| 摘要: |
| 为探讨天然沉积硅藻土的微观结构及变形机制，对硅藻土样进行了SEM电镜扫描、压汞试验和高压三轴试验。采用图像分割原理及最佳阈值法分析了天然沉积硅藻土在不同固结压力下的分形特征和孔隙结构特征参数，探讨了硅藻土分形维数和各向等压固结压力之间的关系。结果表明，硅藻土体多孔隙，具有很强的结构性。土中孔隙孔径大多在0.1~1.0 μm之间。在固结压力达到屈服压力后，孔径大于1 μm的较大孔隙随固结压力的增加而减少，硅藻颗粒破坏，孔隙结构坍塌。获取了灰度阈值及二值化后的SEM图像。得到天然沉积硅藻土在不同固结压力下的分形盒子数和盒维数。结果还表明分形盒维数随固结压力增加而增加，天然沉积硅藻土在固结压力下的微观结构性及孔隙分布可通过分形盒维数来反映。 |
| 关键词: SEM图像 二值化 硅藻土 固结压力 分形特征 |
| DOI： |
| 分类号:TU411.92 |
| 基金项目:国家自然科学基金资助项目（51378327，51378118，51508369）； 江苏省自然科学基金资助项目（BK20150289）； 江苏省建设系统项目（2016ZD26）； 2017年苏州市市级建设科研项目 |
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| Fractal characteristics of natural sedimentary diatomaceous earth based on SEM images |
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WANG Yuexiang1,2, JI Feng3, GU Huanda1, DING Jianwen3
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1.School of Civil Engineering, Suzhou University of Science and Technology, Suzhou;2.Nanjing Tech University, Nanjing;3.College of Transportation, Southeast University, Nanjing
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| Abstract: |
| SEM test, mecury injection test and high pressure triaxial test are conducted to obtain the microscopic structure and deformation of natural sedimentary diatomaceous earth. Fractal characteristics of natural sedimentary diatomaceous earth and evolutions of pore structural characteristic parameters under different consolidated pressures are analyzed by image segmentation and optimal dividing threshold algorithm. The relationship between fractal dimension and isotropic consolidation is discussed. The results show that there are many pores in the diatomaceous earth which is strongly structural. The pore diameter distribution is mainly in the range of 0.1~1.0 μm. When consolidated pressure increases to yield pressure, pores whose diameters are larger than 0.1 μm are changing obviously. The number of large pores decreases with the increase of consolidated pressure, and the diatomaceous particles are destroyed and the pore structure is collapsed. The imaging characteristic of diatomaceous earth is analyzed, and then the gray threshold under different consolidated pressures is calculated by optimum dividing threshold algorithm. Based on the corresponding gray threshold, the grey images are then transformed into the binary image. The fractal characteristics of natural sedimentary diatomaceous earth under different consolidated pressures are studied. It is proposed that the binary images have obvious fractal characteristics and the fractal dimension increases with the consolidated pressure. Fractal dimension can not only represent the variation of micro structure but also represent the variation of void distribution of natural sedimentary diatomaceous earth. |
| Key words: SEM images binary diatomaceous earth consolidated pressure fractal characteristics |
