## 5 Conclusions  
This paper conducts triaxial tests on LGSCR and SCL samples using the discrete element method and explores the effects of the number and thickness of sand layers and geogrid-reinforced sand layers on the numerical triaxial compression test results of the samples. The following conclusions can be drawn from the findings of the current work:  
* Laying the sand layers in the samples can significantly improve their post-peak strain-softening characteristics. Moreover, the geogrid embedment can further enhance the ductility of the samples. The effect of increasing the thickness of sand layers alone on the behaviors of LGSCR and SCL samples is minimal. Thus, in practical engineering, the setting mode of _thin multi-sand layers_ should be adopted to improve the safety of LGSCR structures.
* The influence of the sand layer on the peak stress of LGSCR and SCL samples improves with an increase in the confining pressure. Higher confining pressure causes a more significant difference in the peak stress on different LGSCR or SCL samples, which indicates that the effect of the sand layer on increasing the peak stress on the samples is more noticeable. Thus, raising the number of sand layers reduces the cohesion of the samples but increases their internal friction angles. Therefore, a reasonable test pressure should be determined according to the actual stress state of the LGSCR structure in engineering applications.
* Compared with the SCL samples, the LGSCR samples with geogrid embedment have a higher peak strength under specific confining pressure, and in terms of the shear strength index, the apparent cohesion of the LGSCR samples is larger than that of the  
\begin{table}
\begin{tabular}{l c c c} \hline
**Improvement or** & **Addition of Sand** & **Addition of Geogrids** & **Addition of** \\
**Deterioration** & **Layers in Pure Clay** & **in SCL Samples** & **Geogrid-Reinforced Sand** \\
**Percentages** & **Samples** & **Layers in Pure Clay Samples** \\ \hline \(\varphi\) (three points) & 22.6\% & 12.7\% & 38.2\% \\ \(\varphi\) (five points) & 20.9\% & 8.4\% & 31.1\% \\ \(c\) (three points) & \(-\)37.2\% & 41.6\% & \(-\)11.2\% \\ \(c\) (five points) & \(-\)24.3\% & 54.8\% & 17.1\% \\ \hline \end{tabular}
\end{table}
Table 2: The comparison between the shear strength index of the pure clay sample, the SCL sample, and the LGSCR sample.  
Figure 14: The variation in the shear strength index of the samples with the thickness of sand layers.  
SCL samples. Furthermore, the internal friction angle of the LGSCR samples is also larger than that of the SCL samples when the number of sand layers is equal to or greater than two.  
Methodology, T.Y.; Project administration, W.C.; Resources, Q.S.; Writing--original draft, L.C.; Writing--review & editing, M.X. and P.X. All authors have read and agreed to the published version of the manuscript.  
This work was funded by the National Natural Science Foundation of China (NSFC) (grant numbers 52009129, 52008285, and 52178341), and the Natural Science Foundation of Guangdong Province, China (grant number 2021A1515011682). The authors would like to acknowledge this financial support.  
Not applicable.  
The authors declare no conflict of interest.