Analysis of Permafrost Subgrade Temperature in Qumar River Region along Qinghai-Tibet Railway

The design idea of Qinghai-Tibet Railway permafrost subgrade is active cooling,which has been widely recognized.This paper compared the measured subsurface temperature data of different permafrost subgrade in Qumar River region.The result shows that permafrost under ordinary subgrade obviously trends to be melt,which need to take protecting measures in time.Thinner stone subgrade has a certain role in protecting permafrost,but the effect is not obvious.Therefore,it is recommended to add block stone to form a U-shape subgrade for slope protection.Block-stone slope-protection subgrade can reduce ground temperature and protect permafrost,so it has active cooling effect.