Abstract: Taking a hydropower slope in Tibet as the study example,the governing equation of rock mass transient temperature filed of freezing zone and melting zone are established based on the principle of transient thermal conduction,so as to simulate temperature field response of the slope under low temperature environment.The involution regularity of temperature filed of rock mass with the temperature throughout the year is analyzed and the temperature influence range of cover layer and strong weathering layer in the freezing and melting periods is studied based on the extraction of feature points in different parts of the slope.Based on the above discussion results,the deformation variation characteristics of cover layer and strong weathering layer of the slope under the conditions of thermal effect and freezing-thawing cycles are analyzed by adopting direct coupling method.The study results show that rock temperature of shallow slope has a strong correspondence with the environmental temperature,while the rock temperature of slope deep remains at 3~5 ℃,the maximum freezing depth of slope is 4 m;the influence of environmental temperature on deformation of cover layer and strong weathering layer is great,the sinusoidal distribution of the deformations are displayed with the change of time,the variation deformation caused by freezing-thawing cycle is much greater than the one caused by thermal effect from the aspects of influence degree.

Key words: Slope in cold regions, Freezing-thawing cycles, Transient temperature field, Thermal mechanical coupling