Generalized Model for the Dynamic Behavior of Soils Subjected to Cyclic Loading

The dynamic behavior of soils subjected to cyclic loading, such as seismic events, traffic, or machinery-induced vibrations, is characterized by strong nonlinearity and a marked dependence on shear strain amplitude. Accurate representation of shear modulus degradation and the evolution of damping is essential for local seismic response analysis, geotechnical design, and the assessment of instability phenomena, such as soil liquefaction. In this study, a generalized model is proposed to describe the dynamic behavior of soils, based on a sigmoidal function for shear modulus degradation and a continuous law for cyclic damping. The formulation allows direct calibration of parameters using in-situ data, providing flexibility to describe both granular and cohesive soils while ensuring continuity necessary for nonlinear numerical analyses. The proposed model is compared with classical empirical approaches (Hardin–Drnevich, Vucetic–Dobry, and Darendeli) using experimental data from laboratory tests and field measurements. The results demonstrate that the generalized formulation accurately reproduces the transition from quasi-elastic to nonlinear behavior and provides a consistent description of cyclic damping. This new approach represents a versatile and robust tool for modeling the dynamic behavior of soils, with immediate applications in geotechnical design, local seismic response analysis, and the assessment of risks associated with cyclic loading.