小麦PFC模型细观参数标定方法的验证与分析

Validation and analysis of calibration method for micro parameters of wheat PFC model

为了验证PFC模型细观参数标定方法的可行性,以小麦试样为例,根据PFC软件提供的模型细观参数标定方法的要求,在实验室进行了三轴压缩试验,并利用PFC软件对实验室三轴压缩试验进行了数值模拟。结果表明:通过反复调整PFC模型细观参数能够使数值模拟结果与试验结果基本一致,但很难使二者完全吻合。同等条件下,数值模型的颗粒摩擦系数对偏应力峰值的影响显著,颗粒法向刚度控制偏应力-应变关系曲线的初始斜率,颗粒孔隙率影响偏应力-应变关系曲线达到峰值后的平缓趋势。

In order to verify the feasibility of calibration method for micro parameters of a PFC model, taking wheat samples as an example, according to the requirements of calibration method for micro parameters provided by PFC software, first, triaxial tests were conducted in laboratory, then, numerical triaxial tests to model the laboratory tests were conducted by PFC as well. Research shows that numerical results could approach experimental results by adjusting micro parameters repeatedly, but it is almost impossible to make them coincide with each other.Under the same level, the particle friction coefficient of numerical model has significant effects on deviatoric stress. The initial slope of curve of deviatoric stress and strain is controlled by particle normal stiffness. The tendency of curve of deviatoric stress and strain is impacted by particle porosity.