颗粒组构对砂土三轴压缩性状影响的细观分析

Mesoscopic Analysis on the Effect of Granular Fabric on Triaxial Compression Behavior of Sandy Soil

基于离散元开源系统Yade,开发一种可以确定材料初始孔隙度与级配的滚动阻力DEM模型,结合Labenne砂的室内试验与引入滚动效应的三轴压缩模型的数值试验,探索了组构特性对砂土材料的力学性质及微观参数的影响。基于数值试验结果,分析了模型中颗粒力链、位移场及应变场等随着三轴模型变形的变化规律。通过制备5组不同级配与3组不同孔隙率的数值模拟试样,对比Labenne砂的室内试验。结果表明:①不均匀系数与孔隙率对砂土峰值强度有明显的影响;②不均匀系数对颗粒配位数及局部应力有很大的影响;③砂土剪切面的破坏模式为沿着剪切面由内向外扩展破裂。

The influence of granular fabric on mechanic properties and microscopic parameters of sandy soil was investigated in this research via numerical simulation of triaxial compression test in association with Labenne’s laboratory test of sandy soil.The numerical model which could determine the initial porosity and gradation of materials in consideration of rolling resistance was developed based on discrete element open source system Yade.According to the results of numerical tests,the variation laws of particle force chain,displacement field,and strain field with triaxial model deformation were analyzed.The numerical test involved five groups of particle gradation and three groups of porosity,and were compared with Labenne’s laboratory test of sandy soil.Results conclude that:1)the nonuniform coefficient and porosity have obvious influences on the peak strength of sandy soil;2)the nonuniform coefficient has great influence on the coordination number of particles and the local stress;(3)the failure of sandy soil follows the pattern extending from the interior to the exterior along the shear plane.