Dilatancy

Definition

Dilatancy is the property of soil material that refers to a change in its volume in response to shearing under a certain normal or confining stress.

Context

Soil material in an initially high relative density condition (low initial void ratio, e_o) will increase in volume (increase in void ratio) to a condition of constant volume with continued shearing under the same normal stress. Conversely, the same soil material in an initially low relative density condition (high e_o) will decrease in volume (decrease in void ratio), ultimately converging to the same constant volume with continued shearing under the same normal stress (Houlsby 1991). The high-density soil response is dilative, whereas the low-density soil response is contractive (Fig. 1); the term dilatancy refers collectively to soil volume change response to shearing. The constant void ratio with continued shearing under a certain normal stress is a steady state condition known as the critical void ratio (Fig. 1). The...