精确测量土壤水的体积置换方法研究

发布时间：2018-08-19 14:47

【摘要】：土壤水的测量是相关研究和应用的基础,在土壤力学、作物栽培、农田灌溉、生态环境等研究和实践中十分重要。本研究根据体积置换方法测量的基本思想,以物理性质稳定的不同相态物质所组成的混合物为研究对象,建立了体积置换法在不同情况下测量混合物中各组分物质含量的算法,为土壤含水率等测量研究提供合理依据。根据土体是由土壤颗粒、土壤水和空气三相组成的体系,采用容易测量体积的水置换出不易测量体积的土中气体,通过向待测量的土样中补充水分,称量待测土样的初始质量和补水置换气体后土样的质量,确定置换气体所补充水分的质量/体积,进而计算得到土体中土壤颗粒与土壤水的体积,再根据土体中各物质的质量、体积、密度之间关系,计算得到土壤含水率。通过对采用体积置换法测量含水率的装置不断改进和完善,采用恒容容器体积置换法可以快速、准确测量土壤含水率。将采用体积置换法测量的不同种类土样的含水率和土壤容重,与传统烘干法测量的结果进行对比。2种方法测量的结果相比较,具有很好的线性关系,决定系数R2≥0.98,表明体积置换测量方法的可行性；体积置换法测量土壤含水率的平均值比烘干法(72 h,105℃)测量的结果高约2%,测量土壤容重的误差约为0.5%,表明测量结果精度的合理性。采用体积置换法测量陕西杨凌的粉黏壤土、北京的粉壤土、吉林的壤土和江西的粉黏土的土粒密度分别为：2.66、2.63、2.64、2.67 g/cm3。试验测量结果表明,体积置换法的2种途径(湿土法和干土法)测量土壤颗粒密度可以达到同等效果,湿土法和干土法测量结果的相对误差小于0.5%,并且测量操作过程优于常规比重瓶法和容量瓶法。同时,通过分析土壤有机质含量对含水率测量的影响,表明当有机质含量小于2%,土壤初始含水率大于5%时,可以直接采用土粒密度的平均值2.65 g/cm3测量土壤含水率；当有机质含量较高时,为了保证测量精度,需在测定土粒密度后,再采用体积置换法测量土壤含水率。采用体积置换法测量了土石混合物的含水率、容重、孔隙度和孔隙比,与传统烘干法测量的结果相比较,体积置换法测得的土壤含水率偏大,相对误差约为5%,测量的土壤容重偏小约1%。测量土壤孔隙度的相对误差约为1%,土壤孔隙比的测量误差为1%-1.5%。试验结果表明,采用体积置换法可以较为准确地测量土石混合物中各组分的相对含量,是对以往测量主体为细粒土进行拓展,具有操作便捷、省时省力的优点。采用体积置换法测量径流沉积物中水体积与土壤固体颗粒体积的比值,然后据此计算得到的土壤固体颗粒质量具有合理精度。体积置换法测量土壤含水率、土粒密度等,克服了传统测量方法中存在的缺点,并且测量精度较高,可以方便地应用于相关研究中,为灌溉管理、水文过程模拟等提供有效的研究手段。
[Abstract]:The measurement of soil water is the basis of related research and application. It is very important in the research and practice of soil mechanics, crop cultivation, farmland irrigation, ecological environment and so on. Based on the basic idea of volume displacement method and taking the mixture composed of different phase substances with stable physical properties as the object of study, an algorithm for measuring the content of each component in the mixture by volume replacement method under different conditions is established. It provides a reasonable basis for soil moisture measurement and research. According to the fact that the soil is a three-phase system composed of soil particles, soil water and air, the easily measured volume of water is used to replace the gas in the soil which is not easy to measure, and the water is added to the soil sample to be measured. The initial mass of the soil sample to be measured and the quality of the soil sample after the replacement of the gas with water are measured, and the mass / volume of the water supplied by the replacement gas is determined, and the volume of soil particles and soil water in the soil is calculated, and then according to the mass of each substance in the soil, The relationship between volume and density was used to calculate the soil moisture content. Through the continuous improvement and perfection of the equipment for measuring water content by volume displacement method, the volume displacement method of constant volume container can be used to measure soil moisture content quickly and accurately. The moisture content and bulk density of different kinds of soil samples measured by volume displacement method are compared with the results of traditional drying method. The determination coefficient R2 鈮，

本文编号：2191976