「構造」を持った過圧密土の弾塑性挙動

抄録

Naturally deposited soils are mostly found in structured and overconsolidated states. To describe mechanical behavior of the soils, the original Cam-clay model was newly placed not on the classicalbut on the “unconventional plasticity” theory by introducing super and subloading yield surfaces. Theformer yield surface lies outside the Roscoe Surface and stands for the structured state, while the latterexists inside the former surface and represents overconsolidated state.
Two evolution laws are newly introduced to the constitutive law. One is to govern the rate of theloss of structure, while the other, the rate of the decay of overconsolidation.The difference betweenthese two rates gives a clear distinction between clay and sand.
Both the loss of structure and the decay of overconsolidation proceed with ongoing plastic sheardeformation in the naturally deposited soils. The former proceeds at a much slower phase than thelatter in natural clays while the former progresses more rapidly in sands.