Yin–Yang Slope problem along Qinghai–Tibetan Lines and its radiation mechanism

Qinghai–Tibetan lines, including highways and railways, mainly extend from the north to the south. Long-term ground temperature observation shows that the temperatures on the east slopes have been higher than that on the west slopes. This phenomenon is defined as the Yin–Yang Slope problem. For Qinghai–Tibetan lines located in permafrost regions, especially in the areas with high ice content, the Yin–Yang Slope will bring damages to the roadbed stability. In the sunny slope and sunny shoulder, a lot of long, broad cracks occur along the lines. Some longitudinal slits even penetrate through the roadbed. Under some conditions, such as moving trains or earthquakes, the sunny shoulder will probably sink abruptly. These are very dangerous to the running vehicles. The reason that Yin–Yang Slope develops in the embankment slopes of the Qinghai–Tibet lines is due to the intensive solar radiation, difference of slope orientation and the regularity of solar radiation diurnal variation. Suggestions to eliminating the phenomenon are: (1) to spray or paint materials with high albedo on the slope or the road surface; (2) to reduce the thickness of the roadbed properly and diminish the slope gradient of the embankment slopes.