青藏高原冻融风蚀形成机理的实验研究

青藏高原独特的高寒环境,冻融作用强烈,在干旱多风的气候条件下,容易产生风蚀,导致沙漠化的出现。冻融风蚀作为冻融侵蚀的一种主要形式,在青藏高原表现得尤为突出。为此,对青藏高原采集的土样进行了冻融风蚀模拟实验。结果表明,风蚀强度随着冻融循环次数的增多、冻融过程中含水量以及冻融温差的增大而增强,因此,在水分参与条件下,反复、剧烈的冻融作用所引起的土体结构的破坏是青藏高原冻融风蚀产生的主要原因,而挟沙风又是其主要动力。

Mechanisms of Freezing-Thawing Induced Wind Erosion in Qinghai-Tibet Plateau

Freezing and thawing cycles occur very often in the Qinghai—Tibet Plateau due to its unique environment with high elevation and cold temperature.The frequent freezing and thawing cycles lead readily to wind erosion during the dry windy conditions,resulting in the emergence of desertification.Freezing—thawing induced wind erosion prevails as a major form of erosion on the Qinghai—Tibet Plateau.Based on simulated experiments using soil samples on the surface of the Plateau,we found that the wind erosion intensity increased with the frequency of the freezing—thawing cycles,the water content of the soil,and the temperature difference in the freezing—thawing process.It is concluded that,the damage of soil structure caused by the repeated,fierce freezing—thawing behaviors was the main reason for wind erosion in the plateau,and the sand-suspended wind was the main driving force.