南京粉细砂空间孔隙结构表征单元体确定  

Determination on representative element volume of Nanjing silty-fine sand for its spatial pore structure

作　　者：刘语 张巍[1] 梁小龙[1] 许林 唐心煜 LIU Yu;ZHANG Wei;LIANG Xiao-long;XU Lin;TANG Xin-yu(School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China)

机构地区：[1]南京大学地球科学与工程学院

出　　处：《岩土力学》2019年第7期2723-2729,共7页Rock and Soil Mechanics

基　　金：国家重点研发项目(No.2018YFC1505104);国家自然科学基金重点项目(No.41230636);国家自然科学基金项目(No.40902076);江苏省自然科学基金(No.BK20160366; No.BK20181182);苏州市科技计划项目(No.SYG201613)~~

摘　　要：确定统一的表征单元体(REV)尺寸是研究土体细观孔隙结构时首先需要解决的问题。使用6.5μm分辨率同步辐射显微CT扫描南京粉细砂试样,从土样三维重构模型的5个代表性部位提取5组立方体孔隙REV,对每个REV采用最大球算法分析,建立孔隙网络模型,从中提取孔隙率、单位体积孔隙数、孔隙平均体积、孔隙最小体积、孔隙最大半径、孔隙最小半径、孔隙平均半径、孔隙截面积平均形状因子等8个孔隙结构参数,建立其与REV尺寸间的相关性。利用假设检验T检验和F检验,最终确定样品孔隙结构参数的统一REV边长尺寸为400像素,即2.60mm。该方法可用于砂土、粉土等颗粒土体细观孔隙结构分析。Determining the unified representative element volume(REV) is the primary issue to be solved when studying the meso-scale pore structure of soils. We use the synchrotron radiation μ-CT, in 6.5 μm voxel resolution, to scan a Nanjing silty-fine sand specimen. Five groups of cubic pore REV with the same dimension are chosen from the three-dimensional reconstruction model, at different heights, of the specimen. The maximal ball algorithm is used to analyze each pore REV. The pore network model of each REV is developed to extract eight pore structure parameters, namely porosity, pore number per unit volume, mean volume of pore, minimum pore volume, maximal pore radius, minimal pore radius, mean radius of pore and average shape factor of pore area. Subsequently, the correlations between the eight pore structure parameters and the REV size are established respectively. The results show that all the pore structure parameters tend to converge when the REV size increases. The T test and F test are performed with different REV edge lengths for the eight pore structure parameters in sequence. The REV edge length of each pore structure parameters is determined and the maximal value of them is selected. Finally, unified REV edge length is determined at 400 voxels, namely 2.60 mm, for all the pore structure parameters. This determination method can be used for the meso-scale pore structure analysis of grain soils such as sand soil and silty soil.

关 键 词：南京粉细砂 同步辐射显微CT 表征单元体 三维重构 最大球算法 孔隙结构参数 假设检验 

分 类 号：TU411[建筑科学—岩土工程]