横坡段桥梁桩基受力特性及影响因素分析

发布时间：2018-08-06 14:14

【摘要】：随着公路交通事业的发展,高速公路向山区不断延伸,为保护山区环境及满足路线线形的要求,高速公路往往采用桥梁结构。然而,面对山区横坡段桥梁桩基的大量出现,尚缺乏与之相适应的设计计算规范。因此,本文针对横坡段桥梁桩基承载机理、内力和位移等问题,开展了以下研究工作:(1)基于横坡段桥梁桩基的受荷特点,综合分析了桩基在竖向、横向、倾斜及组合荷载作用下的承载机理,推导了桩侧边坡下滑推力的计算公式,分析了桩侧岩土体抗力的计算方法及其分布规律。(2)通过对横坡段桥梁基桩进行受力分析,得到基桩自由段、受荷段、嵌固段的挠曲微分方程,并对其采用幂级数法进行求解。在此基础上,开展了不同参数对其受力特性的影响因素分析,分析表明:当滑动面位置较浅时,“陡坡效应”显著,基桩上部有较大的内力和位移;推力分布形式对基桩的内力和位移有一定影响,设计中采用三角形分布,计算结果偏于危险;桩径的合理设计可以改善基桩的内力和位移;基桩的内力和位移与坡体下滑推力合力及桩顶横向荷载呈正相关,与受荷段地基抗力折减系数呈负相关。(3)基于横坡段桥梁双桩结构的特点,建立了前后桩各特征桩段的挠曲微分方程,提出了横坡段桥梁双桩结构受力分析计算方法。在此基础上,开展了不同参数对其受力特性的影响因素分析,分析表明:前后桩桩顶水平位移及桩身最大弯矩与桩间距、桩侧边坡下滑推力合力呈正相关,与受荷段地基抗力比例系数呈负相关;前桩自由段过大,将导致“P-Δ效应”显著。(4)通过对某横坡段桥梁双桩结构进行受力计算,并与有限元计算结果对比分析,验证了本文横坡段桥梁双桩结构受力分析计算方法的可靠性,且分析表明该工程实际设计的合理性。
[Abstract]:With the development of highway traffic, the highway extends to the mountain area continuously. In order to protect the environment of the mountain area and meet the requirement of the route line, the highway often adopts the bridge structure. However, in the face of a large number of bridge pile foundations in the mountainous cross-slope section, there is still a lack of corresponding design and calculation code. Therefore, aiming at the bearing mechanism, internal force and displacement of bridge pile foundation in transverse slope section, the following research work has been carried out: (1) based on the characteristics of bridge pile foundation in transverse slope section, the vertical and horizontal pile foundation is comprehensively analyzed. Under the action of inclined and combined loads, the calculation formula of sliding thrust force of pile side slope is derived, and the calculation method of pile side rock soil resistance and its distribution law are analyzed. (2) the stress analysis of bridge foundation pile in transverse slope section is carried out. The flexural differential equations of free segment, loaded segment and fixed segment of foundation pile are obtained, and the power series method is used to solve them. On this basis, the influence factors of different parameters on the mechanical characteristics of the pile are analyzed. The results show that when the sliding surface is shallow, the "steep slope effect" is significant, and the upper part of the pile has greater internal force and displacement; The distribution of thrust has a certain influence on the internal force and displacement of the pile, the triangular distribution is used in the design, the calculation result is more dangerous, and the reasonable design of the diameter of the pile can improve the internal force and displacement of the pile. The internal force and displacement of the foundation pile are positively correlated with the sliding thrust force of the slope body and the lateral load on the top of the pile, and are negatively correlated with the coefficient of resistance reduction of the loaded section of the foundation. (3) based on the characteristics of the bridge double-pile structure in the transverse slope section, The flexural differential equation of each characteristic pile section of front and rear piles is established, and the analysis and calculation method of bridge double pile structure in transverse slope section is put forward. On this basis, the influence factors of different parameters on the mechanical characteristics of the pile are analyzed. The analysis shows that the horizontal displacement of the pile top and the maximum bending moment of the pile body are positively correlated with the pile spacing and the sliding thrust force of the pile side slope. There is a negative correlation with the resistance ratio coefficient of the foundation in the loaded section, and the "P- 螖 effect" will be significant if the free section of the front pile is too large. (4) the stress calculation of a bridge with two piles in a transverse slope section is carried out, and the results are compared with those of the finite element method. The reliability of the method for the analysis and calculation of the double-pile structure of the bridge in the transverse slope section of this paper is verified, and the analysis shows that the practical design of the project is reasonable.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U443.15

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