格栅–砂土界面宏细观关联性与加筋性能评价方法研究

Study of the macro-meso correlation of geogrid-soil interface and assessment method of reinforced performance

土工格栅与填料间作用特性对加筋土结构设计至关重要。为研究界面宏–细观力学响应关联及填料粒径对加筋效果的影响,采用三维离散元方法对三向土工格栅拉拔过程进行仿真模拟,系统分析拉拔作用下筋材及颗粒的力学响应,揭示拉拔力发展与细观组构指标演化规律,建立基于拉拔试验结果的格栅加筋性能评价方法。研究结果表明,界面颗粒速度场可即时反映筋土相互作用;选取组构演化系数描述宏观强度的发展是合适的;在一定粒径范围内,格栅加筋性能主要受控于颗粒体系比表面积,加筋土临塑荷载随填料粒径的增大而降低。

The interface characteristic of geogrid and compacted materials plays an important role in the design of reinforced soil structures. The pull-out test of triaxial geogrid was conducted by 3-D discrete element method to investigate the correlation between macro and meso mechanical responses. Simultaneously, the influence of particle size on reinforcement effect was discussed. The mechanical behavior of reinforced soil and geogrid under pull-out loading was systematically analyzed. The evolution law of the pull-out force and mesoscopic fabric anisotropy indices was shown. Based on the pull-out test results, an assessment method was established to estimate the reinforcement effect of geogrid. Numerical results reveal that the velocity vector of particles in the interfaces can reflect the interaction between geogrid and soil instantaneously. The fabric anisotropy coefficient is suitable to describe the development of macroscopic strength. In a certain particle size scope, the reinforcement effect would be primarily controlled by the specific surface area of grain system and the critical edge load of reinforced soil would decrease with the increase of particle size.