基于DEM-MFBD方法的有砟轨道路基不均匀沉降影响分析

Analysis of uneven subgrade settlement of ballasted track based on DEM-MFBD method

针对有砟轨道路基不均匀沉降现象,开展有砟轨道结构整体变形分析。基于离散元—多柔性体动力学耦合方法(DEM-MFBD),建立了一种简化的2.5维有砟轨道耦合模型,并将其用于有砟轨道细观力学特性研究。基于此耦合模型特性,提出荷载及刚度折减方法,对不同路基沉降波长、幅值下有砟轨道结构整体受力变形进行计算分析,在此基础上研究路基不均匀沉降对轨枕空吊的影响规律。结果表明:路基沉降幅值和波长的增加均导致轨道不平顺明显增大,并促使道床应力集中位置外扩;钢轨沉降面积与路基沉降面积的比值(S_(1)/S_(0))可以反映轨枕空吊情况;路基沉降幅值为10~15 mm时出现轨枕空吊,建议沉降限值不超过10 mm,以便工务部门控制轨枕空吊和轨道不平顺等病害。

In view of the uneven settlement of ballasted track subgrade,the overall deformation analysis of ballasted track structure is carried out.Based on the coupling method of discrete element method and multiflexible body dynamic(DEM-MFBD),a simplified 2.5-dimension coupling model of ballasted track is introduced and applied to the study of meso-mechanical properties of ballasted track.Based on the characteristics of the coupling model,the load and stiffness reduction method is proposed.The global stress and deformation of the ballasted track structure under different subgrade settlement wavelengths and amplitudes are calculated and analyzed.At the same time,influence of uneven subgrade settlement on unsupported sleepers is studied.The results show that the increase of subgrade settlement amplitude or wavelength obviously leads to the increase of track irregularity and the outward expansion of the stress concentration position of the ballast bed.The ratio of rail settlement area to subgrade settlement area(S_(1)/S_(0))can reflect the status of unsupported sleepers.It is found that the unsupported sleepers are produced when the subgrade settlement amplitude is 10-15 mm.Therefore,it is suggested that the subgrade settlement amplitude should be controlled within 10 mm,so that the engineering department can control the problems such as unsupported sleepers and track irregularity.