# A Comprehensive Review of Open Caisson Modeling Technology: Current Practices and Future Prospects
## 5 Challenges and Future Directions
### Challenges
#### 5.1.3 Soil Variability and Unpredictable Subsurface Conditions
To overcome these issues, future research should focus on the integration and strengthening of prediction model resilience by including more varied datasets, such as various soil types and caisson geometries, as well as exploring the impact of groundwater water levels and temperature. Furthermore, adaptive prediction systems and real-time monitoring could improve caisson's dynamic response to abrupt changes in subsurface conditions. Examining the influence of heterogeneous soil layers on the sinking process and subsequent ground movements can yield significant insights for future endeavors. Factors such as soil-structure interaction, caisson geometry, and construction sequence play a crucial role in determining ground movements. The complex interaction between the caisson and the surrounding soil requires detailed investigation. There is a critical need to explore the earth pressure distribution on ultra-deep shafts in complicated soil conditions such as composite, heterogenous soil strata using different modeling techniques to address the existing gap in this area. Experimental modeling has evolved significantly, yet it often faces limitations in replicating in situ conditions. For instance, 1-g models are cost-effective and allow larger-scale experimentation, but they struggle to simulate realistic stress states compared to n-g (centrifuge) models. There is a dire need to improve the fidelity of stress representation in 1-g models while addressing scaling challenges inherent in n-g models. Techniques to reconcile these limitations could include hybrid modeling approaches that integrate both 1-g and n-g methodologies, as well as innovations in material and boundary condition simulations. A comparative summary of parametric aspects, predictive discrepancies and their causes across various modeling approaches is shown in Table 4. \begin{table}
\begin{tabular}{l l l l l} \hline \hline \multicolumn{1}{l}{**FEM (Plaxis \({}^{3D}\)) vs. Centrifuge Modeling [83]**} & & & \\ \hline \hline Parametric Aspect & FEM (Plaxis \({}^{3D}\)) & Centrifuge Modeling & Discrepancy & Causes \\ \hline Soil Constitutive Model & \begin{tabular}{l} Mohr-Coulomb, \\ linear-elastic plastic \\ \end{tabular} & \begin{tabular}{l} True non-linear soil \\ behavior captured \\ \end{tabular} & \begin{tabular}{l} 20-30\% higher horizontal \\ displacement in FEM near \\ shaft wall \\ \end{tabular} & \begin{tabular}{l} Simplified constitutive \\ model, missing \\ strain-softening \\ \end{tabular} \\ \hline Boundary Conditions & \begin{tabular}{l} Fixed lateral and \\ bottom boundaries \\ \end{tabular} & \begin{tabular}{l} Gradual boundary \\ response in centrifuge \\ \end{tabular} & \begin{tabular}{l} Stress redistribution \\ differs near shaft \\ \end{tabular} & \begin{tabular}{l} Rigid boundary \\ assumptions in FEM \\ \end{tabular} \\ \hline Construction Simulation & Simplified excavation steps & \begin{tabular}{l} Real excavation effects \\ modeled naturally \\ \end{tabular} & \
\begin{tabular}{l} Differences in staged \\ settlement behavior \\ \end{tabular} &
\begin{tabular}{l} Over-simplification of \\ installation stages \\ \end{tabular} \\ \hline
**FEM Simulation vs. Field Monitoring (Shanghai Soft Soil Shaft Project)** & & & \\ \hline Parametric Aspect & FEM Prediction & Field Measurement & Discrepancy & Causes \\ \hline Lateral Earth Pressure & \begin{tabular}{l} Slightly underestimated \\ (-7\% lower) \\ \end{tabular} & \begin{tabular}{l} Higher earth pressure \\ recorded \\ \end{tabular} & \begin{tabular}{l} Difficulty modeling true \\ consolidation process and \\ pore pressure dissipation \\ \end{tabular} \\ \hline Ground Surface & \begin{tabular}{l} Predicted profiles close \\ \end{tabular} & \
\begin{tabular}{l} Minor differences \\ (-5-10\%) \\ \end{tabular} & 5–10\% &
\begin{tabular}{l} Soil property variability, \\ non-homogeneity of \\ field conditions \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 4: Comparative summary of parametric aspects, predictive discrepancies and their causes across various modeling approaches.