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Effect of Temporary Internal Water Pressure on Structural Performance of Spiral Case Structure in Pumped-Storage Power Plants

Temporary internal water pressure (IWP) during a construction period fundamentally affects the structural performance of spiral case structures (SCSs) in pumped-storage power plants (PSPPs). However, its actual role is rarely studied. This study focuses on this issue considering the complex construction-to-operation process of SCSs. An ABAQUS-based complete simulation procedure (CSP) is used with contact non-linearity considered. The contact-closing ratio is introduced to quantitively describe the contact status, and different design philosophies for temporary IWP are compared. The results show that the temporary IWP should be no greater than 80% of the minimum static headwater to ensure an overall contact-closing status under normal operating conditions in this study. The findings reveal that the cracking risk of concrete is negatively correlated with temporary IWP, while high temporary IWP is not suggested. Moreover, the stay ring actually shares a certain part of the unbalanced hydraulic thrust, which cannot be ignored. The limitation of this study might mainly lie in the idealized linear-elastic description of concrete. The temporary IWP should be designed with overall consideration of the IWP under normal operating conditions, the IWP-jointly-resisting status and design demands.