Research On Hydraulic Vibration Of Underground Hydropower House Based On Viscous-spring Boundary

One of the most concerned problems in the engineering design was internal vibration of hydraulic powerhouse, which was very complicated. The hydraulic powerhouse has many vibration sources, involving three aspects such as mechanical, electrical and hydraulic. The mechanisms of many vibration sources were still not clear enough, and the vibration of all parts of the hydropower plant which were caused by many vibration sources is mutual coupling. With the increase of the hydraulic power design head, output and other indicators, the strength and durability issue of hydraulic power plants structure under internal vibration load have caused engineering attention. Especially, for the underground powerhouse, the cross-holes, complex structure and complex boundary condition. The problem of hydraulic vibration of the machine and powerhouse has been caused attention. Research on the dynamic response of underground powerhouse under the action of hydraulic vibration source has great significance to ensure the safety of structure. Because the research can predict and optimization design in order to prevent and control the occurrence of severe vibration. In this paper, Xi Luodu hydropower station that is under construction with the biggest installed capacity in China was taken as an example. On the basis of the analysis of natural vibration characteristics and resonance review, the dynamic analysis in time domain for the underground powerhouse excited by pressure fluctuation is performed, including the dynamic responses of displacement, velocity, acceleration and stresses. Based on the vibration criterion of the powerhouse structure, the vibration evaluation was made.Finite element model includes a range of rock. The result of the resonance review and power factor review shows that the structural design of Xi Luodu hydropower station underground powerhouse is reasonable in general. In the absence of other unforeseen special vibration source appears, the significant resonance will not occur. In addition, viscous-spring boundary theory is introduced that the concentrated springs is imposed to consider the elastic support of the rock and the concentrated viscous dampers is applied to simulate to absorb the scattered waves in the boundary surrounding rock which is cut. Based on model test data and resonance review, typical load cases were chosen to perform dynamic analysis in time domain for the underground powerhouse excited by pressure fluctuation. Results show that amplitudes of dynamic displacement, velocity, acceleration and stress meet the corresponding suggested permissible value. The strength and the security of the structure is not impacted.