网孔形状影响格栅道砟界面特性的细观分析

Mesoscopic analysis of influence of aperture shape on mechanical characteristics of geogrid ballast interface

为分析格栅-道砟界面力学响应以及网孔形状对格栅加筋性能的影响,采用颗粒流软件对三向和双向土工格栅拉拔过程进行了仿真分析,揭示了剪切带形成演化机制和剪切带内粒间接触力细观组构特征;同时,从格栅原材料用量角度入手,比较两种网孔形式土工格栅加筋性能.结果表明:界面强度不单受控于网孔有效面积,格栅拉拔力呈现出法向应力高度敏感性,实际工程中应根据荷载工况合理选择土工格栅网孔形状.

In order to study the mechanical response of interface of geogrid-ballast and the influence of aperture shape on the reinforced performance of geogrid,the pull-out process of triaxial and biaxial geogrids were simulated by particle flow software.The evolution mechanism of shear bands as well as mesoscopic fabric characteristics of contact force within the shear bands was revealed.Meanwhile,the reinforced performance of two kinds of aperture shape was compared based on the material consumption of geogrid.Numerical results show that the interface strength is controlled non-monotonously by the effective area of the geogrid aperture,and the pull-out force of geogrid is highly sensitive to normal stress.Moreover,the interaction between the biaxial geogrid and ballast is strengthened under low normal stress conditions,thus the aperture shape of geogrid should be reasonably selected in engineering practice.