The behaviour of clayey soils is strongly correlated to their microstructure and evolution thereof. Microstructural investigations have contributed to understanding soil behaviour and have supported the development of multi-scale coupled models. One of the most accessible methods to characterize soil microstructure is mercury intrusion porosimetry, which provides a pore size distribution (PSD) ranging from few nanometers to several hundreds of micrometers. PSDs can be used to compute micro and macro strains or simply to estimate, in aggregate microstructures, the void ratios associated to macro pores and micro pores. However, in both cases, a boundary has to be set to separate the different pore populations. This paper discusses some criteria that have been proposed in the literature to separate the pore populations. The discussion is illustrated with extensive micro structural data obtained for Maryland clay. The paper highlights the effect of initial conditions and boundary conditions on the delimiting diameter given by some of the criteria. It is also shown that using different criteria will yield different values of delimiting pore size, with a risk of obtaining unrealistic estimates of micro and macro void ratios and strains. Finally, it is suggested to account for known soil behaviour to interpret microstructural data.

中文翻译：

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压实膨胀土中大孔和微孔分离的讨论

黏土的行为与其微观结构及其演化密切相关。微观结构研究有助于理解土壤行为，并支持多尺度耦合模型的发展。表征土壤微观结构最容易获得的方法之一是压汞法，它提供的孔径分布（PSD）从几纳米到几百微米不等。PSD可以用于计算微应变和宏观应变，或者简单地用于在聚集的微结构中估算与宏观孔隙和微观孔隙相关的空隙率。但是，在两种情况下，都必须设置边界以分隔不同的孔群。本文讨论了一些文献中提出的分离孔隙种群的标准。讨论用马里兰粘土获得的大量微观结构数据进行了说明。本文重点介绍了初始条件和边界条件对某些标准给出的定界直径的影响。还显示出使用不同的标准将产生不同的限定孔尺寸值，存在获得微观和宏观空隙率和应变的不切实际估计的风险。最后，建议考虑已知的土壤行为来解释微观结构数据。有可能无法获得微观和宏观空隙率和应变的不切实际的估计。最后，建议考虑已知的土壤行为来解释微观结构数据。有可能无法获得微观和宏观空隙率和应变的不切实际的估计。最后，建议考虑已知的土壤行为来解释微观结构数据。