干湿交替作用下含根系红黏土路堑边坡灾变机制多尺度研究

红黏土路堑边坡常用骨架草本类植物防护，在晴雨交替气候影响下裂隙极为发育，易导致根土界面剥离、土体性质劣化，浅层失稳现象屡见不鲜，且难以治理。现有研究较少从不同尺度研究干湿交替作用诱发裂隙对含根系红黏土路堑边坡的不利影响。鉴于此，本项目围绕干湿交替作用下含根系红黏土路堑边坡灾变机制，开展土水特征曲线、非饱和渗透、直接拉伸与非饱和三轴等试验，从试样尺度研究干湿交替作用下含根系红黏土水力-力学特性衰变行为；借助压汞法、扫描电镜、CT扫描和分子动力学模拟等，从微观尺度探究干湿交替作用下含根系红黏土微观结构特征演变规律；运用PIV-离心模型试验和应力-渗流耦合数值模拟，从工程尺度分析干湿交替作用下含根系红黏土路堑边坡失稳灾变过程。综合上述多尺度研究结果，揭示干湿交替作用下含根系红黏土路堑边坡灾变机制，提出考虑裂隙和根系影响的边坡稳定性分析方法。研究成果可为红黏土路堑边坡灾害防治提供理论依据。

Red clay cut slopes are usually protected by skeleton-plant systems. In alternate sunny and rainy weather, desiccation cracks are easy to develop in red clay, which leads to the separation of root-soil interfaces and deterioration of soil properties. As a result, the shallow instability of rooted red clay cut slopes is common and difficult to control. However, most of the previous studies gave little attention to the adverse effects of the desiccation cracks induced by alternate drying and wetting on rooted red clay cut slopes from a multiscale perspective. For this reason, a multiscale study of the failure mechanism of rooted red clay cut slopes subjected to alternate drying and wetting is carried out. At the sample scale, the deterioration behavior of hydromechanical properties of rooted red clay is investigated by soil-water characteristic curve tests, unsaturated permeability tests, direct tensile tests, and unsaturated triaxial tests. At the microscopic scale, the evolution of microstructural characteristics of rooted red clay is examined via mercury intrusion porosimetry, scanning electron microscopy, computed tomography, and molecular dynamics simulations. At the engineering scale, the failure process of rooted red clay cut slopes is analyzed by PIV-centrifuge model tests and coupled stress-seepage numerical simulations. Based on the above multiscale research, the failure mechanism of rooted red clay cut slopes subjected to alternate drying and wetting is revealed, and a slope stability analysis method considering the influence of cracks and roots is developed. The research results can provide a theoretical basis for the prevention and control of geological hazards involving red clay cut slopes.