Constant volume equivalent undrained testing is performed under cyclic loading by the PFC~(2D) model, and the liquefaction behavior of saturated stratified silty sands is discussed from the viewpoint of meso-mechanism. Meso-scale parameters such as co-ordination number, distribution of contact normal and contact forces are studied under cyclic loading. Some results are obtained. The important factors which control the macro-response of saturated stratified silty sands are the average co-ordination number, distribution of contact normal and contact forces at mesomechanical level. The major characteristics of deformation are stress-induced anisotropy and fabricinduced anisotropy. And the liquefaction behavior of loose saturated stratified silty sands is mainly due to continued and cumulative loss of the co-ordination number under cyclic loading. Numerical simulation can describe the liquefaction behavior of saturated stratified silty sands. The meso-fabric evolutions including co-ordination number, distribution of contact normal and contact forces can be analyzed during liquefaction induced by cyclic loading. Numerical simulation can also be used to illustrate and verify a theoretical relationship between measures of macro- and meso-scopic parameters that describe the anisotropy in contact forces and contact orientations.
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