乌江岸坡特大桥桥墩桩基承载特性的数值模拟研究

发布时间：2018-03-30 04:03

本文选题：岸坡　切入点：特大桥桥墩　出处：《吉林大学》2016年硕士论文

【摘要】：为了解决人口的爆炸增长带来的土地资源日益紧缺难题,建筑开始往高大化方向发展,同时基于战略发展的需要,一些重要的国家级公路、桥梁工程不得不选择穿越一些恶劣的工程地质环境,由此在设计上对于建筑和桥梁桩基的承载性能要求就越来越高。传统的静力荷载等现场原位试验很难准确测定这类特大型桩基的承载力,而且由于理论发展的不完善以及面对的工程挑战越来越复杂,各类测试方法仍存在一些缺陷和不足。受限于中国西部山区特殊的地形地貌条件,许多道路桥梁工程只能依山而建,通过高架桥或者半路半桥的结构建设,使得部分桩基建设在斜坡甚至危险的断臂悬崖之上。对于处在边坡上的桩基承载特性以及桩基工程对边坡稳定性影响方面的研究相对较少,目前也没有相关的行业规范和统一公式可以参照。传统数值计算方法得益于计算机性能的高速提升和程序编程技术的不断完善,近年来取得了飞速发展。本文根据工程项目勘察和试验所获得的工程概况、地层岩性等基础资料,利用FLAC3D软件平台构建了三维数值模型。首先利用强度折减法原理,通过求解安全系数评价了岸坡在天然条件下的稳定状况;然后结合工程实际地理环境条件,利用该模型分析了桥桩在承担上部结构施加的组合荷载之后的受力变形情况;最后运用FLAC3D动力分析模块,分析了桥桩与岸坡在地震荷载作用下的动力响应情况。研究认为:(1)运用强度折减法求得工程施工完成后的岸坡安全系数为2.59,说明桥梁工程的施工对岸坡整体稳定性并未造成太大影响,岸坡仍处于稳定状态。(2)桩基承受的竖向荷载占主导部分,因此竖向位移要比水平向位移要大,模型的最大竖向位移和水平位移都分布在直接受荷的承台部位。(3)桩基在所施加的荷载条件下,未达到极限承载状态。桩基的竖向位移和水平位移均随着桩深增加而减小,桩身出现了挠曲变形。不同位置的桩基轴力出现明显差异,角桩的轴力明显大于中心桩,说明群桩效应发挥了影响。(4)在地震荷载作用下,各监测点的速度时程曲线波动规律与输入的地震波速度时程曲线基本一致,边坡对输入地震波存在垂直放大和临空面放大效应。
[Abstract]:In order to solve the growing shortage of land resources caused by the explosion of population, the construction began to develop in the direction of high scale. At the same time, based on the need of strategic development, some important national-level highways,Bridge engineering has to choose to pass through some bad engineering geological environment, so the design requirements for the bearing capacity of building and bridge pile foundation are more and more high.Traditional in-situ tests such as static load are difficult to accurately measure the bearing capacity of this kind of super-large pile foundation. Due to the imperfection of theoretical development and the increasing complexity of engineering challenges, there are still some defects and deficiencies in various testing methods.Limited by the special topographical and geomorphological conditions in the mountainous areas of western China, many road and bridge projects can only be built according to the mountains. Through the structural construction of viaducts or half-bridges, some piles are built on slopes or even dangerous breakaway cliffs.There are few researches on the bearing characteristics of pile foundation on slope and the influence of pile foundation engineering on slope stability, and there are no relevant industry codes and unified formulas to refer to.The traditional numerical calculation method has made rapid progress in recent years thanks to the rapid improvement of computer performance and the continuous improvement of programming technology.Based on the basic data of engineering survey and test, stratigraphic lithology and so on, a three-dimensional numerical model is constructed by using FLAC3D software platform in this paper.In this paper, the stability of bank slope under natural conditions is evaluated by solving the safety factor by using the principle of strength reduction, and then combined with the actual geographical and environmental conditions of engineering,The model is used to analyze the deformation of the bridge pile under the combined load imposed by the superstructure, and the dynamic response of the bridge pile and the bank slope under the earthquake load is analyzed by using the FLAC3D dynamic analysis module.The study shows that the slope safety coefficient after the completion of the project is 2.59 by using the strength reduction method, which shows that the bridge construction has no great effect on the overall stability of the bank slope.The vertical load of the pile foundation is the dominant part, so the vertical displacement is larger than the horizontal displacement.The maximum vertical displacement and horizontal displacement of the model are distributed in the directly loaded pile cap.The vertical displacement and horizontal displacement of pile foundation decrease with the increase of pile depth, and the pile body appears flexural deformation.The axial force of the angular pile is obviously larger than that of the central pile, which indicates that the pile group effect has played an important role under the earthquake load.The fluctuation law of the velocity time-history curve of each monitoring point is basically consistent with the input seismic wave velocity time-history curve, and the slope has the effect of vertical amplification and near-empty surface amplification on the input seismic wave.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U443.15

【相似文献】