## 5 Conclusions  
This paper focuses on the evolution and characteristics of shear bands in Zhanjiang clay consolidated to various confining pressures. A series of undrained plane strain compression tests with DIC analyses and SEM tests was carried out. The conclusions are as follows:  
1. The basic mechanical properties and representative stress-strain behavior indicates that Zhanjiang clay is a typical naturally structured clay. The mechanical properties of specimens under consolidation stress lower and higher than yield stress differ significantly.
2. When \(\sigma_{x}=100\) kPa, only one localized shear band appears in the specimen. However, when \(\sigma_{x}=300\) and \(500\) kPa, several localized shear bands appear in the specimens during the plane strain compression tests, and the shear strain distribution is much more complicated when \(\sigma_{x}=500\) kPa. When the specimens fail, only one shear band is fully developed for all specimens, and the shear strain in the developed shear band is much larger than those in the other localized shear bands. Based on the results of MIP tests, the change in pore size distribution might have contributed to the different strain distributions in the specimens consolidated at different confining pressures. The measured inclination of the shear bands in the T1, T3, and T5 tests are similar to the inclinations calculated based on the Mohr-Coulomb theory.
3. Before the peak deviatoric stress, the local strain in the specimens is relatively uniform, and the local stress-strain curves for regions inside and outside the shear band are similar. However, strain localization emerges subsequently, and the local stress-strain curves for regions inside and outside the shear band are distinct after the peak deviatoric stress.
4. The SEM results indicate that the micro-structures inside and outside the shear band can be distinguished. The overall particle size and pore size outside the shear band are larger than those in the shear band, and the number of particles outside the shear band is lower than that in the shear band, owing to strain localization and development of the shear band.  
In this study, the evolution and characteristics of shear bands in Zhanjiang clay, consolidated to various confining pressures, are investigated. The real-time evolutions of shear bands of Zhanjiang clay during the plane strain compression tests are obtained. In addition, the buried depths for clays were simulated by the various confining pressures, which contributes to study the shear band characteristics of clays at different positions of slopes under large forces. It is believed that this work would be helpful for the comprehensive understandings of failure of soil, and even the failure of slopes.  
Conceptualization, B.L. and L.K.; methodology, B.L.; software, formal analysis, C.L.; investigation, B.L. and J.W.; resources, L.K.; writing--original draft preparation, B.L.; writing--review and editing, B.L. and L.K.; supervision, L.K.; project administration, L.K. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Natural Science Foundation of China, grant number 41877281.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.