碎石土大孔隙结构定量化表征

Quantitative Characterization of the Macropore Structure of Gravel Soils

为揭示碎石土大孔隙结构的分布规律和形状特征,选取福建安溪某地原状碎石土柱作为研究对象,基于高精度CT扫描,利用二值化图像处理方法提取大孔隙结构与形状参数,实现碎石土大孔隙结构特征定量化表征。结果表明:碎石土在不同垂向深度处大孔隙差异性明显,孔隙度变化范围介于11.9%~33.8%之间,且随着深度增加呈先增加后减小趋势;碎石土大孔隙数量随着大孔隙直径的增加而明显减少,约有75%以上大孔隙直径介于0.32~8.00 mm范围内;碎石土的大孔隙成圆率与大孔隙直径之间存在一定的线性关系,大孔隙直径越大,孔隙成圆率越低;碎石土大孔隙分布广泛,轮廓粗糙,起伏程度大。综上,研究成果为建立大孔隙渗流模型及探究大孔隙优先流形成机制提供理论与试验依据。

In order to reveal the distribution and shape characteristics of gravel soil macropores structure,the undisturbed gravel soil column in Anxi,Fujian province,was selected as the research object. Based on the high precision CT scan,macropores structures and shape parameters were extracted by image binarization. Then,the gravel soil macropore structure quantitative characterization was achieved. The results are as follows. The differences of macropores at different vertical depths are obvious. The porosity varies from 11. 9% to 33. 8% and tends to increase and then decrease with depth. The number of macropores decreases distinctly with the increase of macropores’ diameter.More than 75% of them are in the range of 0. 32 mm ~ 8. 00 mm. There is a linear relationship between macropore roundness and macropore diameter. The larger the macropore diameter,the lower the pore roundness. The macropores of gravel soil feature wide distribution,rough contours and highly undulation. The research results could provide a theoretical and experimental basis for establishing the seepage model of macropores and exploring the formation mechanism of macropores preferential flow.