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 (Cc ), coefficient of secondary compression (Ca ), and the ratio Ca /Cc of Zhuhai clay were determined using the end of primary (EOP) concept. In IL tests, the ratio Ca /Cc 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 Ca /Cc during the loading.