利用时域反射技术测定饱和土壤中轻非水相液体的含量

发布时间：2017-12-28 18:14

本文关键词：利用时域反射技术测定饱和土壤中轻非水相液体的含量　出处：《太原科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：时域反射技术(TDR,Time-Domain-Reflectometry)是一种利用电磁波在介质中的传播时间来确定介质性质的探测技术,已经被广泛应用于工业和农业等多个领域。利用TDR测定土壤中轻非水相液体(LNAPLs,Light Non-aqueous Phase Liquids)的含量具有快速、准确、可连续原位测定、无辐射以及不破坏土壤样品等优点。目前,国内外利用TDR监测轻非水相液体的相关研究还较为薄弱,LNAPLs对土壤介电特性的影响以及污染土壤中LNAPLs含量的定量预测相对较少。本研究利用时域反射技术,测定饱和砂土和壤土的介电常数和电导率随LNAPLs(菜籽油、机油)含量的变化规律,并在此基础上,通过模型模拟及修正,确定了饱和土壤中轻非水相液体含量的预测模型。结果表明:1)饱和土壤中体积含油量在0-0.05 m3m-3时,土壤介电常数并无显著变化;随着LNAPLs体积含量的进一步增加,介电常数呈线性减小趋势;土壤容重和LNAPLs类型对相同饱和度的土壤介电常数未产生影响。2)饱和土壤的电导率与LNAPLs含量存在良好的线性负相关关系(R2=0.96);土壤容重对相同饱和度的土壤电导率未产生影响。3)混合介电模型(α=0.5)高估了饱和土壤中轻非水液体含量,平均RMSE为0.038cm3cm3;参数α调整为0.52后,混合介电模型提高了预测精度,比原混合介电模型(α=0.50)预测精度可以提高23.2%—30.4%。本研究结果表明可利用时域反射技术监测污染土壤的介电常数与电导率并测定饱和土壤中LNAPLs的含量。
[Abstract]:TDR (Time-Domain-Reflectometry) is a detection technology based on the propagation time of electromagnetic waves in the medium to determine the properties of medium. It has been widely applied in many fields, such as industry and agriculture. The determination of LNAPLs, Light Non-aqueous Phase Liquids in soil by TDR is fast, accurate, continuous, in situ measurement, no radiation and no damage to soil samples. At present, the related researches on monitoring light nonaqueous phase liquids by TDR at home and abroad are relatively weak. LNAPLs has little influence on the dielectric properties of soil and the quantitative prediction of LNAPLs content in contaminated soil. This study uses time domain reflectometry, determination of saturated sand and loam soil permittivity and conductivity with LNAPLs (rapeseed oil, oil) the change rules of the content, and on this basis, through the simulation and correction model, the prediction model of LNAPL content in soil. The results show that: 1) the volume of soil saturated oil amount in 0-0.05 m3m-3, no significant changes of soil dielectric constant; with a further increase of LNAPLs content, the dielectric constant decreased linearly; on the same soil dielectric saturation, soil bulk density and LNAPLs type constant did not produce effect. 2) there is a good linear negative correlation between the conductivity of saturated soil and LNAPLs content (R2=0.96); soil bulk density has no effect on soil electrical conductivity of the same saturation. 3) the mixed dielectric model (alpha =0.5) overestimated the content of light and non-aqueous liquids in saturated soil, and the average RMSE was 0.038cm3cm3. When the parameter alpha was adjusted to 0.52, the mixed dielectric model improved the prediction accuracy, and the prediction accuracy of the mixed dielectric model (alpha =0.50) could be increased by 23.2% to 30.4%. The results of this study show that the time domain reflection technique can be used to monitor the dielectric constant and electrical conductivity of contaminated soil and determine the content of LNAPLs in saturated soil.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X833

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