Dynamic responses of frozen subgrade soil exposed to freeze-thaw cycles

The current paper reports an experimental investigation that aims to determine the effects of freeze-thaw cycles (cycle number and freezing low temperature) on the dynamic responses of frozen subgrade soil. The test results indicate that the curve level for the dynamic shear modulus (damping ratio) first decreases (increases) and then remains approximately stable at a small strain range with increasing freeze-thaw cycles. These critical cycle numbers for the dynamic shear modulus (damping ratio) are different at the three freezing low temperatures. A theoretical model is developed to describe the evolutionary features of the dynamic shear modulus (damping ratio) under different conditions. The development of accumulative plastic deformation is strongly sensitive to freeze-thaw cycles and freezing low temperatures. Two-stage evolutionary features for the resilient modulus with a loading cycle number were experimentally verified under different conditions. The freeze-thaw attenuation coefficient was adopted to evaluate the property deterioration with increasing freeze-thaw cycles. The comparison results display good agreement between the experimental data and the predicted curve determined from this proposed theoretical model. This investigation provides a useful and important reference for assessing the degeneration of engineering properties for frozen subgrade soil exposed to freeze-thaw cycles.