Effect Of A Lenticle On Ground Motion

The local site has great effect on the ground motion in earthquake, which is verified by earthquake disaster and theoretical research. The lenticle is one kind of local site in the valley near the sea, lake and river. Finite element method is applied to study the effect of a lenticle on ground motion in this paper, and the influence of different factors such as the width, thickness, depth, material stiffness and material nonlinearity of a lenticle have been analyzed in detail. This research is of great significance for structural earthquake resistance design.The difference between the total response and the free field is compared to study the influence of the a lenticle on the ground motion, and the parameter variations of the frequency spectrum of input seismic ground motion and the width, thickness, depth and material stiffness of the lenticle are considered in this paper. Furthermore, the effect of the lenticle is investigated in layered site. The differences of influence rules between the single layered site and multi-layered site is illustrated by typical numerical example,and the soil layer properties is studied emphatically. It is illustrated a lenticle can significantly affect the ground motion both in homogenous site and layered site, and the amplification effect is more obvious in layered site. The seismic response of nonlinear site involving a lenticle is calculated by an equivalent linear method considering the effects of the lenticle. This study is emphasized on the influence rule of the nonlinear properties of soil and the frequency spectrum of input seismic waves by comparing the seismic response between corresponding analyses models. Further more, the seismic response of nonlinear layered site is modeled and computed, to mainly study the influence rules of the properties of soil layer and the amplititude and frequency spectrum of input seismic waves. It is shown that the amplification effect is significant both in layered site and homogenous site. The nonlinearity behavior of site not only decreases the peak of seismic ground motion, but also prolongs the prominent period. The amplification effect is more significant in layered site, which is similar to the case of linear site.