中国黄土地区基岩地震动经验衰减关系

EXPERIMENTAL ATTENUATION RELATIONSHIP OF GROUND MOTION ON BASEMENT ROCK IN CHINESE LOESS REGION

摘要:

本文收集我国黄土地区历史地震烈度衰减场的资料,以衰减公式Lny=a+bM-clnR-dR为基础,对比美国西部资料,用烈度距离法统计了中国黄土地区分频率的十二个衰减关系。本文的改进尝试是:(1)在历史地震烈度衰减场的娩计中,区分了黄土区和基岩区,並把黄土区的地震动参数以0.6向基岩区折减;(2)对于断层两边不对称的等震线,如果是由于沉积深度不等引起的,出于安全计,取衰减慢的,即等震线半短轴长的一边;(3)在不确定性分析中,鉴于上述衰减公式中,LnR和R相关性极好,没有采取一般表示各参数相互独立的方差分析,而是利用1976年8-9月松潘地震时文县台的五次强震记录作为样板,再进行分析。最后把本文的结果同前人的工作以及实际记录作了对比。

Abstract:

Collecting intensity attenuation information of historical earthquakes and using Lny=a+bm-clnR-dR formula and ground motion attenuation in west part of U.S.A, authors got 20 experi mental attenuation relationships of different frequency by Hu Yuxian's method. Reforming in this paper:(1) Authors talk different from intensity on basement rock and loess region. The ground motion in basement rock is greater 0.6 time than in loess region. The coefficient 0.6 is from site response calculation of Xian and Baojl microzoning. (2) In unsymmetrial isoseismic on fault authors used longer side of short axis for safety. (3) Because of LnR and R is dependence, authors used 5 records of strong motion of Songpan earthquake in Aug.-Sept., 1976 for uncertainty assessment and didn't use formula of error of square.