# Calculation of Displacement-Dependent Active Earth Pressure for Deep Excavations in Soft Soil
## 4 Conclusions  
In this paper, a method for calculating the displacement-dependent active earth pressure of flexible support structures in deep foundation pit engineering was investigated. The following conclusions were drawn from the work:  
Figure 17: Bending moment diagram.  
Figure 18: Shear force diagram.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Stiffness (MN\(\cdot\)m\({}^{2}\)/m)**} & \multicolumn{2}{c}{**m (MN\(\cdot\)m\({}^{4}\)/m)**} \\
**Support** & **Concrete Strut** & **Steel Strut** & **m (MN\(\cdot\)m\({}^{4}\)/m)** \\ \hline
1189.43 & 142.63 & 36.40 & 5.68 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Design parameters.  
Based on the analysis of the lateral unloading stress path triaxial test results, a hyperbolic model was proposed. The comparison between the predictions and test results showed that the proposed model can successfully estimate the radial stress from the soil strain for soft clay under various initial radial stresses.
2. According to a basic hypothesis of the soil, a simplified soil strain distribution assumption was applied to allow for the proposal of a displacement-dependent active earth pressure model. The proposed model was validated by comparison with the experimental results, showing it to be a valid model for estimating the magnitude and distribution of active earth pressure, with a consideration of the displacement of the supporting structure. More work needs to be performed given that the prediction deviation resulting from the model reflected a neglect in the interaction between the support structures and the soil mass.
3. Through an inversion of the proposed model, we confirmed that the earth pressure along the entire depth of the wall could not achieve the active condition simultaneously. This confirmed the validity of our calculation of displacement-dependent active earth pressure for deep excavations. The assumption that the required magnitude of movement of the entire soil in the fully active condition is 1% of the excavation depth is not suitable for a multi-strutted, soft-ground foundation pit; however, this assumption may be reasonable for the retaining walls rotating around the bottom.
4. The present experimental work is limited to the Nanjing floodplain muddy clay. For more generalizable conclusions, further exploration should be carried out for other soils.  
Conceptualization, N.L. and W.L.; methodology, N.L. and J.Z.; software, N.L. and J.Z.; validation, N.L. and W.L.; formal analysis, N.L. and S.Z.; investigation, N.L. and J.Z.; resources, N.L. and J.Z.; data curation, N.L., S.Z. and J.Z.; writing--original draft preparation, N.L.; writing--review and editing, N.L.; visualization, N.L.; supervision, W.L.; project administration, W.L.; funding acquisition, W.L. All authors have read and agreed to the published version of the manuscript.  
National Natural Science Foundation of China: 51778143; Priority Academic Program Development of Jiangsu Higher Education Institutions: CE02-1-51.  
Not applicable.  
The authors declare no conflict of interest.