Based on the continuity

non-Darcy momentum and energy equations for fluid convection in porous media

the velocity and temperature fields of riprap slope embankments under strong ventilation condition were studied numerically in permafrost regions in the Qinghai-Tibet railway. The results show that the riprap slope embankments play a significant role in protecting the permafrost

under which the upper limit of permafrost increasing obviously in summer and the re-frozen process is much faster in winter compared to the permafrost under the native ground surface. The cooling effect of riprap slope embankment is limited mainly in the range of near slope embankment; so the centre of embankment can not be protected very well. With the climate warming

a thawing interlayer looks like an eyeball may be formed in the centre of permafrost under the riprap slope embankment

which is not conducive to the stability of slope embankment. The direction of air flow is from down to up along the slope in riprap slope at following wind side; but it is from up to down at counter wind side. The motion type of air flow in the riprap can be defined as roll flow; and the flow velocity is much larger at the surface of riprap than the inner. Besides

the distribution interval of velocity is between 1.24×10-3 m/s and 12.8 m/s; and the numerical result is mainly in accordance with the site test results.