震源参数对合成时程持时的影响分析

Influence of Source Parameters on the Duration of Simulated Ground Motion

采用随机有限断层法进行了汶川地震加速度时程的合成,对合成时程持时进行了影响参数的敏感性分析,探讨了震源参数及传播路径参数的取值对合成时程持时的影响。结果表明:持时总体上随震级的增大而增大;相对于总体上与应力降成正相关的绝对Bolt持时,相对Bolt持时随应力降的增大而减小;当kappa值增加时,相对持时呈增大的趋势而绝对持时则随之减小;η的取值会影响持时随品质因子Q0的变化趋势,且η不同时,Q0对持时的影响规律可能会完全相反;断层的倾角和上界埋深对持时的影响很小,且规律性不强。将随机有限断层法应用到合成时程的持时特征分析和工程应用中,相较于断层的倾角和上界埋深,更应重点关注震级、应力降、kappa值和品质因子对持时的影响,以模拟出更为合适的地震动。

This paper used the stochastic finite-fault method to simulate the ground motions of Wenchuan earthquake.The sensitivity of influential parameters of the duration of simulated ground motion was analyzed,and then the effects of source parameters and propagation path parameters on the duration of simulated ground motion were discussed.The results show that the duration increases with the increase of magnitude.Compared with the absolute Bolt duration which is positively related to the stress drop,the relative Bolt duration decreases with the increase of stress drop.When the kappavalue increases,the relative duration increases,while the absolute duration decreases.The change trend of duration with the quality factor Q0is affected by theηvalue,and when theηvalue changes,Q0may have a completely opposite effect on the duration.The fault dip and the depth of the top of fault have little influence on the duration,and there is no monotonic relationship.When the stochastic finite-fault method is applied to the research on the characteristics and engineering application of the duration of simulated ground motion,compared with the fault dip and the depth of fault top,more attentions should be paid to the magnitude,stress drop,kappa value and quality factor,so as to simulate more suitable ground motion and get more rational duration.