单轴压缩湿土样最大剪切应变场数字图像相关方法结果的统计分析  

Statistial analyses of maximum shear strain fields for wet soil specimens in uniaxial compression using digital image correlation method

作　　者：王学滨[1,2,3] 张楠[2] 潘一山[2] 杜亚志[2] 

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083 [2]辽宁工程技术大学力学与工程学院,辽宁阜新123000 [3]辽宁工程技术大学计算力学研究所,辽宁阜新123000

出　　处：《岩土工程学报》2016年第6期996-1003,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51374122);高等学校博士点专项科研基金项目(20132121110006);辽宁省科学事业公益研究基金项目(GY2014-C-008)

摘　　要：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 evolution of the mean and standard deviations of the maximum shear strains for wet soil specimens in uniaxial compression and the size of the shear localization region are studied. To explore the occurrence and development of shear bands, some monitored lines are arranged in the specimens according to the positions of apparent shear bands at higher longitudinal strains. The maximum shear strains at these lines are obtained using a bicubic spline interpolation function with good smoothness from the results based on the digital image correlation method. It is found that the distribution of the maximum shear strains along shear bands transits from several peaks with lower values to a few main peaks with higher values with the increase of the longitudinal strain. These main peaks originate from the positions where the maximum shear strains increase rapidly and from those with local higher or lower values. Generally, the mean and standard deviations of the maximum shear strains at monitored lines are convex upwards with the increase of the longitudinal strain. However, at lower longitudinal strains, the two statistical quantities are linear. The mean of the maximum shear strain corresponding to the end of the linear stage of statistical quantities is regarded as the occurrence of shear bands. The size of the shear localization region increases with theincrease of the longitudinal strain. For the same size of the shear localization region, the specimens with higher water contents require higher longitudinal strains. At higher longitudinal strains, the size of the shear localization region forthe specimens with higher water contents is larger than that with lower water contents, which is related to its longer stage of plastic deformation.

关 键 词：湿土样 剪切带 最大剪切应变 统计 剪切局部化 

分 类 号：TU454[建筑科学—岩土工程]