摘要
基于间接边界元法计算沉积河谷对平面P波和SV波的二维散射,着重考察沉积介质波速比和材料阻尼比的随机性对河谷地震动放大效应的影响.利用蒙特卡罗方法随机模拟产生了波速比样本和阻尼样本各30组,给出了不同入射角度和频率的P波和SV波入射下河谷随机响应的单频和频谱结果.算例分析结果表明:(1)地表位移响应幅值的变异系数极值均显著大于波速比变异系数,且波速比的随机性对地表位移的影响在体系共振频率处最为显著,地表位移的标准差最大可达7.168;低频情况下,沉积中部地震动反应的变异性更显著,高频情况下则在沉积河谷边缘变异性最大;(2)入射角对地表位移响应变异系数极值的影响不大,但对变异系数空间变化的影响显著;(3)阻尼比随机性对地表位移的影响在低频情况下较小,在高频情况下则较明显,尤其是在沉积河谷的体系自振频率处,其影响最为显著.
The actual geotechnical property parameters have obvious randomness.The two-dimensional scattering of the P and SV waves in the sedimentary valleys is studied based on the indirect boundary element method（IBEM）in order to explore the effect of the randomness of the medium velocity and material damping on seismic ground amplification effect of the valley.The Monte Carlo method is used to simulate 30 groups of wave velocity ratio samples and 30 groups of damping ratio samples.Finally the present paper gives the single frequency and spectral results of random response of the valley under P wave and SV wave incidence with different incident angles and frequencies.The results show that the variation coefficient extremum of surface displacement response amplitude is significantly larger than the variation coefficient of velocity ratio,and the effect of velocity ratio randomness on surface displacement is the most significant at system resonance frequency,and the maximum standard deviation of surface displacement can reach 7.168.The variation of the ground motion response in the sedimentary center is more significant at low frequency,but it is the largest at the edge of the sedimentary valley at high frequency.On the other hand,the incident angle has little effect on the variation coefficient extremum of surface displacement response amplitude,but it has a significant effect on the spatial variation of the variation coefficient.Meanwhile,the damping randomness has little effect on the surface displacement at low frequencies,but the effect is obvious at high frequencies,especially at the natural vibration frequency of the sedimentary valley,the effect is most significant.
出处
《地震学报》
CSCD
北大核心
2017年第5期764-777,共14页
Acta Seismologica Sinica
基金
国家自然科学基金(51678390)
天津市应用基础与前沿研究计划重点项目(16JCZDJC38900
15JCZDJC39900)共同资助
关键词
河谷放大效应
地震动
间接边界元法
波速比随机性
阻尼比随机性
蒙特卡洛方法
valley amplification effect
seismic ground motion
indirect boundary element method
wave velocity ratio randomness
damping ratio randomhess
Monte Carlo method
