Study on Dynamic Interaction between Machine/Plant and Soil

对土体的流变性等动力响应进行了基础性试验，并尝试用离散单元法模拟土体的动力特性。对于机械零件与土的相互作用，理论上主要采用有限元方法进行研究，而在有限元方法中，土被视为连续介质。这就导致难以处理机械部件冲击或瞬时作用于土壤时经常出现的土块或颗粒分离等离散现象，因此，应用DEM比有限元更适合于研究机械与土壤、植物根与土壤之间的相互作用。考虑到根的形态，根尖的移动和生长将能够被发现是根与土壤相互作用的结果，这将由DEM发现。最终的报告是用英文写的，内容如下：第一章导言，第二章土壤的力学性质，第三章土壤的流变性分析，第四章，有限元方法在寻找土壤应力松弛中的应用，第五章，有限元方法在寻找车轮随时间变化的下沉中的应用，第六章，有限元方法发现轮齿与土壤的相互作用，第七章变形速度对土壤压实的影响(滚动轮胎与土壤的相互作用)，第八章振动对土壤抗剪强度的影响(振动轮胎与土壤的相互作用)，第九章植物根系与土壤相互作用的基础研究，第十章。结论和参考文献。

Fundamental experiments on the dynamic response of soil such as the rheological behavior were conducted and at the same time the distinct element method was tried to be applied to simulate the dynamic behavior of soil. The interaction between machine parts and soil has been investigated theoretically mainly by using the FEM.In the case of the FEM,however, the soil is treated as a continuum. That results in difficulty to handle a discrete phenomenon such as the separation of soil blocks or particles which often occurs by the impact or transient action of machine parts on the soil.Therefore, the application of the DEM would be more preferable than the FEM to clarify both interactions between machine and soil and between plant root and soil. Considering the root morphology, the movement of root tips and the growth would be able to be found as the result of the interaction between the root and the soil which will be found by the DEM.The final report was written in English with the following contents :Chapter 1. Introduction, Chapter 2. Mechanical Properties of Soil, Chapter 3. Analysis of Rheological Behavior of soil, Chapter 4. Application of Finite Element Method to Find the Stress Relaxation of Soil, Chapter 5. Application of Finite Element Method to Find the Time-dependent Sinkage of Wheel, Chapter 6. Interaction between Lugs of Lugged Wheel and Soil Found by the Finite Element Method, Chapter 7. Effect of Deformation Speed on Soil Compaction (Interaction between Running Tire and Soil) , Chapter 8. Effect of Vibration on Soil Shear Strength (Interaction between Vibrating Tire and soil) , Chapter 9. Basic Study to Find the Interaction between Plant Root and Soil, Chapter 10. Conclusion and References.