# Post-Cyclic Mechanical Behaviors of Undisturbed Soft Clay with Different Degrees of Reconsolidation
## 5 Discussion  
The effects of confining pressure, cyclic stress ratio, and the degree of reconsolidation on the post-cyclic shear strength are assessed based on the test results. Figure 16 shows the variation in normalized post-cyclic shear strength ratio (\(S_{c,cut}/S_{cut}\)) under a certain influence factor. It is found that the values of \(S_{c,cut}/S_{cut}\) are all larger than unity of soft soil with full  
Figure 15: The microstructure of the soft soil after cyclic loading with different degrees of reconsolidation: (**a**) undisturbed soil; (**b**) CY\({}_{06}\); (**c**) CY\({}_{10}\); (**d**) CY\({}_{11}\). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Test No.** & **Pore Area (\(\mu\)m\({}^{2}\))** & **Soil Particle Area (\(\mu\)m\({}^{2}\))** & **Void Ratio** \\ \hline Undisturbed & 400 & 2651 & 0.151 \\ CY\({}_{06}\) (SEM) & 408 & 2658 & 0.154 \\ CY\({}_{10}\) (SEM) & 360 & 2727 & 0.132 \\ CY\({}_{11}\) (SEM) & 273 & 2792 & 0.098 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The area of pore fractions and soil particles. reconsolidation. [PERSON] et al. [29; 34] investigated the post-cyclic shear behavior of low-plasticity silt and found that the undrained shear strength after cyclic loading increased with full reconsolidation. [PERSON] et al. [30] and [PERSON] et al. [15; 16] also obtained similar conclusions. It can be seen that the effect of confining pressure on the \(S_{c,cu}/S_{cu}\) can be negligible. [PERSON] et al. [37] also found that the increased range of the normalized deviator stress at failure under different confining pressure was within 10%. The effect of cyclic stress ratio on the \(S_{c,cu}/S_{cu}\) with full reconsolidation is moderate: the maximum difference in \(S_{c,cu}/S_{cu}\) is 0.30. It can be seen that the post-cyclic shear strength of soil increases with the increase of cyclic stress ratio. Similar conclusions can be found in the study of post-cyclic shear behavior on reconstituted marine soft soils [37]. The degree of reconsolidation has the greatest effect on the values of \(S_{c,cu}/S_{cu}\): the maximum difference in \(S_{c,cu}/S_{cu}\) is 0.45. On the whole, the post-cyclic shear strength increases with the degree of reconsolidation. [PERSON] et al. [34] also found that the shear strength and stiffness of MRV silt increased steadily with an increase in the degree of reconsolidation. Besides that, the conclusion that there is a critical degree of reconsolidation between no reconsolidation and full reconsolidation making \(S_{c,cu}/S_{cu}=1\) proposed by [PERSON] et al. [37] also confirmed. At present, some studies have been involved the prediction of the post-cyclic shear strength of the soil. The excess pore water pressure of soil increases, and the effective stress decreases. The post-cyclic shear behavior will be similar to the overconsolidation behavior [5], therefore, some scholars regard the post-cyclic soil as the equivalent overconsolidated soil. [PERSON] et al. [15] used the equivalent overconsolidation ratio to estimate the undrained shear strength of soil after cyclic loading, as shown in Equation (3). It can be used to predict the post-cyclic shear strength after full reconsolidation of soft clay located in the Pearl River Estuary. \[\frac{S_{c,cu}}{S_{cu}}=(1-\frac{(\Delta u)_{cy}}{p_{0}^{{}^{\prime}}})^{ \Delta_{0}-\frac{\Delta_{0}}{1-c_{s}/C_{c}}} \tag{3}\]  
where \((\Delta u)_{cy}\) is the accumulated excess pore pressure generated by undrained cyclic loading; \(C_{s}\) and \(C_{c}\) are the swelling and compression indices, respectively.