菠菜根土复合体离散元模型建立与标定试验  

Establishment and calibration experiment of the discrete element model for spinach root-soil complex

作　　者：梁树建 刘立晶[1] 刘芳建[1] 常贺 崔巍[1] 李贵霖 LIANG Shujian;LIU Lijing;LIU Fangjian;CHANG He;CUI Wei;LI Guilin(Chinese Academy of Agricultural Mechanization Sciences Group Co.,Ltd.,Beijing 100083,China;China Special Equipment Testing and Research Institute,Beijing 100020,China)

机构地区：[1]中国农业机械化科学研究院集团有限公司,北京100083 [2]中国特种设备检测研究院,北京100020

出　　处：《农业工程学报》2025年第5期38-49,共12页Transactions of the Chinese Society of Agricultural Engineering

基　　金：北京市科技计划(Z221100006422007)。

摘　　要：针对现有菠菜根土复合体模型忽略须根对剪切过程力学特性的影响导致标定参数不准确的问题,该研究建立了模拟菠菜实际生长状态的根土复合体离散元模型,并进行了有无须根的对比剪切试验,分析了须根对剪切效果的影响。通过统计菠菜根的外形尺寸与土壤内须根的生长角度及分布特点,利用离散元法建立包括主、须根的菠菜根柔性模型与土壤模型。通过实际与仿真试验对比,标定菠菜主根、须根和土壤间的离散元参数。标定结果显示:主根休止角、极限剪切力仿真结果与实测平均值的相对误差分别为0.23%和0.98%,须根极限拉力仿真结果与实测值相对误差为0.9%,土壤休止角仿真结果与实测平均值的相对误差为0.18%,菠菜根土复合体极限剪切力仿真结果与实测值相对误差为0.44%,表明建立的菠菜根土复合体模型准确可靠,能有效反映采收菠菜时入土切根过程的力学特性。利用标定后的菠菜根土复合体模型对比了有、无须根情况的切根特点,结果显示无须根的根土复合体极限剪切力较有须根的减小约11.4%,主根位移增大约40.3%,说明须根具有明显粘结土壤,稳固主根的作用。该菠菜根土复合体模型可提高菠菜采收时入土切根互作过程的可视性与模拟真实性,便于切根机理研究,可为类似根土复合体模型建立提供依据。Spinach products in China have constituted over 90%of global output in recent years.Among them,root-cutting into the soil has been the sole harvesting method,in order to fully meet the national needs of large-scale production.It is very necessary to reevaluate the existing interaction models among spinach roots,soil,and cutting implements during harvesting.Current root-soil complex models cannot consider the influence of fibrous roots on the mechanical properties during root cutting,leading to the imprecise parameters of calibration.In this study,a discrete element model was presented to simulate the actual growth of spinach.A comparative framework was then established to analyze the scenarios both with and without fibrous root representations.A systematic analysis was implemented on the external dimensions of spinach taproots,the growth angles,and the distribution characteristics of fibrous roots in the soil matrix.A complete soil model was established using the discrete element method,including taproots and fibrous roots.A series of tests were conducted,including taproot accumulation,shear testing of the taproot,tensile testing of fibrous roots,and soil accumulation.The intrinsic,contact,and governing parameters were calibrated to determine the interactions between spinach roots and the soil medium.Calibration results demonstrated that the relative errors of simulation and measured average values in the taproot repose angle and ultimate shear force were 0.23%and 0.98%,respectively.Similarly,the relative error for the ultimate tensile force of fibrous roots was recorded at 0.9%,while the soil repose angle exhibited a relative error of 0.18%.A discrete element model of the spinach rootsoil complex was then established using calibrated parameters.A validation test was conducted for the ultimate shear force within this complex.Single-factor testing revealed that the ultimate shear force escalated with the increase in the static friction coefficient and the bond radius coefficient between the root and soil within th

关 键 词：离散元法 菠菜 根土复合体 入土切根 标定验证 

分 类 号：S225.92[农业科学—农业机械化工程]