青藏铁路沿线多年冻土分布特征及其对环境变化的响应

The distribution characteristics of permafrost along the Qinghai-Tibet Railway and their response to environmental change

针对青藏高原特殊的自然气候条件,按照地形、地貌把青藏铁路沿线多年冻土分为15个区段,并分别介绍了各个区段多年冻土特征.结果表明:在外界环境变化,包括全球气候变暖及工程活动的双重效应下,青藏铁路沿线多年冻土及其存在状态发生了极大变化,这些变化主要包括年平均气温升高、多年冻土退化、热融灾害增加、寒区工程病害不断加剧等.多年冻土及其存在状态发生变化不但导致生态环境恶化,而且对青藏铁路沿寒区工程的安全运营、维护及发展提出新的挑战.

The distribution characteristics of permafrost along the Qinghai-Tibet Railway （QTR） are analyzed ai- ming to understand the special climate condition of the Tibetan Plateau. The railway can be divided into 15 sec- tions by the topography and geomorphology, of which the characteristics and engineering geologic conditions are described. Studying the effect of environmental change, including climate change and engineering activities, on permafrost along the QTR and Qinghai-Tibet Highway indicates that the cutting excavation is one of the most im- portant factors to disturb permafrost, which may lead to instability and slumping of slope, forming surface ponds and thermokarst lakes, result in slope cracking, collapse and slope toe softening, etc. Sand filling roadbed may give rise to warmer permafrost under the roadbed; the microclimate at two sides of roadbed plays an important role to increase surface temperature. Retaining water and drainage facilities also bring on decrease of the thawed depth of permafrost and the thawed roadbed and toe of slope. In sum, the single sand filling roadbed, cutting and surface engineering may lead to warmer permafrost obviously.