摘要
随机有限断层模型是模拟地震动加速度时程的一个重要工具。但将其应用于中强地震时,由于震源信息的准确性较差从而使模型参数具有较大的不确定性。尤其针对其中最为关键的应力降参数,目前相关研究较为缺乏且尚未形成系统的确定方法。本文基于美国Little Skull Mountain MW5.6级地震2个近场台站记录的地震动模拟,详细研究了采用随机有限断层法拟合中强地震地震动伪加速度反应谱(PSA)来确定应力降参数值的方法,并在计算应力降时引入了其它震源参数的不确定性,随后对此方法的可行性进行了验证。研究表明:采用不同频段反应谱残差和计算得到的应力降值差别较大,确定中强地震应力降较为合适的反应谱频段是中高频,采用该频段确定的应力降参数值模拟的反应谱和峰值加速度与实际记录较为符合;脉冲子断层百分比、断层长宽、倾角和深度等震源参数按截断的正态分布或均匀分布随机抽样,拟合得到的应力降参数值与通过实际震源模型参数得到的值相近。以上研究结果对确定一个区域中强地震应力降或中强地震近场强震动模拟研究提供了更进一步的研究方法和研究方向。
Stochastic finite-fault model is an important tool to simulate acceleration time histories.But when applying it to moderate earthquakes the parameters of model usually have large uncertainty due to the poor accuracy of source information.Especially for the stress drop which is one of the most critical parameters,there is a lack of related researches and determination methods.Based on the near-fault ground motion records of two stations in the Little Skull Mountain Mw5.6 earthquake U.S,we carry out a detailed study for the determination of stress drop and introduce the uncertainty of other hypocenter parameters,then verify the feasibility of this method.We found that our results show that the results will vary greatly when using response spectra residuals sum in different frequency ranges to determine the stress drop parameter.The appropriate range is medium-high frequencies which make the simulation results most consistent with actually recorded.When setting other source parameters （such as pulsing sub-fault percentage,fault length and width,dip and depth） to random values with truncated normal or uniform distributions,the value of stress drop obtained by fitting is similar to the value based on actual source model parameters.Our results can help further study of moderate earthquake stress drop for a region and the simulation of near-fault ground motion.
出处
《震灾防御技术》
CSCD
2014年第4期733-747,共15页
Technology for Earthquake Disaster Prevention
基金
大型先进压水堆核电站国家科技重大专项"CAP1400安全评审技术及独立验证试验(2011ZX06002-010)"
设计基准地震动参数确定方法及评价准则研究
