塔里木沙漠公路沿线机械防沙体系效益分析

野外实测和室内风洞实验的数据分析表明,塔里木沙漠公路沿线高立式沙障和半隐蔽式沙障发挥了较大的防沙效益,平沙地上高立式沙障的防护距离在18H左右。3种高立式沙障防沙效益各不相同,以芦苇栅栏最佳,抗紫外线尼龙网栏次之,白尼龙网栏最差。随设置路段、地貌部位、风沙活动强度不同,各种高立式沙障使用年限有差异。沙漠腹地半隐蔽式沙障的掩埋速度为2.0~14.4m·a^-1左右,并随时间推移有一个加速的过程。

The Benefit of the Prevention System along the Desert Highway in Tarim Basin

The paper, based on the data obtained from the survey in field and wind tunnel e xperiments, shows that the prevention system along the desert highway in Tarim B asin is playing with obvious benefits. The grain size analysis shows that on fl oat sand landform the shelter distance of upright sand fence is at about 18 H. Inside the semi covered fences the changes of grain size are evident, more fine sands are concentrated, and with the lapse of time, clay will be formed inside the semi covered fences. Wind tunnel experiments and the results of field observation show that the benefits of the three types high fences are different. Among them the reed fence is optimum, which followed by anti ultraviolet nylon fence and white nylon fence in order. However, with the sand deposition, the whit e nylon fence's benefit of prevention will be higher than anti ultraviolet nylon fence. Based on the data obtained in field, it is estimated that the usable du ration of reed fence is 2~6 years, that of white nylon fence is 1~5 years and t hat of anti ultraviolet nylon fence is 1~4 years, they are different with the locations of fences. The width of the semi covered fences covered by sands is primarily decided by the times of gale and its duration. Furthermore, the speed of the prevention system being covered and the quantities of sand deposition ar e not only extremely related with the stress of the wind sand activities, but also with the angle (T) of the direction of the major sand drifting wind with the desert highway and the landforms that the highway acrossed. For example, the being covered speeds of the prevention systems on dunes concentrated landforms (T < 10°) and the float landforms (T > 60°) are different evidently; the latter is more quickly and is more likely to cause sand disaster to the desert highway. In Tazhong area, the being covered speed of semi covered fences is about 2 0~14 4 m·a^-1, however, with the lapse of time, it will be accelerated.