关键词: 青藏铁路, 风沙危害, 防沙措施

Abstract: The Qinghai-Tibet Railway，the longest high-altitude railway in the world，is frequently damaged by windblown sand because of strong winds and abundant sand. On the basis of meteorological data，in situ observations and wind tunnel experiments，this paper aims to clarify the characteristics of windblown sand，and to show the dynamical environment of sand activities. According to climate data，the windy period combines with an arid seasonal climate to increase the risk of blowing sand in this area. Wind-blown sand presents unidirectional characteristics and its prevailing direction is westerly. The annual drift potential along the Qinghai-Tibet Railway reaches more than 400 VU，which belongs to a high-energy wind environment. The resultant drift potential ranges from 85.8° to 89.8°，which indicates that westerly sand-laden wind prevails in this region. It rarely snows in winter and the earth’s surface is usually bare. Meanwhile，winter is also the windy season with the peak wind speed of 38 m/s. It can be easily found that the windy period always accompanies with a drought season. The dominant directions of sand transport are westerly in the observed period. Sand transport per unit width （cm） from a westerly direction is 55.7 kg in spring in the Cuonahu region，which indicates strong activity of wind-blown sand. The corrosion resistance on earth is very bad because of the multi-agents actions，such as water，wind and freeze-thaw roles. Sand-damage control along the Qinghai-Tibet Railway should adopt an integrated protection system，not a single sand-control measure. The results of the research have three implications for the design of future sand-control structures. Firstly，sand-control measures must be designed to decrease wind velocity sufficiently and protect natural vegetation along the Qinghai-Tibet Railway，so that abundant sands could be blocked away from the railway. Secondly，results show that sand-driving wind presents a unidirectional flow along the Qinghai-Tibet Railway，so sand control structures should be positioned on the upwind side of the railway to ensure that sand could be accumulated at a safe distance. Thirdly，future design of railway in sandy regions should more carefully consider the direction of sand-driving winds.

Key words: the Qinghai-Tibet Railway, sand damages, sand-control measures