中文摘要：

为研究灌木根系固土护坡的力学机制，以西宁盆地为例，对青藏高原黄土区柠条锦鸡儿、白剌、霸王、四翅滨藜4种灌木进行室内单根拉伸、剪切试验，系统分析灌木根系材料的力学特性。试验与研究结果表明：根系抗拉力和抗剪力均与根径呈幂函数或指数函数关系，且随根径增大而增大，生长期为18个月的4种灌木的抗拉力与抗剪力大小依次为：四翅滨藜〉柠条锦鸡儿〉霸王〉白刺；根系抗拉强度与根径间呈幂函数或指数函数的关系，随根径增大而减小。根系拉伸的应力-应变特征随不同灌木种的根系结构组成不同而不同，4种灌木种单根拉伸应力-应变曲线均表现出在根系受拉后的初期阶段，应力-应变呈直线关系，当荷载超过弹性极限，拉力继续增加时，应力-应变关系反映出非线性弹性特征，4种灌木种延伸率均可达13％以上，且根系最大延伸率随根径增大而降低。研究区根系密集且毛细根分布较多的0．3～0．8m的浅层土体具有较大的抗拉强度、抗剪强度和抗变形能力，对防治边坡表层水土流失、增强根-土复合体抗剪强度、减缓与防治边坡的滑移变形具有重要作用。根据4种供试灌木根系力学特性并结合根系形态特征，四翅滨藜和柠条锦鸡儿根系固土护坡作用较大。

英文摘要：

The single root tensile and shear tests were carried out to study the mechanism of slope protection by shrub roots and analyze the mechanical characteristics of shrub roots on Caragana korshinskii, Nitraria tangutorum, Zygophyllum xanthoxylon and atriplex canescens in loess area of Tibetan plateau where Xining basin was taken as an example. Experiments and studies showed that power or exponential relations existed between single root tensile resistance and root diameter of four shrub roots, and both the single root tensile resistance and shear resistance increased with increasing diameter, and the increment rate of Atriplex canescens is the largest, followed by Caragana korshinskii, Zygophyllum xanthoxylon and Nitraria tangutorum for eighteen-month age shrub. Either power or exponential relations were fitted between root tensile strength and root diameter, and the root tensile strength decreased with increasing diameter. The results revealed that various root structures have different tensile stress-strain characteristics. The stress-strain curves of four shrub roots also presented straight line relation in root initial stage after tension. As the pulling force kept increasing after loading over elastic limit, the stress-strain curves reflected the non-linear elastic characteristics. The rate of tensile elongation of four shrub roots was all over 13%, and the elongation rate of roots decreased with increasing diameter. The shallow soil of studied area from 0.3 m to 0.8 m with plenty of hair roots had strong single root tensile strength, shear strength and non-deformability, so the shallow soil played an important role in controlling soil and water loss of slope, reinforcing shear strength of soil-root composite and controlling slide deformation. According to the root mechanical characteristics and root morphological features, Atriplex canescens and Caragana korshinskii had significant function in slope protection in of loess area Tibetan.