Frequency-Dependence of Dynamic Resilient Modulus of Subgrade Clay: Mechanism and Modeling

Existing prediction model for the dynamic resilient modulus of subgrade clay ignores the effects from loading frequency. This study focuses on the frequency dependence of the dynamic resilient modulus of clay subgrades. An experimental study was performed to investigate the dynamic resilient modulus of the clay subgrade material at selected loading frequencies, which corresponds to different vehicle speeds on the road. The frequency dependence of the dynamic resilient modulus of the clay subgrade was significantly affected by the compaction degree and moisture content of the material. In addition, a modified model for predicting the dynamic resilient modulus of a subgrade was proposed by explicitly considering frequency dependence. A preliminary calibration of the model was accomplished, and its validation under various stress states, material conditions, and loading frequencies was found to be promising.