## 7 Validation of the Proposed Diameter Criterion  
The performance of the diameter only criterion was validated using 24 published load tests where in-situ plugging performance was reported. None of these piles were  
Figure 8: Testing the performance of the diameter criterion and two interaction diagrams using a dataset of CPT piles (**a**) The proposed diameter criterion and its respective accuracy; (**b**) The proposed interaction diagram created by the union of the top 5 interactive diagrams and its respective accuracy; (**c**) The proposed interaction diagram created by the union of the top 25 interactive diagrams and its respective accuracy.  
Figure 7: Calculated (\(Q_{c}\)) vs. interpreted (aka measured, \(Q_{m}\)) capacities for the best plugging conditions for the CPT design methods. Statics of \(Q_{c}/Q_{m}\) are shown in the inset tables.  
employed previously in our analyses, so this represents a true arm's length check on the proposed criterion. The new piles in the test dataset ranged in diameter from 0.33 to 1.58 m (13-62 inches), and in length from 9 to 86 m, (30-282 ft). All chosen piles included information about either the Incremental Filling Ratio (IFR), or the Plug Length Ratio (PLR). An IFR of 1.00 indicates that the pile is completely unplugged, while an IFR of 0 represents a completely plugged pile, and anything in between implies a partially plugged pile. Since the measured IFR values are not always 0 s and 1 s, and since the proposed interaction diagram does not account for the partially plugged condition, it was decided that an unplugged pile is any pile with an IFR > 0.3, and a plugged pile is any pile with an IFR < 0.3. The authors performed sensitivity analyses and the results of the analyses remained consistent when the plugging threshold was set to IFR in the range of 0.2 to 0.6.  
The test piles are summarized in Table 1 and are plotted in Figure 9, with the actual plugging condition identified using the symbols **U** for unplugged, **P** for plugged. The actual plugging condition based on the recorded IFR value, along with the forecasted plugging condition based on the diameter criterion are also shown in Table 1. The proposed diameter criterion successfully forecasted the plugging condition in 10 cases out of the 14 test cases that plot in the plugged and the unplugged zones with an accuracy of 71% and was off in 4 cases. The remaining 10 cases are scattered in the transition zone, and hence the plugging condition cannot be determined with confidence since the likelihood of being plugged and unplugged are equal.  
These observations, confirm that the proposed diameter criterion can be employed for preliminary determination of plugging, factoring in that its accuracy is on the order of 70%; however, the results are somewhat skewed by only 3 out of 24 tests in the validation data set exhibiting in-situ plugging.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{\#} & \multirow{2}{*}{**Reference**} & \multirow{2}{*}{**Pile ID**} & **Diameter** & **Length** & \multirow{2}{*}{**L/D**} & **IFR** & \multicolumn{2}{c}{**Plugging Condition**} \\ \cline{5-8}  & & & **m (in)** & & **m (ft)** & & **(\%)** & **Actual** & **Forecasted** \\ \hline
1 & Jeong and Ko [23] & TP-2 & 0.7 (27.6) & 11.4 (37.4) & 16.3 & 60.0 & Unplugged & N/A \\
2 & & TP-3 & 0.9 (36) & 15.5 (50.9) & 17.0 & 60.0 & Unplugged & Unplugged \\ \hline \hline \end{tabular}
\end{table}
Table 1: Test Piles used to evaluate the performance of the proposed interaction diagram, and the actual and forecasted plugging condition.  
Figure 9: Test Piles used to evaluate the performance of the proposed diameter criterion, showing the actual plugging condition and the resulting accuracy.