干湿交替下黄土区苜蓿根系抗拔力学性能

Pullout Mechanical Properties of Alfalfa Roots in Loess Region Under Alternate Drying-Wetting

[目的]研究黄土区干湿交替过程对草本植物根系抗拔力学性能的影响,以期为草本植物根系固土护坡工程提供一定的理论支持和依据。[方法]选取紫花苜蓿为研究对象,采用重塑土根系拉拔试验,研究苜蓿根系抗拔力学性能及其与根径、根长、土壤容重、干湿交替作用等影响因素的关系。[结果](1)苜蓿根系抗拔力学性能指标与根径、根长和土壤容重存在幂函数或指数函数关系。(2)相比未干湿交替试样,干湿交替试样根系抗拔力学性能指标均显著减小。(3)砂壤土中苜蓿根系抗拔力学性能指标均优于壤土,且干湿交替在砂壤土中对苜蓿根系抗拔力学性能指标的影响小于在壤土中的影响。(4)根径、根长及容重和干湿交替的耦合作用对根系抗拔力学性能指标有显著影响。[结论]在干湿交替作用下,根径、根长和土壤容重对苜蓿根系抗拔力学性能有一定影响。

[Objective]The aims of this study are to reveal the effect of alternate drying-wetting on the pullout mechanical properties of herb roots in the loess region,and to provide some theoretical support and basis for herbaceous plant root soil fixing and slope protection engineering.[Methods]pullout test in laboratory was conducted on remolded loess samples with/without alfalfa roots to study the relationship between root pullout mechanical properties and the influencing factors,root diameter,root length,soil bulk density and alternate drying-wetting.[Results](1)The mechanical properties of alfalfa roots were correlated with root diameter,root length and soil bulk density in power functions or exponential functions.(2)The roots pullout mechanical properties of the samples with alternate drying-wetting significantly reduced compared with those of the samples without alternate drying-wetting.(3)The pullout mechanical properties of alfalfa roots in the sandy loam were better than those of the roots in the loam,and the effect of alternate drying-wetting on the mechanical properties of alfalfa roots in the sandy loam was less than that in the loam.(4)The coupling effects of root diameter,root length,bulk density and alternate drying-wetting had significant effects on the pullout mechanical properties of alfalfa roots.[Conclusion]Under alternate drying-wetting conditions,the root diameter,root length and soil bulk density had certain effects on the mechanical properties of alfalfa roots.