Abstract:
A group column type deep mixing (DM) improved ground has been often applied to increase stability
and decrease ground settlement. The design standard for the DM improved ground has been established
in Japan, in which the two failure patterns are assumed: external and internal stabilities. The stability of
the improved ground on an inclined base layer is also evaluated based on the design standard, though
the standard assumes that the improved ground is placed on a horizontal base layer. The authors
conducted a research project on the failure mechanism and stability of group column type DM improved
ground on an inclined base layer. In this study, the internal stability of DM columns on an inclined base
layer was investigated by a series of centrifuge model tests. The study reveals that the stabilized column
did not fail at the same time but one by one and internal stability of the improved ground is decreased
almost linearly with the inclination of the base layer.