Simulation of cyclic stress-strain behavior of sand

A numerical simulation of stress-strain behavior of sand in cyclic loading is presented. The constitutive model used in the simulation employs Tatsuoka's generalized hyperbolic equation for skeleton curves. The hysteretic behavior is represented through a modified Masing's rule, which accounts for non-symmetric nature of loading and unloading curves. A drag rule is also used in the constitutive model to represent drained cyclic behavior of sand that shows increase in stress amplitude during cyclic loading with constant strain amplitude, or decrease in strain amplitude during cyclic loading with constant stress amplitude. The behavior of sand sample in plane strain cyclic loading test is simulated through a plane strain finite element analysis using a four node rectangular element with reduced Gauss point integration scheme. In order to trace a smooth time history of stress-strain curve very small time increment is required for the analysis. As such central difference approach is suited for the dynamic analysis. The simulation is important for situations where soil is subjected to a relatively small number of loading cycles. Since the change of soil property and its subsequent behavior depends on the time-history of loading, the analysis is particularly useful in determining the effect of preloading often applied to reduce ground deformation that would otherwise take place by loading at subsequent stages.