液化土层对地表位移谱的影响
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摘要
通过现场地震记录分析和理论计算,研究了液化土层对地表位移谱的影响规律,提出了液化位移增量谱和液化修正位移谱。对比了美国Superstition Hills地震和日本阪神地震中液化场地加速度时程和位移时程,分析了液化和非液化场地位移谱区别。采用改进的一维有效应力分析方法,计算了在不同强度和波型地震波输入下厚度和埋深不同的液化砂层对地表位移谱的影响。结果表明:液化对地表位移和位移谱有显著放大作用,位移谱在1s左右开始增大,加震最显著频段为1~5s,谱位移增加0.1~0.7m,烈度8度时平均加震增幅0.1~0.25m,9度时平均增幅0.4~0.7m。
The effects of liquefied soil layers on surface displacement spectra are investigated,and the incremental displacement spectra and revised displacement spectra due to liquefaction are presented in terms of earthquake records and theoretical analysis.The surface acceleration and displacement histories in the liquefied sites of the Superstition Hills of USA and the Kobe Earthquake of Japan are compared and the difference of the displacement spectra for the liquefied and the non-liquefied sites are identified.Also,by the modified effective stress method,the effects of the liquefied sand layers with different depth and thickness under the input of seismic waves with different intensities and different forms on the displacement spertra are investigated.The results indicate that the liquefied soil layers show significant amplification on the surface displacement spectra.The amplification is started at 1s and the most amplification period range is 1~5s by increasing of 0.1-0.7m for spectrum displacements.The spectrum displacements increase by 0.1~0.3m and 0.4~0.7m for the intensity Ⅷ and the intensity Ⅸ,respectively.
The effects of liquefied soil layers on surface displacement spectra are investigated,and the incremental displacement spectra and revised displacement spectra due to liquefaction are presented in terms of earthquake records and theoretical analysis.The surface acceleration and displacement histories in the liquefied sites of the Superstition Hills of USA and the Kobe Earthquake of Japan are compared and the difference of the displacement spectra for the liquefied and the non-liquefied sites are identified.Also,by the modified effective stress method,the effects of the liquefied sand layers with different depth and thickness under the input of seismic waves with different intensities and different forms on the displacement spertra are investigated.The results indicate that the liquefied soil layers show significant amplification on the surface displacement spectra.The amplification is started at 1s and the most amplification period range is 1~5s by increasing of 0.1-0.7m for spectrum displacements.The spectrum displacements increase by 0.1~0.3m and 0.4~0.7m for the intensity Ⅷ and the intensity Ⅸ,respectively.
引文
[1]李雨润,袁晓铭.液化场地上土体侧向变形对桩基影响研究评述[J].世界地震工程,2004,20(2):17-22.
[2]凌贤长,郭明珠,王东升,等.液化场地桩基桥梁震害响应大型振动台模型试验研究[J].岩土力学,2006,27(1):7-10.
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[7]孙锐,袁晓铭.液化土层地震动模拟计算方法及验证[J].岩土力学,2007,28(Supp):759-764.
[2]凌贤长,郭明珠,王东升,等.液化场地桩基桥梁震害响应大型振动台模型试验研究[J].岩土力学,2006,27(1):7-10.
[3]蔡晓光,袁晓铭,刘汉龙,等.近岸水平场地液化侧向大变形影响因素分析[J].世界地震工程,2007,23(2):20-25.
[4]黄建文,朱晞.位移为基础的钢筋混凝土连续梁桥抗震设计方法[J].中国公路学报,2005,18(2):28-33.
[5]王东升,李宏男,王国新.统计意义一致的弹塑性设计位移谱[J].大连理工大学学报,2006,46(1):87-92.
[6]孙锐,袁晓铭.液化土层地震动特征分析[J].岩土工程学报,2004,26(5):684-670.
[7]孙锐,袁晓铭.液化土层地震动模拟计算方法及验证[J].岩土力学,2007,28(Supp):759-764.
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