高铁列车动载作用下路基动力特性及累积变形规律研究

为探索列车动载作用下路基的动力特性及累积变形规律,依托沪宁城际铁路工程背景,首先结合现场测试数据对路基沉降超限的原因进行分析,然后建立列车-轨道-路基耦合振动系统三维数值模型,对影响路基动力特性的影响因素(列车速度、基床厚度和刚度、行车方式)进行分析,最后结合室内足尺模型试验,对振动40万次的基床累积变形规律进行分析。结果表明:列车动载作用是运营期路基沉降超限的主要原因之一;列车速度、基床厚度和刚度、行车方式等因素对基床的动应力和动位移均有影响;路基的累积变形随循环加载次数增加而变大,最初振动5万次累积变形增长迅速,而后近似按照线性缓慢发展,振动40万次时的累积变形值为0.78 mm,影响深度约为5 m。

Study on Dynamic Characteristics and Cumulative Deformation Law of Subgrade under Dynamic Load of High-speed Train

In order to explore the dynamic characteristics and accumulative deformation of the subgrade under dynamic train load,the causes of the roadbed settlement overrun are analyzed with the field test data based on Shanghai-Nanjing intercity railway project and then the train-track-subgrade coupling vibration system three-dimensional model is established to analyze the influence factors(such as train speed,bed thickness and rigidity,driving mode). Finally,the accumulative deformation law of the foundation bed with 400 000 vibrations is analyzed by means of indoor full scale model test. The results show that the dynamic train load is one of the main causes for the subsidence of the subgrade in the operational period. The factors such as train speed,bed thickness and stiffness,and driving mode constitute effects on the dynamic stress and the dynamic displacement of the subgrade; with the increase in the number of cyclic loading,the accumulative deformation of the subgrade develops rapidly during the initial 50 000 vibrations and tends to be a slow linear development afterwards. The accumulative deformation is 0. 78 mm after 400 000 vibrations with impacted depth of some 5 m.