堆载作用下黄土冲沟区桥梁桩基础竖轴向承载特性研究

发布时间：2018-01-23 03:03

本文关键词： 黄土冲沟区桥梁桩基础堆载作用竖向承载特性剪切位移法数值仿真人工智能优化设计系统　出处：《长安大学》2014年硕士论文　论文类型：学位论文

【摘要】：堆载作用下黄土冲沟区桩基础受到桩身外侧土体缺失效应与堆载作用的耦合作用影响，使其荷载传递机理和承载特性变化规律极为复杂，国内外研究对这方面关注较少，且我国相关的桥梁基础设计施工规范尚未涉及堆载对冲沟区桩基础的影响。本文在对堆载作用下黄土冲沟区公路桥梁桩基础的实际工程情况进行调研的基础上，通过理论分析计算、数值仿真试验及人工智能优化系统的建立，对黄土冲沟区桩基础在堆载作用下承载特性进行研究，主要工作及成果有： 1.通过理论分析及数值仿真试验得到影响堆载作用下冲沟区桥梁桩基础承载特性的实质是：堆载作用与桩侧土体缺失效应耦合作用引起的桩身两侧的桩周土体剪应力-剪应变关系不协调变化。基于优化的剪切位移法和多层土负摩阻力计算原理，给出了堆载作用下坡顶桩和坡中桩承载力-沉降量理论计算的解析解公式。 2.通过数值仿真试验分析了堆载土层厚度、冲沟坡度、桩径及桩长对不同桩位堆载作用下冲沟桩基础的承载特性的影响，并针对每个影响因素给出相应工程设计建议，得出相应工程设计指导建议——设置合理桩长可以减小堆载给桩基础承载力带来的不利影响。 3.利用基于GA-BP神经网络预测模型针对堆载作用下冲沟区桥梁桩基础进行优化设计，，给出同时满足承载力要求和堆载影响的合理桩长。研究成果将为堆载作用下黄土冲沟地区公路桥梁桩基础的设计与施工奠定坚实的理论基础。
[Abstract]:Pile foundation in loess gully area under surcharge is affected by the coupling effect of soil loss and surcharge on the outside of pile body, which makes the load transfer mechanism and load characteristic change law very complicated. Little attention has been paid to this aspect in domestic and foreign studies. The influence of pile load on pile foundation in gully area has not been covered in the relevant design and construction code of bridge foundation in China. This paper investigates the actual engineering situation of highway bridge pile foundation in loess gully area under the action of surcharge. Through theoretical analysis and calculation, numerical simulation test and the establishment of artificial intelligence optimization system, the bearing characteristics of pile foundation in loess gully area under the action of pile load are studied. The main work and results are as follows: 1. Through theoretical analysis and numerical simulation test, it is found that the essence of bearing characteristics of bridge pile foundation in gully area under the action of surcharge is:. The relationship between shear stress and shear strain on both sides of the pile caused by the coupling of the surcharge action and the soil loss effect on the side of the pile is not in harmony, which is based on the optimized shear displacement method and the calculation principle of the negative friction resistance of the multi-layer soil. An analytical formula for calculating the bearing capacity and settlement of the top pile and the pile in the slope under the action of heaped load is given. 2. Through the numerical simulation test, the influence of the thickness of the surcharge soil, the slope of the gully, the diameter of the pile and the length of the pile on the bearing characteristics of the pile foundation under different pile positions are analyzed. According to each influencing factor, the corresponding engineering design suggestion is given. It is concluded that setting reasonable pile length can reduce the adverse effect of pile load on the bearing capacity of pile foundation. 3. The optimization design of bridge pile foundation in gully area under surcharge is carried out by using the prediction model based on GA-BP neural network. The reasonable pile length which can satisfy both the bearing capacity requirement and the influence of heaped load is given. The research results will lay a solid theoretical foundation for the design and construction of highway bridge pile foundation in loess gully area under the action of heaped load.
【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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