胀裂腐蚀对干寒地区桥梁安全性能影响研究

发布时间：2018-11-28 18:43

【摘要】：我国西北干(旱)寒(冷)地区海拔较高,高山环绕,由于干燥、寒冷、温差、大风和强紫外线等气候特征形成了冻融循环、干湿冷热交替和风沙侵蚀等典型的自然气候环境。在上述自然及工程条件下,既有桥梁在远未达到设计使用寿命时,耐久性退化及安全性能严重不足,出现混凝土胀裂腐蚀、剥落及钢筋锈蚀等严重的病害现象,对桥梁的正常使用造成了极大的影响。目前我国针对西北干寒地区桥梁胀裂腐蚀病害的养护管理技术研究远落后于其他发达国家。为了探究盐冻病害对钢筋混凝土桥梁安全性能的影响,分别从桥梁承载能力和耐久性能两个方面进行分析研究;首先就混凝土冻胀的机理以及氯盐的腐蚀机理进行分析探讨,主要从冻胀裂缝、氯盐腐蚀、冻融剥蚀、钢筋锈蚀、弹性模量下降等各方面的影响下,总结混凝土力学性能的变化规律,以期对钢筋混凝土桥梁进行安全性的准确定位,进一步为西北干寒地区桥梁胀裂腐蚀病害影响下的承载力及耐久性设计提供理论参考。本题以连霍高速嘉峪关段的公路桥梁为工程背景,并以野猪沟大桥、北干渠中桥为主要研究对象,主要研究内容及结论如下:(1)基于对国内外的耐久性研究动态,对西北干寒地区桥梁病害进行调研,总结胀裂腐蚀病害在桥梁中的表现,对干寒地区桥梁盐冻病害产生的原因及机理进行分析。(2)结合所学力学知识,分析混凝土受损伤后的力学性能及本构关系,对冻胀腐蚀破坏进行初步的数值分析及有限元软件的模拟,比较受冻后桥梁各项指标的变化。(3)基于冻胀裂缝的计算原理和氯盐对钢筋混凝土构件的腐蚀原理,分析对桥梁结构承载能力的影响,并对损伤钢筋混凝土桥梁结构的剩余承载力进行计算。(4)对干寒地区盐冻病害环境下的钢筋混凝土构件的耐久性能进行分析,对桥梁胀裂腐蚀病害下其使用寿命进行估算并提出有效的防治建议。
[Abstract]:The dry (dry) cold (cold) area of northwest China has a relatively high altitude and alpine surrounding. Due to the climatic characteristics of dryness, cold, temperature difference, strong wind and ultraviolet rays, the typical natural climate environment is freeze-thaw cycle, alternate dry and wet cold and heat, wind and sand erosion and so on. Under the above natural and engineering conditions, when the existing bridges are far from reaching their design life, the durability of the existing bridges is degraded and the safety performance is seriously inadequate, resulting in serious problems such as concrete expansion, cracking and corrosion, exfoliation and corrosion of steel bars, etc. It has a great impact on the normal use of the bridge. At present, the research on maintenance and management technology of bridge dilatation and cracking corrosion in dry and cold region of northwest China lags far behind other developed countries. In order to explore the effect of salt freezing disease on the safety performance of reinforced concrete bridge, the bearing capacity and durability of the bridge are analyzed and studied respectively. Firstly, the mechanism of frost heaving of concrete and the corrosion mechanism of chloride salt are analyzed and discussed, mainly under the influence of frost heaving crack, chloride salt corrosion, freeze-thaw denudation, steel bar corrosion, and the decrease of elastic modulus, etc. The change law of concrete mechanical properties is summarized in order to accurately locate the safety of reinforced concrete bridges and to provide a theoretical reference for the bearing capacity and durability design of bridges under the influence of dilatation cracking and corrosion diseases in dry and cold regions of northwest China. Taking the highway bridge in Jiayuguan section of Lianghu Expressway as the engineering background, and taking the Wild Pig ditch Bridge and the North main Canal Bridge as the main research objects, the main contents and conclusions are as follows: (1) based on the research trends of durability at home and abroad, This paper investigates the bridge diseases in the dry and cold regions of northwest China, summarizes the manifestation of the expansion cracking and corrosion diseases in the bridges, and analyzes the causes and mechanism of the salt frozen diseases of the bridges in the dry and cold regions. (2) combined with the mechanical knowledge, The mechanical properties and constitutive relation of concrete after damage are analyzed. The preliminary numerical analysis of frost heaving corrosion failure and the simulation of finite element software are carried out. Based on the calculation principle of frost heaving crack and the corrosion principle of chloride salt to reinforced concrete members, the influence on the bearing capacity of bridge structure is analyzed. The residual bearing capacity of damaged reinforced concrete bridge structures is calculated. (4) the durability of reinforced concrete members under the condition of salt and frozen diseases in dry and cold regions is analyzed. In this paper, the service life of bridge under dilatancy and crack corrosion is estimated and some effective prevention suggestions are put forward.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.73

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