Abstract:

Site effect on seismic peak ground acceleration is widely considered in such fields as seismic ground motion parameter zonation, earthquake early warning and quick assessment of seismic damage losses. Documents on seismic safety evaluation of engineering sites, including site type, overburden thickness, shear wave velocity, calculated seismic peak ground accelerations on both rock and soil surface for 2 630 engineering sites in Shandong Province have been collected in this paper. On the basis of these data, site amplification factor and site index for each site have been calculated. The site index is an integrated index to characterize the site condition and is computed from the shear wave velocity, density and thickness of the cover layers. Its values may change from 0 to 1. With the method of regression analysis, the relations among the site amplification factor, peak acceleration of bedrock and the site index are studied. A quantitative statistical relation between site amplification factor and other parameters is achieved. The site amplification factor in this paper is expressed as functions of peak acceleration of bedrock and site index, thus, its value may change continuously with the changing of the other parameters. The statistical relation for the site amplification factor in this paper is acquired on the basis of numerous, widely distributed data in Shandong Province, especially, site conditions can be represented in detail with site index. Therefore, the acquired statistical relation could characterize the changing scenarios of the site amplification factor with both the peak acceleration of the rock surface and the site condition details. The results show that the site amplification factor is negatively linearly related with the rock surface seismic peak ground acceleration and nonlinearly related with the site index.

Key words: seismic peak ground acceleration, site index, site effect, quantitative analysis, Shandong area

摘要：

地震动峰值加速度场地效应研究在地震区划、地震预警及震害快速评估等方面有着广泛的应用前景。收集整理了2004—2012年山东地区2 630个地震安全性评价工程的相关资料, 包括场地类型、覆盖层厚度、钻孔剪切波速、自由基岩和土层表面地震动峰值加速度计算结果。利用上述资料计算得到了每个工程场地的场地效应放大因子和场地指数;采用回归分析方法, 对场地效应放大因子与基岩峰值加速度、场地指数之间的关系进行了研究并得出了三者之间的定量统计表达式, 实现了场地效应放大因子的连续取值。结果表明, 场地效应放大因子与基岩峰值加速度之间为线性负相关, 与场地指数之间为非线性相关。

关键词: 地震峰值加速度, 场地指数, 场地效应, 定量关系, 山东地区