# Dynamic Characteristics of Post-Cyclic Saturated Loess
## 4 Discussion  
The experimental results of dynamic characteristics of post-earthquake saturated loess under different reconsolidation conditions show that the pre-seismic action will lead to the kinetic stiffness of the saturated loess having an obvious attenuation and the \(D\) of the loess increasing significantly. The dynamic stiffness of the saturated loess after the PSR process increases and the \(D\) decreases with an increase in over-consolidation ratio, and there is a nonlinear relationship between \(G_{d}/G_{dmax}\), \(D\), and the OCR. Considering the demand for parameter selection in dynamic response analysis of slope sites, there is a tremendous need to study the effect of pre-seismic and reconsolidation on nonlinear kinetic characteristic  
Figure 12: Normalized curves of the damping ratio versus the dynamic shear strain of the saturated loess under different test conditions. parameters of saturated loess. Furthermore, the structural change of soil is the essential reason for the difference in soil mechanics. The layout of soil particles and the content and distribution of pores in soil have a decisive effect on the mechanical behaviors of soil. Therefore, it is helpful to understand the influence mechanism of strong earthquakes and post-earthquake reconsolidation on the nonlinear dynamic characteristics of saturated loess by analyzing the microstructure characteristics of saturated loess under different PSR conditions. Influence Law of Strong Earthquake and Post-Earthquake Reconsolidation on Nonlinear Dynamic Characteristics of the Saturated Loess  
According to Figures 9 and 12, the relationships of \(G_{d}/G_{dmax}\) versus OCR and \(D\) versus OCR of the saturated loess at different levels of \(\gamma_{d}\) are drawn, respectively. To accurately describe the variation laws of nonlinear kinetic characteristic parameters with OCR at different levels of the \(\gamma_{d}\), the ratio of \(G_{d}/G_{dmax}\) of saturated loess after pre-seismic to that of the original saturated loess at the same level of the \(\gamma_{d}\) is defined as \(G_{\rm u}\), and the ratio of \(D\) of saturated loess after pre-seismic to that of the original saturated loess at the same level of the \(\gamma_{d}\) is defined as \(D_{\rm u}\). Figure 13a shows the relationship between \(G_{\rm u}\) versus OCR, and Figure 13b shows the relationship between \(D_{\rm u}\) versus OCR. According to Figure 13a, with the increase in the OCR, \(G_{\rm u}\) shows an increasing trend generally. In the small shear strain stage, with the increase in the OCR, the variation of \(G_{\rm u}\) is not immediately apparent. In the large shear strain stage, when the OCR increases from one to two, \(G_{\rm u}\) increases sharply; when it is between two and three, the change rate of \(G_{\rm u}\) is small; when it increases from three to four, the growth trend of \(G_{\rm u}\) tends to be obvious, but the growth rate is slower than that of it at one to two. According to Figure 13b, there are significant differences in the changes of \(D_{\rm u}-\)OCR curves at different strain stages. In the small shear strain stage, \(D_{\rm u}\) shows a decreasing-increasing-increasing tendency with the increase in OCR; however, the change in degree is small in general. The influence of the PSR on \(D\) is insignificant at this stage. At the large shear strain stage, \(D_{\rm u}\) decreases monotonously with an increase in the OCR, and its decrease in degrees gradually slows down, indicating that the PSR process has a significant effect on \(D\). When the OCR reaches two, the \(D_{\rm u}\) of saturated loess after pre-seismic is close to one, which shows its \(D\) reaches the level before pre-seismic.