Es: Es is obtained by consolidation test or by empirical relationship with site test(such as cone
penetration test) , actually Es is assumed as constrained modulus (Eoed). In this case, the strain
is not zero only in compression direction. By Hook's law, strains in the other two directions=0,
E=Eoed * (1+v) *(1-2v)/(1-v)
When using Mohr-Coulomb model in PLAXIS, Eref (the parameter in input window) is referred to Eref(50) that means the modulus of soil E. It is independent of stress level.
Here, finally, Eref=Es * (1+v) *(1-2v)/(1-v)
But remember, all these are for drained condition. You should use effective Poisson's ratio.
For undrained condition, you may get Eu value from test or some empirical equations(Eu=a*Su), you should change Eu to E(effective value):
E=2*Eu*(1+v)/3
[ 此贴被mano在2007-08-13 10:15重新编辑 ]