# Force Analysis of Circular Diaphragm Wall Based on Circular Cylindrical Shell Theory
## 7 Results and Discussion
### Radial Displacement of Circular Diaphragm Wall  
The radial displacements of the circular diaphragm wall obtained through the CCSTCM, FENSM and site monitoring are shown in Figure 10. From Figure 10, we can observe that the radial displacements of the circular diaphragm wall obtained through both the CCSTCM and FENSM increase first and then decrease with the increase in depth in different working conditions. The maximum radial displacement increases gradually with the increase in excavation depth, and the position of the maximum radial displacement declines gradually and then tends to be stable with the increase in excavation depth. The TCR values are slightly larger than the NSR values. Except for Working Conditions 1 and 2 (W 1 and W 2), in other working conditions, the radial displacements of the circular diaphragm wall obtained from site monitoring increase first and then basically decrease with the increase in depth. The maximum radial displacement increases gradually with the increase in excavation depth, but there are obvious fluctuations. The position of the maximum radial displacement gradually declines with the increase in excavation depth and then also tends to be stable. Combined with Table 4, it can be further determined that the extremum of the maximum radial displacements obtained from the field monitoring is 11.6 mm, which occurs 35 m from the top of the circular diaphragm wall in the last working condition (W 15). The extremum of the maximum radial displacements obtained from the CCSTCM is 10.1 mm, which is 87.1% of the SMR and occurs 32 m from the top of the circular diaphragm wall in W 15. The extremum of the maximum radial displacements obtained from the FENSM is 9.7 mm, which is 83.6% of the SMR and 96.0% of the TCR, and occurs 32 m from the top of the circular diaphragm wall in W 15 also. Generally speaking, the variation rules of the radial displacements obtained by the three methods are basically the same, and the curves of the radial displacements show the shape of \"big in the middle and small at both ends\"; however, the SMR are slightly larger than the TCR and NSR and closer to the TCR. To a certain extent, the proposed CCSTCM and the numerical calculation model established are reasonable. Because all the maximum radial displacements of circular diaphragm wall obtained by the three methods are generated at the last working condition and the depth range is about 31 m-36 m, the reinforcement measures should be taken within this depth range when the excavation of the north anchorage foundation pit reaches the last several working conditions.  
Figure 12: Vertical bending moment results of the circular diaphragm wall at Point A. (**a**) Variation of vertical bending moments obtained by CCSTCM with depth in different working conditions. (**b**) Variation of vertical bending moments obtained by FENSM with depth in different working conditions. (**c**) Variation of vertical bending moments obtained by site monitoring with depth in different working conditions. (**d**) Variation of maximum vertical bending moments with excavation depth.