移动荷载下高速铁路轨道-路基的动位移分析

建立精细化的足尺轨道-路基-地基耦合系统非线性数值分析模型,考虑岩土材料的非线性应力-应变关系、路基填筑完成后的静应力状态对其后动力计算的影响、底座板底面与路基基床表层表面之间的动力相互作用,模拟轨道与路基系统的建造过程和与8辆编组动车组轮对相对应的荷载以350 km/h的速度的移动过程。结果显示,以实体单元模拟钢轨能获得更符合事实的钢轨空间振动响应,比采用梁单元更具优势;路基各层底面的动位移具有随时间和空间变化的特征;沿路基断面横向,不同时刻的竖向动位移在轨道板宽度范围内的最大波动值约0.04 mm,可认为均匀分布;沿深度方向,竖向动位移在不同时刻的分布相似,按照指数函数衰减,最大值约为0.8 mm,小于我国高速铁路3.5 mm的控制标准;沿线路纵向,竖向动位移峰值出现的位置与该时刻移动荷载所处的空间位置对应,在同一深度条件下,不同时刻的竖向动位移分布形态相似;基床底层底面以上,同一转向架上前后轮对对应的荷载引起的竖向动位移具有可观的叠加效应。

Dynamic Displacement of the Track-Subgrade of High-speed Railways Subjected to Moving Loads

A full-size nonlinear numerical model for a track-subgrade-foundation coupled system was established in this paper. In the model, the nonlinear stress-strain relationship for soil material, influence of static stress state after subgrade construction on subsequent dynamic computation, and dynamic interaction between reinforced concrete base and upper layer of formation were considered, the construction process of a track-subgrade system was simulated. Results show that a more reasonable spatial vibration response of rails can be obtained by using a solid element to simulate the rail than using beam element. Vertical dynamic displacements at the bottom of each layer of subgrade simultaneously vary with time and space. In transverse direction of the subgrade, the maximum vertical dynamic displacement at different moments within the width range of track slab is about 0.04 mm, and can be regarded as uniformly distributed. Distributions of vertical dynamic displacement along the depth at different times are similar, and the maximum value is about 0.8 mm according to the exponential function attenuation, less than the standard of 3.5 mm allowed in Chinese high-speed railway. In the longitudinal direction of the railway, the locations of peak value of vertical dynamic displacement correspond to the spatial location of applied moving loads. Distribution patterns of vertical dynamic displacement at the same depth are similar at different times. Overlap effects induced by adjacent loads corresponding to the front and rear wheelset on the same bogie are noticeable above the bottom of the lower layer of formation.