## 4 SoilWorks Numerical Simulation
### Sensitivity Analysis
#### 4.2.4 Analysis Results  
* Sensitivity Analysis of Friction Angle The results for different assumed geological conditions, including sandy soil and clay (drained and undrained) soil, were integrated and an integrated analysis was conducted. The maximum bending moment (_Mmax_), maximum displacement (_Dmax_), and average axial force (_Favg_) corresponding to the assumed friction angles of 80%, 90%, 100%, 110%, and 120% were compared with the maximum bending moment, maximum displacement, and average axial force at the original friction angle (100%). The percentage changes in the maximum bending moment, maximum displacement, and average axial force due to the variation in friction angle were calculated. The sensitivity of the friction angle (\(\Phi\)) on these three parameters (_Mmax_, _Dmax_, _Favg_) is discussed. The analysis results from [PERSON] et al. 's [26] PLAXIS program are also considered. (1) Sandy Soil Layer From the summarized analysis results in Table 7, it can be observed that when the friction angle varies from 80% to 120% of the baseline value (100%), the range of variation  
Figure 7: Case analysis model for clay layer simulation. in the maximum wall moment (_Mmax_) is 282.78 to 392.24 kN-m, with a percentage change of 88% to 121%. The range of variation in the maximum displacement (_Dmax_) is 29.664 to 40.840 mm, with a percentage change of 90% to 124%. The range of variation in the average axial force (_Favg_) is 223.3 to 278.8 kN/m, with a percentage change of 91% to 114%. Line graphs depicting the percentage change in the three parameters (_Mmax_, _Dmax_, _Favg_) with respect to different friction angles (\(\Phi\)) were plotted. From Figure 8a, it can be observed that the friction angle has a significant sensitivity to _Dmax_, with an increase of 24% when \(\Phi\) is decreased by 20%. When \(\Phi\) is increased by 20%, _Mmax_, _Dmax_, and _Favg_ decrease by approximately 10%. The results indicate that a smaller friction angle has a more significant effect on _Dmax_, while higher friction angles have similar influences on _Mmax_, _Dmax_, and _Favg_. Additionally, the sensitivity analysis results for the friction angle in sandy soils from Qiu et al. 's [PERSON] et al. (2016) PLAXIS program were compared with the SoilWorks program. From Table 8 and Figures 8b and 9a,b, it can be observed that when the friction angle is smaller, the variation in the PLAXIS results is more significant compared to the SoilWorks program. This indicates that PLAXIS is more sensitive to the friction angle than the SoilWorks program. (2) Clay Layer (Undrained Condition)  
From the summarized analysis results in Table 9, it can be observed that when the friction angle varies from 80% to 120% of the baseline value (100%) in the undrained condition, the range of variation in the maximum wall moment (_Mmax_) is 243.96 to 267.27 kN-m, with a percentage change of 97% to 106%. The range of variation in the maximum displacement (_Dmax_) is 46.110 to 48.232 mm, with a percentage change of 98% to 103%. The range of variation in the average axial force (_Favg_) is 232.5 to 252.5 kN/m, with a percentage change of 96% to 105%. Line graphs depicting the percentage change in the three parameters (_Mmax_, _Dmax_, _Favg_) with respect to different friction angles (\(\Phi\)) were plotted. From Figure 10a, it can be observed that the sensitivity of the friction angle (\(\Phi\)) on the clay layer (undrained condition) is relatively small, with changes of approximately 6% in _Mmax_, _Dmax_, and _Favg_ when \(\Phi\) is decreased or increased. The results indicate that the clay layer (undrained condition) is not particularly sensitive to the variation in friction angle. Additionally, the sensitivity analysis results for the friction angle in the clay layer (undrained condition) from Qiu et al. 's [PERSON] et al. (2016) PLAXIS program were compared with the SoilWorks program. From Table 10 and Figures 10b and 11a,b, it can be observed that when the friction angle is increased, both programs show only a slight variation.