Geometrical analysis of laboratory soil spectra in the short-wave infrared domain: Clay composition and estimation of the swelling potential
Geometrical analysis of laboratory soil spectra in the short-wave infrared domain: Clay composition and estimation of the swelling potential
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DOI：
10.1016/j.geoderma.2014.12.014
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发表时间：
2015-04
期刊：
影响因子：
6.1
通讯作者：
G. Dufrechou;G. Grandjean;A. Bourguignon
中科院分区：
文献类型：
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作者：
G. Dufrechou;G. Grandjean;A. Bourguignon
本研究提出了一种新的实验室反射光谱方法，其特征在于土壤光谱的位置，深度，在半深度的不对称性，和宽度在半深度的粘土诊断吸收带（1400 nm，1900 nm，和2200 nm）。的几何参数的计算，这是使用连续去除光谱，是快速和简单地适用于大量的样品，因此，可以用来覆盖大面积。混合物中的伊利石、蒙脱石和高岭石含量分别强烈影响约1400 nm（D1400）、约1900 nm（D1900）和约2200 nm（D2200）处的吸收带深度。D1400、D1900和D2200参数用于创建合成混合物的3D（使用D1900/D2200、D1400/D1900和D2200/D1400作为轴）和2D（使用D1400/D1900和D1900/D2200作为轴）图。在3D和2D图中，绘制的混合物形成三角形形状。由两种粘土矿物组成的混合物限定了三角形的外部包络，并且由三种粘土矿物形成的混合物位于三角形的内部。使用这些3D和2D图作为标准模板，天然土壤的粘土成分估计从（i）平均粘土成分的三个最接近的混合物，当土壤样品位于三角形分布的混合物和（ii）最接近的混合物，当土壤样品位于三角形分布的混合物。与X射线衍射的比较表明，蒙脱石含量的预测，这是用来估计膨胀潜力的土壤的可靠性。该方法提供了一种简单，快速，低成本的方法来分类土壤分为四个膨胀类的基础上比较与亚甲基蓝测试，它可以被用来作为一种补充或替代方法，以传统的岩土分析。
This study presents a new laboratory reflectance spectroscopy method that characterizes soil spectra in terms of the positions, depths, asymmetries at half depth, and widths at half depth of the clay diagnostic absorption bands (1400 nm, 1900 nm, and 2200 nm). The calculation of the geometrical parameters, which is performed using continuum-removed spectra, is rapid and simply applicable to a large number of samples and, therefore, can be used to cover large areas. The illite, montmorillonite, and kaolinite contents in mixtures strongly influence the depths of the absorption bands at approximately 1400 nm (D1400), approximately 1900 nm (D1900), and approximately 2200 nm (D2200), respectively. TheD1400,D1900, andD2200parameters are used to create 3D (usingD1900/D2200,D1400/D1900, andD2200/D1400as the axes) and 2D (usingD1400/D1900andD1900/D2200as the axes) diagrams of synthetic mixtures. In the 3D and 2D diagrams, the plotted mixtures form a triangular shape. The mixtures composed of two clay minerals define the external envelope of the triangular shape, and the mixtures formed of three clay minerals are located inside the triangular shape. Using these 3D and 2D diagrams as standard templates, the clay compositions of natural soils were estimated from (i) the average clay compositions of the three closest mixtures when the soil samples were located inside the triangular distribution of mixtures and (ii) the closest mixture when the soil samples were located outside of the triangular distribution of mixtures. Comparison with X-ray diffraction demonstrates the reliability of the predictions of montmorillonite content, which were used to estimate the swelling potential of the soils. This method offers a simple, fast, and low-cost approach to classifying soils into four swelling classes based on comparison with the methylene blue test, and it could be used as a complementary or alternative method to traditional geotechnical analysis.