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红黏土边坡香根草根土复合体的强度特性
余燚1, 刘思思1, 李某明1, 李梓祥1, 杨擎宇2
1.中南林业科技大学 土木工程学院, 湖南 长沙 410004;2.云南大学 建筑与规划学院, 云南 昆明 650091
摘要:
[目的] 针对植物护坡效应,探究香根草根系的力学特性及其根土复合体强度特征影响因素,为植物护坡工程设计提供参考依据。[方法] 利用模型箱模拟红黏土填筑边坡进行香根草种植,利用根系拉拔试验和原状根土复合体直剪试验等室内试验,研究香根草的力学性能及根土复合体强度特征的影响因素。通过对试验结果进行拟合分析及Spearman相关性分析,分别得出了香根草根系直径与抗拉性能的关系及不同指标对其根土复合体抗剪强度的影响效果。[结果] 试验香根草根系平均抗拉力为19.05 N,平均抗拉强度为20.12 MPa;香根草根系的抗拉力、抗拉强度与根系直径呈显著的幂函数关系;土中的根重密度RWD随着深度增加而降低。Spearman相关分析结果显示,根重密度RWD与根土复合体的黏聚力c呈正向强相关关系(R=0.882)。[结论] 随着香根草根系直径增大,其抗拉力增大,抗拉强度降低;根重密度RWD的提升能显著提高香根草-红黏土根土复合体的黏聚力c,但对于摩擦角φ提升效果不明显。
关键词:  香根草  红黏土  根土复合体  剪切试验  抗拉强度
DOI:10.13961/j.cnki.stbctb.2021.01.014
分类号:U416.1;U411
基金项目:国家自然科学基金项目“基于根系构型定向调控的植物边坡固土机理研究”(51608545);中铁二十局科技研发项目(YF1900SD07B)
Strength Characteristics of Vetiver Root-Soil Complex on Red Clay Slope
Yu Yi1, Liu Sisi1, Li Mouming1, Li Zixiang1, Yang Qingyu2
1.School of Civil Engineering, Central South University of Forestry and Technology, Changsha, Hu'nan 410004, China;2.School of Architecture and Planning, Yunnan University, Kunming, Yunnan 650091, China
Abstract:
[Objective] The slope protection effect of plants, the mechanical properties of the root system of vetiver and the factors influencing the strength characteristics of the root-soil complex were studied to provide a reference basis for plant slope protection engineering design.[Methods] First, an outdoor model box was used to simulate the filling of red clay on the slope for vetiver planting conditions, and the mechanical properties of vetiver and the factors influencing the strength characteristics of the root-soil complex were studied through indoor tests, such as a root pull test and undisturbed root-soil composite direct shear test. Through fitting analysis and Spearman correlation analysis of the test results, the relationship between root diameter and tensile properties of vetiver and the effects of different indices on the shear strength of the root-soil complex were obtained.[Results] The average stretching resistance of the vetiver root system was 19.05 N, and the average tensile strength was 20.12 MPa. The stretching resistance and tensile strength of the root system of vetiver had a significant power function relationship with root diameter. Root weight density(RWD)decreased with increasing soil depth. The results of Spearman correlation analysis showed that the RWD and cohesive force c of the root-soil complex had a positive and strong correlation (R=0.882).[Conclusion] As the diameter of the root system of vetiver increases, its tensile strength increases and its tensile strength decreases. The increase in RWD can significantly increase the cohesive force c of the vetiver-red-clay root-soil complex, but the effect of increasing the friction angle φ is not obvious.
Key words:  vetiver  red clay  root-soil complex  shear test  tensile strength