Analysis on ground temperature changes and landslide process of thaw slumping in permafrost regions

With development of engineering constructions,such as the Qinghai-Tibet Highway and the Qinghai-Tibet Railway,the slope instability problems in permafrost regions of the Qinghai-Tibet Plateau must be carefully considered.Among the slope instability types,thaw slumping is the most hazardous to engineering projects.The ground temperature data of long-term monitoring in the typical thaw slumping indicates that average ground temperature increases and annual fluctuation of ground temperature are reducing under the thaw slumping.The reason is that the heat flux entering permafrost reduces.Retrogressive erosion data of long-term monitoring in the typical thaw slumping indicates that expanding of the thaw slumping fluctuates along with the ground temperature's annual fluctuation,and expanding mostly takes place in 7～9 months.The maximal expanding appears at the direction of the slope tendency.Forming and developing of the thaw slumping are relative to the permafrost conditions and other outer conditions.The basal conditions of slope disappearing must be considered in engineering treatment.