Freeze-thaw cycles extensively and intensely occur in northeast China and generate significant effects on soil pore structure. The objective of this study was to obtain three-dimensional (3D) images of soil pore structures utilizing industrial X-ray microtomography and to apply image analysis techniques to visually and quantitatively evaluate the impact of the freeze-thaw effect on pore characteristics of black soil. The soil samples were subjected to zero (T₀), one (T₁), five (T₅), ten (T₁₀), fifteen (T₁₅), and twenty (T₂₀) freeze-thaw cycles and were then scanned at a 25-μm resolution to construct pore-throat network images. The results showed that the freeze-thaw effect increased the porosity of the soil 3D microstructure and that the pore-throat networks became increasingly complex with a greater number of freeze-thaw cycles. The total porosity and macroporosity increased significantly with an increase in the number of freeze-thaw cycles (p < 0.05). The soil in the T₂₀ treatment displayed the greatest total porosity and macroporosity, which were 247.8 and 251.1 % greater, respectively, than in the T₀ treatment. In freeze-thaw processes, contraction of the solid phase is induced by thawing of ice crystals but is insufficient to counteract the displacement induced by the freezing expansion of ice crystals. Macroporosity contributes to most of the increase in total porosity between each treatment. The numbers of pore throats and paths were significantly and positively correlated (p < 0.05) with the number of macropores. The freeze-thaw effect mainly affected those pores with greater effective diameters, which may include more branch paths and throats. The findings of this study can help to improve the understanding of soil dynamic processes under freeze-thaw cycles and further enable the utilization of pore morphology in monitoring the quality of soil structure.

东北地区广泛发生冻融循环，对土壤孔隙结构产生重大影响。这项研究的目的是利用工业X射线显微照相术获得土壤孔隙结构的三维（3D）图像，并应用图像分析技术从视觉和定量上评估冻融作用对黑土孔隙特征的影响。 。土壤样品分别受到零（T ₀），一（T ₁），五（T ₅），十（T ₁₀），十五（T ₁₅）和二十（T _{20）的作用。}）冻融循环，然后以25μm的分辨率扫描以构建孔喉网络图像。结果表明，冻融作用增加了土壤3D微观结构的孔隙度，并且随着大量的冻融循环，孔喉网络变得越来越复杂。随着冻融循环次数的增加，总孔隙度和大孔隙度显着增加（p <0.05）。T ₂₀处理的土壤显示最大的总孔隙度和大孔隙度，分别比T ₀处理的土壤大247.8和251.1％治疗。在冻融过程中，固相的收缩是由冰晶的解冻引起的，但不足以抵消由冰晶的冻胀引起的位移。大孔隙率导致每种处理之间总孔隙率的大部分增加。孔喉和路径的数量与大孔数量显着正相关（p <0.05）。冻融作用主要影响有效直径更大的那些毛孔，这些毛孔可能包括更多的分支路径和喉咙。这项研究的结果有助于增进对冻融循环下土壤动力学过程的了解，并进一步使孔隙形态学能够用于监测土壤结构的质量。