Abstract: As a result of bad weather，such as hurricane，storm or landslide，some part of buried pipeline may be in a semiburied
state. Currently the“linear interpolation”model is used to calculate the heat loss of partially buried pipe. A mechanism
model of heat transfer of fluid（air/water）-pipe-soil coupling is developed，and the thermal behaviors of pipeline are studied
by numerical simulation. The results show that the changes of the overall heat transfer coefficient，outlet temperature and soil
heat storage of pipeline with the fraction of outside surface of pipe in touch with soil have obvious non-linear characters，both
the trend and value of the linear model deviate from that of the mechanism model greatly. There are significant differences in
the overall heat transfer coefficients/outlet temperatures between the pipe completely exposed to the surrounding fluid and that
just covered by soil. The bigger the pipe diameter is，the greater the differences are. When the temperature of the surrounding
fluid is lower，the outlet temperature is more sensitive to the fraction of outside surface of pipe covered by soil.

Key words: hot oil pipeline, partially buried, heat transfer model, numerical simulation, thermal behavior