By shear test of disturbed silty clay at true triaxial apparatus and triaxial apparatus under isotropic consolidation drainage and lateral unloading
the stress-stain curves are obtained. Analysis shows: these curves are nonlinear and strain hardening; curvilinear shape changes from original straight line into curve; stress value of yield point is larger at true triaxial lateral unloading test( constant
is decreased
0) than at triaxial lateral unloading test; strain value of yield point is smaller at true triaxial lateral unloading test than at triaxial lateral unloading test. Analysis shows: Matsuoka-nakai strength criteria is suitable for sdudy yield property of Wuhan silty clay at lateral unloading.