为揭示三维层面花岗岩残积土内大孔隙分布特征,选取福州某地原状花岗岩残积土作为研究对象,采用计算机断层扫描(CT)技术得到CT扫描图像,并进行三维重构,提取了土壤内相关大孔隙参数,选取代表性体积单元(RVE)对大孔隙特征进行定量表征分析。结果表明:花岗岩残积土中不同试样的连通孔隙数量差异性较大,但由于孔隙形成原因类似,孔隙结构之间差异性较小,且孔隙半径多介于1～4 mm之间;不同位置的土壤内部孔隙拓扑空间结构差异性较大,部分孔隙的配位数可达40以上,但深度对其影响较小;对比不同处理方法可知,二维图像处理得到的孔隙平均直径最小,孔隙差异性较大,孔隙网络模型处理得到的孔隙平均直径最大,孔隙分布较为均匀;而三维重构处理和孔隙网络模型处理平均孔隙体积相差5倍以上。
Abstract
The aim of this research is to reveal the distribution characteristics of macropores in granite residual soil in three-dimensional scale.The characteristics of macropores of undisturbed granite residual soil in Fuzhou are characterized quantitatively as a case study by extracting the parameters of macropores via three-dimensional reconstruction using the representative volume element (RVE) based on CT (computer tomography)scanning images of the soil.Results unveil remarkable difference in the number of connected pores in granite residual soil samples but small difference in pore structure due to the similar causes of pore formation with the pore radius mostly between 1 mm and 4 mm.The topological spatial structure of pores in soil at different locations varies notably,with the coordination number of some pores reaching over 40,which is rarely influenced by depth.The coordination number of pores is mainly concentrated within 20,and the coordination number of pores above 20 is distributed in discrete points.Comparison among different processing methods demonstrate that the average pore diameter obtained by two-dimensional image processing is the smallest,and the porosity is quite different;the average pore diameter obtained by pore network model processing is the largest,and the pore distribution is relatively uniform;the difference of average pore volume between 3D reconstruction processing and pore network model processing is over five times.
关键词
原状土 /
计算机断层扫描 /
孔隙结构 /
三维重构 /
大孔隙
Key words
undisturbed granite residual soil /
CT scan /
meso-structure /
3D reconstruction /
macropores
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基金
国家自然科学基金项目(41772297);福建省自然科学基金项目(2018J01771)
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