Abstract: The collapsibility of loess is closely related with its microstructural character, which is directly affected by the stress state subjected and its moisture condition. The collapsible tests of the intact loess from Xi’an with various water contents and consolidation pressures were carried out. The differences and relations of collapsibility of loess under various conditions were analyzed based on the results of these tests. The scanning electron microscope (SEM) images were obtained both on loess samples of before and after collapsing; then corresponding microstructural parameters were obtained. Comparative analysis of simple microstructural parameters was made. The relationship among these parameters was discussed and the synthetic microstructural parameters were constructed as well. The results indicate that the proportion of particle and the first principal component increases with the increase of consolidated pressure; there is a linear relationship between collapsibility and the first principal component of loess. Based on this understanding, the calculation method of collapse coefficient is established. The collapsibility of loess can be evaluated objectively using the proposed method. The efficient exploration is made in quantificational studying the effects of microstructure on collapsibility of loess.

Key words: loess, collapsibility, microstructural parameters, principal component