呼伦贝尔退化草原土壤离散元仿真参数标定方法

Discrete Element Simulation Parameter Calibration of Soil in Hulunbuir Degraded Grassland

摘要:

针对草原退化严重的问题,在设计和优化与该类型土壤接触部件时,离散元法成为重要工具。为获取呼伦贝尔市周边退化草原土壤离散元仿真参数,以呼伦贝尔市周边退化草原土壤为例,研究采用物理试验与仿真优化设计相结合的方法,对退化草原土壤离散元参数进行标定。以测定的物理参数为参考,以土壤休止角、滑动摩擦角、凝聚力与内摩擦角的试验结果为目标,通过Plackett-Burman 试验筛选出显著性因素,再由最陡爬坡试验沿梯度方向逼近至响应面顶点附近,最后由Box-Behnken 试验引入非线性模型确认最优解,实现对影响仿真结果的接触参数、力学参数标定。结果表明仿真休止角与实际休止角相对误差为0.32%;以滑动摩擦角验证试验数据,仿真试验与物理试验误差为1.35%;凝聚力与内摩擦角拟合值为23.603kPa、26.387°,与实际值误差分别为0.62%、0.5%。标定的参数能真实反映呼伦贝尔周边退化草原土壤的特性,研究结果可为呼伦贝尔退化草原触土部件优化设计提供理论与模型基础。

Abstract:

In view of the serious problem of grassland degradation, the discrete element method becomes an important tool in the design and optimization of this type of soil contact equipment. In order to obtain the discrete element simulation parameters of degraded grassland soil around Hulunbuir City, taking the degraded grassland soil around Hulunbuir City as an example, the method of combining physical experiment and simulation optimization design was used to calibrate the discrete element parameters of degraded grassland soil. Taking the measured physical parameters as references and aiming at the experimental results of soil accumulation angle, sliding friction angle, cohesion and internal friction angle, the significant factors were screened out through the Plackett-Burman experiment, and then the steepest climbing slope experiment approached along the gradient direction to near the vertex of the response surface. Finally, the nonlinear model was introduced by the Box-Behnken experiment to confirm the optimal solution, and the contact parameters and mechanical parameters that affected the simulation results were calibrated. The results showed that the relative error between the simulated stacking angle and the actual stacking angle was 0.32%. The sliding friction angle was used to verify the experimental data, and the error between simulation experiment and physical test was 1.35%. The fitted cohesion and internal friction angle are 23.603kPa and 26.387°, with relative errors of 0.62% and 0.5% compared with the measured cohesion and in ternal friction angle, respectively. The calibration parameters can truly reflect the soil characteristics of the degraded grassland around Hulunbuir, and the research results can provide theoretical and model basis for the optimization design of the soil touching parts of the degraded grassland in Hulunbuir.