(1. College of Civil Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;2. State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-environmental and Resources,Chinese Academy of Sciences,Lanzhou,Gansu 730000,China;3. Geological Hazards Prevention Institude,Gansu Academy of Sciences,Lanzhou,Gansu 730000,China)
Abstract:Changes of air temperature or rainfall will inevitably influence the embankment stability in permafrost regions. Previous studies focused mainly on the influence of air temperature on the thermal stability of the embankment,while the influences of rainfall on the embankment and the influencing mechanism have not been fully considerated. Moreover,the understanding on the role of rainfall is still controversial. Observed data showed that the rainfall increased significantly on the Qinghai—Tibet Plateau during the past 50 years. The increase in rainfall can result in the change of the thermal-moisture activity in the active layer,the near-surface energy and the mass budget. The in-site precipitation and moisture data within railway embankment been measured in Beiluhe permafrost station and the water-vapor-heat transport model established were used to predict the process and mechanism of influence of increasing rainfall on gravel embankment. Collected data indicated that rainfall in summer significantly affected the shallow moisture in short time. But the long-term water content was not affected by rainfall, the moisture evaporation and the liquid water and water vapor transfer in embankment occurred clearly. The increase in rainfall will increase the surface latent heat,lower the heat flux and temperature of surface soil,and raise the artificial permafrost table. The reduction of heat conduction caused by increased rainfall is greater than the increase of heat convection of liquid water. Therefore,the increase in rainfall can mitigate the process of permafrost degradation and will alleviate the thermal influence of embankment engineering on underlying permafrost. While,the increased rainfall infiltrations will result in the increase of water content in embankment and induce the frost heave and thawing settlement.
ENDRIZZI S,GRUBER S,DALL'AMICO M,et al. GEOtop 2.0:simulating the combined energy and water balance at and below the land surface accounting for soil freezing, snow cover and terrain effects[J]. Geoscientific Model Development Discussions,2014,7(6):2 831-2 857.
Your browse does not support frame!