青藏高原多年冻土区地温监测结果分析

根据４个波土长期定位观测场地温资料分析，西大滩观测场深１２￣２０ｍ段地温升高０．２￣０．３℃，多年冻土层由下向上减薄４￣５ｍ；昆仑山垭口观测场深６￣１５ｍ段地温升高０．２￣０．４℃；６６道班观测场内天然场地地温高于人工沙场０．１￣０．５℃；可可里里观测场内天然植被场地地温普遍高于裸露场地约０．２℃。监测结果表明，影响高原多年冻土发育的因素多具有两重性，地表沙层和植被同样具有升高地温和降低地温的作用

Analysis of the Ground Temperatures Monitored in Permafrost Regions on the Tibetan Plateau

Ground temperature monitored at four observation sites in permafrost regions on the Tibetan Plateau are analyzed. It is found that the ground temperature at the depth of 12~20 m increased 0.2~0.4K and the permafrost thickness decreased 4~5 m from the base in Xidatan Site from 1975 to 1989; and the ground temperature at the depth of 6~15 m increased 0.2~0.4 K in Kunlun Pass Site from 1982 to 1997. Contrast observations show that a sand cover, 15-20 cm in depth, can result in a ground temperature decrease of 0.1~0.2 K in MS No. 66 Site; and a remove of vegetation can result in a ground temperature decrease of some 0.2 K in Hob Xil Site. The monitor demonstrates that many factors that control permafrost developing have duality, e.g., sand and vegetation are able to increase or decrease the ground temperature. These factors, in company with permafrost behaviour, play different roles under different conditions. Therefore, it is necessary to study, understand and evaluate permafrost and its engineering geological properties taking a viewpoint of dynamic variation.