不同土壤生物工程措施根系附加黏聚力研究

陳鵬 劉煜 吳耕華

摘要 [目的]研究4種不同土壤生物工程措施對邊坡土體抗剪強度的提高作用。[方法]設置了一處長40 m的人工邊坡，在邊坡上使用扦插、灌叢墊、層栽與梢捆4種土壤生物工程措施，并在施工8、12個月后分別開展根系現場調查，在實驗室進行單根抗拉試驗，并引入RWM模型量化研究4種不同土壤生物工程對邊坡抗剪強度的提高作用。[結果]旱柳根系抗拉強度隨根系直徑增大逐漸減小，能產生顯著的根系加筋作用；隨著土層深度的增加，根的面積比減小，4種土壤生物工程措施完工12個月后的各徑級的根系截面積比率（RAR）相比于8個月后提高43.75%～69.38% ；土壤生物工程可以明顯提高邊坡的抗剪強度，隨著根系的發展，12個月以后各種措施附加黏聚力比8個月時有明顯的增長。20 cm土層深度時灌叢墊與梢捆措施附加黏聚力高于扦插和層栽，且根系所產生的附加黏聚力最大，對邊坡的淺層土壤的加筋作用優于另外2種措施。20 cm深度以下灌叢墊與梢捆措施根系附加黏聚力逐漸下降，而扦插與層栽措施附加黏聚力逐漸增加，對深層土壤具有一定的錨固作用。[結論]研究可為土壤生物工程技術在農田水利護坡中的廣泛應用提供量化評價方法和理論指導。

關鍵詞 農田水利工程；土壤生物工程；河流生態修復；根系固坡

中圖分類號 S278 文獻標識碼 A 文章編號 0517-6611（2018）23-0168-04

Abstract [Objective]The effect of 4 different soil bioengineering measures on the shear strength of slope soil was studied.[Method]An artificial slope of 40 m was set up in the experiment.Four kinds of soil biological engineering measures were used on the slope， including cutting， shrub mat， layer planting and bundling， and the root field investigation was carried out in 8 months and 12 months after construction. Single tensile test was carried out in the laboratory， and RWM model was introduced to quantify the effect of 4 different soil biological engineering on the shear strength of the slope.[Result]The results showed that： the tensile strength of the root system decreased with the increase of root diameter， which could produce a significant root and reinforcement effect. With the increase of soil depth， the area ratio of the root was decreased， and the RAR of the four soil bioengineering measures after 12 months was increased by 43.75% to 69.38% compared with that in 8 months. Soil bioengineering can obviously improve the shear strength of the slope. With the development of the root system， the adhesion of various measures after 12 months is significantly higher than that in August. Scrub pads when 20 cm soil depth and tip add bundle of measures of cohesion is higher than cutting and planting， and the root system produced by the additional cohesive force， the largest of shallow soil on the slope reinforcement effect better than the other two measures. The adhesion cohesion of the root system was gradually decreased with the thickness of the thicknes and the tip bundle， and the adhesion of the cuttings and bedding was gradually increased， which had a certain anchoring effect on the deep soil. [Conclusion]The research results provide quantitative evaluation method and theoretical guidance for the wide application of soil bioengineering technology in farmland water conservancy slope protection.

Key words Irrigation and water conservancy projects；Soil bioengineering；River ecological rehabilitation；Root consolidation

植物根系纖維可以產生對提高邊坡穩定性有積極作用的附加黏聚力 [1]。水平方向的植物根系可以通過相互纏繞來束縛土壤，使根系與土體形成具有一定強度的整體，而垂直生長的根系則會穿過淺層土壤，錨固深層土壤，并可以增加土體的遷移阻力[2]。……