生態植生毯於逕流作用下之抗沖蝕行為

Erosion Resistance of Geomesh subjected to Run-off Impact

周冠翰(Guan-Han Zhou)

指導教授 ： 何嘉浚

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00169

摘要

台灣地處亞熱帶，因降雨豐沛，其降雨量無法為土壤吸收便匯集成地表逕流，倘若地表逕流集中產生強烈的侵蝕力，進而造成邊坡滑動及邊坡破壞等災害，更造成人民之生命財產安全。本研究採自行設計之切向水流沖蝕試驗儀來進行實驗，試驗材料採用友蚋溪之現地土壤，並配合兩種不同開孔徑之生態植生毯及不同粒徑大小之拋石組合，進行不同流速之試驗。實驗過程中，透過觀察試驗槽內之變化狀況，且配合量測系統所記錄之流量與濁度變化情形，以評估每組實驗之沖蝕行為。試驗結束後蒐集被沖蝕帶出之土壤，並進行粒徑分析試驗，以探究土壤沖蝕機制。由試驗結果可知沖蝕行為主要分為兩階段，分別為尚未沖蝕階段及穩定沖蝕階段；為能精確界定土壤沖蝕行為，採用統計學之盒鬚圖法來定義不同之沖蝕階段。
試驗結果顯示：(1)拋石孔隙率、生態植生毯之開孔徑大小及覆蓋率，皆為影響土壤沖蝕量之重要因素；(2)拋石孔隙率愈小、生態植生毯開孔徑愈小及覆蓋率愈大，其抗沖蝕能力愈高；(3)試驗所採用之兩種植生毯，其立體的組織結構編織方式，會產生囚砂之效果，提高土壤抗沖蝕之能力。

關鍵字

切向水流 ； 生態植生毯 ； 土壤沖蝕

並列摘要

Located within the subtropics, Taiwan has a climate characterized by abundant rainfall, which cannot be fully absorbed by soil, thus giving rise to surface runoff. When runoff flows converge, the thus generated strong erosive forces can occasion disasters such as slope sliding and failure, which further pose threat to the safety of people’s lives and properties. In this study, experiments were conducted to test tangential flow erosion at different flow rates using a tester developed by the author for this purpose, the situ soil collected from Yourui Creek as the test material, and geomesh in two aperture sizes with riprap in different particle sizes. During the experiment, changes in flow and turbidity in the test tank were observed and recorded in a measurement system. Based on the records, the erosion behavior in each of these experiments was evaluated. The soil washed out by erosion was collected at the end of the testing and put to a particle size analysis test to investigate the mechanisms of soil erosion. Testing results show that erosion behavior can be divided into two stages: non erosion and steady erosion. To precisely define erosion behavior on soil, box and whisker plots in statistics were used for the definition of different erosion stages.
Testing results show: (1) riprap porosity, geomesh aperture size and coverage are important factors that affect the amount of soil erosion; (2) lower riprap porosity, smaller geomesh aperture size and greater geomesh coverage contribute to the increase in soil resistance to erosion; and (3) the 3D woven structure of the two types of geomesh tested has an sediment trapping effect that also increases soil resistance to erosion.

並列關鍵字

Tangential Flow ； Geomesh ； Soil Erosion

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