Development of universal soil-tool-residue interaction models using the discrete element method (DEM)

使用离散元法 (DEM) 开发通用土壤-工具-残留物相互作用模型

• 批准号: RGPIN-2014-05464
• 负责人: Chen, Ying
• 金额: $ 2.84万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611660
• 关键词: Development; universal; soil; tool; residue

Soil-tool-residue interaction is at the centre of many agricultural field operations. Soil-tool-residue interaction is also one of the fundamental aspects of soil dynamics in agricultural engineering. In a field operation, tillage tools (e.g. plows, chisels, sweeps, etc.) loosen soil for seedbed preparation, or seed openers (e.g. hoes, discs, shovels, etc.) open soil for seed placement. A general term for these tillage tools and seeding openers is “soil engaging tool”. As agricultural fields retain more or less crop residue from previous crops, soil engaging tools interact with both soil and crop residue during field operations. Soil-tool-residue is a complex system, since soil consists of a matrix of discrete particles that are of random, heterogeneous nature, and exhibit sophisticated non-linear behaviours. Such a system cannot be modelled using traditional analytical or numerical methods. THE STATE-OF-THE-ART RESEARCH proposed here will develop a universal model of soil-tool-residue interaction, which can address the complex nature of soil and the existence of residue particles in agricultural fields. In the proposed research program, A NEW, INNOVATIVE NUMERICAL METHOD - DISCRETE ELEMENT METHOD (DEM) - will be used to develop the universal soil-tool-residue interaction model. In the model, basic soil particles will be represented by spherical particles of various sizes. The particle constitutive laws will be defined in such a way that basic particles can form aggregates and have frictional, cohesive, viscous, and deformable behaviours like real agricultural soil (1st INNOVATION). The cohesive behaviour will be described using bonds between soil particles that are in contact. Bonds connect soil particles together, forming soil aggregates, and bonds are breakable under the impact of soil engaging tools. The model must include the microproperties of particles and bonds (such as particle modulus of elasticity, strength of bond, and particle friction coefficient). These microproperties will be defined to be independent of particle sizes, so that they are universal (2nd INNOVATION). As the DEM particle microproperties are not measurable owing to their micro-scales, methods will be developed to calibrate the microproperties. Calibration will be performed using fundamental soil mechanical tests, so that the calibrated microproperties are universal, independent of soil engaging tool (3rd INNOVATION). In the model, a residue particle will be represented by a cluster of basic spherical particles arranged in a way that reflects the shapes of real crop residues. Different sizes of residue clusters will be integrated into soil particles, forming a heterogeneous model domain with a mixture of discrete soil and residue particles (4th INNOVATION). The universal model will be able to predict soil micro dynamics (e.g. forces and displacements of each individual soil particle). Models will be validated using laboratory and field data. DEM modeling of dynamic behaviours of agricultural soil is an emerging field. The universal soil-tool-residue model to be developed will mark a potential BREAKTHROUGH in the area of soil dynamics, in that the model can be used to simulate the micro soil dynamic behaviours for any soil engaging tool, in any soil condition. The simulation results will lead to the emergence of new high performance tillage and seeding tools that consume minimal tractor power and create optimal soil conditions for crop growth. The outcome will be also useful in crop residue management for sustainable agriculture.

土壤-工具-残留物相互作用是许多农业田间作业的核心。土壤-工具-残渣相互作用也是农业工程中土壤动力学的一个基本方面。在田间作业中，耕作工具（如犁、凿、扫等）松动土壤以备苗床，或开种器（如锄头、圆盘、铲子等）打开土壤以播种。这些耕作工具和播种器的通称是“吸土工具”。由于农田或多或少地保留了以前作物的作物残留物，土壤接合工具在田间作业中与土壤和作物残留物相互作用。土壤-工具-残渣是一个复杂的系统，因为土壤是由离散颗粒的矩阵组成的，这些颗粒具有随机、异质的性质，并表现出复杂的非线性行为。这样的系统不能用传统的解析或数值方法来模拟。这里提出的最先进的研究将开发一个土壤-工具-残留物相互作用的通用模型，该模型可以解决土壤的复杂性质和农业领域中残留物颗粒的存在。在本研究计划中，将采用一种新的、创新的数值方法——离散元法（DEM）来建立通用的土壤-工具-残渣相互作用模型。在模型中，基本土壤颗粒将用不同大小的球形颗粒表示。粒子本构定律将以这样一种方式定义，即基本粒子可以形成聚集体，并具有摩擦、内聚、粘性和变形行为，就像真正的农业土壤一样（第一次创新）。粘性行为将用接触的土壤颗粒之间的键来描述。化学键将土壤颗粒连接在一起，形成土壤团聚体，在土壤接合工具的影响下，化学键容易断裂。该模型必须包括颗粒和键的微观特性（如颗粒弹性模量、键强度和颗粒摩擦系数）。这些微特性将被定义为与颗粒大小无关，因此它们是通用的（第二次创新）。由于DEM粒子的微观尺度，其微观性质无法测量，因此将开发各种方法来校准其微观性质。校准将使用基本的土壤力学测试进行，因此校准的微特性是通用的，独立于土壤啮合工具（3rd INNOVATION）。在该模型中，残茬颗粒将由一组基本球形颗粒表示，其排列方式反映了真实作物残茬的形状。不同大小的残渣团簇将被整合到土壤颗粒中，形成离散土壤和残渣颗粒混合的非均匀模型域（4th INNOVATION）。通用模型将能够预测土壤微动力学（例如，每个土壤颗粒的力和位移）。模型将使用实验室和现场数据进行验证。农业土壤动态行为的DEM建模是一个新兴的领域。即将开发的通用土壤-工具-残留物模型将标志着土壤动力学领域的一个潜在突破，因为该模型可用于模拟任何土壤条件下任何土壤参与工具的微观土壤动力行为。模拟结果将导致新的高性能耕作和播种工具的出现，这些工具消耗的拖拉机功率最小，并为作物生长创造最佳的土壤条件。研究结果也将有助于可持续农业的作物残茬管理。