湿陷性黄土对梁桥桩基承载力的影响

发布时间：2018-03-05 06:30

本文选题：湿陷性黄土　切入点：桥梁桩基　出处：《长安大学》2014年硕士论文　论文类型：学位论文

【摘要】：由于湿陷性黄土引起的工程事故屡见不鲜，在众多的经验教训之后，我们虽然对黄土地区桩基工程设计问题有一些局部认识和实践经验，但是还是缺少更透彻的研究，所以该问题也更多的受到了各界的重视。提出一套适用的湿陷性黄土区桩基设计技术体系，对当下的工程建设来说尤为要紧且紧迫。为了深入研究湿陷性黄土区桩基的承载特性，本文总结了大量工程试验的数据资料，并且采用先进的数值模拟手段和传统理论计算相结合的方式来分析该问题，得出若干结论，以期对当下桥梁工程设计及施工有所助益。本文基于剪切位移法及弹性理论，推导了自重湿陷性黄土条件下桩基沉降、轴力及中性点计算公式。并利用有限元差分软件（FLAC3D）建立桥梁桩基单桩空间轴对称有限元模型；结合此模型采用叠加法计算自重湿陷性黄土地区合理桩长，得出当中性点上、下土层摩擦力分布形式相同时，应增加的桩长与摩擦力的分布形式无关，而只与极限摩擦力的大小有关的结论。运用此方法分析自重湿陷性黄土湿陷特性对桩基承载性状的影响规律，结果表明：在极限荷载时，中性点深度与桩长有关；湿陷系数对桩剩余承载力的影响是非线性的；定量给出了中性点深度及应增加桩长的范围。最后将上述理论及模拟计算结果与桩基现场浸水加载试验数据进行比对，对比结果显示了本文所建桩基计算模型是正确合理的。
[Abstract]:Because It is often seen. engineering accident caused by collapsible loess, after numerous lessons, although we have some local knowledge and practice experience for the design of pile foundation engineering in loess area, but still lack a more thorough study, this problem has been more attention from all walks of life. A set of collapsible foundation design technical system of loess area, the current construction is particularly important and urgent. In order to further study the bearing characteristics of pile foundation in collapsible loess area, this paper summarizes a large number of engineering test data, and combined with advanced mining calculation methods of numerical simulation and traditional theory method to analyze the problems, some conclusions are drawn, expecting to be helpful to the design and construction of the bridge project.
In this paper, the shear displacement method and based on the elastic theory, deduced the weight of pile foundation in collapsible loess under the condition of settlement calculation formula and the neutral axis force. And difference by using the finite element software (FLAC3D) to establish the axisymmetric finite element model of bridge pile foundation pile space; this model combined with the superposition calculation of collapsible loess area reasonable pile length, when the neutral point, under the soil friction distribution form is the same, regardless of the distribution form of added pile length and friction, and friction force and limit the conclusions. By using the method of self weight collapsible loess characteristics influence of the character of the pile bearing results show that: in the limit load, the depth of neutral point and the pile length; influence coefficient of collapsibility of pile residual bearing capacity is nonlinear; given the depth of neutral point and should increase the range of pile length.
Finally, the above theory and simulation results are compared with the data of in-situ immersion test of pile foundation, and the comparison results show that the pile foundation calculation model established in this paper is correct and reasonable.

【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U443.15

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