基于微观图像处理技术的土体三轴试验颗粒流模型

以扫描电子显微镜拍摄获取的粉土图片为研究对象,把数字图像处理技术引入土体的细观结构观察和定量分析中,求解土颗粒孔隙度、颗粒粒径及颗粒形状等微观颗粒组成参数,为建立颗粒流离散元细观模型提供物理参数。在此基础上,对土样的三轴试验进行模拟,并研究细观力学参数(包括:摩擦系数、平行连接强度及刚度比)对宏观性质的影响。研究表明:通过颗粒簇模型和颗粒排斥法可以实现土体微观颗粒形状和粒径组成模拟。所建立的颗粒流模型能够很好地拟合土体的应力-应变关系和模拟试验中的剪缩-剪胀现象;摩擦系数、平行连接强度和刚度比对土体的初始模量和残余强度的影响规律有所不同;通过监测孔隙率的变化,可以反映土体剪切带发展的过程。

GRANULAR FLOW MODEL OF TRI-AXIAL TEST OF SOIL BASED ON THE MICRO IMAGE TREATMENT TECHNOLOGY

Taking silt soil image photographed by scanning electron microscope as the research object,using image treatment technology for microstructure observation and quantitative analysis of soil,the parameters of particle composition of soil were solved,such as porosity,grain diameter,granular shape,which provided physical parameters for setting up granular flow model.And then it was simulated the tri-axial test of the soil and studied the variation rules of property of silt soil with micro-parameters,such as friction coefficient,parallel-bond and stiffness ratio.The result showed that using clump model and particle repulsion method,the granular shape and grain diameter distribution could can be simulated.The model developed by this method fitted the stress-strain curves of soil and simulated the phenomenon of shear contraction and shear dilatation,the influence laws of friction coefficient,parallel-bond and stiffness ratio to the initial modulus and residual strength were different.The development process of shear zone could be reflected by monitoring the change of porosities.