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研究了单轴压缩湿土样沿剪切带方向的最大剪切应变的均值和标准差以及剪切局部化区域尺寸的演变规律。为了深入揭示土样剪切带萌生的过程,根据纵向应变较高时清晰剪切带所处位置在土样上布置测线,对由数字图像相关方法获得的结果进行双三次样条插值,从而获得测线上光滑性较好的最大剪切应变分布。研究发现,随着纵向应变的增加,沿剪切带方向的最大剪切应变由低值多峰向高值少峰转变。测线上最大剪切应变发生突增的点、局部高值点及低值点均有可能发展成为主峰。测线上最大剪切应变的均值和标准差随纵向应变的演变规律在总体上均呈上凹形,但当纵向应变较低时,二者均呈线性。以上述两种统计量线性规律丧失所对应的平均最大剪切应变作为剪切带萌生的条件。随着纵向应变的增加,土样中发生剪切局部化的区域越来越大。欲达到相同的剪切局部化区域尺寸,含水率高的土样所要求的纵向应变较高。当纵向应变较高时,含水率高的土样的剪切局部化区域尺寸比含水率低的土样要大,这与其塑性变形阶段较长有关。
The mean and standard deviation of the maximum shear strain in the direction of the shear band and the evolution of the size of the shear localized area are studied. In order to reveal the process of initiation of shear zone in soil sample deeply, according to the location where the clear shear zone is located at high vertical strain, the survey line is arranged on the soil sample, and the result obtained by the digital image correlation method is subjected to bi-cubic spline interpolation Obtained the measured line on the smoothness of the better the maximum shear strain distribution. The results show that with the increase of longitudinal strain, the maximum shear strain in the direction of shear band changes from low value multi-peak to high value less peak. The point at which the maximum shear strain in the survey line suddenly increases, and local high points and low points may develop into the main peak. The mean and standard deviation of the maximum shear strain on the survey line are generally concave with the longitudinal strain, but both are linear when the longitudinal strain is low. With the above two statistics, the linear law of loss corresponding to the average maximum shear strain as a shear band initiation conditions. As the longitudinal strain increases, the shear localized areas in the soil sample become larger and larger. To achieve the same shear localized area size, soil samples with high moisture content require higher longitudinal strain. When the longitudinal strain is high, the shear-localized area size of soil samples with high moisture content is larger than the soil samples with low moisture content, which is related to the longer plastic deformation stage.