液化场地单桩-土-桥梁结构地震相互作用大型振动台试验研究
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摘要
基于振动台试验,研究三层土地层结构条件液化场地单桩-土-桥梁结构的地震反应特性。试验较好地再现了场地液化条件下单桩-柱墩的动力反应宏观特征,柱墩及振动台动位移、桩-柱墩动应变、砂土层孔隙水压力及孔压比都表现出随输入地震波幅值增大而反应更加剧烈的一般规律。而且,小震输入时未见永久变形,大、小震输入时柱墩位移幅值都远大于振动台;动应变最大幅值出现在上覆黏土层与砂土层界面处,并向两端逐渐减小;桩在小震时属弹性变形,大震时非线性显著,拉压区应变的对称性消失。输入地震波幅值、埋深和桩距是影响孔压和孔压比的重要因素,小震输入时孔压上升快、达到峰值快、消散也快,大震输入时孔压上升也快、但达到峰值慢、消散慢。研究结果对于合理认识液化场地桩-土-桥梁结构地震反应具有一定意义,也为进一步开展液化场地桥梁结构地震安全性评价积累了部分基础资料。
Based on shaking table test at scale ratio of 1∶10,seismic response characteristics of single pile-soil-column pier at liquefiable site were studied.Dynamic macroscopic characteristics of single pile-column pier at liquefiable site were well reproduced.Dynamic displacement of column pier and shaking table,dynamic strain of pile and column pier,pore water pressure and pore water pressure ratio of sand layer are all satisfied with the general law—reactions are stronger with the increasing of input acceleration.Further more,permanent deformation does not arise with input of weak shake;displacement of the column pier is much bigger than that of the shaking table with various shake inputs;the biggest dynamic strain of the pile appears near the interface of upper clay and sand layer and decreases gradually to the two ends;deformation of the pile belongs to elastic with input of weak shake,but nonlinearity becomes remarkable and symmetry of strain increment in tensile and compressive zone disappears with input of strong shake.Amplitude of the input shake,buried depth,and horizontal distance to the pile are important influential factors to pore water pressure and the ratio.Pore water pressure increases,reaches its peak value and disperses fast with input of weak shake as compared with it increases fast,but reaches peak value and disperses slowly with input of strong shake.The results are useful to recognize seismic response of pile-soil-bridge structure and accumulate basic test data to further seismic safety evaluation of bridge structure at liquefiable site.
Based on shaking table test at scale ratio of 1∶10,seismic response characteristics of single pile-soil-column pier at liquefiable site were studied.Dynamic macroscopic characteristics of single pile-column pier at liquefiable site were well reproduced.Dynamic displacement of column pier and shaking table,dynamic strain of pile and column pier,pore water pressure and pore water pressure ratio of sand layer are all satisfied with the general law—reactions are stronger with the increasing of input acceleration.Further more,permanent deformation does not arise with input of weak shake;displacement of the column pier is much bigger than that of the shaking table with various shake inputs;the biggest dynamic strain of the pile appears near the interface of upper clay and sand layer and decreases gradually to the two ends;deformation of the pile belongs to elastic with input of weak shake,but nonlinearity becomes remarkable and symmetry of strain increment in tensile and compressive zone disappears with input of strong shake.Amplitude of the input shake,buried depth,and horizontal distance to the pile are important influential factors to pore water pressure and the ratio.Pore water pressure increases,reaches its peak value and disperses fast with input of weak shake as compared with it increases fast,but reaches peak value and disperses slowly with input of strong shake.The results are useful to recognize seismic response of pile-soil-bridge structure and accumulate basic test data to further seismic safety evaluation of bridge structure at liquefiable site.
引文
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[2]Liu HS,Chen K J.Test on behavior of pile foundation in liquefiable soils[C]//Proceedings:Second International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics,1991,233-236
[3]Miura F,Stewart H E,O’Rourke T D.The effects of liquefaction-induced lateral spreading on pile foundations[J].Soil Dynamics and Earthquake Engineering,1991,10(5):271-279
[4]黄志全,王思敬.离心模型试验技术在我国的应用概况[J].岩石力学与工程学报,1998,17(2):199-203(Huang Zhiquan,Wang Sijing.The dynamic centrifuge model test in geotechnical engineering[J].Chinese Journal of Rock Mechanics and Engineering,1998,17(2):199-203(in Chinese))
[5]雷胜友.离心模型试验技术及其在中国的应用[J].西安公路交通大学学报,1998,18(4):222-226(LeiShengyou.Centrifuge shakers and testing technique[J].Journal of China Institute of Water Resources and Hydropower Research,1998,18(4):222-226(in Chinese))
[6]凌贤长,王丽霞,王东升.非自由液化场地基动力性能大型振动台模型试验研究[J].中国公路学报,2005,18(2):34-39(Ling Xianzhang,Wang Lixia,Wang Dongsheng.Study of large-scale shaking table proportional model test of the dynamic property of foundation in unfreedom ground of liquefaction[J].China Journal of Highway and Transport,2005,18(2):34-39(in Chinese))
[7]凌贤长,王臣,王志强.自由场地基液化大型振动台模型试验研究[J].地震工程与工程振动,2003,23(6):138-143(Ling Xianzhang,Wang Chen,Wang Zhiqiang.Study on large-scale shaking table proportional model test for free-ground liquefaction arisen from earthquake[J].Earthquake Engineering and Engineering Vibration,2003,23(6):138-143(in Chinese))
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