关键词: 砾石级沙粒胶结体, 覆盖度, 风蚀率, 抗风蚀效率

Abstract: There are some larger granular materials whose diameter reach the level of coarse sand, very coarse sand and gravel, naturally distributed on some inter-dune corridors in the hinterland of the Taklimakan Desert. They were made up of a mass of sands which be cemented together by a certain substance, we call them sand cemented bodies (SCB). In order to research the effect of SCB on windblown sand movement, this study investigated the anti-wind erosion ability of the sand surface being covered with gravel-size sand cemented bodies (GSSCB) collected in the field by wind tunnel simulation in net-wind conditions and sand-driving wind conditions respectively. The results indicate that the conditions of erosion-deposition on sand surface depended on the inflow conditions, wind speeds and degrees of GSSCB coverage. All sand beds in all GSSCB coverage treatments showed an erosion status under net-wind condition. But there were three conditions of erosion, erosion-deposition balance and deposition under sand-driving wind conditions, the conditions varied with the degree of GSSCB coverage and wind speed. When the sand beds were in a condition of erosion, the erosion rates decreased exponentially with the increasing degree of GSSCB coverage and increased in forms of different functions with the increasing wind speed. As the coverage rise, the anti-wind erosion rates gradually increased, but the increased ratios were different in different ranges of GSSCB coverage. When the sand bed showed in a condition of erosion-deposition balance under a sand-driving wind condition, its degree of GSSCB coverage reached a critical value C_b in that environment. The value of C_b increased with the increasing speed, whose relationship could be described as a power function. When the coverage was greater than C_b, the sand bed showed a sand deposition status; however, the relation between the sand deposition rates and wind speeds was complex. The sand deposition rates increased as a logarithm function at the coverage of 80% and decreased as an exponent form at the coverage of 40% with the raising wind speed under the sand-driving wind condition. As a result, for the similar physical natures like gravel, the GSSCB coverage does have an anti-erosion benefits for the sand surface, GSSCB can also capture windblown sand from wind-sand flow at a given coverage. So we should pay attention to the effect of GSSCB on the windblown sand movement in the hinterland of the Taklimakan Desert in future aeolian research. A new type of sand fixation technology can be developed soon inspired by GSSCB.

Key words: gravel-size sand cemented bodies, coverage, wind erosion rate, anti-erosion efficiency