## 4 Results and Discussion  
### Effect of Construction Condition  
In this subsection, the raising deformation of the SSC is numerically reproduced and compared with the in-situ measured data. Meanwhile, in order to investigate the effect of construction condition on this issue, a hypothetical case is also considered in which the temporary IWP is specified equal to 1.60 MPa, according to Chinese design code [26]. Hereafter, the terms unwatered case and pressurized case will be used to refer to the two cases for brevity. The only difference between these two cases is the construction condition. The unwuered case simulates the construction procedure of M-type SCSs, where sealing devices and pressurization is not needed. The pressurized case simulates the construction procedure of P-type SCSs. Figure 11 shows the raising deformation of the upper stay ring. Overall, although there is some inconsistency between the FEA results and the in-situ measured data, no substantial difference is found in their distributions and ranges. The peak value of the FEA results is 27.58 mm, which is slightly higher than the in-situ measured data. Accordingly, it is reasonable to believe that the assumed load condition can well represent the actual situation. The raising deformation values of more than one third of the notes in the unwuered case are over 10 mm, which makes it impossible for the turbine set to operate in a stable and reliable state. Figure 11: Raising deformation of the upper stay ring. Figure 10: The arrangement of dial indicators. As for the pressurized case, the peak value is 10.26 mm, which is 37% of that in unwattered case. Except for the node with peak value, the raising deformation values of other nodes are below 10 mm, which benefits the structural stability greatly. The distributions of the raising deformation of two cases are similar, while the values of the pressurized case are much lower than that of the unwatered case. Figure 12 shows the vertical displacement of the stay ring. The effect of the external load is quite obvious in both cases. The maximum vertical displacement in the unwatered case is 31.10 mm, while that in the pressurized case is 12.95 mm. Meanwhile, negative vertical displacement is observed in the pressurized case, and the maximum negative vertical displacement is 5.14 mm. Accordingly, the temporary IWP in the construction period does help control the raising deformation of the stay ring. The results indicate that the temporary IWP not only helps create an initial gap between the SSC and the concrete, but also plays an important role in controlling the reliability of the construction procedure. Moreover, the pressurized case also indicates that construction condition is not the only factor that caused the raising deformation accident, and the effect of external load cannot be simply offset by temporary IWP. This accident is actually the result of multiple factors. Figure 13 shows the raising deformation of the upper flange. Compared with that of the upper stay ring, there exist several abnormal values in the in-situ measured data. This may be attributed to the structural deformation of the flange itself, which the FEA fails to simulate. Even though, the distribution of the raising deformation of the FEA results is still similar to that of the stay ring, and the peak value of the FEA results is 25.69 mm. However, it should be noted that negative value is observed around section 8, while all the FEA results are positive. The peak value of the FEA results in pressurized case is 8.49 mm, which is only 33% of that in unwatered case. This result tends to be consistent with that of the upper stay ring, and temporary IWP helps a lot in controlling the raising deformation of the upper flange. Apart from the deformation of the stay ring and the flange, the structural displacement of the SSC is also worth paying attention to. Figure 14 shows the vertical displacement of the SSC in the unwatered case. The maximum vertical displacement of the SSC appears at the external load area.