为探究承受轴向荷载和径向荷载时植物根系材料力学特性的差异性,针对水土流失地区常见植物种紫穗槐1~5 mm径级范围内直根,采用TY8000伺服控制试验机,研究在2种荷载下根系强度特征、本构特征及弹性变形性质。结果表明:(1) 在轴向荷载、径向荷载下,直根极限力与根径幂函数正相关,极限强度与根径幂函数负相关;(2) 直根本构曲线在轴向荷载及径向荷载下均表现为由弹性变形过渡到塑性变形,且直根极限应力、弹性应力均无差异性;但轴向荷载下的极限应变(15.04%)及弹性应变(2.71%)显著小于径向荷载(20.39%、4.19%);(3) 直根的拉伸弹性模量及弯曲弹性模量均与根径幂函数负相关,抗拉刚度及抗弯刚度与根径幂函数正相关,轴向荷载下各径级平均弹性应力占极限应力的百分比(50.45%)显著大于径向荷载(34.08%)。总体而言,紫穗槐根系在轴向荷载下表现出更优良的弹性性能,紫穗槐更适宜栽种于主荷载类型为轴向荷载的风力、水力侵蚀区域。

The strength characteristics, constitutive relation, and elastic deformation characteristics of the straight roots of Amorpha fruticose, with diameters of 1-5 mm, were measured using a TY8000 servo control testing machine to clarify the mechanical properties of the materials of the plant roots under axial or radial loads. We found that the limit force was negatively correlated and limit strength was positively correlated with root diameter as a power function. When the stress-strain curve (σ-ε curve) was calculated from elastic deformation to plastic deformation under two type loads, there was no significant difference between the ultimate stress and elastic stress of straight roots, but the ultimate strain (15.04%) and elastic strain (2.71%) under axial load were significantly smaller than the radial load (20.39%, 4.19%). The tensile modulus and bending modulus were negatively correlated with root diameter as a power function, and the tensile stiffness and bending stiffness were positively correlated with root diameter as a power function. The percentage of the average elastic stress to the ultimate stress under axial load of each diameter level (50.45%) was significantly higher than the radial load (34.08%). Overall, the elastic property of root system is better under an axial load, and Amorpha fruticosais best suited to planting in an area of wind and hydraulic erosion where the primary load type is axial load.