Modeling of soil-tool interaction in material incorporation

在土壤中掺入有机物质对环境、土壤肥力和土壤侵蚀保护具有显著的效益。这项研究的目标是开发一种独特的通用方法来设计土壤啮合工具(扫地机、圆盘、开启器、滚齿等)。用于在农业中有效地将有机物质(如牲畜粪便和作物残渣)并入土壤。与现有土壤啮合工具相关的问题包括保护性耕作系统中作物残留物的记录，饲草和免耕系统中土壤干扰程度高，以及作业对能量的高要求。在世界粮食需求、能源成本和环境影响成为事实的时候，迫切需要振兴土壤啮合工具设计，以提高其效率和效果。土壤接合工具的性能在很大程度上取决于它与土壤及其所处理的有机材料的相互作用。目前，商用土壤啮合工具的设计仍然依赖于传统的土壤-工具相互作用模型，即土壤行为和土壤-工具相互作用。在大多数传统模型中，采用有限元方法，将土体视为连续弹塑性介质，而土体作为非连续介质，以单个颗粒(集料和土块)的形式在工具周围流动。因此，有限元不能完全模拟农业土壤和土壤-工具在颗粒水平上的相互作用。此外，有限元不能在“颗粒”层面上处理不同材料的混合物，例如将作物残渣“颗粒”与土壤“颗粒”混合。有限元分析的这些不足，长期以来限制了土壤啮合工具的设计。离散单元法(DEM)允许将土壤建模为团聚体/土块的集合，并处理在材料结合中遇到的多种类型的颗粒。DEM在土壤动力学中的应用是一个新兴的领域，该领域还处于起步阶段。这项拟议的研究将利用申请者实验室的现有专业知识和研究工具，在推进该领域方面迈出重要的一步。该实验室是加拿大最后一个功能齐全的土壤动力学实验室。

Incorporation of organic materials into soil has significant benefits to the environment, soil fertility, and soil erosion protection. The goal of this research is to develop a unique and universal approach to design soil engaging tools (sweeps, discs, openers, rolling tines, etc.) for efficient incorporation of organic materials (such as livestock manure and crop residue) into soil in agriculture. Problems associated with the existing soil engaging tools include logging of crop residue in conservation tillage systems, high soil disturbance in forage and no-till systems, and high requirement of energy for operations. At a time when world food demand, cost of energy, and environmental impact are a matter of fact, it becomes urgent to rejuvenate soil engaging tools design to improve their efficiency and effectiveness. The performance of a soil engaging tool highly depends on how it interacts with soil and the organic materials they deal with. Currently, the design of commercial soil engaging tools still rely on the traditional soil-tool interaction models on soil behaviour and soil-tool interactions. In most traditional models, the Finite Element Method (FEM) was used and soil is considered as a continuous elastic-plastic media, whereas, soil behaves as a discontinuous media and flows as individual particles (aggregates and clods) around the tool. Thus the FEM is not fully capable to model agricultural soil and soil-tool interactions at the particle levels. Also, the FEM is not able to deal with a mixture of different materials at the "particles" levels, such as mixing crop residue "particles" with soil "particles". These incapacities of FEM have limited soil engaging tool design for ages. The Discrete Element Method (DEM) allows to model soil as an assembly of aggregates/clods and deal with more than one types of particles encountered in material incorporations. Using the DEM in soil dynamics is an emerging field, and this field is at its infancy stage. The proposed research will take a significant step in advancing the field, with the available expertise and research tools in the applicant' lab, the last soil dynamics lab in Canada which is fully functional.