NUMERICAL ANALYSIS OF THE AXIAL AND RADIAL SWELLING OF UNSATURATED COMPACTED BENTONITE
Keywords:Bentonite, Swelling, Finite element Analysis, elastoplastic constitutive model
This study deals with the problem of axial and radial swelling of a cylindrical bentonite specimen with a gap at the top or side. Unsaturated soil water coupled finite element analyses are carried out to analyze how the bentonite specimen changes during the process of swelling due to water absorption from the surface facing the gap. The behavior of the bentonite after the finite gap is filled by the swollen bentonite until the equilibrium state is also analytically evaluated. The analysis results show that the distribution of void ratio and swelling pressure in the specimen remains non-uniform in both axial and radial swelling, even if the bentonite specimen reaches a saturated and equilibrium state. In the case of axial swelling, the radial and hoop stresses remain equal at all positions in the specimen, whereas in the case of radial swelling, an anisotropic stress state, in which even the radial and hoop stresses are different, is observed immediately after the start of water absorption, resulting in the formation of complex stress distribution in the radial direction.