液化场地桥梁群桩基地震反应影响因素分析

发布时间：2018-01-13 14:27

本文关键词：液化场地桥梁群桩基地震反应影响因素分析　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：场地液化是导致桩基桥梁震害的重要原因之一。液化场地桩-土动力相互作用研究是解决液化场地桩基桥梁抗震问题的有效途径。液化场地桥梁桩基震害,地震中孔隙水难以排出是可液化土动力性能改变的主要原因,土中孔隙水压力上升引起有效应力降低而导致土的强度损失或完全丧失强度,进而严重影响桥梁桩基稳定性、或使之抗震性能完全丧失而致使桥梁倒塌。鉴于上述,本文针对液化场地桩-土地震相互作用问题,采用振动台试验且理论分析相结合手段,开展液化场地桥梁群桩基地震反应与影响因素研究工作。本文主要研究工作与取得的若干认识如下:(1)采用钢筋混凝土群桩-柱墩基础型式,针对表层覆盖粘土层的液化场地,实施可液化场地桥梁桩基地震反应振动台试验,研究了场地液化过程中桥梁桩基地震反应规律与场地动力特性。并基于OpenSees有限元数值模拟平台,直接针对上述振动台试验,桩采用基于欧拉-伯努利梁理论建立的梁-柱单元模拟,桩-土动力相互作用采用考虑体积效应的刚性连接单元处理,建立试验受控条件下液化场地桩-土动力相互作用三维有限元分析模型与相应的计算方法。通过桩基近场土体加速度、孔压、桩身应力等数值模拟与振动台试验结果比较分析,验证了建立的有限元分析模型与相应的计算方法的正确性。(2)采用所建立的三维有限元分析模型与相应的计算方法,基于振动台试验结果,针对液化场地桩-土-桥梁结构动力相互作用,桩基为2×2群桩输入El Centro波进行反复的数值模拟,以墩重、墩高、桩间距、上部土层渗透系数等为基本控制量,建立不同参数下近场土体加速度、土体有效应力下降速率、桩身弯矩及剪力、桩位移及加速度等时程曲线,从而分析上述主要因素对化场地桩-土动力相互作用的影响情况。(3)以上述2×2群桩数值模型为基础,扩展出2PS群桩模型(2根桩在一行)、2PP群桩模型(2根桩在一列)、3PS群桩模型、3PP群桩模型、3×3群桩模型。根据上述数值模型所用变量,针对不同配置群桩基础对液化场地桩-土地震相互作用的影响展开具体分析。
[Abstract]:Site liquefaction is one of the important causes of earthquake damage of pile foundation bridge. The study of pile-soil dynamic interaction in liquefaction site is an effective way to solve the seismic problem of pile foundation bridge in liquefaction site. The main reason for the dynamic change of liquefiable soil is that the pore water is difficult to be discharged in earthquake. The increase of pore water pressure in the soil leads to the decrease of effective stress which leads to the strength loss or complete loss of soil strength. Furthermore, the stability of bridge pile foundation is seriously affected, or the seismic behavior of bridge is completely lost and the bridge collapses. In view of the above mentioned, the pile-soil interaction in liquefaction site is discussed in this paper. The shaking table test and theoretical analysis were used. The research work on seismic response and influencing factors of bridge group pile foundation in liquefaction site is carried out in this paper. The main research work and some understandings obtained in this paper are as follows: 1) the reinforced concrete pile-column pier foundation type is adopted. For the liquefaction site covered with clay layer, the shaking table test of seismic response of bridge pile foundation in liquefiable site is carried out. The seismic response law and site dynamic characteristics of bridge pile foundation during site liquefaction are studied. Based on the OpenSees finite element numerical simulation platform, the shaking table test is carried out directly. The pile is simulated by the beam-column element based on the Euler-Bernoulli beam theory, and the pile-soil dynamic interaction is treated by the rigid connection element considering the volume effect. A three-dimensional finite element analysis model and corresponding calculation method for pile-soil dynamic interaction in liquefaction site under controlled experimental conditions were established. The results of numerical simulation and shaking table test are compared and analyzed. The correctness of the established finite element analysis model and the corresponding calculation method is verified. The established three-dimensional finite element analysis model and the corresponding calculation method are adopted, based on the shaking table test results. In view of the pile-soil-bridge structure dynamic interaction in liquefaction site, the pile foundation is inputted to El Centro wave for 2 脳 2 pile groups, and the pile weight, pier height and pile spacing are simulated repeatedly. The soil permeability coefficient of the upper layer is the basic control quantity. The time history curves such as near-field soil acceleration, soil effective stress decreasing rate, pile bending moment and shear force, pile displacement and acceleration are established under different parameters. The influence of the above main factors on the pile-soil dynamic interaction is analyzed. (3) based on the above 2 脳 2 pile group numerical model, the 2PS pile group model with two piles in one row is extended. 2PP pile group model and two piles in a row of pile group model 3PP group model and 3 脳 3 pile group model. According to the variables used in the above numerical model. The effects of different pile groups on the pile-soil seismic interaction in liquefaction sites are analyzed in detail.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.1;U442.55

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