既有铁路盖板涵耐久性评估与寿命分析

发布时间：2018-05-20 17:43

本文选题：大秦重载铁路 + 疲劳　；参考：《兰州交通大学》2015年硕士论文

【摘要】：大秦铁路作为中国“西煤东运”的最重要通道,2010年总运量达到4亿吨,是设计年运输量的4倍,同时大秦铁路的列车轴重也在不断提高,已远远超出设计标准。从大秦线现在的运行状况看,路线所经过盖板涵常处于超载的工作状态,盖板涵耐久性下降严重,影响线路的运营安全。因此,对大秦铁路盖板涵进行耐久性研究成为了亟待解决的问题。疲劳因素和外界环境因素对既有铁路盖板涵的综合作用,使得盖板涵发生耐久性劣化。本文通过现场调查、室内试验、建模分析等对盖板涵进行耐久性评估和寿命分析,主要研究内容为:(1)对大秦重载铁路既有盖板涵进行现场实测,测试内容包括混凝土强度、混凝土碳化深度、混凝土保护层厚度、氯离子含量等,通过调查可知既有盖板涵强度降低、氯离子侵蚀深度大于碳化深度。(2)通过对盖板涵进行25t、27t、30t轴重下疲劳性能足尺模型室内试验,可以得到,钢筋和混凝土的应变与加载力基本呈线性关系;钢筋与混凝土的应变和应变幅值随疲劳次数的发展规律为先快后慢,大约在5万次后增长幅度减缓,前期增长幅度较大;疲劳荷载为27t、30t时,盖板梁跨中挠度均超过规范容许值值。根据试验测试结果,计算分析不同轴重下盖板疲劳寿命,可知轴重对盖板疲劳寿命影响较大。(3)通过学习向量化(LVQ)神经网络评估法和有限元分析对盖板涵进行耐久性评估;并利用材料S-N曲线、概率极限状态分析计算方法和以Fick第二定律为基础的氯离子侵蚀寿命预测模型对盖板涵进行寿命预测。可以得到,得出钢筋锈蚀对盖板涵受力性能影响较大;盖板涵评估结果除强度外其他均良好;随着轴重的增加,钢筋与混凝土的疲劳寿命锐减,钢筋疲劳寿命降低比例高于混凝土;25T轴重下盖板涵碳化剩余寿命为48年;25T轴重下盖板涵氯离子侵蚀剩余寿命为13.5年。各计算方法只考虑单因素作用下的盖板涵寿命,为受荷载和环境综合影响下的既有盖板涵寿命提供参考。
[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.
【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】：U449

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