离心机振动台与大型振动台自由场砂土液化试验研究

发布时间：2018-03-31 20:51

本文选题：砂土液化　切入点：自由场地　出处：《中国地震局工程力学研究所》2017年硕士论文

【摘要】：地震过程中饱和砂土液化是造成地基失效,引起建筑及工程结构严重破坏的主要原因之一。饱和砂土液化问题的研究已取得了丰富的研究成果,这些主要集中在两方面:其一是基于震害资料利用统计回归方法给出的各种经验判别方法;其二是利用室内动三轴试验给出的砂土液化机理及抗液化强度的试验研究成果。而利用大型振动台及离心机振动台联合试验研究液化机理方面的工作还不多见。本文针对自由场地饱和砂土,利用大型地震模拟振动台及离心机振动台进行了对比试验研究,并利用有限元软件Open Sees对试验结果进行了数值检验。目的是分析两种振动台试验的合理性,并研究自由场地饱和砂土地震过程中的加速度变化特征及孔隙水压力发展规律,为可液化场地的土工结构抗震设计提供参考。本文完成的主要工作如下:1、设计了离心机振动台饱和砂土液化试验及大型地震模拟振动台试验方案,完成了两种振动台饱和砂土多工况的地震模拟液化试验。2、对两种振动台试验的结果进行了详细的分析,并进行了对比研究,分析结果表明:离心机振动台试验的应力与应变与原型是一致的,能够模拟原型应力场中的应力条件,可再现原型在实际应力条件下的真实动力响应。大型振动台试验在研究重力起主要作用的问题时,无法同时满足应力应变的相似关系,但仍可以定性的反应一些地震液化的规律。3、利用有限元软件Open Sees对两种振动台试验进行了数值模拟,结果表明离心机振动台试验结果与数值模拟结果在大震时两者的地震反应规律一致,在中震时上部土层规律一致。这表明数值模拟和离心机振动台试验差异不大,可以利用有限元软件Open Sees做数值模拟研究饱和场地地震液化问题。数值模拟和大型振动台试验的结果存在一定差异,大型振动台试验的液化程度低,大型振动台试验对饱和砂土液化模拟是不够合理的,只能做一些液化规律的定性研究。
[Abstract]:The liquefaction of saturated sand during earthquake is one of the main causes of ground failure and serious damage to buildings and engineering structures.The research on the liquefaction of saturated sandy soil has obtained a lot of research results, which are mainly focused on two aspects: one is the use of statistical regression method based on seismic disaster data to identify various empirical methods;Secondly, the liquefaction mechanism and liquefaction resistance of sand are studied by dynamic triaxial test.However, it is rare to study liquefaction mechanism by using large shaking table and centrifuge shaking table.In this paper, a comparative experimental study on saturated sand in free site is carried out by using a large earthquake simulation shaking table and a centrifuge shaking table, and the results are tested numerically by the finite element software Open Sees.The aim of this paper is to analyze the rationality of the two shaking table tests and to study the characteristics of acceleration variation and pore water pressure development during the seismic process of saturated sand in free site, and to provide a reference for seismic design of geotechnical structures in liquefiable sites.The main work accomplished in this paper is as follows: 1. The saturated sand liquefaction test of centrifuge shaking table and the test scheme of large-scale earthquake simulation shaking table are designed.The seismic simulation liquefaction test of two kinds of shaking table saturated sand is completed. The results of the two shaking table tests are analyzed in detail, and the results are compared and studied.The results show that the stress and strain of the centrifuge shaking table test are consistent with the prototype, which can simulate the stress conditions in the prototype stress field and reproduce the real dynamic response of the prototype under the actual stress condition.The large-scale shaking table test can not satisfy the similar relation of stress and strain when studying the problem that gravity plays a major role.However, it is still possible to qualitatively reflect some laws of seismic liquefaction. The finite element software Open Sees is used to simulate the two kinds of shaking table tests.The results show that the results of centrifuge shaking table test are consistent with the results of numerical simulation, and the law of the upper soil layer is consistent with that of the medium earthquake.This indicates that there is no difference between the numerical simulation and the shaking table test of centrifuge, so the seismic liquefaction problem in saturated site can be studied by using the finite element software Open Sees.The results of numerical simulation and large-scale shaking table test have some differences. The liquefaction degree of large-scale shaking table test is low, and the large-scale shaking table test is not reasonable to the simulation of saturated sand liquefaction, so it can only do some qualitative research on liquefaction law.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU435

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