基于坍落度试验的扰动饱和水田土壤离散元参数标定

Calibration of Disturbed-Saturated Paddy Soil Discrete Element Parameters Based on Slump Test

摘要:

针对扰动饱和水田土壤环境下触土工作部件与土壤间相互作用关系需要，对高含水率、高流变性和高粘附性的扰动饱和水田土壤离散元仿真模型开展了研究。基于坍落度试验，利用EDEM软件中的Hertz-Mindlin with JKR接触模型构建了土壤颗粒和水颗粒二相混合模型，对扰动饱和水田土壤进行离散元仿真参数标定。以坍落拓展度w为试验指标，利用Plackett-Burman试验从 8个相关参数中筛选出对拓展度影响显著的 3个参数，其中土壤-水间 JKR表面能和土壤-土壤间滚动摩擦因数对拓展度影响极显著，土壤-土壤间恢复系数对拓展度影响显著。根据Box-Behnken试验建立并优化拓展度与显著性参数的二阶回归模型，获得最优参数组合为：土壤-土壤间恢复系数为0.402，土壤-土壤间滚动摩擦因数为0.136，土壤-水颗粒间JKR表面能为0.920 J/m2。基于标定后的参数组合，以滑板牵引阻力为指标，进行水稻直播机播种滑板模型与扰动饱和水田土壤间互作关系仿真模拟及土槽试验验证，结果表明仿真与试验获得的滑板模型阻力误差为6.46%，扰动饱和水田土壤离散元仿真模拟与试验一致，表明本研究参数标定方法准确可行。研究可为该类型土壤下的农业机械及触土部件的相关研究奠定基础与提供支撑。

Abstract:

In response to the lack of effective discrete element model for the simulation analysis of the interaction between soil-engaging components and soil in disturbed saturated paddy soil environment, the disturbed saturated paddy soil with high moisture content, high rheology and high adhesion was taken as the research object. A two-phase mixing model of soil particles and water particles was established by using the Hertz Mindlin with JKR contact model in EDEM software. The discrete element parameters of the disturbed saturated paddy soil model was calibrated through slump tests and soil bin tests. With the slump flow was the experimental indicator, the Plackett-Burman experiment was used to screen out three parameters from eight relevant parameters, namely, the soilwater JKR surface energy, the soil-soil rolling friction coefficient and the soil-soil recovery coefficient. The soil-water JKR surface energy and the soil-soil rolling friction coefficient had a highly significant influence on the slump flow, and the soil-soil recovery coefficient had a significant influence on the slump flow. A second-order regression model of the slump flow and significance parameters was established and optimized based on the Box-Behnken experiment. The results of variance analysis of single factor showed that the soil-water JKR surface energy had a highly significant influence on the slump flow, and the soil-soil rolling friction coefficient had a significant influence on the slump flow. The interaction between the soil-soil recovery coefficient and the soilsoil rolling friction coefficient had a significant influence on the slump flow. Furthermore, the optimal parameter combination was obtained as follows： the soil-soil recovery coefficient was 0.402, the soilsoil rolling friction coefficient was 0.136, and soil-water particles JKR surface energy was 0.920 J/m2.The traction resistance of sliding plate of the rice seeder during its movement in disturbed saturated paddy soil as the indicator, a simulation of the interaction between the sliding plate of the rice seeder and the disturbed saturated paddy soil was conducted based on the calibrated parameter combination, and verified by the soil bin test. The results showed that the average value of traction resistance of the sliding plate in the simulation was 130.239 N, and the average value of traction resistance in the soil bin test was 139.231 N. The resistance value error of the sliding plate model obtained from the simulation and test was 6.46%. The discrete element simulation of the disturbed saturated paddy soil was consistent with the test, indicating that the parameter calibration method was accurate and feasible. The discrete element model of disturbed saturated paddy field soil established can provide technical support for the study of the interaction between soil and soilengaging components.