(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Second Highway Consultants Co.，Ltd.，China Communications Construction Co.，Wuhan，Hubei 430056，China)
Abstract：A new earthquake input method based on infinite element dynamic artificial boundary is proposed. In this new method，radiation damping of the strata and reflection，scattering of the seismic wave in the strata are both considered；and equivalent earthquake load formulae in different boundary surfaces for seismic waves vertically incident from the bottom of computational domain are deduced by using the wave field separation method. Meanwhile，a numerical example is given to verify the validity and accuracy of the method. The results show that the distortional disturbance appears in the result adopting fixed boundary，whereas the results using the method proposed tally with the results using analytical method well so as to prove the effectiveness of the presented method. At last，the new earthquake input method is applied to the three-dimensional aseismic analysis of Galongla tunnel，and some meaningful conclusions are drawn.
