中文摘要：

以自建的西宁盆地周边试验区为例,通过对寒旱环境4种类型试样即素土、草本–土复合体、灌木–土复合体、灌木–草本–土复合体试样分别进行三轴压缩试验,对比分析这4种试样的强度及其相应的应力–应变特征,评价试验区植物根系对边坡土体的加筋效应及其固土护坡贡献。结果表明：（1）在围压20,30和40 kPa作用下,根–土复合体和素土的主应力差随着轴向应变的增大而呈增大趋势,且最终趋于稳定值,曲线形态基本属于应变硬化型。在荷载作用的初始阶段,根–土复合体的抗剪能力较素土增长快;（2）在3级围压作用下,根–土复合体试样的剪切峰值均大于素土,且4种试样的剪切峰值具有一致性的变化规律,即柠条锦鸡儿根–芨芨草根–土复合体〉芨芨草根–土复合体〉柠条锦鸡儿根–土复合体〉素土;（3）根–土复合体较素土的黏聚力c值增长率依次为94.1%,66.6%,39.2%,且柠条锦鸡儿根–芨芨草根–土复合体的黏聚力较芨芨草根–土复合体、柠条锦鸡儿根–土复合体的黏聚力增长率分别为16.5%,39.4%。该变化规律反映试验区植物根系对边坡土体具有显著的加筋作用,同时也说明草本与灌木植物组合种植的形式对试验区土体的加筋效果较单一种植草本或灌木植物显著。研究成果为试验区和相似地区,开展边坡浅层滑坡、水土流失等地质灾害的防治提供理论依据。

英文摘要：

The triaxial compression tests have been conducted in cold and arid environments on four samples： soil without roots, herb root-soil composite system, shrub root-soil composite system and shrub root-herb root-soil composite system. By comparing the strength and corresponding stress-strain properties of the four samples, the effects of the roots reinforcement on soil and slope protection have evaluated. The results show that： （1） Under the confining pressure at 20, 30 and 40 kPa, the main stress differences of root-soil composite system and soil without roots increase with the growing of axial strain, finally drive to the stable values. The relationship curves of main stress difference and axial strain belong to the strain hardening type. The shear capability of root-soil composite systems increases more quickly than that of soil without roots at the early stage of loading. （2） Under three degrees of confining pressure, the shear strength peaks of root-soil composite system samples are larger than that of soil without root, and the order of the shear strength peaks of the four samples from big to small is caragana korshinskii root-achnatherum splendens root-soil composite system〉achnatherum splendens root-soil composite system〉caragana korshinskii root-soil composite system〉soil without root. （3） Compared with soil without roots, the increasing ratio of cohesion of three root-soil composite system are 94.1%, 66.6%, 39.2% respectively. The increasing ratio of the combination of Caragana korshinskii root and Achnatherum splendens root-soil composite system is 16.5% bigger than Achnatherum splendens root-soil composite system, 39.4% bigger than Caragana korshinskii root-soil composite system. The varying law shows that plant roots have obvious effects on slope reinforcement, especially the combination of herb roots and shrub roots, which owns greater effects than herb roots or shrub roots alone. The achievements can supply theoretical reference for geological catastrophes, such as soil and water