干湿循环下新近系黏土杂岩裂隙演化研究

本文对武乡盆地黏土杂岩在反复干湿循环下的裂隙演化特征进行室内试验研究。试验采用烘干法模拟脱湿过程，水膜转移法模拟增湿过程，每完成一次脱湿增湿过程都要进行数码摄影、称重以记录裂隙变化情况，从而进行定性分析。通过应用Matlab软件进行图像处理以获取裂隙演化过程中的几何特征值。定性分析与定量分析相结合得到裂隙演化规律有:（1）脱湿过程:黏土杂岩裂隙率不断增加最终趋于稳定，第2次脱湿对裂隙率影响最大；几何特征上裂隙的变化先是沿着中间大裂隙向四周继续生长发育，然后随着循环次数增加转而形成新的大裂隙。（2）增湿过程:黏土杂岩吸水膨胀，裂隙逐渐趋于闭合，但出现不可逆形变量，随着增湿次数增加，这种累积变形量逐渐减小，第5次的干湿循环后，累积变形量基本消失，试样结构重新归于相对均一的松散结构。

A study of fissures evolution of the Neogene clay complexs under wetting and drying cycles

In the present investigation, laboratorial test is conducted to examine the evolution law of fissures of the Wuxiang clay complexs under wetting and drying cycles. The oven drying method and the water film transfer method are employed to simulate the drying and wetting process, respectively. Digital photography and weighing are used to record the changes of fissures in each drying and wetting process, so as to conduct qualitative analyses. Matlab is applied to image processing to obtain the geometric feature values in the evolution process of fissures. The evolution rules of fissures are obtained by combining qualitative analyses and quantitative analyses, including: (1) in the drying process, the fissure rate of the clay complexs increases continuously and finally tends to be stable, and the first and second drying have the greatest influence on the fissure rate. In terms of the geometric characteristics, the fissures first grow and develop in all directions along the middle large fissure, and then turn to form a new large fissure with the increase number of cycles. (2) In the wetting process, the clay complexs expands when it absorbs water, and the fissures gradually tend to close, but the plastic deformation occurs. With the increasing wetting times, the accumulated deformation gradually decreases. After the fifth drying and wetting cycle, the accumulated deformation basically disappears, and the soil structure returns to a relatively uniform loose structure.