三向土工格栅筋土界面及摩擦特性的离散元模拟

为研究筋土界面细观结构演化并定量评价格栅摩擦特性对加筋性能的影响，建立三维离散元模型，运用“clump”较真实地模拟了三向格栅的增强型节点。通过分析拉拔荷载下界面内颗粒及筋材的力学响应，并将其与前人模型试验及理论分析结果进行对比，验证了文中模型的准确性，得出了局部孔隙率以及配位数等细观参数的变化规律。分析格栅表面摩擦系数参数发现，表观黏聚力与摩擦系数具有正相关性，当摩擦系数达到一定值时摩擦角不再增长。统计结果表明，宏观上界面强度提高可归因于细观上的组构优化。分析筋土界面采用的方法和所得的结果可为加筋土结构机制分析提供新的认识。

Discrete element simulation of interface characteristic and frictional properties of triaxial geogrid

Aiming at studying the evolution of the microstructure in the interface and quantitatively assessing the extent that friction coefficient influences the reinforcement performance, a three-dimensional discrete element model is established; and the strengthened node of triaxial geogrid is factually simulated by jointing the surrounding particles with the assistance of “clump” logic. The mechanical responses of reinforced soil and geogrid under pull-out loading are analyzed. Compared with the experimental and theoretical results of previous reports, the accuracy of the model used in this study is verified. Meanwhile, the variation law of meso-structure parameters, such as local void ratio and coordinate number are obtained. Afterwards, parametric study on friction coefficient is carried out, and it can be found that the apparent cohesion is positively related to the friction coefficient. However, the internal friction angle cannot increase continuously when friction coefficient reaches a certain value. The statistical results demonstrate that the improvement of macroscopic interface strength could be reasonably attributed to the optimization of microscopic fabric. The presented methods in analyzing soil-geogrid interface and achievements in this paper could provide a new understanding for mechanism analysis of reinforced earth structure.