粗粒土细观组构分析的影响因素研究

Study on influential factors of micro-fabric analysis of granular sand

基于离散元方法,采用PFC2D模拟分析了土样在双轴等向压缩和双轴剪切两种不同加载方式下的细观组构及接触演化规律.通过采取不同的颗粒级配、不同的试样尺寸、不同的制样方法和不同的加载方式等数值模拟条件,从试样颗粒的接触力网络、平均接触数、组构偏量和应力应变关系变化等方面研究各种条件变化对粗粒土结构及细观组构演化规律的影响.研究表明:试样的颗粒级配和制样方法对粗粒土的细观组构和各向异性组构分析有一定的影响;试样的几何尺寸对组构各向异性分析的影响较小,但是试样尺寸大小对研究土样的应力—应变关系会有影响;加载方式是土样诱发各向异性和导致土样力学行为差异性的根本原因.

The purpose of this study is to identify the influential factors of the micro fabric analysis of granular materials by the discrete element method(DEM).Based on PFC simulations,numerical discrete specimens are set up to study the micro fabric evolution and contact force spreading within granular materials under isotropic compression and biaxial shearing,respectively.A parametrical study is carried out with different particle gradations,specimen sizes,sample preparation methods,and loading paths.By tracing the variation of the contact force network,the coordination number,and the fabric deviator under different conditions,the factors that affect the micro-fabric study are identified.It is found that the particle gradation and the sample preparation method both exert a certain effect on the micro-fabric formation of samples.Although the size of specimens has little influence on the micro fabric setup,the stress-strain behavior of specimens are affected to a certain extent.The behavior of granular soil under different loading paths is related to the micro-fabric evolution due to loading.