Shear modulus and damping ratio of clay soil under repeated freeze-thaw cycles
Mahya Roustaei, Michael Hendry, Eisa Ali Aghaei, Meysam Bayat
Abstract
The dynamic properties of soil deposits subjected to dynamic loading, such as the shear modulus G and material damping ratio D, are important parameters in ground response seismic analysis. In seasonally frozen regions, these properties can be significantly affected by microstructural changes that occur during freeze-thaw cycles. The current study evaluated the dynamic properties of clayey soil exposed to freeze-thaw cycles. Dynamic triaxial testing was conducted to determine the influence of mean effective consolidation stress, cyclic stress ratio, loading frequency, and freeze-thaw cycles on G-γ and D-γ curves. Scanning electron microscopy (SEM) was carried out to investigate microstructural changes in the clay soil fabric. The results indicate the freeze-thaw process has an important effect on dynamic properties of the soil. The dynamic shear modulus increases with increasing effective confining pressure, loading frequency, and confining pressure, and decreases with increasing number of freeze-thaw cycles. Development of more voids between clay particles after ice lens formation during these cycles results in an increase in the damping ratio, but this trend decreases with increasing confining pressure. Increasing the loading frequency increases or decreases the damping ratio depending upon the mean effective confining pressure and number of freeze-thaw cycles.