场地液化对反应谱影响评价
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摘要
土层液化除引起土体失稳和沉降外,也会对地表加速度反应谱产生重要作用.本文采用实际地震记录和理论分析相结合的方法,研究了典型液化场地对地表加速度反应谱的影响问题.结果表明:液化对地表加速度反应谱有非常显著的影响,液化引起地表加速度反应谱变化的基本特征为高频降低、低频增大;低频加震效应明显大于高频减震效应,加震与减震的谱烈度比平均约为20;高频减震的主要范围为0.1—0.6s,低频加震的主要范围为1—4s,减震到加震的转换点在0.7—0.9s间.分析表明,液化对长周期显著的放大,如仍按常规反应谱进行抗震设计,则对长大和高柔结构会导致偏于危险的结果,即使地基经过基础加固,但因场地特性不能改变,因此这种危险仍然存在.
Soil liquefaction would make ground failure and have effect on ground acceleration spectrum in addition.In this paper,the effect of liquefaction on ground acceleration was investigated by analyzing the earthquake records and numerical simulation.The results indicated that the effect of liquefaction on the surface acceleration spectrum was remarkable and the feature of the effect is that the high frequency of the acceleration spectrum decrease while the low frequency of that increase.Meanwhile,the effect of increasing the long period was more than that of decreasing the short period about 20 times in average.The range of decreasing and increasing was 0.1—0.3s and 1—4s,separately.The division line between increasing and decreasing was 0.7—0.9s.The results in the paper showed the tall slender structure designed by standard spectrum would be dangerous because of the magnification of liquefaction-induced long period even though the ground treatments ware conducted by foundations.
Soil liquefaction would make ground failure and have effect on ground acceleration spectrum in addition.In this paper,the effect of liquefaction on ground acceleration was investigated by analyzing the earthquake records and numerical simulation.The results indicated that the effect of liquefaction on the surface acceleration spectrum was remarkable and the feature of the effect is that the high frequency of the acceleration spectrum decrease while the low frequency of that increase.Meanwhile,the effect of increasing the long period was more than that of decreasing the short period about 20 times in average.The range of decreasing and increasing was 0.1—0.3s and 1—4s,separately.The division line between increasing and decreasing was 0.7—0.9s.The results in the paper showed the tall slender structure designed by standard spectrum would be dangerous because of the magnification of liquefaction-induced long period even though the ground treatments ware conducted by foundations.
引文
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[2]高玉峰,刘汉龙,朱伟.地震液化引起的地面大位移研究进展[J].岩土力学,2000,21(3):294-298Gao Yufeng,Liu Hanlong,Zhu Wei.Advances in large ground displacement induced by seismic liquefaction[J].Rock and Soil Mechanics,2000,21(3):294-298
[3]李雨润,袁晓铭.液化场地上土体侧向变形对桩基影响研究综述[J].世界地震工程,2004,20(2):17-22Li Yurui,Yuan Xiaoming.State-of-art of study on influences of liquefaction-induced soil spreading over pile foundation response[J].World Earthquake Engineering,2004,20(2):17-22
[4]刘汉龙,陆绍俊.1995年日本阪神大地震及其震害[C].大连:第五届全国土动力学学术会议论文集,1998,550-555Liu Hanlong,Lu Shaojun.Review on the damage in1995great Hanshin Earthquake of Japan[C].Dalian:Proceeding of the5th National Conference on Soil Dynamics,1998,550-555
[5]孙锐.液化土层地震动和场地液化识别方法研究[D].中国地震局工程力学研究所博士论文,2006Sun Rui.Study on seismic ground motion on liquefiable soil layer and site liquefaction detection[D].Institute of Engineering Mechanics,China Earthquake Administration,2006
[6]中华人民共和国国家标准.《建筑抗震设计规范》(GB50011-2001)[S]National Standards of the People's Republic of China,Code foe seismic design of buildings(GB50011-2001)[S]
[7]孙锐,袁晓铭.液化土层对地表加速度反应谱的影响[J].世界地震工程,2004,20(3):33-38Sun Rui,Yuan Xiaoming.Effect of soil liquefaction on response spectrum of surface acceleration[J].World earthquake engineering,2004,20(3):33-38
[8]孙锐,袁晓铭.液化对设计反应谱和场地分类的影响[J].地震工程与工程振动,2003,23(5):46-52Sun Rui,Yuan Xiaoming.Effect of soil liquefaction on design response spectrum and site classification[J].Earthquake Engineering and Engineering vibration,2003,23(5):46-52
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