穿越多层溶洞桥梁桩基的竖向承载力及沉降变形研究

发布时间：2018-03-03 23:05

本文选题：桥梁桩基　切入点：穿越多层溶洞的嵌岩桩　出处：《西南交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：岩溶地区地质条件较为复杂,溶洞的存在对于桥梁桩基工程的工作性状影响很大。本文依托四川宜宾—叙永高速公路爪龙岩大桥工程,其中K59+019至K59+125段岩溶发育,溶洞呈串珠状,部分有填充,桥梁的多个桥墩柱下的桩基穿过多层溶洞。在分析了岩溶区桩基的竖向承载机理的基础上,研究了穿越多层溶洞的桥梁桩基竖向承载力和沉降变形的计算分析方法。主要研究工作及结果如下：(1)分析讨论了岩溶区嵌岩桩桩侧阻力和桩端阻力的发挥特点,推导出了当嵌岩桩存在下卧溶洞时或者桩基穿越多层溶洞时的考虑溶洞顶板厚度的桩基竖向承载力计算公式。(2)基于荷载传递法,给出了当桩基穿越多层溶洞时,按桩顶沉降控制的桩基竖向承载力计算公式。(3)通过数值模拟讨论分析了溶洞高度、宽度、数量以及溶洞间竖向相对距离对桩基桩身位移、桩身轴力以及桩侧摩阻力分布的影响,分析结果表明,当桩顶的竖向荷载较小时,溶洞高度、数量以及溶洞间竖向相对距离仍会对桩身的受力和位移分布产生影响,而溶洞宽度对桩基影响较小。同时,模拟分析了实际工程中桥墩下群桩基础的桩身位移和受力分布特征。(4)针对爪龙岩大桥工程实例,采用所提出的理论计算方法和数值分析方法得到的桩基极限竖向承载力差值在15%以内,同时两种方法得到的桩顶荷载-沉降曲线也较为接近。本文在穿越多层溶洞桥梁桩基的竖向承载力及沉降变形方面的研究结果,可为岩溶地区相关工程设计与施工提供参考。
[Abstract]:The geological conditions in karst area are more complicated, and the existence of karst cave has a great influence on the working characteristics of bridge pile foundation engineering. This paper relies on the project of Chaolongyan Bridge of Yibin Xuyong Expressway in Sichuan Province, in which the karst develops from K59 019 to K59 125. The cavern is beaded, partially filled, and the pile foundation under the pier column of the bridge passes through the multi-layer cavern. Based on the analysis of the vertical bearing mechanism of the pile foundation in karst area, This paper studies the calculation and analysis method of vertical bearing capacity and settlement deformation of bridge pile foundation passing through multi-layer karst cave. The main research work and results are as follows: 1) the characteristics of pile side resistance and pile tip resistance in karst area are analyzed and discussed. The calculation formula of vertical bearing capacity of the pile foundation considering the thickness of the roof of the cavern is derived when the rock-socketed pile exists in a horizontal cavern or when the pile foundation passes through a multi-layer karst cave. The formula of vertical bearing capacity of the pile foundation is derived. Based on the load transfer method, when the pile foundation passes through a multi-layer cavern, the formula is given. According to the calculation formula of vertical bearing capacity of pile foundation controlled by settlement of pile top, the influence of the height, width, quantity and vertical relative distance of karst cave on the displacement of pile body, axial force of pile body and the distribution of frictional resistance of pile side are discussed through numerical simulation. The results show that when the vertical load on the top of the pile is small, the height, quantity and vertical relative distance between the caverns will still affect the stress and displacement distribution of the pile body, while the width of the karst cave will have little effect on the pile foundation. The displacement and stress distribution characteristics of pile body under piers in practical engineering are simulated and analyzed. The difference of ultimate vertical bearing capacity of pile foundation obtained by the proposed theoretical calculation method and numerical analysis method is less than 15%. At the same time, the load-settlement curve of pile top obtained by the two methods is similar. The research results of vertical bearing capacity and settlement deformation of pile foundation through multi-layer cavernous bridge in this paper can provide reference for the design and construction of relevant engineering in karst area.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U443.15

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