摘要
植物根系抗拉变形机制反映根系抵抗外力作用的自适应过程,对土少石多的喀斯特边坡治理具有积极作用。为探究护坡灌木根系的抗拉力学性质,以5年生双荚决明根系为研究对象,通过单根拉伸试验,探讨根长和拉伸速率对双荚决明的单根抗拉变形特性的影响。结果表明:1)单根抗拉力与直径之间呈幂函数关系增大,单根抗拉强度与直径之间呈对数函数关系减小;2)双荚决明单根受拉变形多样且过程复杂,以弹性变形、弹塑性变形及根皮撕裂等方式抵抗外力,不同单根以不同的变形方式发挥其抗拉最佳效果;3)根长对单根抗拉变形特性无显著影响,拉伸速率对单根抗拉变形特征有显著影响,当拉伸速率为500 mm/min时,应力应变曲线均为单峰型。双荚决明根系有较强的变形能力,受力时可通过复杂的变形起到维持坡体稳定的作用,在较快的拉伸速率下根系更容易被破坏。
[Background]The role of vegetation(grasses,shrubs,and trees)in slope stability and erosion has been well recognized and incorporated.The plant material especially the root system plays an important role in stabilizing slope and enhancing soil strength.The root system is very significant especially in karst areas with little soil and lots of stones.Root tensile properties are the basis for enhancing slope stability,and the process of root tensile deformation reflects the process of root system resisting external force.Therefore,it is useful to study the tensile properties of plants in karst area.[Methods]In order to explore the tensile deformation characteristics of a single root of Cassia bicapsularis,5-year-old shrubs were selected as the research objects.Under the condition of different root diameter levels,different root length levels(50 and 100 mm)and different tensile rate levels(10 and 500 mm/min),the tensile force of a single root and tensile strength of a single root were assessed via tensile test for a single root.Furthermore,the stress-strain curves during the tensile process were recorded by experimental machine.[Results]1)The tensile force of a single root of C.bicapsularis increased with the increase of root diameter according to a power function,while the tensile strength of a single root decreased with the increase of root diameter according to a logarithmic function.2)The tensile deformation modes of C.bicapsularis were various and the process was complex.According to the shape of stress-strain curve,the curves were divided into three types:serrated type,single peak type and multi-peak type,and different types of curves corresponded to different deformation processes of a single root.The roots deformed in different ways to resist external forces,including elastic deformation,elastic-plastic deformation and root skin tearing.Different single roots exerted maximum tensile force through different deformation modes.3)Chi-square test was carried out for stress-strain curves with different root lengths and different tensile rates.The results showed that there was no significant correlation between root length and tensile deformation characteristics of a single root,but the tensile rate had significant effect on the tensile deformation characteristics.When the tensile rate was 500 mm/min,all of the stress-strain curves were single peak type,because the fiber bundles were broken before they exerted tensile properties to external forces at a faster rate.[Conculsions]In this study,the root system of C.bicapsularis plays a better role in stabilizing the slope through complex deformation during tension.In the process of stretching,the complex deformation mode is used to resist deformation by the single root of C.bicapsularis.When landslide occurs,the complex deformation mode is more conducive to maintaining the stability of slope.But the root system is more likely to be destroyed at a faster stretching rate.The mechanical characteristics of single root deformation of plant roots were discussed in order to provide a theoretical basis for the mechanism of soil consolidation and slope protection of roots in karst areas.
作者
潘露
张乔艳
郭欢
唐丽霞
PAN Lu;ZHANG Qiaoyan;GUO Huan;TANG Lixia(College of Forestry, Guizhou University, 550025, Guiyang, China;Zhazuo Sate-Owned Forest Farm of Guizhou Province, 550025, Guiyang, China)
出处
《中国水土保持科学》
CSCD
北大核心
2021年第6期131-137,共7页
Science of Soil and Water Conservation
基金
国家自然科学基金“喀斯特地区护坡灌木根系构型的固土变形机制研究”(31960332)。
关键词
双荚决明
单根抗拉
变形
力学特性
应力-应变曲线
Cassia bicapsularis
tensile of a single root
deformation
mechanical property
stress-strain curve
作者简介
第一作者:潘露(1996—),女,硕士研究生,主要研究方向:灌木根系力学,E-mail:1102324199@qq.com;通信作者:唐丽霞(1976—),女,博士,副教授,主要研究方向:根系力学,E-mail:248206125@qq.com。
