Study On The Response Of Concrete Gravity Dam Under Velocity Pulse Seismic Load

Earthquake is one of the most harmful natural disasters to human survival and safety.From a large number of seismic records,most of the economic losses occurred near the epicenter.In recent years,scholars at home and abroad began to pay attention to the characteristics of nearsite vibration and its influence on structure,but most of the research focused on high-rise buildings,bridges and so on.There is not much research on reservoir water-concrete gravity dam-infinite foundation system.Most of the large water conservancy projects that have been built or are under construction in China are located in earthquake-prone areas.Once a strong earthquake occurs,dam break will cause serious consequences.Therefore,it is of great importance to study the seismic response of reservoir water-concrete gravity dam-infinite foundation system.In this paper,based on the finite element coupling acoustic-structural(CAS)and impedance boundary condition,the seismic response of reservoir water-concrete gravity dam-infinite foundation system is studied.The main research work includes:(1)Factors influencing the hydrodynamic pressure of the reservoir water-dam system under seismic loadFirstly,the CAS method was used to calculate the hydrodynamic pressure,and the results were compared with those calculated by Westergaard method.The accuracy of CAS method was verified.On this basis,the effects of the compressibility of reservoir water,the gravity wave at the reservoir surface boundary,the truncation size of the reservoir water boundary and the absorption coefficient at the bottom of the reservoir on the hydrodynamic pressure are studied,and the calculation parameters in this paper are determined,which will lay a foundation for the subsequent calculation of the seismic response of the reservoir water-gravity dam-infinite foundation system.(2)Secondary development of parametric modeling for seismic response calculation of reservoir water-concrete gravity dam-infinite foundation systemCombined with ABAQUS software and Python language,the pre-processing and postprocessing modules of user interface for parametric modeling of reservoir water-gravity damfoundation system are developed.By modifying the parameters,the common characteristics of modeling,calculation process and post-processing display of calculation results are standardized.At the same time,the data of reservoir water concrete gravity dam infinite foundation,including node coordinates,displacement and stress,can be automatically extracted,which improves the work efficiency of pre-processing and post-processing.(3)Calculation of seismic response of dam-reservoir water-foundation system under velocity pulse seismic loadIn this paper,four groups of eight seismic waves from the Landers earthquake in the United States,the Kocaeli earthquake in Turkey and the Chi-Chi earthquake in Taiwan are selected for calculation.The results show that,without considering the effect of reservoir water,the average value of the maximum relative displacement of three different height dams under the action of velocity pulse seismic load is 1.4 times,1.4 times and 1.3 times of the average value of the maximum relative displacement under the action of without velocity pulse seismic load;the average value of the maximum tensile stress of three different height dams under the action of velocity pulse seismic load is 1.5 times,1.4 times and 1.3 times of that under the action of without velocity pulse seismic load.Considering the effect of reservoir water,the average value of the maximum relative displacement of three different height dams under the action of velocity pulse seismic load is 1.7 times,1.5 times and 1.6 times of the average value of the maximum relative displacement under the action of without velocity pulse seismic load;the average value of the maximum tensile stress of three different height dams under the action of velocity pulse seismic load is 1.5 times,1.5 times and 1.6 times of that under the action of without velocity pulse seismic load.In conclusion,the dynamic response under the action of velocity pulse seismic load is greater than that under the action without velocity pulse seismic load.Therefore,the velocity pulse effect of near site vibration in the design of gravity dam and seismic code cannot be ignored.