非发震断层场地地震动力响应特性研究

Study on earthquake dynamic response of non-causative faults site

建立了 12 个理想化断层场地模型,采用粘弹性人工边界及相应的波动输入方法,用二维动力有限元分析了非发震断层场地的动力响应。结果表明,断层对场地的地震动有明显的影响,距断层越近的场地震动的放大系数越大。对于垂直断层,场地的振幅放大效应对称分布,而倾斜断层对其上盘地震动的影响要大于下盘场地地震动的影响。断层破碎带厚度变化对场地的地震动影响不大,而断层的深度变化对场地地震动的影响作用明显。断层破碎带边界处发生了强烈的波型转换,而中间位置波型转换较小。

Twelve ideal fault site models are established by considering factors, such as fault dip, depth of fault trace, thickness of fault fracture zone. The viscoelasticity artificial boundary is used in models to prevent the reflection of travel-out wave. After inputting the artificial seismic wave, the faults' effect on sites earthquake response is analyzed by 2-dimensional dynamic finite-element method and the displacement in time domain of sites is given. It is found that faults have influence on the dynamic response of site which can't ignored, and the closer to fault, the more remarkable the amplification effect of earthquake motion is. To vertical fault, the amplification effect of site is symmetrical distribution. To inclined fault, the amplification effect of hanging plate site is more remarkable than lying plate site's. Increasing the depth of fault will cause the greater changes in earthquake motion of site, but the increasing in thickness of fault will cause very slight changes in earthquake motion of site. Furthermore, the research results indicate that, at the boundary of fault fracture zone, the wave mode changes greatly, but at middle place of fault fracture zone, the wave mode change is slight.