无碴轨道桩板结构路基在地震荷载下的动力响应分析

结合遂渝线无碴轨道桩板结构路基,采用天津(1976年)地震波,基于弹塑性本构关系,建立桩、板和土体的三维实体模型,利用有限元软件ANSYS,对桩板结构路基在地震荷载下的动位移、加速度及竖向应力的动力响应进行数值模拟。分析计算结果可知,在地震荷载下桩板结构路基不同位置处的动位移、加速度响应基本一致,滞后现象不明显;桩底持力层的动位移、加速度幅值略小于其他位置。相对于输入的地震加速度,桩板结构路基响应的加速度幅值被放大,而对应的时刻都滞后于输入的加速度最大值的时刻。在桩截面处的承载板受力不利,所以在桩截面处的板截面需加固处理以满足抗震设计要求。桩的存在对周围土体的动力响应有一定的影响,但总体来说,影响程度很有限。

Dynamic Response Analysis on the Pile-Plank Structure Roadbed of Ballastless Track under Earthquake Load

In combination with the pile-plank structure roadbed of the ballastless track of Suiyu railway,3D solid model of pile,plank and soil mass is established on the basis of elastoplastic constitutive relation and by adopting the earthquake wave in Tianjin(1976).By using finite element software ANSYS,the dynamic response of pile-plank structure roadbed is simulated in terms of dynamic displacement,the acceleration and the vertical dynamic stress under earthquake load.Analysis and calculation results show that the dynamic displacement and the acceleration respond approximately consistent at different positions of the pile-plank structure roadbed under earthquake load.There is no obvious lag phenomenon.Values of the dynamic displacement and acceleration at the force bearing strata of pile bottom are slightly less than those at other positions.Relative to earthquake acceleration input,the acceleration value of pile-plank structure roadbed response is enlarged.However,the corresponding time lags behind the time of the maximum acceleration value input without exception.Since the stress of the force-bearing plank is disadvantageous at the pile section,the plank section at the pile section needs to be reinforced so as to meet the requirements for earthquake resistance design.The existence of the pile has certain influence on the dynamic response of the surrounding soil mass.But generally speaking,the influence degree is quite limited.