自重荷载下非均匀支撑板式无砟轨道静态响应

Static Responses of Unevenly Supported Ballastless Track under Self-weight Loads

针对高速铁路路基不均匀沉降诱发的板式无砟轨道几何形态和应力状态恶化问题,建立了高速铁路CRTSII型板式无砟轨道-路基三维有限元模型,模拟了64种路基不均匀沉降组合(波长5~40 m,波幅5~40 mm),提出了基于混凝土底座柔度的形态映射和应力水平定量表征方法.研究结果表明,轨道结构的形态映射特征主要由混凝土底座柔度决定,在沉降波长小于15 m、或者波长在15~20 m之间且沉降幅值大于15 mm时,轨道结构与路基因变形不协调而出现脱离.轨道结构变形量的增加会导致混凝土结构附加拉应力和路基接触应力的增大,且易接近或超过相应的强度允许值而产生损伤破坏.同时,增加混凝土底座的模量和厚度,对提高轨面几何平顺性的效果并不显著,反而会增大结构自身的拉应力和路基接触应力.

To evaluate the deterioration problem of geometry and stress states for the ballastless track caused by the uneven subgrade settlement of high-speed railway,a 3D FEM model of the CRTSΙΙtype ballastless track-subgrade system was established in this paper.A total of 64 types of differential settlements were simulated(with wavelengths of 5~40 m and amplitudes of 5~40 mm).Based on the flexibility of the concrete base,quantitatively characterizing method for the geometry mapping and stress level of the track structure was proposed.The results show that the mapping characteristics of the track structure are mainly determined by the flexibility of the concrete base.When the settlement wavelength is less than 15 m or the wavelength is between 15~20 m with the settlement amplitude greater than 15 mm,the subgrade and track are separated due to uncoordinated deformation.The increase of the track structure deformation leads to the development of additional tension stresses in the concrete structure and the subgrade contact stresses,which are prone to approach or exceed their allowable strength and results in damaged failure.Meanwhile,an increase of the modulus and thickness of the concrete base is not significant for improving the smoothness of the rail surface.On the contrary,it increases the track tensile stress and the subgrade contact stress.