## 5 Conclusions  
The total amount of consolidation settlement in the field can be determined by the changes in void ratio based on the clay characteristics evaluated in the laboratory. This study focused on clays that creep, in which strain rate effects can be neglected, and especially clays exhibiting a curved portion followed by a straight portion in their \(e-log\sigma^{\prime}{}_{\text{\tiny{P}}}\). We propose new equations that can fit well to the laboratory consolidation curve without any assumptions and additional testing. The proposed equations include (1) the revised version of the AJOP for normally consolidated clay, and (2) equation for both symmetrical and asymmetrical hysteresis of overconsolidated clay. With these equations, the analytical solution for consolidation settlement for clays can be established. A comparison between the existing methods and the proposed method was investigated. The three methods of calculation were linear function (LF), curve function (CF), and the revised AJOP equation (function for curve and linear portions in a single equation). In addition, three models of clay layering were investigated, i.e., single layer, and multilayers with equal and varied thickness. Three clay datasets from different continents were used in the analysis, i.e., Bangkok clay, Boston blue clay and London clay. For normally consolidated clay, it was revealed that the LF method yielded significantly higher consolidation settlement compared to the CF and AJOP methods for all clays and all layering conditions. Additionally, the single-layer model gave lower consolidation settlement than both layered soil models. These phenomena are influenced by two key factors: (1) the presence of curved portion in \(e-log\sigma^{\prime}{}_{\text{\tiny{P}}}\), and (2) the omission and commission of the curved portion in calculations due to the soil layering method. Therefore, the CF \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Soil** & **Case** &
\begin{tabular}{c} **AJOP** \\ **(Equation (6))** \\ \end{tabular} \\ \hline \multirow{3}{*}{Boston blue clay} & (a) Single layer & 1.084 \\ \cline{2-3}  & (b) Equal layer thickness & 1.139 \\ \cline{2-3}  & (c) Varied layer thickness & 1.138 \\ \hline \multirow{3}{*}{London clay} & (a) Single layer & 0.397 \\ \cline{2-3}  & (b) Equal layer thickness & 0.417 \\ \cline{2-3}  & (c) Varied layer thickness & 0.417 \\ \hline \multirow{3}{*}{Bangkok clay} & (a) Single layer & 3.578 \\ \cline{2-3}  & (b) Equal layer thickness & 3.659 \\ \cline{1-1} \cline{2-3}  & (c) Varied layer thickness & 3.651 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of total consolidation settlement for overconsolidated clay for high surface loading of 1000 kN/m\({}^{2}\). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Soil** & **Case** &
\begin{tabular}{c} **AJOP Method** \\ **(Equation (6))** \\ \end{tabular} \\ \hline \multirow{3}{*}{Boston blue clay} & (a) Single layer & 0.178 \\ \cline{2-3}  & (b) Equal layer thickness & 0.207 \\ \cline{2-3}  & (c) Varied layer thickness & 0.205 \\ \hline \multirow{3}{*}{London clay} & (a) Single layer & 0.072 \\ \cline{2-3}  & (b) Equal layer thickness & 0.080 \\ \cline{2-3}  & (c) Varied layer thickness & 0.080 \\ \hline \multirow{3}{*}{Bangkok clay} & (a) Single layer & 1.015 \\ \cline{2-3}  & (b) Equal layer thickness & 1.119 \\ \cline{1-1} \cline{2-3}  & (c) Varied layer thickness & 1.101 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of total consolidation settlement for overconsolidated clay for low surface loading of 200 kN/m\({}^{2}\). method provided greater accuracy than the LF method because the curved portion exists in CF. However, the AJOP method reduced errors at both shallow and greater depths, as it incorporates both curved and linear segments within a single equation. For overconsolidated clay, only AJOP equation was selected in the analysis. The calculations yielded similar results across all models.