摘要
基于二维有限单元法使用接触单元模拟断裂带的非连续破裂过程,建立2017-08-08四川九寨沟M7.0地震近场强地面运动估计模型,并对应力降和屈服应力等关键震源参数进行研究。在利用国家强震数据中心提供的实际观测波形开展地震动参数信度检验基础上,给出地震动峰值加速度(PGA)分布,探讨近场强地面运动方向效应特征及其成因机理。结果表明:1)随着震源接触单元屈服应力及应力降参数的增大,水平向PGA整体增大,前者对于强地面运动的影响更为显著;应力降为8.5 MPa、屈服应力为4.0 MPa时,强地面运动模拟结果的相对误差百分比整体小于40%,51JZB等近场强震台相对误差均小于5%。2)九寨沟M7.0地震水平向PGA模拟结果等值线整体呈椭圆状,椭圆长轴与发震断层树正断裂走向具有较好的一致性;震中附近PGA最大值约为720 Gal,且整体随震中距的增大不断衰减;跨龙日坝断裂北段及跨雪山梁子断裂PGA分别突降16.67%及22.72%,这种断裂带的隔震效应或与地震动沿断层面的透射降低有关。
Based on the two-dimensional finite element method,we use the contact element to simulate the discontinuous fracture process of fault zone,and establish the near-field strong ground motion estimation model of the Jiuzhaigou M7.0 earthquake in Sichuan on August 8,2017.We also study the key source parameters such as stress drop and yield stress.Based on the reliability test of ground motion parameters using the actual observation waveforms provided by the national strong earthquake data center,we give the PGA distribution,and discuss the characteristics and mechanism of directional effect of near-field strong ground motion.The results show that:1)With the increase of yield stress and stress drop parameters of the source contact element,the horizontal PGA increases as a whole,and the influence of the former on strong ground motion is more significant.When the stress drop is 8.5 MPa and the yield stress is 4.0 MPa,the relative error percentage of strong ground motion simulation results is less than 40%on the whole,and the relative error of 51JZB and other near-field strong seismic stations is less than 5%.2)The contour of horizontal PGA simulation results of the Jiuzhaigou M7.0 earthquake is generally elliptical,and the major axis of the ellipse is in good agreement with the strike of seismogenic fault.The maximum value of PGA near the epicenter is about 720 Gal,and decreases with the increase of epicenter distance.The PGA dropped by 16.67%and 22.72%respectively when cross the north section of Longriba fault and Xueshanliangzi fault.The isolation effect of fault zone may be related to the transmission reduction of ground motion along the fault plane.
作者
张严方
胡其志
张洁
游姗
ZHANG Yanfang;HU Qizhi;ZHANG Jie;YOU Shan(Urban Construction College,Wuchang Institute of Technology,110 Baishazhou Road,Wuhan 430065,China;School of Civil,Architecture and Environment,Hubei University of Technology,28 Nanli Road,Wuhan 430068,China)
出处
《大地测量与地球动力学》
CSCD
北大核心
2023年第11期1136-1142,共7页
Journal of Geodesy and Geodynamics
基金
湖北省教育厅科研项目(B2022359)~~。
关键词
二维有限元
强地面运动
九寨沟地震
方向效应
地震动参数
two-dimensional finite element
strong ground motion
Jiuzhaigou earthquake
directional effect
ground motion parameters
