Seismic Response Analysis Of Gravity Dams Based On Dynamic Testing Data

The number and scale of water conservancy projects in China are among the highest in the world.As a common structural form,the gravity dam is widely distributed throughout China and is numerous in quantity.However,China is also a country with frequent earthquakes.Once a gravity dam encounters an earthquake and causes dam break,it will cause great harm to people's lives and property in the downstream areas.Therefore,the study on the sesmic resistance of gravity dams is of great significance.Taking the gravity dam of Lechangxia water conservancy project in Guangdong Province as the research background,this paper corrects the dam's dynamic finite element model,compares and analyzes the non-massive foundation model and the viscoelastic artificial boundary to the dam earthquake.Based on the response,the dynamic response of the dam and the effect of the state of the transverse joint on the seismic response of the structure are analyzed.The main contents are as follows:(1)Based on the structural characteristics of gravity dams,a detailed test scheme for dynamic characteristics was developed.The dam was tested under two different water levels,the natural frequencies of three dam sections were obtained using random subspace method and enhanced frequency domain decomposition method based on the response data.(2)The impact of the state of the transverse joint on the stiffness of the dam is simulated using spring elements on both sides of the dam.The stiffness coefficient of the spring is modeled using a measured frequency value to invert the model,and the material parameters of the dam are modified.The revised model is The vibration frequency is close to the measured value,which proves that the modified model is more reliable.(3)Select a dam section,use the visco-elastic artificial boundary and the non-massive ground model to analyze the seismic response,and compare the displacement and stress extremes of the key points under the two boundary conditions.The calculation results show that the viscoelastic artificial boundary considers radiation damping of the infinite foundation,the seismic response is relatively small,and the calculation results of the non-massive foundation model are conservative.(4)Taking three characteristic dam segments as the research object,the influence of the water level and the connection status of the transverse joints on the seismic response of the gravity dam is analyzed,from the perspective of stress response and displacement response.The results show that due to the influence of the hydrodynamic pressure,the seismic response of the dam will increase as the water level rises.a complete disconnection of the transverse joint will weaken the stiffness of the dam and increase the seismic response of the dam.Therefore,in the earthquake-resistance calculation of gravity dams,the unfavorable seismic factors caused by high water level and the complete disconnection of transverse joints cannot be ignored.