基于压实分析模型的土壤应力传递系数研究

发布时间：2018-02-03 06:02

  本文关键词： 土壤压实 分析模型 集中系数 土壤环境 应力传递系数　出处：《农业机械学报》2017年06期 　论文类型：期刊论文

【摘要】：机械压实是造成土壤退化的重要原因之一,研究并预测土壤应力有助于科学规划田间机械使用,缓解压实问题。基于分析模型预测土壤应力的关键在于选择合适的集中系数。然而在已有的研究中集中系数取值混乱,导致该模型使用时存在很大争议,其原因在于对该参数随土壤环境的变化缺乏规律性认识。本文通过对集中系数表达式的进一步推导,在理论上提出了能够代表土壤环境对集中系数影响的无量纲参数σ_z/σ_0,定义为应力传递系数(STC)。基于水稻土和黄棕壤两种土壤,通过控制含水率和湿密度于室内重塑30种状态的土壤,在单轴压缩实验中运用土压力传感器测量计算应力传递系数,建立应力传递系数与土壤环境参数,如含水率、干密度和先期固结压力等之间的相关性分析。结果表明应力传递系数随土壤含水率的增大而增大,土壤初始干密度和先期固结压力与应力传递系数之间负相关性明显。根据所得应力传递系数计算相应土壤状态下的集中系数,其取值在1.20~12.39之间,与以往的研究结果相差不大,但包含了关于集中系数随土壤环境变化的具体信息。这意味着作为一个稳定可测的无量纲参数,应力传递系数为集中系数的计算提供了一个相对科学的方法,在定量描述土壤环境对集中系数影响的同时,完善了分析模型。
[Abstract]:Mechanical compaction is one of the important causes of soil degradation. The key to predicting soil stress based on the analytical model is to select the appropriate concentration coefficient. However, the confusion of the concentration coefficient in the existing research leads to great controversy in the use of the model. The reason lies in the lack of regular understanding of the variation of this parameter with soil environment. The dimensionless parameter 蟽 _ (z) / 蟽 _ (0), which can represent the effect of soil environment on concentration coefficient, is proposed theoretically, and is defined as stress transfer coefficient (STC), which is based on paddy soil and yellow brown soil. Through controlling moisture content and moisture density to reconstruct 30 kinds of soil in indoor, the stress transfer coefficient was calculated by using earth pressure sensor in uniaxial compression experiment, and the stress transfer coefficient and soil environmental parameters were established. The results show that the stress transfer coefficient increases with the increase of soil moisture content. The initial dry density of soil and the pre-consolidation pressure have negative correlation with the stress transfer coefficient, and the concentration coefficient under the corresponding soil condition is calculated according to the obtained stress transfer coefficient. Its value is between 1.20 and 12.39, which is not different from the previous research results. But it contains specific information about the variation of concentration coefficient with soil environment, which means that as a stable and measurable dimensionless parameter, stress transfer coefficient provides a relatively scientific method for the calculation of concentration coefficient. At the same time, the analytical model was improved while quantitatively describing the effect of soil environment on concentration coefficient.
【作者单位】： 南京农业大学工学院;扎林盖大学农业工程系;
【基金】：国家自然科学基金项目(41371238)
【分类号】：S152.9
【正文快照】： 引言田间机械作业过程中,土壤-轮胎交互作用产生土壤应力改变土壤状态[1-4]造成的土壤压实是导致世界范围内土壤出现退化的重要原因之一[2,5-10]。研究并预测土壤应力可以科学规划田间机械的使用,缓解这一问题[2,11-12]。在以往的研究中,计算土壤应力的方法有仿真法(有限元和，

本文编号：1486634