基于CT数字体相关法测量红砂岩单轴压缩内部三维应变场

基于X射线工业CT实时获取单轴压缩过程中红砂岩试件的三维数字体图像,采用数字体相关(digital volume correlation,DVC)法测量、分析受载过程中试件内部三维变形场及应变场。通过位移场和应变场的分析,揭示试件内部应变局部化演变及破坏过程。红砂岩内部结构可以作为散斑结构,成为变形信息的载体,DVC法的精度可达0.05体素;红砂岩变形破坏中存在明显的应变局部化特征,在峰值荷载的68.9%时试件内部出现应变局部化区域,并逐渐发展至试件破坏,局部化区域与试件最终破坏面位置相一致。研究结果表明,DVC法测量结果能够直观地反映出试件内部应变局部化特点及其演化的过程,为岩石内部变形可视化提供了方法。

MEASUREMENT OF 3D STRAIN FIELD IN RED STONE SAMPLE UNDER UNIAXIAL COMPRESSION WITH COMPUTER TOMOGRAPHY AND DIGITAL VOLUME CORRELATION METHOD

3D digital volumetric images of red sandstone specimen during uniaxial compression were obtained in real time by using industrial computer tomography(CT) of X-ray. The digital volume correlation(DVC) method was applied to calculate the three dimensional displacement and strain fields inside of the sample. The development of strain localization and the failure process were revealed. The internal features of red sandstone were used as speckle patterns，the information carriers of deformation. The accuracy of measurement by DVC method reached 0.05 voxels. The notable strain localization inside the red sandstone specimen was observed and the zones of strain localization occurred at 68.9% of peak load and developed gradually until finally the specimen was broken. The localized strain zone is consistent with the final position of failure surface in the specimen.