Failure Analysis of Buried X65 Steel Pipeline Under the Influence of Permafrost Thawing Settlement Based on Moisture-Heat-Stress Coupled Method

Division / Sponsors: 
Pipeline Systems Division

Paper Proceedings: https://asmedigitalcollection.asme.org/IPC/IPC2020/volume/84447

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