中文摘要：

为了探寻植物根系加固土体、防护边坡的作用机理，该文从细观角度对根系固土的力学特性进行了探讨，并利用长江科学院研制的CT三轴仪，分别对素土样和2种含根土样进行不固结不排水的CT实时三轴剪切试验。通过对试样3个断面在不同应变时刻所对应的CT扫描数据进行定量分析发现，3个扫描层中素土样的（CT数均值）ME-ε1关系曲线下降段和（CT 数方差）SD-ε1关系曲线上升段的变化幅度均大于2种含根土样曲线相应阶段的变化幅度；这说明含根土体内部缺陷发育速度更慢，含根土样内部裂纹萌生和扩展得更加缓慢，根系具有阻裂作用。文中重点对3种土样在高度的7/16处的断面上的CT扫描图片进行了定性和定量分析。利用Matlab软件自编后处理程序，对 CT 扫描图片进行了二值化处理，并统计出断面上的裂隙率、根附近区域及其之外区域的总裂隙大小、最大裂隙区域的长度和宽度信息。通过对含根土样和素土样受压过程的 CT 演化图片和断面上统计的裂缝数据信息进行比较分析，来对比说明素土和含根土样中裂纹扩展以及试样破坏过程的差异，从而揭露了根系的阻裂作用和桥联作用。最后得出根系固土的细观力学机理主要表现为根系对土体的阻裂作用和桥联作用。

英文摘要：

In order to explore the mechanism of soil reinforcement and slope protection by plant roots, in this paper, the mechanical characteristics of roots on soil stabilization were discussed from the meso angle, and using a CT triaxial apparatus developed at the Yangtze River Scientific Research, a series of unconsolidated-undrained CT real-time triaxial shear test of the non-rooted clay sample and two kinds of Broussonetia papyrifera-rooted clay samples with different root diameters were carried out. Through a quantitative analysis of CT scan data of three sections at the different strain for three kinds of samples, it was found that both the downward section of （mean CT number） ME-ε1 curve and the upward section of （the variance of CT number） SD-ε1 curve of the non-rooted soils had a greater changing amplitude than those of the rooted soils in three different scan layer sections. It indicated that the internal defects of the rooted soil grew more slowly and weakly, the initiation and propagation of internal cracks slower, and the roots resist cracks. This paper focused on the qualitative and quantitative analysis of CT scanning images of the height of a 7/16 cross section at the different strain for three kinds of soil samples. Using the program self-prepared in Matlab software, the CT scan images were binarized, and the statistical crack data of the scan layer section were obtained including the crack rate of cross section, the total crack size in the area near the root and beyond the root respectively, and the length and width of the maximum crack area. Through the comparative analysis of CT scan images evolution under pressure and the statistical crack data of them for the non-rooted soils and the rooted soils, the fundamental differences in destruction process of the soil and crack propagation between the non-rooted soil and the rooted soil were described, thus exposing the crack resistance and the bridging effect of roots. It was concluded that the mesomechanics mechanism of roots reinforcement is main