發(fā)布時間：2018-05-20 17:43

  本文選題：大秦重載鐵路 + 疲勞��； 參考：《蘭州交通大學》2015年碩士論文

【摘要】：大秦鐵路作為中國“西煤東運”的最重要通道,2010年總運量達到4億噸,是設(shè)計年運輸量的4倍,同時大秦鐵路的列車軸重也在不斷提高,已遠遠超出設(shè)計標準。從大秦線現(xiàn)在的運行狀況看,路線所經(jīng)過蓋板涵常處于超載的工作狀態(tài),蓋板涵耐久性下降嚴重,影響線路的運營安全。因此,對大秦鐵路蓋板涵進行耐久性研究成為了亟待解決的問題。疲勞因素和外界環(huán)境因素對既有鐵路蓋板涵的綜合作用,使得蓋板涵發(fā)生耐久性劣化。本文通過現(xiàn)場調(diào)查、室內(nèi)試驗、建模分析等對蓋板涵進行耐久性評估和壽命分析,主要研究內(nèi)容為:(1)對大秦重載鐵路既有蓋板涵進行現(xiàn)場實測,測試內(nèi)容包括混凝土強度、混凝土碳化深度、混凝土保護層厚度、氯離子含量等,通過調(diào)查可知既有蓋板涵強度降低、氯離子侵蝕深度大于碳化深度。(2)通過對蓋板涵進行25t、27t、30t軸重下疲勞性能足尺模型室內(nèi)試驗,可以得到,鋼筋和混凝土的應(yīng)變與加載力基本呈線性關(guān)系;鋼筋與混凝土的應(yīng)變和應(yīng)變幅值隨疲勞次數(shù)的發(fā)展規(guī)律為先快后慢,大約在5萬次后增長幅度減緩,前期增長幅度較大;疲勞荷載為27t、30t時,蓋板梁跨中撓度均超過規(guī)范容許值值。根據(jù)試驗測試結(jié)果,計算分析不同軸重下蓋板疲勞壽命,可知軸重對蓋板疲勞壽命影響較大。(3)通過學習向量化(LVQ)神經(jīng)網(wǎng)絡(luò)評估法和有限元分析對蓋板涵進行耐久性評估;并利用材料S-N曲線、概率極限狀態(tài)分析計算方法和以Fick第二定律為基礎(chǔ)的氯離子侵蝕壽命預測模型對蓋板涵進行壽命預測�？梢缘玫�,得出鋼筋銹蝕對蓋板涵受力性能影響較大;蓋板涵評估結(jié)果除強度外其他均良好;隨著軸重的增加,鋼筋與混凝土的疲勞壽命銳減,鋼筋疲勞壽命降低比例高于混凝土;25T軸重下蓋板涵碳化剩余壽命為48年;25T軸重下蓋板涵氯離子侵蝕剩余壽命為13.5年。各計算方法只考慮單因素作用下的蓋板涵壽命,為受荷載和環(huán)境綜合影響下的既有蓋板涵壽命提供參考。
[Abstract]:Daqin Railway is the most important passage for "transporting coal from west to east" in China. In 2010, the total transportation capacity reached 400 million tons, which is four times of the designed annual transport volume. At the same time, the axle weight of Daqin railway is also increasing, which has far exceeded the design standard. According to the current operating condition of Daqin Line, the overloaded cover culvert is often in the working state, and the durability of the cover plate culvert decreases seriously, which affects the operation safety of the line. Therefore, the durability of the Da-Qin railway cover culvert has become an urgent problem to be solved. The fatigue factor and the external environment factor have the comprehensive action to the existing railway cover plate culvert, causes the cover plate culvert to have the durability deterioration. In this paper, durability evaluation and life analysis of cover plate culvert are carried out through field investigation, indoor test, modeling analysis, etc. The main research contents are: 1) on site test of existing cover plate culvert of Daqin heavy haul railway, including concrete strength, The carbonation depth of concrete, the thickness of concrete cover layer, the content of chloride ion, etc., through the investigation, we can know that the strength of the existing cover plate culvert is decreased. The corrosion depth of chloride ion is larger than that of carbonation. (2) the strain and loading force of steel bar and concrete are basically linearly related to the fatigue behavior of cover culvert under 25 t ~ 27 t ~ (30 t) axial load. The strain and strain amplitude of steel bar and concrete are fast and slow with the fatigue times, and the increase range is slow after about 50,000 times, and the increase range is large in the early stage, and when the fatigue load is 27t ~ 30t, the strain and strain amplitude of steel bar and concrete are fast and slow. The mid-span deflection of the cover beam exceeds the allowable value of the code. According to the test results, the fatigue life of the cover plate under different axle loads is calculated and analyzed. It is known that the axle load has a great influence on the fatigue life of the cover plate. (3) the durability of the cover plate culvert is evaluated by the neural network evaluation method of learning vectorization and the finite element analysis. The material S-N curve, probabilistic limit state analysis method and chloride ion erosion life prediction model based on Fick's second law are used to predict the life of cover culvert. It can be concluded that the corrosion of steel bar has a great influence on the mechanical properties of the cover culvert, the evaluation results of the cover culvert are good except for the strength, and the fatigue life of steel bar and concrete decreases sharply with the increase of axle load. The reduction ratio of fatigue life of steel bar is higher than that of concrete overburden culvert under 25T axle load. The residual life of carbonation of cover culvert under 25T axle load is 48 years or 25T, and the residual life of chloride ion erosion of cover plate culvert under 25T axle load is 13.5 years. The calculation methods only consider the service life of the slab culvert under the action of single factor, which provides a reference for the life of the existing slab culvert under the comprehensive influence of load and environment.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U449

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