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塔克拉玛干沙漠腹地部分垄间地表发育了一种由众多砂粒胶结而成的大颗粒物质,称为砂粒胶结体(sand cemented bodies,缩写为SCD),其直径达到粗砂级、极粗砂级和砾石级。为研究其对地表风沙活动的影响,以野外采集SCD颗粒为实验材料,对不同SCD盖度下输沙通量垂直分布及输沙率变化进行了风洞实验。结果表明:风沙通量在SCD盖度沙床面表现为指数变化,主要集中在风沙活动底部。同时,随着SCD盖度的增加,总输沙量降低,部分沙量运移到较高层面,输沙率随SCD盖度变化可分成3个梯度区域,且曲线斜率反映不同风速等级下,SCD盖度对地表沙物质沉积过程的影响。当SCD盖度小于10%时,风沙活动强烈且风速在输沙过程中起主导作用。当SCD盖度在10%~40%时,随着SCD盖度增加输沙率降低,盖度对地表风沙活动的影响更为明显,特别是对近地表风沙活动的影响。当SCD盖度大于40%时,床面风沙活动趋于稳定,输沙率变化微弱,随SCD盖度变化输沙率保持不变,沙床面不易受侵蚀。因此,砂粒胶结体覆盖沙床面能够有效降低地表风蚀,且在一定盖度下还能捕获流沙颗粒。塔克拉玛干沙漠腹地丘间地天然发育的SCD对于地表风蚀过程具有重要的影响,可作为一种新型固沙材料进行开发。
Part of the surface of the ridge in the hinterland of the Taklamakan Desert developed a large particulate material cemented by numerous sand grains called sand cemented bodies (SCDs) with grit diameters, gritty gravels and gravel level. In order to study its effect on surface wind and sand movement, SCD particles collected from the field were used as experimental materials to carry out wind tunnel experiments on the vertical distribution of sediment flux and sediment transport rate under different SCD coverage. The results show that the flux of wind-blown sand varies exponentially with the bed surface of SCD, and mainly concentrates at the bottom of the sandstorm. At the same time, with the increase of SCD coverage, the total sediment discharge decreased and some sand transported to a higher level. The sediment transport rate could be divided into three gradient regions with the change of SCD cover, and the slope of the curve reflected different wind speed grades. Effect of SCD Coverage on Surface Sediment Matter Deposition. When SCD coverage is less than 10%, wind-blown sand activities are strong and wind speed plays a dominant role in sediment transport. When SCD coverage is between 10% and 40%, the sediment transport rate decreases with the increase of SCD coverage, and the influence of cover degree on surface wind and sand movement is more obvious, especially on near-surface wind and sand movement. When the coverage of SCD is more than 40%, the sand-bed movement tends to be stable and the sediment-carrying rate changes little. With the change of SCD cover, the sediment-carrying rate remains unchanged, and the sand bed is not easily eroded. Therefore, the sand cementing body covering the sand bed can effectively reduce surface wind erosion, and can capture quicksand particles under a certain coverage. The natural development of SCD in the hinterland of the Taklimakan Desert plays an important role in the process of surface wind erosion and can be developed as a new type of sand-fixing material.