Abstract: Aimed at the collapsibility of unsaturated loess in Northwest China, an unsaturated consolidation instrument is used to test matric suction and to conduct compression test of lime loess. Different contents of lime are added with different dry densities of the loess; various characteristics of the improved soil, including soil-water characteristic, compression property, moistening and collapse deformation, are measured and examined. Results show that lime content has little effect on the soil-water characteristic curve of lime-improved loess, while dry density produces a great influence. Compression index and yield stress increase with the increase in matric suction, while the expansion index is nearly independent of it. Under the same vertical pressure, the collapsibility coefficient increases with initial suction. As initial matric suction increases, initial collapse pressure decreases, while both the maximum collapsibility coefficient and highest collapse pressure increase. When lime content exceeds 3%, the collapsibility coefficient??s (p = 200 kPa) will be less than 0.015, indicating that the collapsibility of lime- improved loess is nearly eliminated, which can be useful in engineering application.

Key words: unsaturation, lime-improved loess, soil-water characteristic curve, Humidification deformation coefficient, collapsibility coefficient