Dynamic properties of frozen silty soils with different coarse-grained contents subjected to cyclic triaxial loading

In cold seismic regions, the dynamic properties of frozen silty soils with different coarse-grained contents have great influence on the stability of core-wall dam in hydraulic engineering subjected to seismic/repeated loading. In order to investigate their dynamic behaviors, the materials were prepared with silty soils incorporating different percentages of coarse grains, and the mass ratios of coarse particles to silty soils for the samples are 0%, 20%, 40%, 60% and 80%, respectively. A series of cyclic triaxial compression tests at the temperature of −6°C were carried out with 1.0 Hz frequency by employing the modified MTS-810 apparatus with confining pressures ranging from 0.3 to 4.0 MPa. Laboratory results demonstrate that the coarse-grained contents have great effect on the static and dynamic behaviors of frozen soil mixtures. With the increasing coarse-grained contents, the static strength first decreases to a smaller value and then increases slightly. When subjected to cyclic loading, the resilient modulus increases all the time, whereas the damping ratio presents conversely a decreasing tendency. As the loading cycles increase, the accumulative plastic strain presents an accelerating development at the virgin stage and then gradually approaches the failure strain, whose evolving rule can be well predicted by the modified Monismith model, and the rate of accumulative plastic strain descends first and then reaches a stationary value. The dynamic strength increases with the increase of confining pressure, and the damage evolution can be denoted by the axial strain method in the process of cyclic loading.