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A study of local amplification effect of soil layers on ground motion in the Kathmandu Valley using microtremor analysis

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Earthquake Engineering and Engineering Vibration 2012年第2期11卷 257-268页

作者： Paudyal Y.R. Yatabe R. Bhandary N.P. Dahal R.K. Geo-disaster Research Laboratory Graduate School of Science and EngineeringEhime UniversityEhimeMatsuyamaJapan

Past researchers have anticipated the occurrence of a great earthquake in the central Himalayas in the near *** may cause serious damage in the Kathmandu Valley,which sits on an ancient lake bed zone,with lacustrine sediments of more than 500 m *** this study,the predominant frequency of ground motion is evaluated using the Horizontal-to-Vertical (H/V) spectral ratio technique and recordings of ambient *** results of the H/V ratio show two peaks in about 20 percent of the locations,which are distributed mainly in and around the center and northern part of the Kathmandu *** predominant frequencies vary from 0.5 Hz to 8.9 Hz in the study area,whereas the second resonance fiequency varies from 4 Hz to 6 Hz in the center and northern part of the *** indicates that the center and northern part of the valley have a wide range of resonance frequency due to two levels of impedance contrast- one may be from the surface layer and the other may be from the layer *** two levels of resonance indicate the importance of considering the effects of surface and lower layers during the planning and designing of infrastructures in the Kathmandu Valley.

关键词： microtremor predominant frequency resonance Kathmandu Valley

Microtremor-based analysis of the dynamic response characteristics of earth-fissured sites in the Datong basin, China

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 567-582页

作者： Xuan You Deng Yahong He Jia Chang Jiang Yan Zuofei Wu Wei Department of Geological Engineering Chang′an UniversityXi′an 710064China Key Laboratory of Mine Geological Hazards Mechanism and Control Xi’an 710064China

This study conducted microtremor testing along six survey lines that cross three typical earth fissures in the Datong basin to determine the dynamic response characteristics of earth fissure sites with regard to the Fourier amplitude spectrum,response spectrum,and Arias *** results show the following.(1)The predominant frequency of an earth fissure site is mainly affected by the thickness and the shear wave velocity of the soil layer and is minimally effected by the presence of an earth fissure.(2)Earth fissures have a pronounced amplification effect on dynamic *** amplitude,response acceleration,and Arias intensity are high near an earth fissure and decrease with an increase in distance from the earth fissure,tending toward stability at a distance of 20 m.(3)The area that is seriously affected by this amplification is within 6-8 m of an earth fissure,and the general affected area is farther out than this,to a distance of 25 m.(4)New construction should be avoided in an area affected by the amplification,and existing buildings in general and seriously affected areas need to be reinforced to increase their seismic fortification intensity.

关键词： earth fissures microtremor testing predominant frequency amplification effect affected area mitigation measures

Estimation of damping ratio of soil sites using microtremor

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Earthquake Engineering and Engineering Vibration 2002年第1期1卷 45-49页

作者：郭迅黄玉龙袁一凡 Institute of Engineering Mechanics China Seismological BureauHarbin 150080China Professor Department of Civil and Structural Engineering The Hong Kong Polytechnic UniversityHong KongChina Associate Professor

It is widely known that the seismic response characteristics of a soil site depends heavily on several key dynamic properties of the soil stratum,such as predominant frequency and damping ratio.A widely used method for estimating the predominant frequency of a soil site by using microtremor records,proposed by Nakamura,is investigated to determine its effectiveness in estimating the damping *** authors conducted some microtremor measurements of soil sites in Hong Kong and found that Nakamura's method might also be used to estimate the damping ratio of a soil *** ratio data from several typical soil sites were obtained from both Nakamura's ratio curves using the half power point method and resonant column *** analysis indicates that there is a strong correlation between the damping ratios derived from these two different approaches.

关键词： microtremor predominant frequency damping ratio