【摘要】 通过阐述地震安全性评价工作中地震动衰减关系的演变介绍了衰减关系的三种类型,其差别在于是否含有高频地震动震级饱和因子C3M2项和加速度近场饱和因子C5eC6M项;分析了这两个因子的由来和作用,并举实例说明,当场地所处的地震环境受高频地震动影响较小时,可忽略C3M2项的影响;而加速度近场饱和因子因包含了震源体尺度的影响,并与实际观测记录相符,是衰减关系必须包含的内容。更多还原

【Abstract】 Through the description of the evolution of attenuation relation,three types of attenuation relations are introduced(typeⅠ,typeⅡ,typeⅢ),with the differences among them including whether they contain the high-frequency ground motion magnitude saturation factor C3M2(a non-linear attenuation factor of magnitude M)and the acceleration near-field saturation factor C5eC6M(a distance factor).The origins and functions of two such factors are analyzed in this study.The ground motion increases with the increasing of M,but the amplitude of it rapidly decreases with the increasing of M.C5eC6 Mplays a role in the seismic source body’s range scale,in which the ground motion varies not along with the distances’ change in the epicentral area.The combined effects of C3M2 and C5eC6 Mstrongly inhibit the false information that the near-field ground motion is too large in the case of high-magnitude,so as to reach a level consistent with the actual situation.The acceleration near-field saturation factor C5 eC6 Mis the content that the attenuation relation must contain,because it contains the influences of the seismic source size and correlates with the actual observation data. In the seismic safety evaluation,C3M2item can be chosen according to the local seismic environment.Examples are presented to explain that the influences of C3M2 can be neglected and the attenuation relation without C3M2 can be selected during the seismic safety evaluation when the local seismic environment suffers from fewer influences due to the high-frequency ground motion; if the local environment has more influences,an attenuation relation with C3M2 should be selected.This essay chooses of a set of typeⅡand then a set of typeⅢto make a comparative analysis of the attenuation relation.In general,type ⅡI decays faster than type Ⅱ.As the distance increases,the peak accelerations with the use of typeⅢare smaller than that with the use of typeⅡ.In addition,type ⅡI matches well with the actual records in the case of high-magnitude and short distance earthquakes,because it contains C3M2.Therefore,in the evaluation of seismic safety, from a conservative perspective,the attenuation relation of typeⅢshould be used to evaluate the impact of potential seismic source zone at a short distance,and the attenuation relation of type Ⅱ should be used to evaluate the impact of the potential seismic source zone at a long distance.This study uses the engineering sites of Kunming and Guiyang and the aforementioned typeⅡand type Ⅲattenuation relations to make calculations of a probabilistic seismic hazard analysis,with results that are consistent with the conclusions of the above analysis.更多还原