道砟压实质量与颗粒运动关联特征及内在机制研究

Investigating correlation characteristics and intrinsic mechanism between compaction quality and particle movement of railway ballasts

级配较为均匀的道砟其捣固(压实)质量对铁路有砟道床的服役性能起着至关重要的作用。然而,目前尚无统一的标准或规范可用于指导和控制道砟捣固(压实)参数选择,传统的路基填料压实也未能考虑散体颗粒的自组织行为和细观运动特征等。基于正交设计方案开展缩放道砟级配的室内旋转压实试验,在试样的不同位置预置了新型智能颗粒传感器用于监测旋转压实过程中颗粒的运动参数,揭示道砟压实质量与颗粒运动参数的关联特征,从颗粒细观运动角度探究压实机理,提出考虑颗粒细观运动特征的压实度控制新指标。研究结果表明:智能颗粒传感器可用于测量旋转压实过程中粗颗粒的细观运动参数;3个方向的相对旋转模式与旋转压实过程中试样干密度和高度的变化直接相关,据此可将压实过程分为初始压实、旋转压密和稳定压密等3个阶段;试样上部位置处智能颗粒传感器的相对转角可作为新的压实度控制指标。研究成果有望为铁路道砟的室内外压实技术选取和压实质量控制提供技术参考和指导。

The quality of tamping or compaction operations of ballast particles with uniform gradation plays a vital role in railway track-bed performance;however,there are currently no unanimously-accepted techniques or quality control criteria available for selecting proper tamping or compaction parameters,and traditional compaction standards of foundation geomaterials barely consider self-organizing feature and meso-scale particle movement.The laboratory gyratory compaction tests designed by the orthogonal array method were conducted with scaled ballast gradations,and the newly-invented SmartRock sensors were placed at different locations of the gyratory specimens for recording particle movement characteristics during compaction.The correlation characteristics and intrinsic mechanism between compaction quality and particle movement of railway ballasts were disclosed,and a new index for controlling ballast compaction quality was proposed by considering mesoscale particle movement.It was found that the SmartRock sensors are capable of capturing meso-scale particle motion,and that the relative rotation pattern of the particles along x-and y-directions was directly related to changes in dry density and height values of specimens during gyratory compaction.Therefore,the compaction process can be divided into initial compaction stage,transition stage,and stabilization stage.The relative rotation angle of the SmartRock sensors embedded in the upper part of the specimens can be used as a new compaction quality control index.The findings could provide technical insights and guidance to field tamping and compaction of ballasts in heavy-haul railroads.