蒙皂石含量与膨胀土光谱吸收参量相关关系研究

对沿南水北调中线工程邯郸—永年、南阳、平顶山等地区及襄樊、荆门钟祥地区采集的各类地表、近地表膨胀土样品55件,运用现代XRD定量方法和有机染料吸附方法测量了粘土矿物成分和蒙皂石含量,计算了有效蒙皂石含量,同时测定了它们的可见光短波红外光谱,并参量化计算了吸收光谱的位置、深度、宽度、对称性和面积,统计分析了光谱吸收参量与有效蒙皂石含量及胶粒、粘粒含量之间的关系。结果表明:根据蒙皂石2200nm,1900nm,1400nm吸收的相对强度,可以划分不同的膨胀土类型;根据膨胀土实验室光谱1900nm,1400nm吸收深度和吸收宽度可以估算膨胀土的有效蒙皂石含量及胶粒、粘粒含量;吸收对称性和面积不能运用于与有效蒙皂石含量及胶粒、粘粒含量的光谱估算;运用实验室光谱测量分析,可以在工程现场经济、方便、快捷地识别膨胀土、划分膨胀土类型、估算有效蒙皂石含量及胶粒、粘粒含量,能够产业化应用。

A Study on the Correlation Relationships between Smectite Contents and Spectral Absorption Indices of Swelling Soils

55 surface and sub-surface samples of expansive soilswere collected in theHandan-Yongnian area, Nanyang dis- trict, Pingdingshan area alongthe middle line oftheNorth-SouthDiversionWaterProject and in Xiangfan area and Zhongxiang districts in Jingmeng city. Clay mineral composition and smectite contents were measured using XRD and dye absorption meth- ods. The effective smectite contentswere calculated. Meanwhile the visible-shortwave infrared spectra of the swelling soils was collected, the spectral absorption indices, such as: wavelength position, depth, width, asymmetry, area, were calculated auto- matically. Then the correlation relationships between the spectral indices and the smectite contents and the colloid contents and clay contents of the swelling soilswere statistically analyzed. The results showthatthe very high, high, medium, weak potential soils can be identified accordingtothe relative strengths ofthe 2200nm, 1900nm, 1400nmabsorptions inthe spectral features of the swelling soils; the smectite contents and the colloid contents and the clay contents ofthe swelling soils can be estimatedwith the 1400nm and 1900nm absorption; the absorptionwidths of the 1900nm and 1400nm absorptions can be used to estimate the smectite contents; the absorption area and asymmetry cannot be used to estimate the contents of smectite and colloid and clay; the laboratory spectral measurement and analysis techniques to the dried and homogenous swelling soils can be productively used for quickly, economically, and conveniently identifying swelling soils, and estimatingthe contents of smectite, colloid, and clay in the engineering sites.