西南地区地震动特性和参考模型研究

A study on the ground-motion characteristics and reference models for the Southwestern China

地震动模型用于计算给定震级、距离和场地条件下的地面加速度、速度和反应谱等地震动参数,是地震工程的重要组成部分。目前我国大部分高质量强震记录来自西南地区,但这部分记录数量偏少且关于地震动参数的分布较差,难以直接建立地震动模型,在重大工程项目设计和地震风险评估中,对只建立于国内地震记录的衰减关系仍需要谨慎评价。文章分别选择了美国、日本等基于数量丰富、分布良好的强震记录建立的5个水平向和5个竖向地震动模型,对比分析了其与我国西南地区强震记录数据。结果表明:基于日本浅壳和上地幔记录建立的地震动模型是我国西南地区的最佳模型,同时根据该地区的数据进行修改,建立了适用于该地区的地震动模型的最佳参考模型。

Ground-motion prediction equations(GMPEs)are used to calculate the response spectrum for a scenario earthquake with known magnitude,source distance,and site condition.The prediction variable can be acceleration,velocity,and displacement spectra.GMPEs are extensively important part of earthquake engineering.Up to now,most strong-motion records in China are from the southwestern region.The number of records is still relatively small and the distributions of records with respect to many ground-motion parameters may be too poor to build a reliable GMPE.The existing GMPEs based on this dataset only would require scrutiny for engineering applications.This study compares the datasets obtained in the southwestern part of China with five GMPEs for the horizontal component and five GMPEs for the vertical component,which are from America,Japan and some other countries,based on large datasets.The results show that the GMPEs based on shallow crustal and upper mantle records from Japan appear to be the best model to be used in the Southwestern China without modification and also appear to be the best reference model that can be modified by the local dataset to build a new model for this region.