# Static Properties of Kaolinite Samples from Different Structures and the Influence of Strain Rate
## 4 Determination of Strain Rate and Experimental Details
### Shear Strength Formula Considering the Influence of Strain Rate
#### 5.3.1 Strain Rate Sensitivity Parameter
Therefore, it is necessary to eliminate the influence of strain rate when studying the effect of structure on shear strength, thus it is best to adopt the same strain rate. [PERSON] [35] constructed a hysteretic deformation model that can reflect the rheological properties of soil. This model can explain the effects of intermediate principal stress, rheological properties, and initial consolidation states (isotropic consolidation and \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample** & **Flocculated** & **Dispersed** & \begin{tabular}{c} **G-B Clay-De-** \\ **Structured** \\ \end{tabular} & \begin{tabular}{c} **G-B Clay-** \\ **Structured** \\ \end{tabular} & \
\begin{tabular}{c} **Olga Clay-De-** \\ **Structured** \\ \end{tabular} &
\begin{tabular}{c} **Olga Clay-** \\ **Structured** \\ \end{tabular} \\ \hline Strain rate & 4.79 & 2.31 & 12.54 & 12.05 & 12.64 & 10.03 \\ parameters \(\rho\) (\%) & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Strain rate sensitivity parameters, \(\rho\) (%). Figure 13: Shear strength–strain rate responses of different types of clay [36]. consolidation). He proposed that there is a specific relationship between the strain rate sensitivity parameter (\(\rho\)) and the ratio of the primary consolidation coefficient to the secondary consolidation coefficient, namely \(C_{a}/C_{c}\). \[\rho=10^{C_{a}/C_{c}}-1 \tag{9}\]  
At the same time, based on the statistical analysis of many strain rate sensitivity parameters \(\rho\) of clay, [PERSON] [35] also found that the strain rate sensitivity parameter values of most clays range between 8% and 20%, with an average value of approximately 12%. The magnitude of the strain-rate sensitivity parameter depends on the type of clay; clays composed of different minerals have different strain rate sensitivity parameters. The strain rate sensitivity parameter is independent of the test type, and under the same conditions, this parameter is only related to \(C_{a}/C_{c}\). There are many specifications for determining the strain rate, and the specifications mentioned earlier show that the effect of strain rate on the shear strength of clay is closely related to the consolidation characteristics of the clay. [PERSON] and [PERSON] [37] studied \(C_{a}\) and \(C_{c}\) and believed that for both cohesive and non-cohesive soils, the volume change mechanism of each soil particle is a chain reaction process that is dependent on time effects. They conducted consolidation tests on 22 natural soils and calculated \(C_{a}/C_{c}\) values ranging from 0.025 to 0.05 with higher values applicable to highly organic clays. According to Equation (9), when the strain rate increases ten-fold, the strain rate sensitivity parameter \(\rho\) ranges from 5.9% to 12.2%. This indicates that for normally consolidated clay, each ten-fold increase in strain rate results in an increase in undrained shear strength of 5.9% to 12.2%. The kaolin used in this study contained almost no organic matter; therefore, the \(C_{a}/C_{c}\) value was low, and the strain rate sensitivity parameter was smaller.