Static And Dynamic Analysis Of Large Scale Hydropower House And Spiral Case Structure

With the shortage of the power resource day by day, and the strategy of Western Development and Power Transmission from West to East implemented, a great deal of huge hydroelectric projects have been constructed. Safety and stability of the hydro-power house, an important part of the hydroelectric project, has been paid more attention to. Static and dynamic nonlinear characteristic and fluid-structure interaction characteristic of the hydro-power house were studied through theory analysis and numerical simulation in this paper. The relevant calculation theory, methods and conclusions could provide technical support and reference for similar problems. The paper includes the following sections:Firstly, base on the current research, the nonlinear numerical model of directly embedded steel spiral case was made considering the elastic contact behavior occurring between the steel liner and the surrounding concrete, and the tension softening and damage characteristic of the concrete. The stress state of the spiral case was analyzed under the static loads such as internal water pressure. The flexibility of the stay rings was checked on the basis of plastic damage model of the concrete, which was compared with that of the linear elastic model. Through the resultant comparison of different FEM models, the existing influence of the super-& sub-structures of the spiral case was studied according to damage evolution of the surrounding concrete, steel liner stresses and flexibility of the stay rings. Furthermore, the stress state of the overall hydro-power house was studied through the numerical simulation under the repeated loading of internal water pressure.Secondly, the dynamic response of the hydro-power house under the pulsation water pressure load was studied including the fatigue characteristic of the steel liner, and the stress state and damage evolution of the surrounding concrete, after the static damage of the surrounding concrete of the spiral case appeared. The dynamic safety of the power house was evaluated according to the above analysis and the relevant rules. What's more, the influence upon the dynamic characteristic of the whole power house caused by damage or crack of the surrounding concrete of the spiral case under different degree was analyzed by the comparison of the linear elastic model, the model considering concrete damage or crack under once or repeated internal water pressure loading and so on.Thirdly, the ground motion input method was verified, which uses the infinite elements as dynamic artificial boundary, and the range sensitivity of the finite discrete region was analyzed. So the hydropower house infinite foundation was simulated by the coupling model of the finite and infinite element (FE-IE). After the static nonlinear analysis, the resultant data of the whole power house was obtained under the design ground motion by dynamic nonlinear simulating. The damage evolutions, dynamic stresses, vibration amplitudes, velocity and acceleration of the surrounding concrete of the spiral case were studied. Furthermore the response of the power house was analyzed under the seismic overloading conditions and compared with that of the design seismic loads conditions. The concrete damage and steel liner stresses were evaluated.Fourthly, different numerical models of the powerhouse, partial and overall models, were established, and the natural vibration characteristic was analyzed taking the damage or crack of the surrounding concrete of the spiral case into consideration. Following, a reasonable model was selected to check the resonance probability, and finally the security of the powerhouse was evaluated.In the last section, the potential-based fluid elements in ADINA software were used to simulated the fluid in the flow passage of the hydropower house. The natural vibration characteristic and seismic response are calculated by using FEM. The results were compared with those obtained by the model without the fluid, and the effect of the fluid in flow passage on the structure dynamic characteristic is analyzed.