基于离散单元法农田土壤单轴压缩模型的建立及参数校核

建立基于离散单元法的农田土壤单轴压缩可靠模型,并较准确模拟真实土壤力学性能,在有限元理论的基础上,借助Flunet-UDF能将模型网格信息写出的特点,利用EDEM软件自定义工厂生成不饱和土壤单轴压缩模型,并对其进行仿真试验。仿真试验结果表明:切向接触刚度和曲线的上升段与应变轴夹角、峰值、下降段与应变轴夹角均有关,上升段、下降段与应变轴夹角、峰值随切向接触刚度增大而增大;曲线的峰值在随临界切向应力减小而减小,下降段落点随临界切向应力减小而离原点越近;下降段与应变轴夹角随法向接触刚度增大而增大;下降段与应变轴夹角随临界法向应力减小而增大。当法向接触刚度为210 MN/m3、切向接触刚度为80 MN/m3、临界法向应力为30kPa和临界切向应力为8kPa时,该组黏结参数能较可靠表征含水率为10.5%的耕地土壤力学特性。

Establishment and parameter verification of farmland soil model in uniaxial compression based on discrete element method

Farmland soil in uniaxial compression was modeled based on discrete element method and the mechanics property of real soil was simulated.On the basis of the finite element theory, with the aid of Flunet-UDF that data of finite element meshes can be written, soil model in uniaxial compression was generated using a custom factory in EDEM software.Simulation results show:Shear stiffness are positive related with the included angle between upward section in the curves and the strain axis, peak value, the included angle between downward section in curves and the strain axis.Peak in the curves decreases with shear critical stress decrease.Drop points of downward section in the curves are far away from original point as shear critical stress decrease.Included angle between downward section in curves and the strain axis increases as normal stiffness decrease.Peak in curves increases as normal critical stress increase.On the basis of above regular pattern from analysing the curves of unaxial compression force-strain, 4 main parameters of bonding model that simulation model in uniaxial compression applied were adjusted to make curves of simulation and test.That is when normal stiffness is 210 MN/m³, shear stiffness is 80 MN/m³, normal critical stress is 30 kPa, shear critical stress is 8 kPa, the bonding parameter can be more reliably to characterize the mechanical properties of soil holding 10.5% moisture.This research will provide reference for model establishing and parameter verification of agricultural complex materials.