多花木蓝根系与土体界面摩阻特征

为研究灌木植物根系的固土护坡力学效应,探讨根系与土体间相互作用的特性。以多花木蓝为供试植物,进行植物根系切片并计算根系的表面凹凸度,选取0~0.5,0.5~1.0,1.0~1.5,1.5~2.0mm 4种粒径的粉质黏土,在不同的土体含水率和根径条件下,制备根土复合体扰动试样,进行单根抗拔摩阻试验和直剪摩阻试验,探讨土体含水率、植物根径以及土体粒径对根土界面摩阻特性的影响。结果表明:多花木蓝根系的表面凹凸度随根径变化无显著性差异,根系的拉拔剪应力集中在17.36~32.76kPa,而根土界面的摩擦系数为0.10~0.20;根系拉拔剪应力和根土界面摩擦系数随土体粒径和土体含水率的增加逐渐下降;土体含水率和土体粒径愈低,根系形态特征对根系的拉拔剪应力和根土界面摩擦系数的影响愈显著。研究结果对分析根土界面摩阻特性的影响因素,以及利用灌木植物提高边坡土体结构稳定和防治水土流失、土壤侵蚀等地质灾害具有重大的指导意义。

Characteristics of Interface Friction Between Indigofera amblyantha Root System and Soil

To study the mechanical effect of shrub plants on slope protection and to investigate the friction characteristics of root-soil interface, the roots of Indigofera amblyantha were sliced and the root surface roughness of this kind of plant were calculated. In order to evaluate the influence of different root diameters, soil moisture content and soil particle size on friction characteristics of root-soil interface, pull-out friction tests and shear friction tests were conducted on the root - soil composites with the particle size of 0 ~ 0.5,0.5 ~ 1.0,1.0 ~ 1.5 and1.5 ~ 2.0 mm which prepared by sieving and remolding. The results showed that there was no significant difference in root surface roughness of I. amblyantha with the gradual increasing of root diameter, the pull-out shear stress of root system was concentrated in 17.36 ~ 32.76 kPa, and the friction coefficient of root-soil interface varied between 0.10 and 0.20. The pull-out shear stress of roots and the friction coefficient of root-soil interface in soil-root composites presented a downward trend with the increase of soil moisture content and soil particle size. When soil particle size and soil moisture content were small, the effects of root morphology on the pull-out shear stress of I. amblyantha roots and the friction coefficient of root-soil interface were more significant. These results were great guiding significance to analyze the influence factors of root-soil interface friction characteristics, and use shrub plants to improve the stability of slope soil structure and prevent soil erosion and other geological disasters.