基于堆积试验的黏壤土仿真物理参数标定

为获取南方黏壤土的离散元仿真模型精准接触参数,构建土壤离散元仿真模型,基于土壤堆积试验,结合试验测定和EDEM软件推荐的参数构建土壤仿真模型,以休止角为响应值,采用Design Expert软件依次设计Plackett-Burman试验、最陡爬坡试验和Box-Behnken试验完成土壤仿真物理参数标定及优化。进一步通过成穴装置成穴的仿真试验与土槽试验的对比分析,验证黏壤土仿真模型的精准性。成穴试验的仿真与土槽试验结果表明,装置在仿真土壤中运动规律与土槽试验中差异较小,成型穴孔的开口纵长和有效深度的误差分别为3.98%和1.87%,模拟仿真土壤的物理力学特性与实际土壤一致,表明黏壤土的离散元仿真参数系统标定研究的方法准确可行。研究构建了南方黏壤土精准的离散元仿真模型,为该类型土壤与触土部件相互作用的动力学研究提供技术支持。

Calibration of simulation physical parameters of clay loam based on soil accumulation test

Abstract: In order to obtain the precise physical parameters of the discrete element simulation model of typical cultivated soil clay loam in southern China, this paper constructed a soil discrete element simulation model. Based on a soil accumulation test, this study proposed a method for combining the significance analysis and response surface method, which calibrated and optimized the simulation parameters of clay loam in southern China. Combining the results of actual test and GEMM database parameters recommended by constructing the DEM model of the soil, repose angle of soil was taken as response value, using the Design Expert software through the Plackett-Burman test, the steepest climbing test and Box-Behnken test, simulation physical parameters were calibrated and optimized. The simulation model of discrete element in clay loam was verified to be accurate by analyzing the simulation and soil bin testing of hole forming device. The DEM model of soil was established on the basis of the parameters determined by the basic test. The 8 initial physical parameters were screened for significance using the Plackett-Burman test. The results show that: the surface energy of soil for JKR model, soil-soil restitution coefficient, and the soil-soil static friction coefficient have significant effects on the response value and repose angle. Based on the optimal interval value of the significant parameters are determined by the steepest ascent test and the Box-Behnken test result, the quadratic regression model of significance parameters and repose angle is established and optimized to obtain the optimal combination of the significance parameters: The surface energy of soil for JKR model is 12.73 J/m2. The soil-soil restitution coefficient is 0.55. The soil-soil static friction coefficient is 0.84. Other insignificance parameters are as recommended by the GEMM database (Poisson''s ratio of soil is 0.38. Soil-soil rolling friction coefficient is 0.1. Soil-steel restitution coefficient is 0.3. Soil-steel static friction coefficient is 0.6. Soil-steel rolling friction coefficient is 0.1). By the analog simulation of optimal parameter combination, it can be obtained that the simulated repose angle is 42.9° and the measured repose angle is 42.4°, therefore, the relative error is only 1.2%. There is no significant difference in shape and relevant value between the soil in simulation and the soil in experiment (P>0.05). The optimized parameters can be used for further DEM analog simulation between the clay loam and the soil-contacting components and revealing the law of motion of clay loam under the action of soil-contacting components. The results of the simulation and soil bin testing of hole forming device show that, motion law of the soil-engaging component in the simulated soil model is slightly different from that in the soil groove test, with the numerical difference within 3.98%, which proves that the soil simulation model after parameter calibration and optimization can accurately replace the real soil for simulation. The research can provide theoretical basis and technical support for the dynamic study of the interaction between this type of soil and the contact soil components.