高烈度山区复杂场地环境地震响应研究

通过对艰险山区5类典型场地环境建立三维模型,采用ALGOR分析软件、Midas/FEA分析模块,对其进行地震作用下的时程分析,得到了山区5类典型场地环境地表位移、地震加速度以及频谱分布的地震响应。总结典型场地环境地震响应特点,提出如下有关设计建议:在选择桥位时尽量避开盆状沉积软弱土层和凹凸坡面场地环境;在峡谷上进行大跨度桥梁设计时,应提高大跨度桥梁的抗震设防水平,同时控制桥梁的基本频率,消除与坡面地震共振现象;重视倾斜岩面上覆土层、山前孤突山包、凹凸坡面场地环境中不同位置的地震加速度响应的差异。

Study on Seismic Response of Complex Site Environment in Mountain Area with High Seismic Intensity

In this paper,by establishing three-dimensional models base on five typical types of site environments in precipitous mountain area,and after carrying out time-history analysis under the action of earthquake by means of ALGOR software and Midas/FEA module,the seismic responses of five typical types of site environments in mountain area were acquired,including the displacements of earth surface,seismic accelerations and the distributions of frequency spectrum.Afterwards,by summarizing the characteristics of seismic responses,the authors proposed relevant design advices as below: firstly,the site of a bridge should not be located at basin-shaped sedimentary soft strata or at concave-convex hillside;and then when a long span bridge need to be built above a canyon,the seismic resistance level should be raised,and the fundamental frequency should be controlled so that the resonance effect between bridge and earth in seismic response can be avoided;finally,the seismic acceleration response differences in different positions of different site environments including the overburden layer on steep rock surface,the solitary mound in front of mountain and the concave-convex slope surface,should be taken seriously.