中国天山艾肯达坂透风式下导风防雪工程

APPLICATION OF BLOWER FENCES WITH A PERMEABILITY NEW TECHNOLOG6Y ON AIKEN PASS IN TIANSHAN MOUNTAIN OF CHINA

据艾肯达坂风雪流形成条件，提出了贴地气层分离是公路吹雪堆积的机理，通过对密闭式下导风能量转换和流场结构的剖析，创造了透风式下导风防雪工程。其实施后，改变了公路因冬半年严重雪阻而不能通车的状况，经济效益和社会效益俱佳；

Tianshan Mountahs inner China extend in WE,the altitude is usually over 4 000m,the coldand warm seasons can be divided clearly,Aiken Pass(at the aititude 2 840 3050m)is situatedin west part of Mt. Tianshan and the intersected site of windward slope and wind gaps. Here isthe most precipitational region on Mt. Tianshan, the annual precipitation is 1 000mm, The winterhalf an year(during october in year to April in next year) is the main snowfall period,the ave-rage temperature is below 0℃, the lowermost temperature reaches-37℃;the average snowfallis 350mm ,the maximum one reaches 394mm, the maximum natural snow deposit>145cm;theveIocity of wind >5. 0m/s reaches 1 600h, the occurring frequency of snow drift is 50%,andthe total snow transportation is 100-500m￣3/m。 The section along Aiken Pass(23km long)in National Highway from Yining to Ruoqiang isthe key section which connects the sOuth and north Xinjiang each other. Before 1981 ,this part isthe serious snow blockage section in this region , the maximum snow deposit reached 8m, duringthe period of winter half an ycar,all automobiles should take a devious round for 807km. More than 7 0% of hlghway snow blockage is caused by continuous snowfail, The snowdeposit type belongs to “dty-cold type ” which is fit for starting and movement of snow grain,thefavourable roabded Sectional type for snow drift deposition is mainly in a leeward one-sided cut,windward one-sided cut and typical cut etc. All these factors become the formation condition ofsnow drift and snow block age disasters in Aike n Pass,The vortex velocity reduction zone causedby separation of boundar y layer on road surface is the main generation of road snow blockage。The blower fence and blower fence with a permeability are all the snow dirft preventionalworks , but the first one needs much deflector material,it is easy to be destoyed and difficult tomaintenance,the late one can avoid these weaknesses。The observation on two upright blower fence in leeward one-side cut on Aiken Pass(Fig。3-4)shows that both of which has appeared five united wind veIocity zones, but their scale andintensity are different.The blower fence with a permeability can let some airflow permeatethrough deflectors, the range of vortex zone behind of deflectors become smaller,so there arefewer snow drift depositing. The mOst important point is that comparing with blower fence ,thefront of blower fence with a permcability is much smaller no matter the scale and intensity ofvortex veIocity reduction zone。The snow deposit is 6. 3m in front of the first one , but it is only1. 3m in front of later one。 The snow deposits is relative thin in front of blower fence with a per-meability,this phenomena indicates that the airflow passed through deflectors is very strong,sothe velocity on road surface behind of deflectors will be increased , the blowing width bv airflowwill be enlarged 2m,The blower fence with a permeability is the best snow drift preventionworks。In 1981,the highway departments set up 8 468m long blower fence with a permeability andother supplementary works on Aiken Pass, Since then,there is no snow blockage during winterhalf an ycar and ensure the safety of transportation, automobiles is not needed to take a deviousround。After 11 year from 1982 to 1992,479M yuan(RMB)of highway transportation fee wassaved