关键词: 重塑黄土, 均匀性, μCT扫描试验, 3D重构, 孔隙分布, 压实制样法, 分层击实法

Abstract: The effect of preparing remoulded loess samples by different methods in laboratory is studied in this paper to provide accurate index parameters for geotechnical engineering. Triaxial remoulded loess samples prepared by pressing and bumping were scanned by high precision μCT to reconstruct the soil’s microstructure in three dimensions by VG Studio MAX2.2 image processing software. The structure, 3D information of pores, and pore distribution of loess samples were quantified; the influences of pore uniformity and confining pressure on the ultimate strength of loess samples were examined by means of triaxial shear test. Results show that: (1) layered pressing is prone to result in severe damage to the internal structure of loess sample; layered bumping lead to the non-uniform distribution of pores. The pore size of main volume frequency of samples undergone one-time pressing is 40 μm smaller than that of bumped samples, and the difference of porosity in different zones is less than 3%. (2) The greater the gap between the soil porosity distribution, the smaller the ultimate strength. Conclusion was drawn as follows: the characteristics of loess is affected by the spatial distribution of porosity, and one-time bumping method is recommended for the preparation of remoulded loess sample.

Key words: remolded loess, uniformity, μCT scanning test, 3D reconstruction, pore distribution, pressing, bumping