降雨作用下裂隙红黏土边坡渗流特征与冲刷模式

针对降雨作用下裂隙红黏土边坡失稳破坏问题，开展红黏土边坡裂隙演化、降雨入渗及冲刷模型试验，提出基于图像摄影识别技术的边坡裂隙特征及含水率分布定量表征方法，揭示红黏土边坡裂隙演化规律，分析裂隙发育程度与降雨强度对红黏土边坡渗流特征与冲刷模式的影响。结果表明：干燥作用下红黏土边坡表面裂隙发育，其中坡面裂隙发育最强烈，其最大裂隙平均宽度为4.1 mm，最大裂隙深度为7.7 cm，最大裂隙率为10.4%，但坡底子裂隙和分支裂隙发育最充分，且主裂隙最先出现于远离坡面处；降雨作用下，雨水极易沿坡表裂隙形成优势流迅速渗入边坡内部，使边坡含水率增加且呈不均匀分布，出现局部暂态饱和区；裂隙发育程度和降雨强度的增强均会提高前期降雨入渗速率，并增加最终降雨入渗深度，其中坡底处入渗深度最大；极端降雨对裂隙红黏土边坡冲刷作用明显，造成坡面松散层流失，坡底显现冲刷痕迹，坡脚局部发生滑动。基于图像摄影识别技术定量分析边坡含水率分布的方法简单有效，研究成果可为裂隙性红黏土边坡灾害防治提供参考。

Seepage Characteristics and Scouring Modes of a Cracked Red Clay Slope Under Rainfall

Focused on the instability problem of cracked red clay slopes subjected to rainfall, model tests were performed to investigate the crack evolution, rainfall infiltration and scouring mode of a red clay slope. A quantitative method that is based on the image recognition technique was proposed to characterize the crack development and water content distribution of the slope. The evolution law of desiccation cracks on the red clay slope was revealed, and the effects of crack development and rainfall intensity on the seepage characteristics and scouring modes of the red clay slope were analyzed. The results show that drying leads to desiccation cracks on the red clay slope, and the crack development is the strongest on the slope surface, with the maximum average crack width of 4.1 mm, the maximum crack depth of 7.7 cm and the maximum crack rate of 10.4%. However, sub-cracks and branch cracks are most fully developed on the foot of the slope, where the main cracks initiate at the place far away from the slope surface. During rainfall, rainwater easily infiltrates into the slope via surface cracks as preferential flow, which causes an increase and uneven distribution of water contents and forms local transient saturation zones in the slope. The enhancement of crack development and rainfall intensity leads to increases in both the early rainfall infiltration rate and the final rainfall infiltration depth. The bottom of the slope presents the largest rainfall infiltration depth among different parts of the slope. Because of the presence of desiccation cracks on the slope surface, the red clay slope is obviously scoured by extreme rainfall. The scouring mode is characterized by the loss of loose soils on the slope surface, the appearance of scouring traces at the slope bottom, and local slides at the foot of the slope. The quantitative analysis method of water content distribution in slopes based on the image recognition technique is simple and effective, and the research findings can provide a reference for the disaster prevention of cracked red clay slopes.