| Rubble slope and gravel pavement are two kinds of engineering measures protecting permafrost under embankment. In order to hold their effect, three kinds of different thickness rubble slope embankment and three kinds of different size gravel pavement embankment are constructed in Wudaoliang test segment of Qinghai-Tibet Railway permafrost region, then ground temperature and railway shoulder distortion of test segment and adjacent natural ground temperature are monitored in two freezing-thawing cycles, natural ground freezing-thawing characteristic and test segment embankments freezing-thawing and distortion characteristic are analyzed, at the same time, different test embankments and natural ground are contrasted one another. The following basal cognition and primary conclusions have been drawn:(1) The natural ground lies in low temperature steady permafrost region, temperature field is on balanceable state, permafrost table is steady, and the curve of temperature changing with deepness is zero grads.(2) Left shoulder and right shoulder freezing-thawing process of rubble slope and gravel pavement embankments bears an analogy to natural ground, but the curve of temperature changing with deepness is minus grads, tending to become zero grads for rubble slope and gravel pavement refrigeration effect.(3) Rubble slope and gravel pavement embankments expand and sink in freezing-thawing process every year, but sinking distortion is dominant.(4) Rubble slope and gravel pavement are effective engineering measures refrigerating embankments on their own initiative, they also make embankments quantity of heat tend to decrease year after year.(5) Although asymmetry rubble slope and gravel pavement are set up, embankment temperature field is still uneven, so it is very difficult to adjust uneven temperature field completely by setting up different thickness rubble slope or different length gravel pavement on the...
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