| 摘要: |
| 利用X射线计算机层析术（CT）对混凝土试件单轴压缩过程进行原位扫描，获得了不同荷载下试件的CT图像.通过对CT图像进行分析，获得了灰度均值及其均方差、孔隙率和计盒维数随荷载变化的规律.结合数字体散斑法（DVSP）获得了试件内部三维位移场与应变场.结果表明：试件内部不同尺度裂隙的发展导致灰度均值及其均方差、孔隙率和计盒维数发生相应的变化，灰度均值及其均方差可以揭示小于CT尺度裂隙的发展规律，孔隙率和计盒维数更适用于描述大于CT尺度裂隙的特征.试件内部的位移场与应变场能够直观地揭示出小于CT尺度微裂隙引起的应变局部化区域的产生及发展过程，为混凝土细观破坏机理研究提供了新方法. |
| 关键词: 混凝土 单轴压缩 计算机层析术 裂隙 三维应变场 数字体散斑法（DVSP） |
| DOI：103969/j.issn1007 9629201603006 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目（51374211）；国家重大科学仪器设备开发专项资助项目（2013YQ240803）；中央高校基本科研业务费专项资金资助项目（2009QM02） |
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| Crack and Strain Field Analysis in Concrete under Uniaxial Compression Based on CT Images |
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MAO Lingtao1, SUN Qianwen2, YUAN Zexun2, LIU Yongliang2, LIU Hongbin1
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1.State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & TechnologyBeijing,Beijing 100083, China;2.School of Mechanics & Civil Engineering, China University of Mining & TechnologyBeijing,Beijing 100083, China
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| Abstract: |
| Concrete under uniaxial compression was scanned by industrial computer tomography(CT) in situ. By analyzing the CT images under different loads, the variations of mean gray value, gray value variance, porosity and fractal dimension with the increasing load were obtained. Combined with digital volumetric speckle photography(DVSP), the 3D displacement fields and strain fields were investigated. The results indicate that the development of the different size cracks in the specimen under different loads results in variations of the mean gray value, gray value variance, porosity and fractal dimension. Mean gray value and gray value variance indicate the whole development rule of micro cracks under CT resolution. Porosity and fractal dimension are better for the description of the cracks above CT resolution. The displacement fields and strain fields obtained by DVSP can visually reveal the development of strain localization areas caused by the micro cracks, which provides a new method to study the failure mechanism of concrete. |
| Key words: concrete uniaxial compression computer tomography(CT) crack 3D strain field digital volumetric speckle photography(DVSP) |
