Stiffness and damping radio evolution of frozen clays under long-term low-level repeated cyclic loading: Experimental evidence and evolution model

The dynamic properties of frozen clays under repeated cyclic loading is changing with the increasing number of loading cycles. Compared with the short-term low-level repeated cyclic loading, the variation of the dynamic properties of frozen clays under long-term low-level repeated cyclic loading should not be ignored. So far, the evolutions of the dynamic properties as well as the stiffness and damping ratio of frozen clays under long-term low-level repeated cyclic loadings have rarely been studied. In this study, a series of cyclic tri-axial tests were carried out and the influence of the dynamic loading amplitudes, the confining pressures, the temperatures, the moisture contents and the salt contents of the specimens on the dynamic properties were studied. Thereby, the observation that stiffness increased and damping ratios decreased with the increasing number of repeated loading cycles were obtained. Based on the experimental evidence, the conclusion that the evolutions of the dynamic properties under long-term low-level repeated cyclic loading were related to the accumulative axial strain was achieved. The accumulative axial strains were normalization through introducing the accumulative axial strain ratio. A subsequent work focused on establishing the stiffness and damping ratio evolution models. Combined with the Hardin–Drnevich hyperbolic model, the evolutions models can be used to calculate the dynamic response of the frozen clays which had experienced long-term low-level repeated cyclic loading.