嵌岩桩竖向荷载传递机理及其工程特性研究

发布时间：2018-05-12 14:42

本文选题：桩基础 + 嵌岩桩　；参考：《湖南大学》2015年硕士论文

【摘要】：嵌岩桩通常被用于对沉降要求严格、上部荷载较大的工程之中。但由于其承载力较高,很少有现场试验能加载到极限状态,因此对其承载力及荷载传递特性的理解仍存在许多含糊之处,使得实际中常因过于保守而出现一些桩长和桩径不合理的设计,既加大了施工难度,降低了施工效率,又造成了经济上的浪费。因此,对嵌岩桩荷载传递特性的研究具有较大的理论和实践价值。由于桩岩接触与桩土接触存在着本质上的区别,且通常情况下嵌岩段所提供的承载力为嵌岩桩总承载力的最重要的组成部分,本文在考虑桩岩接触面上粗糙特性的基础,探讨嵌岩桩的荷载传递特性的计算方法,并对相关的影响因素做进一步的分析研究。首先,对现阶段国内外的相关研究成果进行总结归纳,深入理解考虑桩岩接触面粗糙及其对承载特性的影响时所面临的困难及其可行的研究方向,并探讨了嵌岩桩的荷载传递特性及其承载力发挥的机理,利用合理假设对桩岩结构面上粗糙体形状规则和不规则两种情况进行描述,结合相关试验结果给出了粗糙程度与力学参数之间的关系。其次,利用滑移线场法求得了桩岩结构面峰值摩阻力,并求得其对应的剪切位移,在此基础上建立了考虑桩岩结构面剪胀特性的剪切函数,结合荷载传递法对桩身的荷载传递特性进行了求解,利用荷载和位移连续条件,推导轴力沿深度的表达式。最后,将本文建立的荷载传递函数与一组室内模型直剪试验的结果进行对比,验证荷载传递函数的适用性。结合某特大桥的现场测试结果,将本文理论方法的计算结果与实测数据进行对比,表明本文方法具有较好的预测效果;对相关参数做了进一步分析,探讨了其对嵌岩桩荷载传递特性的影响。
[Abstract]:Rock-socketed piles are usually used in projects with strict settlement requirements and high upper loads. However, because of its high bearing capacity, very few field tests can be loaded to the ultimate state, so there are still many ambiguities in the understanding of its bearing capacity and load transfer characteristics. It makes some unreasonable design of pile length and diameter often appear because of being too conservative in practice, which not only increases the construction difficulty, reduces the construction efficiency, but also causes the economic waste. Therefore, it is of great theoretical and practical value to study the load transfer characteristics of rock-socketed piles. Because there is an essential difference between pile-rock contact and pile-soil contact, and the bearing capacity provided by rock-socketed segment is the most important part of the total bearing capacity of rock-socketed pile, this paper considers the foundation of the rough characteristics of pile-rock contact surface. This paper discusses the calculation method of load transfer characteristics of rock-socketed pile, and makes further analysis and research on the related factors. First of all, it summarizes the relevant research results at home and abroad at present, and deeply understands the difficulties and feasible research directions when considering the roughness of pile-rock contact surface and its influence on bearing characteristics. The load transfer characteristics of rock-socketed pile and the mechanism of its bearing capacity are discussed, and the shape rules and irregular shape of rough body on the pile-rock structure surface are described by reasonable assumptions. The relationship between the degree of roughness and the mechanical parameters is given based on the experimental results. Secondly, the peak frictional resistance of pile-rock structure surface is obtained by slip line field method, and the corresponding shear displacement is obtained. On the basis of this, a shear function considering the shear dilatancy of pile-rock structural plane is established. Combined with the load transfer method, the load transfer characteristics of the pile body are solved, and the expression of axial force along the depth is derived by using the continuous condition of load and displacement. Finally, the load transfer function established in this paper is compared with the results of a group of indoor model direct shear tests to verify the applicability of the load transfer function. Combined with the field test results of a large bridge, the calculated results of the theoretical method in this paper are compared with the measured data, which shows that the method in this paper has a good prediction effect, and the related parameters are further analyzed. Its influence on load transfer characteristics of rock-socketed pile is discussed.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU473.1

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