In order to study the seismic dynamic response law of high arch dams,based on the measured seismic waveform of Dagangshan arch dam with a height of 210 m and a distance of 21 km from the epicenter in the Sichuan Luding Ms 6.8 earthquake,the seismic response characteristics and laws are analyzed by time domain and spectrum analysis methods.The results show that under the main shock excitation of the Luding earthquake,the peak acceleration(PGA)of the arch dam along the river is 586.63 cm/s2(#6 dam crest),and the PGA of the bedrock along the river is 229.18 cm/s2.The acceleration distribution is generally greater than the horizontal and vertical directions,and the dam body is greater than the resistance body on both sides.The dynamic response of the dam is the most significant along the river.As the elevation increases,the dynamic amplification effect gradually increases,and the maximum amplification factor reaches 4.2 times(#6 dam crest).The results of spectrum analysis show that the main frequency of the earthquake is about 1.73 Hz,and the main frequency of the dam above 1 081 m is between 1.52 and 1.75 Hz,which is close to the modal frequency of the dam.This is one of the reasons why the dam has a strong sense of earthquake.Combined with the dynamic response analysis of typical earthquake dams in recent years,earthquakes with large magnitude and far epicenter distance are more likely to stimulate the low-frequency dynamic characteristics of dams.The relevant results can provide reference for post-earthquake dam safety assessment,seismic design and research of high arch dams.
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