液化场地桩—土—桥梁结构动力相互作用振动台试验研究

It was given wide attention internationally in recent ten years that pile-soil-bridge structure interaction was studied by dynamic test, and dynamic test of pile-soil-bridge structure interaction in ground of soil liquefaction is one highlight of it, also is recognized difficulty. Nowadays, shaking table scale model tests is an effective method to study soil-structure dynamic interaction, and specially in the study of pile-soil-bridge structure dynamic interaction in ground of soil liquefaction get great attention and much application gradually. Abroad scholars have got a lot of valuable conclusions on shaking table scale model test of pile-soil-structure dynamic interaction in ground of soil.liquefaction, such as the joint project EDUS organized by American and Japan since 1992 , and this project has achieved industrialization step in Japan. But, so far there aren’t any domestic documents or papers on this theme.For the reason above, it is the first time that National Natural Science Foundation of China sponsored shaking table scale model tests of pile-soil-bridge structure dynamic.interaction in ground of soil liquefaction in 2001 in the form of tryout .Being the form of tryout , money is limited and time is only one year, so studying scope of the theme mainly concentrate on two aspects. First is how to progress the design of scale model similitude of the shaking table tests of pile-soil-bridge structure dynamic interaction. Second is to affirm the reality of the tests. In the first aspect study, it is the first time in China to aim at the ground condition of soil liquefaction, and the dimensional analysis method is applied to solve scale model similitude of the test based on Bockingham π theorem, soil-structure dynamic interaction and material.strain-stress constitutive relationship of foundation and structure between model and prototype. All tests in second aspect study have been completed during 10/19/2002~11/5/2002 in State Key Laboratory for Disaster Reduction in Civil Engineering in Tongji university. “Shaking table 1:10 scale model test of liquefaction in.free field” and “Shaking table 1:10 scale model test of liquefaction in non-free field” are respectively accomplished, one test for each. Input seismic wave is EL Centro(NS). We.can say that the serial tests are very succeed. Macro-phenomena of soil liquefaction and structure destroy arisen from natural earthquake are recurred well, such as sand to boiled,.water to be emitted, foundation and structure to be sunk, and so on, especially the destroyed status of scale model agree with the actual destroyed phenomena of prototype.which is Victory Bridge collapsed in Tangshang earthquake,1976. Furthermore, a valuable phenomena is observed in the shaking table scale model tests, which is about excess pore pressure progress that is also intituled instantaneous negative excess pore pressure in sand layer. “Instantaneous negative excess pore pressure” arose from “Instantaneous sand shear expand” is observed at the time of initial acceleration peak.Analogous phenomena be observed by Kagawa(1994) in the shaking table scale model.test of pile-soil dynamic interaction in ground of liquefaction in NIED, too. Though domestic scholars have done some shaking table test in ground of soil liquefaction successionally, “Instantaneous sand shear expand” or “Instantaneous negative excess.pore pressure” have not been mentioned in any document.In a word, some very valuable experiences are accumulated by studying on this tryout project. These can contribute to progressing of shaking table scale model test on.seismic interaction of pile-soil-bridge structure in the ground of liquefaction or other analogous projects, both in design of scale model simulated and technique or key operation step of shaking table scale model test. In our country, it can have a good effect.intituled “casting a brick to attract jade” on that other scholars are inspired to carry on analogous tests at least that this project brings to success. It is

探索液化场地桩—土—桥梁结构相互作用振动台试验技术，研究场地液化过程中钢砼桩柱式桥墩失效破坏过程；基于土体地震反应有效应力分析技术建立液化条件下桩—土—桥梁结构相互作用理论分析模型和计算方法，结合分线性文克尔地基梁法改进现行规范液化场地桥梁抗震分析方法。对加深桥梁震害理解、提高桥梁抗震水平及发展桥梁工程学具有重要意义。