Experimental Study on Dynamic Characteristics of Loess in Xining Area under Freeze-thaw Cycles

As a kind of special soil widely distributed in Qinghai Province, loess has long been impacted by both freeze-thaw cycle and seismic loading. The seismic susceptibility and water sensitivity of loess have been widely discussed. Taking loess in Xining area as the research object, the change rule of dynamic properties of loess under the coupling effect of freeze-thaw cycle and dynamic load was studied. The dynamic triaxial test with cyclic dynamic load in the form of sinusoidal wave was carried out, and the evolution laws of perimeter pressure, the number of freeze-thaw cycles and the amplitude of dynamic shear strain γd on the backbone curve of loess, the dynamic shear modulus Gd, the dynamic shear modulus ratio Gd/Gd max, and the damping ratio λ were analyzed. The results show that: the backbone curve of loess tends to be stabilized after 6 freeze-thaw cycles, and the development process of the backbone curve can be divided into elastic and elastoplastic stages; the dynamic shear modulus curve is fitted by Ha