加筋土挡墙仿真模拟分析

发布时间：2018-02-24 15:40

本文关键词： 地震作用加筋土挡墙有限元分析动力性能　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：从古代人们将草筋混入泥中修建加固墙壁到现代的加筋土路基，挡墙，桥台等，加筋土技术已经有一段悠久的应用历史了，其中加筋土挡墙由于有着造型美观，建造经济，施工方便及技术性能优良等优点成为现代加筋土技术应用的重要方面，备受工程界的青睐。与加筋土挡墙应用历史和范围相比，对其理论研究显得滞后与不足，尤其在动力特性及动力设计方面。我国是地震多发区，这要求土工结构有一定的抗震性能，而我国以及其它各国对加筋土挡墙的抗震设计至今还没有一套完善的理论与标准，所以对加筋土挡墙在地震作用下的动力性能的研究就显得十分的必要和迫切。本文主要针对加筋土挡墙地震作用下的动力性能进行仿真分析。主要研究内容和取得的成果如下：（1）介绍了加筋土挡墙的发展历史、国内外研究动态以及地震作用下加筋土挡墙的破坏实例。对加筋土挡墙的组成部分，选材要求及结构特点等方面进行了归纳与总结。介绍分析了土工格栅的加筋机理:摩擦加筋原理、准粘聚力原理、均质等代材料原理、等效围压理论及弹性层板理论。并对加筋土挡墙各种破坏模式及其内外稳定性设计方法进行分析和总结。（2）根据加筋土挡墙的结构特点，将其简化成平面应变问题进行分析。依据加筋土挡墙的组成材料特点，选择适合的的单元类型。设置关键参数，利用ANSYS有限元软件建立了由土体单元、筋材单元、接触单元，面板单元组成的非线性有限元模型，设置关键参数，并进行了地震力作用下有限元分析。（3）从挡墙水平位移，加速度放大效应，，筋带拉力分布三个方面对加筋土挡墙模拟结果进行分析。挡墙水平位移方面：在各级地震作用下，挡墙水平位移沿着墙高方向增大，在地震加速度较小时，挡墙沿着墙高方向的水平位移变化平缓，增量较小，在地震加速度较大时，挡墙沿着墙高方向水平位移的变化较大，增量较大。随着地震波加速度峰值的增大，加筋土挡墙顶部一质点的水平位移最大值呈增大的趋势，远离挡板的点的水平位移越小；加筋土挡墙的最大位移点在顶部靠近面板处的地方；在地震加速度到达峰值的时刻，挡墙的水平位移并未达到最大。加速度放大效应方面：挡墙质点的加速度放大倍数随地震加速度的峰值的增大而增大；沿墙高方向，加速度放大倍数呈变大的趋势；加筋土挡墙顶部质点的加速度放大倍数最大。筋带拉力分布方面：在加速度峰值为0.1g的地震作用下，筋带拉力最大值沿墙高方向增大，沿着筋带长度方向减小，由于筋带与挡板固定连接，筋带拉力最大值在挡板与筋材连接处，在对挡墙的抗震设计时应考虑对二者连接点的加固；在加速度峰值为0.2g～0.4g地震波作用下，筋带拉力沿长度方向先增大后减小，随着地震强度增大，潜在破裂面向后移动，在挡墙筋材的长度设计时，应考虑地震强度的影响。
[Abstract]:From ancient times people mixed grass bars into mud to build reinforced walls to modern reinforced earth subgrade, retaining wall, bridge abutment and so on, reinforced earth technology has a long history of application, in which reinforced earth retaining wall has beautiful shape, so it is economical to build. The advantages of convenient construction and excellent technical performance have become an important aspect of the application of modern reinforced earth technology, and have been favored by the engineering circles. Compared with the history and scope of application of reinforced earth retaining wall, the theoretical research on it is lagging behind and insufficient. Especially in the aspect of dynamic characteristics and dynamic design, our country is an earthquake prone area, which requires geotechnical structure to have certain seismic performance. However, there is no perfect theory and standard for seismic design of reinforced earth retaining wall in our country and other countries up to now. Therefore, it is very necessary and urgent to study the dynamic performance of reinforced earth retaining wall under earthquake. This paper mainly analyzes the dynamic performance of reinforced earth retaining wall under earthquake. The main research contents and results are as follows:. 1) the development history of reinforced earth retaining wall, the research trends at home and abroad, and the failure examples of reinforced earth retaining wall under earthquake action are introduced. The material selection requirements and structural characteristics are summarized and summarized. The reinforcement mechanism of geogrid is introduced and analyzed, including friction reinforcement principle, quasi-cohesive force principle, homogenization material principle, etc. The equivalent confining pressure theory and elastic laminate theory, and the analysis and summary of various failure modes and internal and external stability design methods of reinforced earth retaining wall are carried out. According to the structural characteristics of reinforced earth retaining wall, the problem of plane strain is simplified and analyzed. According to the material characteristics of reinforced earth retaining wall, the suitable element type is selected and the key parameters are set. A nonlinear finite element model consisting of soil element, steel element, contact element and panel element is established by using ANSYS software. The key parameters are set up and the finite element analysis is carried out under the action of seismic force. 3) the simulation results of reinforced earth retaining wall are analyzed from three aspects: horizontal displacement of retaining wall, acceleration amplification effect and distribution of tension force of reinforced soil. The horizontal displacement of retaining wall increases along the direction of wall height under earthquake action at all levels. When the earthquake acceleration is small, the horizontal displacement of the retaining wall along the direction of the wall height changes slowly, and the increment is small. When the earthquake acceleration is large, the horizontal displacement of the retaining wall along the direction of the wall height changes greatly. The increment is larger. With the increase of the peak acceleration of seismic wave, the maximum horizontal displacement of a particle at the top of reinforced earth retaining wall tends to increase, and the horizontal displacement of the point far away from the baffle is smaller. The maximum displacement of the reinforced earth retaining wall is near the top of the slab; at the moment when the seismic acceleration reaches its peak, The horizontal displacement of the retaining wall does not reach the maximum. In terms of acceleration amplification effect, the acceleration amplification multiple of the retaining wall particle increases with the increase of the peak value of the seismic acceleration, and along the direction of the wall height, the acceleration amplification multiple tends to increase. The maximum magnification of acceleration at the top of reinforced earth retaining wall is maximum. The maximum tensile force increases along the height of the wall and decreases along the direction of the length of the reinforcement band under the earthquake with a peak acceleration of 0.1 g. Because of the fixed connection between the steel strip and the retaining plate, the maximum tensile force of the steel band is at the joint of the retaining plate and the steel bar, and the reinforcement of the joint points should be considered in the seismic design of the retaining wall, under the action of the earthquake wave with a peak acceleration of 0.2 g / 0. 4 g, The tensile force of the reinforcement increases first and then decreases along the length direction. With the increase of the earthquake intensity, the potential rupture moves backward. The influence of seismic intensity should be taken into account in the length design of the retaining wall reinforcement.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U417.11

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