DEVELOPMENT OF THAWING HAZARDS AND THERMAL INFLUENCE ON PERMAFROST ALONG QINGHAI-TIBET ENGINEERING CORRIDOR

Under the combined influences of the human activities and climatic warming, the thawing hazards are widely distributed in the permafrost regions along the Qinghai-Tibet Engineering Corridor. Research of development status of the thawing hazards and their impact on permafrost thermal regime within the corridor are significant to the engineering construction and environment protection in the future. Based on the field investigations, we summarize the types and development status of the thawing hazards within the corridor. We also monitor the ground temperature of three typical thawing hazards and analyzed their thermal influence on permafrost. The research results show that the typical thawing hazards developed in the corridor mainly include thaw slump and landslide, thermokarst pond, thawing settlement. They are widely distributed in the high ice content permafrost regions along the Qinghai-Tibet Highway and Railway. According to the field ground temperature monitoring, thawing hazards have significantly influenced the thermal regime of permafrost in development area and nearby area. The influence scope is differed among the three thawing hazards. Thaw slump and thaw subsidence usually influence the shallow permafrost. But the influence of thermokarst lake is more significant, which usually results in the formation of talik under the lake bottom. In addition, the modeled results show that the thawing hazards always release heat to its nearby permafrost. The amount of heat released by thermokarst lake is usually more than that released by thawing ditch. The thawing ditch is usually more than the thaw slump. If the thawing hazards are close to the roadbed, the lateral thermal erosion would lead to the temperature increases in frozen soil subgrade and induce the embankment disease. Therefore, full consideration of all kinds of thawing hazards must be given for road construction in permafrost regions. If the condition allows, the road should bypass or away from these hazards.