干湿循环下红黏土边坡裂隙演变规律

为研究干湿循环下红黏土边坡裂隙的演变规律,采用室内边坡模型模拟日照-降雨干湿循环方式,并使用图像处理技术对获得的裂隙光栅图像进行二值化处理,提取了红黏土边坡裂隙率、裂隙条数、裂隙总长度、土块个数等定量化指标,分析了降雨-蒸发循环作用下裂隙指标的演变规律与干湿循环次数的关系。结果表明:导致红黏土开裂的主要原因是含水率梯度引起的土体上下部基质吸力的差异性,致使土体收缩不均匀,而土体的胀缩性、渗透性和脱湿速率的空间分布则是决定含水率梯度的关键因素; 裂隙的宽度、深度和裂隙率随干湿循环次数的增加先增大然后趋于稳定; 裂隙总条数、土块个数和裂隙总长度在第1次干湿循环后达到最大值,第2次干湿循环后均出现不同程度的降低,之后裂隙总数量趋于稳定,但裂隙总长度和土块个数在后期干湿循环中仍有小幅增大。

Evolution Law of Fissures of Red Clay Slope Under Wet-dry Cycles

In order to study the evolution law of fissures of red clay slope under wetting and drying cycles, the indoor slope model was used to simulate the sunshine-rainfall dry-wet cycle, and the grating images were binarized by image processing technology. The quantitative indexes such as the fissure rate, the number of fissures, the total length of fissures and the number of soil blocks were extracted. The relationship between the evolution of fracture indexes and the number of cycles was analyzed under the rainfall evaporation cycle. The results show that the main cause of red clay cracking is the difference of matric suction between upper and lower parts of soil caused by water content gradient, resulting in uneven soil shrinkage, and the spatial distribution of soil swelling and shrinkage. Permeability and dehumidification rate are the key factors to determine the water content gradient. The width, depth and fracture rate of the fissure increase firstly and then tend to be stable with the increase of the number of cycles. The total number of fissures, the number of soil blocks and the total length of the fissure reach the maximum after the first dry-wet cycle, and decrease to varying degrees after the second cycle, and then the total number of fissures tends to be stable, whereas the total length of the fissure and the number of blocks still increase slightly in the later cycle.