Abstract:Based on the static isotropic elastoplastic damage and Prevost model theory,a new damage model for saturated soft clay under cyclic loading is developed. The classical isotropic damage theory based on the strain equivalence hypothesis,in which the damage state is described by a single scalar damage variable,considers that the Poisson¢s ratio doesn¢t change;and the bulk modulus and shear modulus change with the same rule if the damage of soil takes place. But it doesn¢t agree with the mechanical characteristics of soil. An isotropic elastoplastic damage model described by double-scalar damage variables,which can consider respectively the compression and shear damage,is set up and generalized to the dynamic analysis of soil. Then damage evolution equations,which are related respectively to the bulk modulus and shear modulus are established. Finally this model is employed into the calculation about seismic building settlement to verify its reliability.