青藏铁路措那湖沿岸防风固沙工程效益

Efficiency of wind erosion control measures along Cuona Labe on Qinghai-Tibet railway,western China

青藏铁路格拉段北起青海省格尔木,基本沿青藏公路南行抵至拉萨市,线路全长1140km。铁路沿线遭受轻度以上风力侵蚀的线路长约260km,风蚀严重影响着铁路的安全运营。以西藏安多县境内措那湖沿岸布设的以高立式沙障、石方格沙障、碎石压沙措施相结合的综合防风固沙体系为研究对象,对其降低风速和输沙量的特征进行了研究。结果表明:位于风沙流活动前沿的高立式沙障具有显著的降低输沙率和风速的功效,和对照区相比,第1、2,第2、3排高立式沙障中间的输沙率分别降低了72.00%和99.30%;障后的风速降幅也较大,第1排沙障后降低风速的范围为35.54%～92.82%,第2排沙障后降低风速的范围为8.66%～92.98%,第3排沙障后降低风速的范围为26.84%～90.13%。高立式沙障障后不同距离的石方格和碎石压沙防护区的输沙率降幅更大,在距离第3排高立式沙障50和150m处石方格沙障区,其输沙率分别是0.59%和0.24%。距离第3排高立式沙障100和200m处的碎石压沙区,其输沙率分别是0.53%和0.25%。

The Geerm-Lhasa section of the Qinghai-Tibet railway starts from Geerm City in Qinghai Province, stretches southwards along the Qinghai-Tibet road and reaches Lhasa City of Tibet. The railway is 1 140 km long and suffers from wind erosion for a range up to 260 km. Wind erosion seriously endangers the safety of railway operation. A comprehensive defense system,combining the upright-concrete sand fence, stone checkerboard sand barriers and gravel mulch along Cuona Lake, Ando County of the Tibet Autonomous Region, was selected to evaluate the efficiency of wind erosion control measures based on field investigations of wind speed and the amounts of sand discharged. Three pieces of upright-concrete sand fences were arranged towards windward ,with the stone checkerboard sand barriers and gravel mulch alternately arranged to leeward. Upright-concrete sand fences greatly decreased the amount of sand discharged and wind speed compared with that of control. In the middle region between the first and second structures as well as between the second and third structures of the upright-concrete sand fences, the sand discharge ratios were 28.00% and 0.70% , i. e. a reduction of 72.00% and 99.30%. Behind the first structure of upright-concrete sand fence, wind speed decreased by 35.54% to 92.82% , by 8.66% to 92.98% behind the second upright-concrete sand fence,and by 26.84% to 90. 13% behind the third upright-concrete sand fence. Stone checkerboard sand barriers and gravel mulch also greatly reduced the amount of sand discharged. Behind the third upright-concrete sand fence, at distances of 50 and 150 m,the sand discharge ratio at the stone checkerboard sand barriers were 0.59% and 0.24% , respectively,and 0.53% and 0.25% at the gravel mulch at distances of 100 and 200 m.