Abstract: The swelling and collapse characteristics of compacted Gaomiaozi(GMZ) 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 increasing the initial dry density and there is a linear relation between them in the semi- logarithmical scales. The swelling strain due to wetting decreases with increasing vertical stress or initial water content, but it increases with increasing the initial dry density. The swelling rate increases with increasing the initial dry density, but it decreases with increasing vertical stress or initial moisture content. The void ratios at full saturation by three different testing methods are almost the same for the same vertical stress, and there is a linear relation between the void ratio and the vertical stress in their logarithmical scales.

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