Study on the compression behavior and strain rate effect of Zhuhai soft clay

Abstract

As a marine deposit, Zhuhai soft clay generally exhibits poor mechanical and engineering properties. In order to investigate its compression behavior, a series of incremental loading (IL) tests and constant rate of strain (CRS) tests were conducted on both intact and reconstituted samples. The compression index (C_c), coefficient of secondary compression (C_a), and the ratio C_a/C_c of Zhuhai clay were determined using the end of primary (EOP) concept. In IL tests, the ratio C_a/C_c was found to be non-constant, but varied with time and vertical stress. Furthermore, CRS tests revealed an unexpected strain rate effect that deviated from the classical stress-strain-strain rate relationships. Specifically, the compression curves obtained at different strain rates were not parallel, but gradually approached each other at high stress levels. Regression analysis results suggested a positive correlation between the strain rate and the compression index, indicating that higher strain rates resulted in a greater compression index. To acquire a comprehensive understanding of this unusual phenomenon, a concise review of several relevant works was conducted. It is postulated that the observed discrepancy between Zhuhai clay and the classical isotache concept may be attributed to the development of microstructure and the evolution of C_a/C_c during the loading.

Keywords:

• Soft clay
• compression behavior
• secondary consolidation
• strain rate effect
• stress-stran-strain rate lines
• isotache concept

Acknowledgements

This work was supported by National Natural Science Foundation of China under Grant No.52090083; China Scholarship Council under Grant CSC202106260162; China Construction Second Engineering Bureau Co. Ltd under Grant CSCEC2B-SZ-HQKA-ZY-080.

Data availability statement

The data that support the findings of this study are openly available in “Zenodo” at https://doi.org/10.5281/zenodo.7627773.

Disclosure statement

No potential conflict of interest was reported by the authors.