土壤含水量与容重对砂姜黑土抗压强度的影响及其传递函数构建

Influence of Soil Water Content and Bulk Density on Precompression Stress of Shajiang Black Soil and Establishment of Pedo-transfer Function

    摘要
  • 摘要:
    目的 砂姜黑土表现出湿时泥泞，干时僵硬的物理性质，探究砂姜黑土的抗压强度对于土壤结构保护和农机作业时间选择具有重要意义。
    方法 以砂姜黑土为研究对象，设置5个不同的土壤含水量水平（田间持水量的100%、85%、70%、55%及40%），以及3个土壤容重级别（1.2、1.4和1.6 g cm−3），采用高压固结仪进行单轴压缩试验，分析土壤含水量（θ）和容重（ρ）对抗压强度（σp）的耦合影响。
    结果 Van Genuchten 方程拟合土壤压实曲线效果良好（R2 > 0.99）。砂姜黑土耕层土壤的抗压强度范围为15.2 ~ 150.6 kPa，且受到土壤含水量和容重以及二者交互作用的显著影响（P < 0.05）。当土壤含水量 ≥ 70%田间持水量且初始容重 ≤ 1.4 g cm−3时，农机装备的施加压力已经超过土壤抗压强度，压实风险较高。本研究采用MATLAB进行多元回归分析的方法，构建了土壤含水量、湿容重与抗压强度三者的土壤传递函数（σp = aexp(bθ + cρ)，R2 = 0.832, P < 0.01）。
    结论 土壤含水量与容重是调控砂姜黑土抗压强度的两个关键因素，建议选择土壤含水量较低且容重较大的时期进行农事操作。研究建立的土壤传递函数可以较好地预测砂姜黑土的抗压强度，研究结果可为农机具在田间作业时的压实风险评估及合理作业时机选择提供科学依据。

     

    Abstract:
    Objective The Shajiang black soil (Vertisol) is characterized by high bulk density and high clay content, which often leads to problems such as swelling and shrinkage, limited infiltration and increased strength. At the same time, agricultural machinery is often used for field work in the district. Precompression stress is often used to evaluate the compressive properties and bearing capacity of soils. An in-depth study of soil compression characteristics of Shajiang black soil is of great significance for the protection of soil structure and the uptime of agricultural machinery.
    Method Repacked Shajiang black soil was chosen to examine the effects of initial water content and bulk density on precompression stress and to establish a Pedo-transfer function. The soil bulk densityies(ρ) were established at 1.2, 1.4, or 1.6 g·cm−3, while the soil water contents (θ) were set at 100%, 85%, 70%, 55%, and 40% of field capacity. Uniaxial compression tests were conducted using a consolidator to obtain soil compression curves, and the precompression stress was calculated using the Casagrande method.
    Result The van Genuchten equation provided a good fit for the soil compression curve, while the initial void ratio, soil water content, and bulk density significantly influenced the soil compression characteristics (P < 0.05). The precompression stress of Shajiang black soil varied between 15.2 kPa and 150.6 kPa and showed a significant negative exponential correlation with soil water content and a significant positive correlation with bulk density. (P < 0.05). A Pedo-transfer function (σp=aexp(bθ + cρ), R2 = 0.832, P < 0.01) was established among water content (θ), bulk density (ρ), and precompression stress (σp), considering the swelling and shrinkage characteristics of Shajiang black soil.
    Conclusion The soil water content and bulk density are the two core elements these regulate the compressive strength of Shajiang black soil. The results of this study can serve as a reference for assessing the risk of compaction and determining a suitable time for trafficability.

     

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