黄土场地地震动力响应及变形分析
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摘要
基于甘肃平凉大寨乡典型黄土塬地质构造为研究背景,以大型振动台试验方法获得的原始数据为依据,分析了加速度响应特征、频谱和反应谱变化,揭示了该黄土场地地震动反应特性,结合数值仿真模拟方法,对比了该黄土场地在单一地震荷载和累计地震荷载作用下加速度响应特征和位移变化特征。结果表明:黄土场地峰值加速度(PGA)和PGA放大系数与高程呈正相关性,PGA放大系数随地震动强度增大呈递减趋势;随着高程的增大,该黄土场地卓越频率缓慢向低频方向移动,卓越频率与输入地震动强度呈现负相关性;随着覆盖层厚度的增加,加速度反应谱峰值和特征周期先增加后减小,地震动强度增大时,特征周期向长周期方向偏移,幅值成倍增大;多烈度累计荷载作用对黄土场地的PGA放大系数影响较小,对水平位移的影响较为明显,抗震设计时应予以考虑。
Based on shaking table test data of loess plateau in Dazhai Township, acceleration response, the change of spectrum and response spectrum are analyzed, the seismic response characteristics of the loess site are then revealed. Moreover, the characteristics of acceleration response and displacement of the loess site under a single seismic load and cumulative seismic load are compared by numerical simulation. The results show that: the peak acceleration(PGA) and PGA amplification coefficient of the complex soil structure are positively correlated with the elevation and the amplification coefficient of PGA decrease with the increase in ground vibration intensity; the low frequency components become more abundant with increase in elevation of loess site, the excellent frequency was negatively correlated with ground vibration intensity; the peak value of acceleration response spectrum and characteristic period first increase and then decrease, with the increase of overburden thickness, and when the seismic intensity increases, the characteristic period is shifted to the long period, and the amplitude is multiplied; different loading modes have little influence on PGA amplification factor of the loess site, and the effect of horizontal displacement is more obvious.
Based on shaking table test data of loess plateau in Dazhai Township, acceleration response, the change of spectrum and response spectrum are analyzed, the seismic response characteristics of the loess site are then revealed. Moreover, the characteristics of acceleration response and displacement of the loess site under a single seismic load and cumulative seismic load are compared by numerical simulation. The results show that: the peak acceleration(PGA) and PGA amplification coefficient of the complex soil structure are positively correlated with the elevation and the amplification coefficient of PGA decrease with the increase in ground vibration intensity; the low frequency components become more abundant with increase in elevation of loess site, the excellent frequency was negatively correlated with ground vibration intensity; the peak value of acceleration response spectrum and characteristic period first increase and then decrease, with the increase of overburden thickness, and when the seismic intensity increases, the characteristic period is shifted to the long period, and the amplitude is multiplied; different loading modes have little influence on PGA amplification factor of the loess site, and the effect of horizontal displacement is more obvious.
引文
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[15] 寇甄涛,杨旭,刘魁.黄土半填半挖地基破坏形式及机理研究[J].水利与建筑工程学报,2018,16(3):175-181.
[2] 王兰民,等.黄土动力学[M].北京:地震出版社,2003:2-5.
[3] Mohammed M A,Abudeif A M,Omar K A,et al.Estim ation of site effect using microtremor technique at 15th May City Helwan Erypt[J].Arabian Journal of Geoscoences,2018,11(16):1866-7511.
[4] 夏坤,张令心,董林.汶川地震远震区黄土场地地震反应特征分析[J].地震工程学报,2018,40(3):121-128.
[5] Wu Z J,Wang L M,Chen T,et al.Study of mechanism of site amplification effects on ground motion in far field loess during Wenchuan Ms8.0 earthquake[J].Rock and soil Mechanics,2012,33(12):3736-3740.
[6] Bonilla L F,Steidl J H,Lindley G T ,et al.Site amplification in the san fernando valley,california:variability of site-effect estimation using the S-wave,coda,and H/V methods[J].Bulletin of the Seismological Society of Amercia,1997,87(3):710-730.
[7] 薄景山,李秀领,刘红帅.土层结构对地表加速度峰值的影响[J].地震工程与工程振动,2003,23(3):35-40
[8] 吴俊,廖炜,王涛.高强度地震下建筑施工场点危险性建模分析[J].地震工程学报,2018(4):833-840.
[9] 吴海波,王新妮.圆柱形支撑大跨度建筑结构强震冲击分析模型仿真[J].地震工程学报,2018,40(1):48-53.
[10] 靳聪聪,迟世春,聂章博.基于完全耦合理论的涉水边坡地震响应分析[J].水利与建筑工程学报,2018,16(5):103-108.
[11] 叶海林,郑颖人,杜修力,等.边坡动力破坏特征的振动台模型试验与数值分析[J].土木工程学报,2012,45(9):128-135.
[12] 耿敏,王德斌,李培勇.加筋路基动力特性的数值模拟研究[J].水利与建筑工程学报,2018,16(1):211-215.
[13] 张建华,夏岸雄,王涛.FLAC3D数值模拟在路基施工中的应用[J].辽宁工程技术大学学报(自然科学版),2013,32(11):1447-1452.
[14] 冯勇,李平,姜春艳.FLAC3D在深基坑工程开挖中的数值模拟分析[J].水利与建筑工程学报,2013,11(4):17-20.
[15] 寇甄涛,杨旭,刘魁.黄土半填半挖地基破坏形式及机理研究[J].水利与建筑工程学报,2018,16(3):175-181.
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