Fig. 2 presents the variation of A with 'Ye and the plasticity
index of the soil, PI, summarizing many tests conducted on a
broad range of soils in a number of different laboratories (Vucetic
and Dobry 1991). Lines showing the approximate range
and average values of the threshold volumetric cyclic shear
strain, 'Y,VO for different values of PI are also included (Vucetic
1994).