【作者】 杨雪；

【导师】 时瑾；

【作者基本信息】 北京交通大学 ， 道路与铁道工程， 2015， 硕士

【摘要】 近年来我国重载运输取得了快速发展,目前既有重载线路已普遍开行25t轴重万吨列车,27t、30t大轴重列车也已上线运行。重载货车作用下线路破坏问题与基床表层应力状态密切相关。本文通过建立重载货车作用下路基动力分析模型,分析了车辆通过时基床表层应力状态变化规律,研究了速度、道床厚度、轴重、基床表层刚度、随机不平顺等因素对基床表层应力状态及服役寿命影响。通过本文研究得到主要结论如下：(1)列车通过时基床表层土单元应力状态遵循从纯剪到三轴剪切再回到纯剪状态的变化规律,整个过程中主应力轴连续旋转1800。(2)通过比较不同因素对基床表层应力状态的影响发现：在填料性能劣化(内摩擦角低于320)情况下,速度大于120km/h、轴重超过30t、道床厚度低于0.3m均有可能使得基床表层土单元应力路径曲线超过摩尔-库伦破坏线,具有破坏风险。(3)随机不平顺对基床应力状态存在较大影响。线路平顺性状态越差,基床垂向动应力分布愈加离散,较大动应力出现的可能性提高,易于降低基床服役寿命,增大基床表层破环风险。计算表明：25t轴重货车以80km/h的速度运行时,五级谱和四级谱轨道平顺性条件下基床服役寿命比六级谱平顺性条件下寿命分别降低了33.78%、99.11%。(4)轴重提高显著降低基床服役寿命。计算表明：列车80km/h运行速度情况下,在完全平顺、六级谱、五级谱、四级谱轨道平顺性条件下轴重从25t增加到30t时,基床服役寿命分别降低50.31%,56.67%、61.02%、70.2%。(5)速度对基床服役寿命有一定影响。计算表明：25t轴重重载铁路,在完全平顺、六级谱、五级谱、四级谱轨道平顺性条件下列车速度从60km/h增加到80km/h时,基床服役寿命分别降低42.6%、62.73%、67.04%、75.67%;速度从80km/h增加到1OOkm/h,基床服役寿命分别降低29.71%,33.69%、44.9%、50%。更多还原

【Abstract】 The heavy haul freight transportation has got great development in recent years. Generally axle load on present heavy line is25t, but27t and30t axle load have been running. The failure of heavy haul line during train passage is closely related to the stress state of subgrade surface. In order to study the stress path in soil element of subgrade under moving train load, in this paper, a dynamic freight-railway model is used to analyze the stress state of subgrade surface during freight train passage and influence of thickness of ballast layer, axle load, speed, and modulus of subgrade surface, track roughness on stress state and service life of subgrade surface have been investigated. It is found that:(1)Results indicate that the stress state changes from initial state to pure shear to triaxial shear and back to pure shear and the principle stress axes rotate1800though it is more complex due to the interaction of wheels.(2)Comparing effects of different factors on stress state,it is shown that:As velocity is higher than120km/h, axle load exceeds30t, thickness of ballast under0.3m, the stress path will surpass the Mohr-coulomb failure line. Which means that subgrade is not safe.(3)Track roughness has some influence on stress state of subgrade surface. Distribution of vertical stress will become more discrete with the deterioration of track irregularity, which can also increase the probability of higher stress. All of these cases tend to decrease subgrade service life. It is shown that:as25t axle load heavy haul drive at speed of80km/h, subgrade service life of FRA5and FRA4deceased respectively by33.78%and99.11%compared with case of FRA6.(4)Axle load has greater influence on subgrade service life. It is shown that:As velocity is80km/h, service life of subgrade surface dropped by50.31%,70.2%,61.02%,56.67%for case of without track roughness、FRA4、FRA5、FRA6when axle load increase from25t to30t.(5)Velocity has some influence on subgrade service life. It is shown that:as axle load is25t, service life of subgrade surface dropped respectively by42.4%,62.73%,67.04%,75.67%for case of without track roughness、FRA4、FRA5、FRA6when velocity rise from60km/h to80km/h. While service life of subgrade surface dropped respectively by29.71%,33.69%,44.9%,50%for case of without track roughness、FRA4、FRA5、FRA6when velocity rise from80km/h to100km/h.更多还原