不同材料攔沙構造物防治飛沙功效試驗

STUDIES ON EFFECTS OF FIXED SAND FENCE WITH DIFFERENT MATERIALS

10.29417/JCSWC.198503_16(1).0006

江永哲(Yung-Cheh Chiang)；林壯沛(Jaung-Pey Lin)

攔沙籬 ； Fixed sand fence

中華水土保持學報

16卷1期（1985 / 03 / 01）

60 - 77

繁體中文

本文試驗方法分為野外現場試驗與室內風洞試驗兩部分。野外現場試驗設置於苗栗縣後龍鎭海寶里海邊之試驗地，自民國67年11月20日至民國68年3月17日，共觀測四個月，以竹梢、尼龍網、竹片、木板片等材料爲四種處理，行四個重複之拉丁方格試驗設計。室內風洞模型試驗設於國立中興大學水土保持館人工降雨試驗室，係針對不同材料攔沙構造物之竹梢、竹片、尼龍網、木板片等材料，在10 m/sec、8.4 m/sec.5.7 m/sec三種風速下，探討各種不同材料攔沙構造物之防風效果與堆沙功效。經詳細探討後扼要列其結果如下：竹梢攔沙構造物具有屈撓性、堆沙高度爲91％，平均堆沙長度爲17 H（H：攔沙籬高），平均單位寬之堆沙量爲11.63 m^2，為四種材料中堆沙效果最佳者。尼龍網攔沙構造物通透率均匀，堆沙高度爲90％，平均堆沙長度爲14 H，平均單位寬之堆沙量為7.908 m^2。木板片與竹片攔沙構造物受氣體之折流與射流影響，於迎風面堆沙量少，籬脚前後有明顯向下挖之淘沙現象，堆沙高度分別爲85％及75％，平均堆沙長爲16 H及16.4 H，堆沙量爲8.88 m^2及8.33 m^2。風洞模型試驗：由各種不同材料攔沙構造物之風速比水平分佈曲線得知，減低風速之效果竹梢＞竹片＞尼龍網＞木板片。而減低風速50％之範圍，竹梢在20H以上，竹片爲8H〜16H，尼龍網爲5H〜18H，木板片爲5H〜9H。就堆沙高度、長度及堆沙量，其結果爲竹梢＞尼龍網＞竹片＞木板片。

There are two experimental methods in this study. Field experimental site is located in the coast of Naio-li. Experiment had been performed from November 20, 1978 to March 17, 1979. The Latin Square Design was empolyed to distinguish the fixed sand fences with different materials, namely, bamboo bush, nylon net, sheet bamboo and board plate with four replications. The model experiment of fences was conducted in the wind tunnel at Soil & water Conservation Department, National Chung Hsing University. We investigated the effects of wind reduction and sand fixation under three wind velocities: 10m/sec, 8.4m/sec and 5.7m/sec. The results were obtained as follows: The fence of bamboo bush was with flexibility. It had the best effect of fixing sand among four materials. Ninety one percent of the height of heaping sand, 17H (H:height of fence) of the length of heaping sand and 11.63 m^3 of the volume of heaping sand per unit width were observed for the fence of bamboo bush. The fence of nylon net was with uniform permeability. Ninety percent of the height of heaping sand, 14H of the length of heaping sand and 7.908m^3 of the volume of heaping sand per unit width were observed for the fence of nylon net. Since the fences of board plate and sheet bamboo were influenced by deflection flow and jet flow, the volume of heaping sand on windward was small. The windward and leeward of the fence had downward erosion observable. Their heights of heaping sand were 85% and 75%, the lengths of heaping sand were 16H and 16.4H the volumes of heaping sand per unit width were 8.88m^3 and 8.33 m^3 respectively. From wind tunnel experiment, horizontal distribution curve of wind velocity ratio with different materials showed that the effects of reducing wind velocity by the fences were in the following order: bamboo bush ＞ sheet bamboo ＞ nylon net ＞ board plate. The horizontal distances of 50% wind reduction were more than 20H for the fences of bamboo bush 8H-16H for sheet bamboo, 5H-18H for nylon net and 5H-9H for board plate. The height, length and: volume of heaping sand were in the order: bamboo bush ＞ nylon net ＞ sheet bamboo ＞ board plate.