石漠化根土复合体本构模型及玉米免耕播种“自保护”破茬防堵机理研究

In order to solve the problem of releasing seeding artificially and achieving the implementation of no-tillage hardly, the project intends to carry out the theoretical research of anti-blocking and the innovation design of the device in the rocky desertification area, Southwest China. By studying the mechanical properties of soil-engaging components, the constitutive model of root-soil-engaging components is established in the rocky desertification area, considering the factors of strengthening the shear strength in the Coulomb Formula. It provides a basis for the construction of anti-blocking mechanism. The theoretical and experimental research is carried out, which on anti-blocking mechanism of "self-protecting" stubble-cutting and anti-blocking. Analyzing of the kinematics and dynamics model of stubble-cutting and anti-blocking mechanism, the mechanism of cutting roots, soil and soil-engaging components is illuminated. Analyzing of the collision motion between the mechanism and the soil-engaging components and the rock, the mathematical model of collision motion is established, by resolving the rule of the rebound critical velocity and the input parameters. Verifying the theoretical model of used by the simulation experiments, the relationship between the device of stubble-cutting and anti-blocking and the geometric parameters of the structure and the mechanism driving characteristics. Development of a prototype and performance test of stubble-cutting and anti-blocking mechanism, the mechanism of stubble-cutting and anti-blocking is clarified, after modifying the theoretical model. It provides theoretical basis and method support for no tillage sowing equipment in rocky desertification area and even in hilly and mountainous areas.

针对西南石漠化地区保护性耕作中人工播种劳动强度大和免耕破茬防堵机构难以实现的问题，本项目拟开展石漠化地区免耕播种时破茬防堵的理论研究和装置的结构创新设计。通过研究石漠化地区根土复合体力学特性，在库仑公式中引入根系增强抗剪强度的因素，建立石漠化根土复合体本构模型，为构建破茬防堵机构提供依据。重点开展“自保护”主动破茬防堵机构理论与试验研究。进行“自保护”破茬防堵机构的运动学和动力学分析，构建其在切削根土复合体过程中根、土及根土复合体的空间分布及接触-切削过程的影响机制；分析该机构与根土复合体及裸露基岩的碰撞运动规律，解析其弹回临界速度与输入参数的关系，建立碰撞运动数学模型；基于仿真试验，探明其破茬防堵性能与机构结构几何参数之间及机构驱动特性之间的关系及变化规律；研制样机并进行破茬防堵机理性能试验，修正理论模型，阐明破茬防堵机理。为石漠化地区乃至丘陵山区的免耕播种装备提供理论基础和方法支持。

保护性耕作是解决西南石漠化地区“耕地-粮食-人口”矛盾的有效新途径。但该区域土壤粘重、秸秆根茬量大，相应的防堵机理认知缺乏，现有的破茬防堵装置不能有效地实现玉米免耕播种作业。.针对这一问题，项目组以中度石漠化区域玉米免耕播种为试验分析对象，开展基于石漠化根土复合体本构模型的自保护破茬防堵机理研究。主要修正了适于石漠化根土复合体的本构模型，标定了石漠化土壤、秸秆和根土复合体离散元仿真模型参数，提出了正反转动力有支撑切割防堵新思路，建立了仿云斑天牛口器轮廓的啮合齿刃曲线，进行了建立了“破茬防堵机构-作物秸秆-土壤”数值模拟分析，在优化其结构参数和作业参数的基础上，试制了正反转动力切茬式玉米免耕播种样机，并进行了田间试验。.课题完成的内容和取得的成果主要有以下几个方面：.（1）分析石漠化根土复合体力学特性，以修正剑桥模型为基础，引入石漠化土壤特性参数和玉米根系参数，构建了适于石漠化根土复合体的本构模型。.（2）优化Hertz-Mindlin with Bonding接触模型，采用有限尺寸的粘结键将颗粒粘结，以玉米秸秆临界载荷仿真试验，通过单因素试验、Plackett-Burman试验、最陡爬坡试验和Box-Behnken响应面法试验，标定了玉米秸秆离散元模型。.（3）基于云斑天牛口器轮廓曲线，设计了正反转动力切茬式防堵机构，以粘接键断裂数量和作业功率为试验指标，通过二次回归正交旋转组合仿真试验，解析了“破茬防堵机构-作物秸秆-土壤”互作的力学行为和演变规律，阐明了动态有支撑切割的破茬防堵机理。.（4）基于BP模糊神经网络自抗扰控制系统优化了转向避障和提升避障的自保护系统，探讨了正反转动力破茬式防堵结构几何参数之间及机构驱动特性之间的关系及变化规律，优化其结构参数和作业参数，应用试制的样机进行了田间试验。.（5）发表论文10篇，其中SCI/EI8篇，申请专利10件（授权5件），培养硕士生10名，培养骨干教师2名，项目主持人入选云南省“兴滇人才”。