可液化土-高层结构地震相互作用振动台试验
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摘要
进行了可液化土-高层结构地震相互作用的振动台试验,试验采用柔性容器以减小边界影响,采用饱和砂土作为模型土.试验中再现了液化场地土中高层结构的震害现象.得出的主要规律有:相互作用体系的振型曲线与刚性地基上结构的振型曲线明显不同;随着振动次数的增加,体系的频率降低,阻尼比增大;砂土对地震动可起滤波和隔震作用;当最初加速度峰值到达前,砂土层中的孔压比存在负值;震后土中孔隙水压力不一定随振动的停止而立即开始消散,在短期内可能继续增长;桩身应变幅值呈桩顶大、桩尖小的分布;桩土接触压力幅值分布规律与输入激励地震大小有关.
Shaking table model test was made on high-rise buildings with a consideration of the liquefiable soil-structure interaction with the saturated sand soil as model soil.A flexible container was fabricated to minimize the box effect.Macro-phenomena of high-rise building in ground of soil liquefaction due to natural earthquake were reproduced well.Test results show that the mode shape of the system is different from that of the structure on the fixed base in that there are rocking and swing at the foundation.The natural frequency of interaction system decreases and the damping ratio of soil increases with the increase of the shaking.The liquefied soil can filter and isolate vibration.Transient minus pore pressure occurs.Pore water pressure does not always dissipate in short time immediately after the excitations,but it may keep on increasing too.The distribution of the strain amplitude along the pile is the shape where the large strain is at the top of the pile and the small strain is at the tip of the pile.And the distribution of the contact pressure on the pile-soil interface is related to the excitation magnitude.
Shaking table model test was made on high-rise buildings with a consideration of the liquefiable soil-structure interaction with the saturated sand soil as model soil.A flexible container was fabricated to minimize the box effect.Macro-phenomena of high-rise building in ground of soil liquefaction due to natural earthquake were reproduced well.Test results show that the mode shape of the system is different from that of the structure on the fixed base in that there are rocking and swing at the foundation.The natural frequency of interaction system decreases and the damping ratio of soil increases with the increase of the shaking.The liquefied soil can filter and isolate vibration.Transient minus pore pressure occurs.Pore water pressure does not always dissipate in short time immediately after the excitations,but it may keep on increasing too.The distribution of the strain amplitude along the pile is the shape where the large strain is at the top of the pile and the small strain is at the tip of the pile.And the distribution of the contact pressure on the pile-soil interface is related to the excitation magnitude.
引文
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[9]LU Xilin,LI Peizhen,CHEN Bo,et al.Computer si mulation of the dynamic layered soil-pile-structure interaction system[J].Canadian Geotechnical Journal,2005,42(3):742.
[2]Tamura S,Suzuki Y,Tsuchiya T,et al.Dynamic response and failure mechanisms of a pile foundation during soil liquefaction by shaking table test with a large-scale laminar shear box[C/CD]∥12th World Conference on Earthquake Engineering.Auckland:New Zealand Society for Earthquake Engineering,2000.
[3]Kagawa T,Minowa C,Abe A.EDUS(earthquake damage to underground structures)project[C/CD]∥12th World Conference on Earthquake Engineering.Auckland:New Zealand Society for Earthquake Engineering,2000.
[4]陈跃庆,吕西林,侯建国,等.有建筑物存在的软土地基液化模拟地震振动台试验研究[J].武汉大学学报:工学版,2003,36(1):59.CHEN Yueqing,LU Xilin,HOU Jianguo,et al.Shaking table testing on seismic liquefaction of soft soil under buildingfooting[J].Engineering Journal of Wuhan University,2003,36(1):59.
[5]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.LI NG Xianzhang,GUO Mingzhu,WANG Dongsheng,et al.Large-scale shaking table model test of seismic response of bridge of pile foundationin ground of liquefaction[J].Rock and Soil Mechanics,2006,27(1):7.
[6]孟上九,刘汉龙,袁晓铭,等.可液化地基上建筑物不均匀震陷机制的振动台试验研究[J].岩石力学与工程学报,2005,24(11):1978.MENG Shangjiu,LI U Hanlong,YUAN Xiaoming,et al.Experi mental study on the mechanism of earthquake-induced differential settlement of building on liquescent subsoil by shaking table[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(11):1978.
[7]冯士伦,王建华,郭金童.液化土层中桩基抗震性能振动台试验研究[J].土木工程学报,2005,38(7):92.FENG Shilun,WANG Jianhua,GUO Jintong,et al.A shake table test onthe seismic resistance of pile foundationinliquefied soil[J].China Civil Engineering Journal,2005,38(7):92.
[8]陈跃庆,吕西林,李培振,等.分层土-基础-高层框架结构相互作用体系振动台模型试验研究[J].地震工程与工程振动,2001,21(3):104.CHEN Yueqing,LU Xilin,LI Peizhen,et al.Shaking table testing for layered soil-foundation-structure interaction system[J].Earthquake Engineering and Engineering Vibration,2001,21(3):104.
[9]LU Xilin,LI Peizhen,CHEN Bo,et al.Computer si mulation of the dynamic layered soil-pile-structure interaction system[J].Canadian Geotechnical Journal,2005,42(3):742.
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