【摘要】 植物根系对增强土体抗剪强度具有一定作用。为研究公路边坡喷播绿化初期根系特征及其对抗剪强度的影响,通过喷播的方式制备灌草混播试样,人工模拟边坡绿化7种灌草组合,植物生长3个月后进行原位剪切试验。挖取试样内植物根系,测定根系直径、根长密度、总表面积、总体积、根尖数、分叉数、根系密度、倾斜角度等根系特征指标,并通过灰色关联度法分析根系特征对土体抗剪强度的影响。结果表明:不同灌草混播组合根系特征随土层深度的变化存在一定差异;喷播绿化初期,0～2 mm细根占整个根系系统的96%～99%;水平根、侧根及垂直根分别占整个根系系统的7%～16%、44%～57%、33%～47%;不同灌草组合植物根系可增加土体抗剪强度6～17 k Pa,且不同灌草比试样抗剪强度大小依次为灌草比1∶1>灌草比1∶4>灌草比1∶5>灌草比3∶1。灰色关联度分析结果表明,各根系指标对抗剪强度的影响大小依次为侧根数量>水平根数量>根系分布深度>根系密度>剪切面上部根长密度>根长密度> 0～2 mm细根数量>剪切面下部根长密度>总表面积>总体积>根尖数>垂直根数量>分叉数>2～10 mm根系数量。该结果可为评价公路边坡喷播绿化初期坡体稳定性、指导边坡植被恢复提供依据。更多还原

【Abstract】 Plant roots could enhance the shear strength of soil. To understand the root characteristics and their impacts on shear strength at the initial stage of highway slope greening,the mixed grass-shrub samples were prepared by spraying seeds. Seven kinds of grass-shrub combinations were artificially simulated in the slope greening. The in-situ shear test was carried out three months after plant growth. Plant roots were excavated,with root characteristics such as root diameter,root length density,total surface area,total volume,number of root tips,number of branches,root density and inclination angle being measured. The effects of root characteristics on the shear strength of soil were analyzed by grey correlation method. The results showed that there were differences of root characteristics in various grass-shrub combinations with the changes of soil depth. At the initial stage of greening,fine roots of 0-2 mm accounted for 96%-99% of the whole root system. The horizontal roots,lateral roots and vertical roots constituted 7%-16%,44%-57% and 33%-47% of the total root system,respectively. The roots of different grassshrub combinations increased the shear strength of soil by 6-17 k Pa,and the shear strength of the different ratios of shrubs and grasses was in the order of 1 ∶ 1 > 1 ∶ 4 > 1 ∶ 5 > 3 ∶ 1. The results of grey correlation analysis showed that the effects of root characteristics on shear strength were as follows: number of lateral roots > number of horizontal roots > depth of root distribution >root density > root length density above shear plane > root length density > number of fine roots( 0-2 mm) > root length density below shear plane > total surface area> total volume > number of root tips > number of vertical roots> number of branches > number of roots( 2-10 mm). Our results provide a basis for evaluating the stability of the slope at the initial stage of highway slope greening and guiding vegetation restoration of the slope.更多还原