A Study on the Correlation Relationships between Smectite Contents and Spectral Absorption Indices of Swelling Soils
蒙皂石含量与膨胀土光谱吸收参量相关关系研究

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.