Effect of Seismic Wave Input Interface on Ground Motion Parameters of Deep Site

On the basis of the deep borehole profile near Yangtze River in Wuhan City, eight interfaces of soil layers, whose shear wave velocities range from 414 to 912 m.s(-1), are selected as the seismic wave input interfaces. Effects of input interface on ground motion parameters are analyzed with one-dimension equivalent linear method by choosing Taft, Lushan and Kobe strong motion records as seismic input. The results of seismic soil-response show that: (1) Peak ground acceleration(PGA) increases with the growth of depth and shear wave velocity of the input layer, but rising rate gradually decreases. (2) Ground motion characteristic period of response spectrum(Tg) changes little as depth or shear wave velocity of the input layer increases. (3) Curves of surface acceleration response spectra gradually rise with the increase of input depth, but rising magnitude slows down. High-frequency components of response spectra weaken while low-frequency ones enrich if the intensities of input seismic motion enhance. (4) For buildings with moderate-long natural vibration periods on deep sites, soil layers with shear wave velocity not less than 600m.s(-1)can be chosen as input seismic interface.