Monitoring and analysis of cooling effect of block-stone embankment for Qinghai-Tibet Railway

Block-stone embankment is one of the most important engineering measure for protecting permafrost of Qinghai-Tibet Railway which has been used in about 60% sections of warm permafrost with high ice content.After monitoring analysis of soil temperature beneath the block-stone embankment of Qinghai-Tibet Railway,it can be concluded that the block-stone embankment is working positively for cooling the roadbed and making the great rise of permafrost table,but also causing a temperature rise of permafrost.The trend of permafrost temperature rise will be gradually restrained by reducing engineering thermal disturbances and soil temperature drop beneath the block-stone embankment.And,for cold permafrost,a better thermal stability situation will be developed under the condition that the temperature near the permafrost table beneath the block-stone embankment has largely dropped.But,even the permafrost table has highly raised the annual thermal imbalance of soil and the process of temperature rise,it is disadvantageous for the thermal stability of permafrost.Thus,the applicability of block-stone embankment structure is worth to be discussed in order to take corresponding measures to solve the stability problems of embankment in warm permafrost regions.