【摘要】：我國(guó)西北干(旱)寒(冷)地區(qū)海拔較高,高山環(huán)繞,由于干燥、寒冷、溫差、大風(fēng)和強(qiáng)紫外線等氣候特征形成了凍融循環(huán)、干濕冷熱交替和風(fēng)沙侵蝕等典型的自然氣候環(huán)境。在上述自然及工程條件下,既有橋梁在遠(yuǎn)未達(dá)到設(shè)計(jì)使用壽命時(shí),耐久性退化及安全性能嚴(yán)重不足,出現(xiàn)混凝土脹裂腐蝕、剝落及鋼筋銹蝕等嚴(yán)重的病害現(xiàn)象,對(duì)橋梁的正常使用造成了極大的影響。目前我國(guó)針對(duì)西北干寒地區(qū)橋梁脹裂腐蝕病害的養(yǎng)護(hù)管理技術(shù)研究遠(yuǎn)落后于其他發(fā)達(dá)國(guó)家。為了探究鹽凍病害對(duì)鋼筋混凝土橋梁安全性能的影響,分別從橋梁承載能力和耐久性能兩個(gè)方面進(jìn)行分析研究;首先就混凝土凍脹的機(jī)理以及氯鹽的腐蝕機(jī)理進(jìn)行分析探討,主要從凍脹裂縫、氯鹽腐蝕、凍融剝蝕、鋼筋銹蝕、彈性模量下降等各方面的影響下,總結(jié)混凝土力學(xué)性能的變化規(guī)律,以期對(duì)鋼筋混凝土橋梁進(jìn)行安全性的準(zhǔn)確定位,進(jìn)一步為西北干寒地區(qū)橋梁脹裂腐蝕病害影響下的承載力及耐久性設(shè)計(jì)提供理論參考。本題以連霍高速嘉峪關(guān)段的公路橋梁為工程背景,并以野豬溝大橋、北干渠中橋?yàn)橹饕芯繉?duì)象,主要研究?jī)?nèi)容及結(jié)論如下:(1)基于對(duì)國(guó)內(nèi)外的耐久性研究動(dòng)態(tài),對(duì)西北干寒地區(qū)橋梁病害進(jìn)行調(diào)研,總結(jié)脹裂腐蝕病害在橋梁中的表現(xiàn),對(duì)干寒地區(qū)橋梁鹽凍病害產(chǎn)生的原因及機(jī)理進(jìn)行分析。(2)結(jié)合所學(xué)力學(xué)知識(shí),分析混凝土受損傷后的力學(xué)性能及本構(gòu)關(guān)系,對(duì)凍脹腐蝕破壞進(jìn)行初步的數(shù)值分析及有限元軟件的模擬,比較受凍后橋梁各項(xiàng)指標(biāo)的變化。(3)基于凍脹裂縫的計(jì)算原理和氯鹽對(duì)鋼筋混凝土構(gòu)件的腐蝕原理,分析對(duì)橋梁結(jié)構(gòu)承載能力的影響,并對(duì)損傷鋼筋混凝土橋梁結(jié)構(gòu)的剩余承載力進(jìn)行計(jì)算。(4)對(duì)干寒地區(qū)鹽凍病害環(huán)境下的鋼筋混凝土構(gòu)件的耐久性能進(jìn)行分析,對(duì)橋梁脹裂腐蝕病害下其使用壽命進(jìn)行估算并提出有效的防治建議。
[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.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U445.73

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本文編號(hào)：2363917