In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring poin...In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements.展开更多
基金National Natural Science Foundation of China under Grant No.41772275the Fundamental Research Funds for the Central Universities under Grant No.CHD300102268203。
文摘In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements.
文摘基于2018年松原5.7级地震的强震动记录,结合在强震台站获取的地脉动数据,采用水平与竖向谱比(horizontal-to-vertical spectral ratio,HVSR)法和速度反应谱谱比(velocity response spectral ratio,VRSR)法,探究了强震台站场地的地震响应特征。结果表明:(1)地脉动水平与竖向谱比(horizontal-to-vertical spectral ratio of microtremors,MHVR)法、强震动水平与竖向谱比(horizontal-to-vertical spectral ratio of earthquake motions,EHVR)法以及VRSR都能较好地表征出场地地震响应峰值频段,达里巴、东三家子、风华以及宝甸等4个强震台站场地的(一阶)峰值频率范围分别为0.90~1.48 Hz,0.51~0.89 Hz,0.47~0.98 Hz,0.66~1.10 Hz;(2)同一场地条件下,MHVR,EHVR以及VRSR得出的场地放大系数差别较大,MHVR的放大系数最小,VRSR的放大系数整体较EHVR大,达里巴、东三家子、风华以及宝甸等4个强震台站场地与(一阶)峰值频率对应的放大系数范围分别为2.63~8.60,3.21~8.19,3.56~8.41以及4.14~7.96;(3)与MHVR相比,EHVR和VRSR都能较好地体现出地震动高频特征,且具有大致相同的变化趋势;(4)与EHVR相比,VRSR给出的低频信息更为丰富,但较为频繁的波动变化对峰值频率的快速识别具有一定程度的影响。该研究可为依托强震记录和地脉动数据开展场地地震响应分析提供参考,具有一定的工程应用价值。
