邊坡防護工程中植物根系固土機制與穩定分析初探

A Study on Mechanism and Ability Analysis of Plant Root Reinforcement in Slope Protection

沈哲緯(Che-Wei Shen) ； 曹鼎志(Shen Che-Wei)

《水保技術》 4卷1期 (2009/01) Pp. 47-55

https://doi.org/10.30040/JSWCT.200901.0005

摘要

植物覆蓋於地表可以避免雨滴打擊地面，防止土壤沖蝕；枝葉掉落所形成的腐植層可改善土壤的理化性質，促進土壤團粒穩定，增加土壤滲透性並減少逕流，有效抑制土壤沖刷；又植物根系的錨錠作用，可有效控制淺層崩塌的風險。本研究首先蒐集植物根系現地直剪試驗結果與常見植物根之拉力強度迴歸式，以評估不同植生與不同根系深度加勁效益，進而探討植物根系對邊坡穩定之貢獻。分析結果顯示，以木本植物植生的效益比草本植物為優，而草本植物邊坡植生的功能主要為固土防止坡面沖蝕，避免土壤流失為主；以本研究列舉之植生為例，木本植物根系深度約在0.8m，在坡高3m時可提升1.5倍以上，坡高6m 時安全係數提升約為1.2倍，坡高10m時平均安全係數提升小於1.1倍，草本植物根系深度約不超過0.4m，於坡高3m時對邊坡穩定性約可提升10%~20%，坡高6m和10m 時對邊坡穩定性的貢獻很低。

關鍵字

植物覆蓋 ； 土壤沖蝕 ； 錨錠作用 ； 根系力學

並列摘要

The coverage of vegetation can prevent raindrop erosion, the humus layer from falling branches and leaves not only improve the chemical and physical condition of the soil but also improve the stability of soil aggregate, increase soil permeability, and reduce surface runoff, effectively prevent the soil erosion. Also the roots anchor can reduce the risk of shallow slope failure. Thus, it is necessary to evaluate the effectiveness of plant root to slope stability. This study collect the results of several plant root direct shear tests and tensile strength regression equation of several types of plants to evaluate the reinforced effect of various plants and root depth. The contribution of roots anchor to slope stability is also discussed in this study.

並列關鍵字

Vegetation cover rate ； Soil erosion ； Anchoring effect ； Root mechanics