Abstract: The swelling and collapse characteristics of compacted Gaomiaozi Ca-bentonite are studied by conducting a series of swelling deformation tests, swelling pressure tests and collapse tests. It is found that the swelling pressure increases with the increase of the initial dry density. There is a linear relation  between them in semi-logarithmic scales. The swelling strain due to wetting decreases with the increase of the vertical stress or initial water content, but increases with the increase of the initial dry density. The swelling rate increases with the increase of the initial dry density, but decreases with the increase of  the vertical stress or initial water content. The void ratios at full saturation by three different testing methods are almost the same for the same vertical stress. There is a linear relation between the void ratio at full saturation and the vertical stress in logarithmic scales.

Key words: collapse, swelling deformation, swelling pressure, swelling rate, Gaomiaozi Ca-bentonite