渭河盆地中土层场地对地震动的放大作用   总被引：11，自引：1，他引：10       下载免费PDF全文

王海云 《地球物理学报》2011,54(1):137-150

土层场地对地震动的影响较大,建(构)筑物的选址及其抗震设防必须考虑土层场地的放大作用,以避免或减轻其震害.汶川地震中,布设在渭河盆地中的数字强震动台网共有27个台站(包括2个基岩台站和25个土层台站)获得良好的主震加速度时程.利用这些加速度时程,选择汤峪台做为参考场地,基于考虑几何衰减的传统谱比法分析研究了25个土层场...  相似文献   

Effect of soil depth on inelastic seismic response of structures     

《Soil Dynamics and Earthquake Engineering》2014

Effect of depth of soil stratum on estimated inelastic displacement of three typical structures, viz. a four storey building, a continuous bridge, and a tower, is studied and adequacy of the site amplification models of the current design codes and available empirical relationships is examined. The structures are assumed to be located on well-defined sites with varying bedrock depths, and effect of depth on elastic response spectrum, site amplification factor, displacement modification factor and inelastic displacement is studied, numerically, for two values of PGA. It is observed that soil depth has a significant effect on elastic as well as inelastic response of the structures; however, the effect of soil amplification on inelastic response is not as pronounced as in case of elastic response. Therefore, use of empirical site amplification models based on elastic response may be too conservative, for estimating inelastic response.  相似文献   

近断层竖向地震动P-Δ效应研究   总被引：1，自引：1，他引：0  

范优铭  夏群 《震灾防御技术》2017,12(1):177-184

竖向效应是近断层地震动的主要特点，竖向地震动对工程结构形成的P-Δ效应是造成结构破坏的主要原因。本文以单自由度体系为研究对象，选取汶川地震的近断层强震数据进行研究，分析竖向地震动所产生P-Δ效应的放大作用特征。分析结果表明汶川地震中，相比于中远场区域，近断层区域内竖向地震动作用所产生的P-Δ效应具有明显的放大作用，且近断层内这种放大作用具有普遍性；当自振周期一定时，不同台站获得地震动的放大系数离散性较小，主要分布于均值附近；其分析结果符合地震动的一般规律，分析结果合理。在此基础上建立了以均值为代表值的放大系数谱，可以与抗震设计反应谱结合使用，从而为活断层附近区域内的结构抗震设计问题提供定量化参考依据。  相似文献   

Local amplification of deep mining induced vibrations Part 1: Experimental evidence for site effects in a coal basin     

L. Driad-Lebeau  N. Lokmane  J.F. Semblat  G. Bonnet 《Soil Dynamics and Earthquake Engineering》2009

The work presented in this paper lies under the scope of a research program aiming to assess the impact of deep coal mining induced vibrations on the surface constructions. The concerned section of the program is dedicated to the study of geological site effects and their influence on the mining induced vibrations for which the experimental investigations have been carried out and developed in this paper (Part 1). The empirical methods based on H/V spectral ratios have been applied on data sets provided from mining induced vibrations recorded within private residences above the deep coalmine as well as complementary measurements of ambient noise. The results evidence an amplified zone in the southern part of the Gardanne basin where drilling data confirmed the presence of particularly fractured and soft stratigraphic units. This joint analysis of induced seismicity and ambient noise enabled to validate the method based on H/V ratios applied to the mining context.  相似文献   

Ground vibrations from sheetpile driving in urban environment: measurements, analysis and effects on buildings and occupants     

G. A. Athanasopoulos  P. C. Pelekis 《Soil Dynamics and Earthquake Engineering》2000,19(5)

Following a comprehensive review of the subject of man-made ground vibrations, measurements of ground vibration caused by vibratory sheetpile driving in recent soil deposits are reported in terms of particle velocities vs. distance from the source of vibration. The measurements were conducted on paved surfaces and sidewalks in the inner urban environment. Reconstructed particle displacement paths indicated, predominantly, vertical vibrations of the Rayleigh type. The attenuation rate of vibrations with distance was compared to published results of other studies and satisfactory agreement was found to exist. Values of particle velocity measured in this study, however, were lower than corresponding values of other studies under comparable values of rated vibratory kinetic energy. This is possibly due to different soil conditions. Average and upper bound linear log–log attenuation relationships are proposed, which fit the results of measurements and are representative of the conditions likely to be encountered in the urban environment. Measurement of vibrations on higher floors of multistory reinforced concrete buildings indicated a significant amplification of vertical vibration and an average curve for amplification magnitude vs. floor level was fitted to the results of measurements. A comparison of measured values of vibration with the observed performance of buildings and with damage threshold values suggested by existing codes and standards indicated that the latter do not provide safety against damage caused by vibratory densification of loose sandy soils. On the other hand, the existing criteria for human exposure to vibrations in buildings, according to the results of this study, seem to adequately define the degrees of human discomfort.  相似文献   

Simulation of seismic response in a city-like environment   总被引：1，自引：0，他引：1  

Jean-Philippe Groby  Chrysoula Tsogka  Armand Wirgin   《Soil Dynamics and Earthquake Engineering》2005,25(7-10):487-504

We study the seismic response of idealized 2D cities, constituted by non-equally spaced, non-equally sized homogenized blocks anchored in a soft layer overlying a hard half space. The blocks and soft layer are occupied by dissipative media. To simulate such response, we use an approximation of the viscoelastic modulus by a low-order rational function of frequency and incorporate this approximation into a first-order-in-time scheme. Our results display spatially variable, strong, long-duration responses inside the blocks and on the ground, which qualitatively match the responses observed in some earthquake-prone cities of Mexico, France, the USA, etc.  相似文献   

Using numerical modelling to evaluate tsunami hazard near the Kuril Island     

L. B. Chubarov  Yu. I. Shokin  K. V. Simonov 《Natural Hazards》1992,5(3):293-318

A sequence of computer experiments is used to study questions concerning the tsunami problem as a quantitative estimate of tsunami danger, detailed geographical tsunami classification, determination of the parameters of critical tsunami waves, and the conditions of their development. We call a wave critical, if its impact on the coast is most hazardous.Using the Middle Kuril Island as an example, we present the results of a computer experiment which includes determining the wavefields on the shelf and estimating the effects connected with the deep-water Bussol and Diana Straits.Numerical simulation of tsunami waves of different sources permits the assessment of the extent of tsunami danger in different areas of the coastal zone of Simushir Island, depending on the location of the focus zone and their geometry.The major singularities of the wavefield arise in the zones of the deep-water straits. The distribution of the amplification factors is determined by both the global parameters of the wavefields and the local properties of individual harbours. The results obtained for a particular harbour in the northern part of Simushir Island, formed the basis for the quantitative estimate of tsunami danger for this area.  相似文献   

地形影响地面运动的观测研究     

吴富春  许俊奇 《地球物理学报》1990,33(2):186-195

本文利用矿山爆破,进行了地形对地面运动影响的观测研究.9次爆破的结果表明,山顶处位移和速度的谱曲线的峰区较山前和其它测点的集中,振幅的量值也大,其放大倍率约为3,其中与山体走向平行的水平分量放大得最大,与之垂直的次之,而垂直于地面的最小;山顶测点不同分量上最大位移所对应的周期接近,其对山前的放大量值近于2,也是水平分量大于垂直分量;山顶处地面运动的延续时间取决于爆破的药量和方式,山前等测点延时的放大为3-4倍,也是水平分量大于垂直分量.山顶上地面运动的这种特殊性,是由于入射波所激发的山体共振所引起的.  相似文献   

波动性生态脆弱带的特征   总被引：24，自引：1，他引：24  

孙武 《中国沙漠》1997,17(2):199-203

波动性生态脆弱带是生态脆弱带的基本类型之一，跃变性是波动性的实质，降水的高变率与人类活动的保守性、稳定性的尖锐矛盾是形成脆弱的主要原因。牧草、粮食的放大性是对降水波动性的进一步体现，波动性是对农林牧土地利用结构，经济水平，人口超载状况的综合反映，是度量脆弱度的实用指标之一。  相似文献   

Viscous damping formulation and high frequency motion propagation in non-linear site response analysis     

Youssef M. A. Hashash   《Soil Dynamics and Earthquake Engineering》2002,22(7)

Non-linear time domain site response analysis is widely used in evaluating local soil effects on propagated ground motion. This approach has generally provided good estimates of field behavior at longer periods but has shortcomings at relatively shorter periods. Viscous damping is commonly employed in the equation of motion to capture damping at very small strains and employs an approximation of Rayleigh damping using the first natural mode only. This paper introduces a new formulation for the viscous damping using the full Rayleigh damping. The new formulation represents more accurately wave propagation for soil columns greater than 50 m thick and improves non-linear site response analysis at shorter periods. The proposed formulation allows the use of frequency dependent viscous damping. Several examples, including a field case history at Treasure Island, California, demonstrate the significant improvement in computed surface response using the new formulation.  相似文献