高铁荷载下桩-土复合地基振动响应特性研究

Study on dynamic response characteristic of PCC pile-soil composite foundation under high-speed railway train load

采用一种复合正弦波(M波)模拟列车移动荷载,建立轨道-路堤-PCC桩-土复合地基三维动力有限元模型,研究高速铁路路堤及PCC桩复合地基在列车荷载作用下的振动响应特性。研究结果表明:在靠近列车荷载作用处振动响应比较强,随着与轨道的距离增加,振动响应值也逐步降低,至地基远处24.5 m处,振动响应已经很小。路堤内振动波远低于枕木处振动幅值,振动波经路堤、垫层、桩体和土体层层过滤衰减作用,在地基下部土体中振动被削弱,振动的幅值和频率范围均受到影响。经过滤后地基下部土体振动响应频率接近或者低于土体自振频率,路堤、桩体和地基振动响应曲线体现了振动波在路堤系统各部分传播特点,反映出各部分振动特性。

In this paper, a composite wave vibration wave （M wave） was used to simulate the moving train load,and a three-dimensional dynamic finite element model of tracks embankment pile-soil composite foundation wasestablished. The dynamic character of embankment and composite foundation was then simulated. The resultsshow that, the vibration response is much stronger near the vibration source. The vibration value decreases withthe distance from the vibration source, and it reaches a lower level at the position 24.5 m away from the railway.The vibration amplitude in subgrade is much lower than that in sleeper. The vibration waves are weakened by theenergy attenuation when they go through the subgrade, cushion, pile and soils. The vibration amplitude andfrequency ranges are influenced as well. The vibration waves filtered by superstructure include low frequencies,which are equal to or lower than the natural vibration frequency of soils. Thus, the vibration response curves ofsubgrade, pile, foundation reflect the spread law of vibration waves and their vibration character.