| 颗粒形状对粗粒土孔隙特征和渗透性的影响 |
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| 引用本文： | 彭家奕,张家发,沈振中,叶加兵.颗粒形状对粗粒土孔隙特征和渗透性的影响[J].岩土力学,2020,41(2):592-600. |
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| 作者姓名： | 彭家奕 张家发 沈振中 叶加兵 |
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| 作者单位： | 1. 河海大学 水利水电学院，江苏 南京 210098；2. 长江科学院 水利部岩土力学与工程重点实验室，湖北 武汉 430010；
3. 长江科学院 国家大坝安全技术研究中心，湖北 武汉 430010；4. 武汉大学 土木建筑工程学院，湖北 武汉 430072 |
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| 基金项目： | 国家自然科学基金（No. 51279016，No. 51479148，No. U1765205）。 |
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| 摘 要： | 粗粒土的颗粒级配、形状和密实度都是影响其孔隙结构，进而影响其渗透特性的重要因素。但长期以来，对颗粒形状影响的关注度较少，其主要原因在于不容易定量描述颗粒形状及其影响的孔隙结构特征。选取已获取长宽比和圆形度的不规则形状碎石、规则形状的球和八面体颗粒分别装填试样，针对颗粒级配和颗粒形状的差异，开展孔隙结构特征和渗透性的对比研究。通过CT扫描试样内部结构图像，重构试样的三维孔隙结构并计算孔隙比表面积。通过渗透试验测得试样的渗透系数。结果表明：试样孔隙比表面积是表达孔隙结构特征的有效参数，在相同级配和孔隙率的条件下，试样孔隙比表面积随颗粒圆形度和趋近球形程度的增加而减小；相同级配和孔隙率的条件下，渗透系数随孔隙比表面积的减小而增大，随颗粒圆形度增大而增大；球形颗粒试样的渗透性最强，试样颗粒越偏离球形，孔隙系统中水流阻力越大，试样渗透性越弱。
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| 关 键 词： | 颗粒形状 CT扫描技术 孔隙结构 比表面积 渗透系数 |
| 收稿时间： | 2019-01-11 |
| 修稿时间： | 2019-05-09 |
Effect of grain shape on pore characteristics and permeability
of coarse-grained soil |
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| PENG Jia-yi,ZHANG Jia-fa,SHEN Zhen-zhong,YE Jia-bing.Effect of grain shape on pore characteristics and permeability
of coarse-grained soil[J].Rock and Soil Mechanics,2020,41(2):592-600. |
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| Authors: | PENG Jia-yi ZHANG Jia-fa SHEN Zhen-zhong YE Jia-bing |
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| Institution: | 1. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, Jiangsu 210098, China;
2. Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources,
Changjiang River Scientific Research Institute, Wuhan, Hubei 430010, China;
3. National Dam Safety Research Center, Changjiang River Scientific Research Institute, Wuhan, Hubei 430010, China;
4. School of Civil and Architectural Engineering, Wuhan University, Wuhan, Hubei 430072, China |
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| Abstract: | Grain size distribution, grain shape, and filling density are the critical factors that affect the pore structure and permeability of coarse-grained soil. However, only a few studies have examined the effect of grain shape on the permeability of coarse-grained soil. The main reasons are that it is not easy to quantitatively describe the grain shape and to study its influences on pore system characteristics. This study compares the pore system characteristics and permeability of samples filled with irregular gravels, spherical and regular octahedral grains, respectively. The grain shape was quantified by the length-width ratio and roundness obtained in the previous study. The images of internal structure for samples were obtained by the computed tomography (CT) scanning, and then the specific surface area was obtained for reconstructed three-dimensional (3D) pore structure of samples. The results indicate that the specific surface area is a reliable parameter to identify the pore structure characteristics of coarse-grained soil. For samples with the same grain size distribution and porosity, the specific surface area of the pore system decreases as grain roundness increases and grain shape approaches sphere. The hydraulic conductivity results show that for these samples, the hydraulic conductivity increases with the increase of grain roundness but the decrease of the specific surface area of pore system. The samples filled with spherical grains have the highest permeability. The samples filled with the more nonspherical grains contain pore systems with more resistance to seepage flow and are less permeable. |
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| Keywords: | grain shape CT scanning technique pore system specific surface area hydraulic conductivity |
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