摘要
本文首先回顾了用烈度资料估计地震动参数衰减关系的现有方法,分析了其中存在的问题,进而提出地震烈度与地震动参数的更合理的转换模型。地震动衰减模型中采用了与震源体大小相关的近场距离饱和因子,使换算模型能体现与近场高烈度相应的地震动峰值的饱和特性。确定衰减关系时除了考虑地震动或烈度的不确定性之外,还包含了震级M和距离R的不确定性,烈度衰减关系的确定考虑了场地原始烈度点与等震线的差别,使参与换算的地震动和烈度均取自于同一地点。文中还对转换所得地震动衰减关系的方差进行了合理估计,换算结果的不确定性综合了参考地区用原始资料进行烈度与地震动换算的离散性和参考地区与研究地区烈度衰减规律不确定性的差异,使之与当前人们对地震动不确定性的认识水平相协调。新模型不受烈度和地震动参数衰减规律形式的限制。用新方法确定了华北、华南、西南、西北等四区的地震动幅值的衰减规律,并与华北、西南两区取得的少量强震记录进行了比较,结果甚为吻合。
In the present paper,the currently ased methods of estimating ground motion parameters from earthquake intensity data are reviewed first and the fallacies involved are investigated at the same time. Then a more proper conversion method from intensity data to ground motion parameters is proposed. The new conversion model shows the saturation character of peak ground motion corresponding to the high intensity near source by accounting tor the magnitude dependent saturation factor of distance R0(M) and the nonlinear term of magnitude in the ground motion attenuation model. The randomness or uncertainties of not only ground motion and intensity but also magnitude and distance are all involved in the procedure of attenuaion determination. The difference between original site intensity and isoseismal is considered in the intensity attenuation law, which makes the ground motion and intensity used for conversion coming from the same site, while in the routine methods,the isoseismal is used for conversion of ground motion but the meanings of two parameters are different; and the result thus obtained must be the out contour of ground motion distribution which is not consistent with seismic hazard analysis. The deviation expressing the uncertainties in the converted ground motion attenuation is also estimated more reasonably in the suggested method. Furthermore, the proposed conversion model is not confined by the forms of both intensity and ground motion attenuation relations,which makes the model more flexible in practice. Finally the attenuation laws of PGA,PGV,PGD ane obtained for North, South, Southwest, and Northwest China.
出处
《地震工程与工程振动》
CSCD
北大核心
1992年第3期1-15,共15页
Earthquake Engineering and Engineering Dynamics
基金
地震科学联合基金
