Abstract: The process of rice straw and soil burial is an important factor affecting the return of straw to the field. In this paper, based on the previously established simulation model of the interaction between the straw return knife roller, soil, and rice straw, the motion state of soil particles was further studied. When the tillage depth was 20cm, the rotation speed of the cutter shaft was 240r/min, and the unit straw amount was 3.5kg/m2, simulation and indoor experiments were carried out with the straw burial rate and returning depth as the test indicators. The results showed a burial rate of 87.5% and 86.7% and a returning depth of 19.16 cm and 18.68cm, respectively, which validated the simulation and met the requirements of national standards. The simulation results showed that when the calibrated particle 152658 was in contact with the knife roller, it initially moved backward and downward. After reaching the lowest point, it was thrown backward and upward due to the rotation of the knife roller. The movement trajectory was approximately parabolic. The particle then fell back to the ground under the influence of gravity. It collided with other particles and generated fluctuations until it finally came to rest. The soil stress was studied by randomly calibrating the particles. The results showed that when the knife blade first contacts the soil particles, the forces in the X, Y, and Z directions of the particles increased linearly, and the maximum values were 15.61N, 37.2N, and 50.37N, respectively. After the soil particle mass was chopped by the knife blade, the force gradually decreased to 0. Similarly, by calibrating straw particle 45681 and analyzing its movement trajectory, the simulation showed that soil particles initially exhibited a dual effect of promoting and inhibiting the straw velocity. As the soil returned to the surface, the straw was mainly affected by soil friction under the soil layer until the straw velocity dropped to 0. The simulation analysis revealed the working principle of the straw return knife blade for straw burial and returning to the field from a microscopic point of view and provided theoretical support for the optimal design of components.

Key words: straw returning, soil particles, straw particles, movement trajectory, burial movement

摘要： 水稻秸秆与土壤翻埋过程是影响秸秆还田的重要因素。在前期建立的还田刀辊—土壤—水稻秸秆三者仿真互作模型的基础上，进一步研究土壤颗粒的运动状态。在耕深为20cm、刀轴旋转速度为240r/min、单位秸秆量为3.5kg/m2时，以秸秆翻埋率和还田深度为指标，分别进行仿真与室内模拟试验，翻埋率分别为87.5%、86.7%，还田深度分别为19.16cm、18.68cm，模拟试验验证仿真试验的有效性。仿真结果显示所标定颗粒152658与刀辊接触时，开始向后下方位移，到达最低点后随着刀辊的旋转向后上方抛洒，此时运动轨迹近似抛物线，随后在重力作用下回落到地表，与其他颗粒碰撞产生波动，直至最终停下。通过随机标定颗粒研究土壤受力情况，结果表明：当弯刀在开始接触土壤颗粒时，颗粒X、Y、Z方向受力均直线上升，最大值分别为15.61N、37.2N、50.37N，直到该土壤颗粒团被弯刀切碎后，力逐渐下降为0。同理标定秸秆颗粒45681，分析其运动轨迹，仿真结果表明：起初土壤颗粒对秸秆速度产生促进和抑制双重作用，随着土壤回落地表，秸秆在土层下主要受到土壤摩擦作用，直至秸秆速度降为0。仿真分析从微观角度揭示弯刀对秸秆翻埋还田的工作机理，为部件优化设计提供理论支持。

关键词: 秸秆还田, 土壤颗粒, 秸秆颗粒, 运动轨迹, 翻埋运动