强地面运动中后继波特征的数值模拟  

Simulations for property of late arrival wave on strong ground motion

作　　者：赵志新[1] 徐纪人[1] 

机构地区：[1]中国地质科学院地质研究所

出　　处：《地球物理学进展》2016年第5期2056-2062,共7页Progress in Geophysics

基　　金：国家自然科学基金(41374052)资助

摘　　要：本文用错格实数似谱法数值模拟分析了在盆地中地震波传播时空变化,及后继地震波的视速度及频率等动力学特征的的空间变化.结果表明来自岩层的波动折射入盆地后,可形成次生面波及多重反射波.地震波能量容易由高速度岩层介质传入低速的沉积土层中,相辅地,地震波能量却极难由低速的沉积土层传入高速度岩层介质中.这对地震勘探研究是有意义的见解.多重反射波在盆地中多次上下震荡,对地面建筑物造成连续多次破坏.不同波之间的干涉及盆地底部拐角的聚焦作用都可能增幅地面运动.峰值地面运动远离震中,这意味着非均匀地质构造对地面运动的影响有时大于距离的影响.视速度可能随多重反射次数的增加而变小,也随盆地底部形状而变化.多重反射波的后继震相可能发生频散.多震相的不同频率的峰值地面运动可能对地面建筑物造成延时性多次破坏.不同频率的后继转换波拓宽了入射地震波的频带,可能对具有相应不同固有周期的建筑物造成严重的破坏.反射波的频率变化特征对于地震勘探中识别和消除多次反射干扰也具有重要意义.Simulations for seismic wave propagation and late arrival dynamic property in the sedimentary basin were performed in this analysis. The results indicated that the basin shape and late arrivals in heterogeneous structures deeply affected the wave amplitude distributions, the wave kinematic and dynamic characteristics on strong ground motion. The refraction wave from the rock brought the muhireflection wave and the secondary surface wave in the basin. The waves oscillating up-down within the basin shook the buildings time after time, resulting in heavy damage. The late-arrival waves also resulted in the peak ground motion. The geometrical focusing by basin corners and the physical interference between waves significantly amplified the ground motions. The location of peak ground motion due to the interference was attributable to the apparent velocity difference between the secondary surface wave and the body wave. The multi-reflection wave might result in frequency dispersion. The late-arrival conversion waves with various frequencies widened the frequency band of waves shaking buildings and could seriously damage buildings with corresponding intrinsic frequencies.

关 键 词：后继波形 视速度 频散 峰值地面运动 

分 类 号：P631[天文地球—地质矿产勘探]