Study On Dynamic Characteristics Analysis And Cracking Mode Of Outlet Tower With Multiphase Coupling

Based on the regional characteristics and operation of Jingdianchuan Electric Power Irrigation Pumping Project,a three-phase coupling finite element model of water body-structure-foundation is established by numerical simulation and working mode identification.The dynamic characteristics and damage pattern of the multi-phase coupling structure of the pumping station’s water outlet tower are studied in this paper.The main research contents are as follows:(1)Considering the fluid-solid coupling effect and based on the elastic wave theory,the mass-free foundation model and viscoelastic boundary model of the pump station outlet tower structure are established to study whether the pump station outlet tower system has water body or not.According to the field measured data of the pump station outlet tower,the CEEMDAN-SVD method and variance contribution rate information fusion method are used to extract the natural working frequency of the pump station outlet tower,and the natural working frequency of the pump station outlet tower is extracted with the flow field data.The results of dry and wet modes of solid-solid coupling model are compared and analyzed to verify the rationality of the fluid-solid coupling model and the influence of fluid on the system of pump station outlet tower.(2)Considering the multi-phase coupling effect of water body-structure-foundation,the linear elastic seismic response analysis is carried out by using the ouelet towermodel with different foundation conditions.The seismic wave input of the mass-free foundation model and the viscoelastic boundary model is carried out respectively,and the corresponding dynamic response is compared and analyzed,and the influence law of the interaction of water body-structure-foundation coupling system is discussed.The results show that the working fundamental frequency of the pump station outlet tower is 3.3 Hz;the water body in the structure reduces the natural frequency of the pump station outlet tower and increases the seismic response of the pump station outlet tower,which should not be neglected in seismic calculation and analysis;the viscoelastic boundary model can consider the radiation damping effect in seismic calculation,and the position of the characteristic points of the pump station outlet tower is compared with that of the mass-free foundation model.The maximum displacement response decreases by 38.5% and the stress amplitude decreases by 37.8%.Therefore,the viscoelastic boundary is recommended for the foundation.The research results can provide theoretical guidance for the modal identification and seismic analysis of the outlet tower structure of subsequent pumping stations.(3)Using ABAQUS software with more powerful non-linear function,the seismic response of ouelet towerwas calculated under different seismic peak acceleration,and the damage and cracking law of ouelet towerwas obtained.The main damage locations of ouelet towerunder earthquake were the bottom bent-pier contact position and the middle ring beam-diaphragm contact position.With the increase of inertia force(peak acceleration is 0.4g),damage begins to occur in this part,and the damage develops upward along the bent.When the peak acceleration reaches 0.6g,the damage location range increases,and damage occurs in the two-storey bent and partition of tower structure,with damage reaching 0.970 and compression damage reaching 0.5068.