Abstract: The external load（such as geology landslide，collapse，loose soil deposition，collapsible loess，earthquakes，water
damage，etc.）caused by complex geological features and poor natural conditions along long-distance the pipeline will result
in a large span of vacancy of the pipeline. Slightly inciting the large deformation of the pipeline，a large area of vacancy，the
local deformation or stress concentration，resulting in greater displacement and stress，buckling or creep，or even badly cause
pipeline rupture，producing pipeline safety hazards. We establish suspended pipeline model in this paper，calculate maximum
suspended length of X52 refined oil pipeline by using the theory of elastic foundation，large deflection beam theory，pipeline
soil interaction，Winkler presumption model and considering the geometric nonlinearity and soil physical nonlinearity on the
basis of Lan–Cheng–Yu，Deyang，Shijiangting oil pipeline large area suspended for flood water.

Key words: long-distance pipeline, the winkler presumption, vacant, nonlinear, finite element simulation