土工格栅加固铁路道砟的颗粒离散元模拟研究

Simulation Research on Geogird Reinforcing Railway Ballast Based on Particle Discrete Element Method

研究目的:道砟是有砟轨道的关键构成,其变形累积将直接造成轨道的下沉破坏。随着列车运行速度的提高,道砟的变形对有砟轨道的行车安全性、舒适性和轨道养护维修工作量的影响也越来越大。因此,开展高速铁路道砟变形机理的研究具有重要意义。近年来,一些学者开始将土工格栅应用到铁路道砟的加固中,用以减小铁路道砟的沉降变形,但总体来说还不够成熟和完善。为进一步研究铁路道砟的变形机理及土工格栅加固铁路道砟的效果,本文以铁路道砟为研究对象,建立土工格栅加固铁路道砟的三维颗粒离散元模型,进行循环荷载作用下的数值试验,分别研究土工格栅不同安设位置、不同刚度以及不同网格尺寸对铁路道砟加固效果的影响。研究结论:(1)土工格栅加固铁路道砟效果明显,能够有效减小铁路道砟的沉降变形;(2)土工格栅安设位置不同,其加固效果也不同,当土工格栅距离模型箱底面100 mm时效果最好;(3)随着土工格栅刚度的增大,道砟的沉降变形逐渐减小,但当刚度增大到一定值后,对减小道砟沉降的作用有限;(4)土工格栅网格尺寸对铁路道砟加固效果有明显影响,但这种影响不是单调的,即存在一个合理的土工格栅网格尺寸使其加固铁路道砟的效果最好;(5)该研究成果对深入理解铁路道砟的沉降机理及土工格栅在铁路道砟加固中的应用均具有一定的参考意义。

Research purposes： The ballast is the key element of ballast track, and its accumulative deformation Will directly cause the damage and settlement of track. With the improvement of train speed, the effect of ballast deformation on running safety, comfort and workload of maintenance of ballast track is growing. Therefore, it is of great significance to carry out the research on the mechanism of high - speed railway ballast deformation. In recent years, in order to reduce the settlement deformation of railway ballast, some scholars began to apply geotechnical grid to the reinforcement of railway ballast, but it is not enough mature and perfect in general. In order to explore the deformation mechanism of ballasts and study the effect of geogrid reinforcing railway ballast, the 3 - D particle discrete element model of geogrid reinforcing railway ballast was established, and numerical tests of the model under cyclic loading were carried out. The influences of geogrid with different locations, different stiffness and different grid size on the reinforcing effect were researched respectively and compared with the related test results.Research conclusions： （ 1 ） The effect of geogrid reinforcing railway ballast is obvious, which can effectively reduce the settlement deformation of railway ballast. （2） The effect of reinforcement varies with the location of geogrid. When the distance between geogrid and the bottom of model box is 100 ram, the effect is best. （3） With the increase of stiffness of geogrid, the settlement deformation of ballast will decrease. But when the stiffness increases to a certain extent, the effect is not obvious with further increase of stiffness. （4） The influence of the grid size on the reinforcing effect is obvious. However, the effect is not monotonous, which means that there exists a grid size to achieve the optimal effectiveness. （4） The research result is helpful to understand deeply the settlement mechanism of railway ballast and the application of geogrid reinforcing railway ballast