中文摘要：

作为断层破碎带对地震动的影响研究的第二部分，采用有限元方法研究了断层破碎带对地震动的非线性放大作用，分析了非线性放大作用和线性放大作用之间的差别，以及断层破碎带宽度、刚度、倾角以及输入地震波幅值和频谱等因素对非线性放大作用的影响。研究表明，断层破碎带对地震动有显著的非线性放大作用，在水平地震作用激励下，破碎带对地震动的非线性放大作用具有如下特征：非线性情况竖向加速度最大峰值可以达到水平加速度最大峰值，非线性情况水平向加速度最大峰值完全可以大于线性情况，且非线性情况竖向加速度最大峰值可以显著大于线性情况。破碎带宽度、刚度及倾角对地震动的非线性放大作用有很大影响，其规律与线性情况基本一致；而与线性情况不同的是，破碎带宽度、刚度和倾角对竖向地震响应的影响显著大于线性情况。地震激励频谱对地震动的非线性放大作用也有很大影响：非线性情况下场地卓越周期明显加长，可能会造成非线性情况下地震响应反而比线性情况下地震响应大的现象。

英文摘要：

As a continuous study, this paper investigates the nonlinear amplification of ground motion around fault fracture zone using finite element method, and discusses the difference between the nonlinear and linear amplifica- tions, and the effect of the width, stiffness and inclined angle of fault fracture zone and the spectrum of incident seismic waves on the nonliriear amplification of seismic ground motion. It is shown that fault fracture zone has sig- nificant nonlinear amplification on seismic ground motions and the amplification under horizontal seismic excitation has following characteristics. The maximal peak of vertical acceleration in nonlinear case may reach that of horizon- tal acceleration; the maximal peak of horizontal acceleration in nonlinear case may be larger than that in linear case ; the maximal peak of vertical acceleration in nonlinear case may be much larger than that in linear case. The width, the stiffness and the inclined angle of fault fracture zone have significant nonlinear amplification on seismic ground motions, and their characteristics are roughly in accordance to those in linear case. The difference is that the effects of the width, the stiffness and the inclined angle of fault fracture zone on vertical seismic response are much larger than those in linear case. The spectrum of seismic excitation also has significant influence on the non- linear amplification, and due to the longer predominant period of the site, nonlinear seismic response may be larger than that in linear case.