乌玛高速公路腾格里沙漠段防护体系典型断面风沙活动特征

Characteristics of aeolian sand activity in typical section of protection system of Wuhai-Maqen Highway (G1816) in Tengger Desert

乌玛高速公路(G1816)腾格里沙漠段风沙活动威胁公路安全运营。对风沙活动典型路段防护体系内的风况特征、地表沉积物粒度特征和近地表(0~2 m)水平沙尘通量进行了研究。结果表明:观测期间年平均风速为3.13 m·s^(-1),平均起沙风速为7.66 m·s^(-1),起沙风频率为17.6%,起沙风风向以W-NNW、E、S为主。年输沙势为187.57 VU,合成输沙势为78.6 VU,合成输沙方向为135°,RDP/DP为0.419,属于低等风能环境、风向变率中等的钝双峰风况。防护体系内0~2 m水平沙尘通量空间差异显著,从公路上侧流动沙丘观测点至靠近公路草方格沙障观测点水平沙尘通量衰减了99%,公路下侧从流动沙丘观测点至草方格沙障观测点水平沙尘通量衰减了93.6%。防护体系内地表沉积物以中沙和细沙为主,不同高度沙尘粒度由防护体系外围至防护体系内部逐渐变细。

Aeolian sand activities threaten highway safety operation in Wuhai-Maqen Highway(G1816)in Tengger Desert.The characteristics of wind conditions,grain size and near-surface(0-2 m)horizontal dust flux in typical section of protection system were investigated.The results show that the average annual wind speed is 3.13 m·s^(-1),the average annual sand driving wind speed is 7.66 m·s^(-1),the frequency of sand driving wind is 17.6%,and the direction of sand driving wind is mainly W-NNW,E and S.The annual sand drift potential is 187.57 VU,the resultant sand drift potential is 78.6 VU,the direction of resultant sand drift potential is 135°,and the RDP/DP is 0.419,which belongs to the low wind energy environment and blunt bimodal wind condition with moderate wind direction variability.The spatial difference of horizontal sand and dust flux in the protection system is significant,and the horizontal sand and dust flux decreased by 99%from moving dune observation point to straw checkerboard barriers observation point near the road upwind,and it also decreased by 93.6%from moving dune observation point to checkerboard barriers observation point near road downwind.The surface sediment in the protection system is mainly consist of medium sand and fine sand,and the particle size of sand and dust at different heights gradually becomes finer from the outside to the inside of the protection system.