Loess is a structured soil that tends to undergo collapse when loaded and wetted. X-ray micro-computed tomography (μ-XCT) is increasingly employed to study loess collapse, but some questions still need to be addressed including the method’s capabilities to effectively characterize loess micro-fabrics and how this can be best achieved. This study addresses these questions by investigating the evolution of pore structure during loess collapse through a combined approach involving the oedometer test, mercury intrusion porosimetry (MIP) and X-ray micro-computed tomography (μ-XCT). The pore size distribution (PSD) in terms of entrance diameter was obtained from μ-XCT images. This PSD corresponds well with that obtained from MIP. For the characterisation of pore evolution during loess collapse, a voxel size of 1 μm is shown to provide good results relevant to the evolution of PSD as a result of loess collapse. The effectiveness of PSD characterization for loess materials progressively deteriorates and rapidly loses significant value when the voxel size is increased. Different geometry concepts and pore size descriptors were evaluated and the discrete PSD approach was found to result in larger pore sizes compared to the continuous PSD method. A so-called ‘ink-bottle’ effect (where the volume of large pores that are only accessible through smaller pore entrances is incorrectly associated with the smaller pore fraction) was observed in both intact and collapsed samples. This highlights that the hierarchal morphology of loess pore structure is preserved during collapse. The PSD evolution due to loess collapse can be captured by either continuous or discrete descriptor demonstrating that μ-XCT forms a powerful complementary tool in characterizing loess pore structure and its evolution caused by mechanical loading or wetting.

黄土是一种结构化的土壤，在加载和润湿时往往会发生塌陷。X 射线微计算机断层扫描 (μ-XCT) 越来越多地用于研究黄土塌陷，但仍有一些问题需要解决，包括该方法有效表征黄土微织物的能力以及如何最好地实现这一点。本研究通过结合测厚仪测试、压汞法 (MIP) 和 X 射线微计算机断层扫描 (μ-XCT) 的方法研究黄土塌陷过程中孔隙结构的演变，从而解决了这些问题。从 μ-XCT 图像获得以入口直径表示的孔径分布 (PSD)。该 PSD 与从 MIP 获得的 PSD 非常吻合。为了表征黄土塌陷过程中的孔隙演化，由于黄土塌陷，1 μm 的体素尺寸被证明可以提供与 PSD 演变相关的良好结果。当体素尺寸增加时，黄土材料的 PSD 表征的有效性逐渐恶化并迅速失去显着价值。评估了不同的几何概念和孔径描述符，发现与连续 PSD 方法相比，离散 PSD 方法产生更大的孔径。在完整样品和塌陷样品中都观察到了所谓的“墨水瓶”效应（其中只能通过较小孔入口进入的大孔的体积与较小的孔分数错误地相关联）。这凸显了黄土孔隙结构的层次形态在塌陷过程中得以保留。