非基岩场地地震动转换的适用性分析

Applicability of transformation of ground motion records from non-rock site

基于NGA衰减关系中的场地修正模型,将剪切波速Vs30低于500 m/s的非基岩场地上的强震记录转换为Vs30=500 m/s的等效基岩记录,对等效基岩记录与基岩记录进行了统计一致性的分析,认为这种转换方法在能够保证等效基岩记录和基岩记录的统计一致性的同时,对于记录数量充足的地震能够有效减小地震动分布的离散,而对于记录数量较少的地震,如果有足够数量的等效基岩记录加入,能够改善其由于基岩记录数量不足或分布不合理所导致的不合理的地震动空间分布。这种方法对于以前限于基岩地震动数量不足或分布不合理而无法进行的研究工作,提供了一种增加可用地震动记录的可能。而对于这种方法的不足和今后需要完善的几个方面问题,也进行了初步的讨论。

By applying the site condition correction models of the next generation of attenuation(NGA) relationships,the equivalent rock site(Vs30 = 500 m) ground motion from ground motion records at non-rock site(Vs30 < 500 m/s) is calculated.The obtained equivalent rock site ground motions show consistency with the available true rock site records statistically.It concludes that this transformation method is applicable for calculating the equivalent rock site ground motion from non-rock site records.Furthermore,the obtained equivalent rock site ground motion data can reduce the non-coherency in the data from an earthquake event with abundant records,as well as improve the spatial data distribution in the data from an event with limited true rock site records.The equivalent rock site ground motion data obtained from the ground motion by this transformation method may help overcome the barriers in some researches due to limited data distribution.Finally,the limitations and some factors needing further investigation in this method are also discussed.