增强节点影响格栅-道砟界面特性的离散元分析

Discrete Element Analysis on the Influence of Enhanced Nodes on the Characteristics of Geogrid Ballast Interface

为研究双向土工格栅增强型节点对加筋道砟界面力学特性的影响,本文采用三维离散元法对格栅加筋道砟拉拔试验进行了模拟,通过在节点处引入副颗粒的方法来还原增强型节点格栅的几何形状,并基于拉拔阻力变化、颗粒体系能量耗散、接触力链演化特征及法向接触力的细观组构变化对不同节点类型双向土工格栅加筋道砟的筋土界面特性进行了对比分析。研究表明:节点处副颗粒对格栅与填料间的摩阻力贡献有限,但能与其周围填料相互作用承担拉拔扰动使得格栅可以更均匀地调动填料;节点的增强有利于强化筋材对内部能量的储蓄,使其拉伸性能得到较充分的发挥;对于格栅加筋粗粒道砟体系,宜根据颗粒体系的细观组构演化考虑其界面强度衰减规律。

In order to study the influence of bidirectional geogrid enhanced nodes on the mechanical properties of reinforced ballast interface,a three-dimensional discrete element method was used to simulate the pull-out test of geogrid reinforced ballast.The geometric shape of the enhanced node geogrid was reduced by introducing secondary particles at the nodes.Based on the change of pull-out resistance,energy dissipation of particle system,evolution characteristics of contact force chain and meso-structure change of normal contact force,the reinforced soil interface characteristics of bidirectional geogrid reinforced ballast under different nodes were compared and analyzed.The results show that the contribution of the secondary particles at the nodes to the frictional resistance between the grid and the filler is limited,but it can interact with the surrounding fillers to bear the pulling disturbance,which makes the grid more uniform to mobilize the filler;the enhancement of the nodes is beneficial to the internal energy saving of the reinforced material,and the tensile properties are fully developed;for the grid reinforced coarse-grained ballast system,the interface strength attenuation law should be considered according to the meso-structure evolution of the granular system.