## 4 Effect of OCR on Pore Pressure Dissipation
### Effect of OCR on Pore Pressure Dissipation Curve  
The pore pressure dissipation curve with OCR = 1, 3 and 5 at \(\sigma_{\rm v}\) = 30 kPa is shown in Figure 8. It shows that a higher OCR leads to a faster normalized dissipation response, and the same trend was observed at \(\sigma_{\rm v}\) = 60 kPa and \(\sigma_{\rm v}\) = 90 kPa. [PERSON] and [PERSON] [20] suggested the use of \(T^{\star}\) instead of \(T\) and gave the corresponding \(T^{\star}\) for the cone shoulder position under different consolidation degrees. The consolidation degree and \(T^{\star}\) are defined as:  
\[U(t)\ =\ \frac{u_{i}-u_{t}}{u_{i}-u_{0}} \tag{22}\]  
\[T^{\star}\ =\ \frac{c_{\rm h}t}{r^{2}\sqrt{I_{r}}} \tag{23}\]  
where \(u_{\rm i}\) is the initial pore pressure; \(u_{\rm t}\) is the pore pressure over time; \(u_{0}\) is the hydrostatic pressure; \(u_{\rm t}=u_{0}\) and \(U(t)=1\) when the dissipation is complete; and \(c_{\rm h}=c_{\rm v}\) when the soil is isotropic. However, the stress is anisotropic in this paper. [PERSON] et al. [21] gave  
Figure 7: \(\Delta u\) contours after dissipation for 0 s, 0.3 s and 1.5 s in kaolin silty clays. (**a**) \(t\) = 0 s; (**b**) \(t\) = 0.3 s; (**c**) \(t\) = 1.5 s.  
the relationship between \(c_{\rm h}\) and \(c_{\rm v}\) under stress anisotropy, and the expression of \(c_{\rm h}\), which can also be expressed as  
\[c_{\rm h}\ =\ \frac{3(1-\
u)k}{(1+\
u)\gamma_{\rm w}}\frac{(1+e)p^{\prime}}{ \kappa}(1-\Lambda)^{1-\alpha} \tag{24}\]  
\(\Lambda\) is the same as mentioned above, and \(\alpha\) is a weighting factor defining the contribution of elastic and plastic behavior with a default value of 0.5. The soil is in a one-dimensional consolidation stress state and on the \(\kappa\) line, so \(c_{\rm v}\) can also be used to normalize:  
\[c_{\rm v}\ =\ \frac{k(1+e)\sigma_{\rm v}{}^{\prime}}{\gamma_{\rm w}\kappa} \tag{25}\]  
The initial pore pressure distribution in over-consolidated soil has a crucial role in determining the behavior of pore pressure around the cone tip during cone penetration tests. As a result of this initial pore pressure distribution, it has been observed that the pore pressure at the cone shoulder initially increases before it decreases during penetration. The  
Figure 8: Pore pressure dissipation curve under different OCR at \(\sigma_{\rm v}\) = 30 kPa. (**a**) Kaolin silty clay; (**b**) Yellow River Delta silty clay. maximum pore pressure was adopted to replace the initial pore pressure. The consolidation degree normalized time curve is shown in Figures 9 and 10 with different normalization methods. Due to the influence of stress anisotropy, the curve normalized by \(c_{\rm h}\) was different from that of [PERSON] and [PERSON]'s [20] results. Under normal consolidation conditions (OCR = 1), the relationship between the consolidation degree and \(T^{\star}\) normalized with \(c_{\rm h}\) was the same as [PERSON] and [PERSON]'s [20] method. Figures 9 and 10 illustrate that the optical character recognition (OCR) process has had an impact on the calculated value of \(T^{\star}\). The results depicted in these two figures suggest that the accuracy of the OCR system may be a critical factor in determining the validity and reliability of \(T^{\star}\) measurements. It is evident from the figures that the use of OCR technology can lead to errors in the calculated \(T^{\star}\) values, which can ultimately affect the interpretation  
Figure 9: The consolidation degree normalized time curve under different OCR in kaolin silty clay. (a) \(T^{\star}\) normalized with \(c_{\rm v}\); (b) \(T^{\star}\) normalized with \(c_{\rm h}\)[20]. and usefulness of the data obtained from this analysis. Therefore, it is essential to evaluate the accuracy and reliability of OCR systems used in \(T^{\star}\) measurements to ensure the validity of the results obtained. Figure 11 shows the results of \(c_{\text{h}}\) normalization for kaolin silty clay and Yellow River Delta silty clay.