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34 results on '"Bai, Ruiqiang"'

24. Rainfall- and Irrigation-Induced Landslide Mechanisms in Loess Slopes: An Experimental Investigation in Lanzhou, China.

Author

Liu, Wei, Bai, Ruiqiang, Sun, Xinran, Yang, Fang, Zhai, Weiji, and Su, Xing

Subjects
*LANDSLIDES, *MASS-wasting (Geology), *LOESS, *SHEAR strength of soils, *SHEAR strength, *SLOPE stability, *SOIL structure
Abstract

To reveal the mechanism of rainfall- and irrigation-induced landslides in loess slopes within cold regions, a series of tests on loess samples subjected to different permeability durations were conducted, and the effects of rainfall on several performance indicators, including the permeability coefficient, composition, microstructure, soil–water characteristic curve, and the shear strength of the loess, were investigated. The results show that the permeability coefficient of the loess decreased by 68% after permeability testing. With increased permeability duration, there is a marked decrease in total dissolved solids, sand particles, and clay particles, contrasted with an increase in silt particles. This dynamic alters the original soil structure and impacts the soil–water characteristic curve of the loess. Additionally, rainwater infiltration heightens the effective saturation of the loess, in turn diminishing the shear strength of the loess as effective saturation increases. This reduction in shear strength is further intensified with extended infiltration time (or rainfall duration). A landslide is triggered once the shear strength diminishes to the level of the geostatic stress of the loess slope, and the influence of the rainfall-induced loss of soil shear strength should be taken into account during slope stability analysis. This study enhances the understanding of the initiation mechanisms of rainfall-induced landslides in loess slopes. [ABSTRACT FROM AUTHOR]

Published
2024
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31. A Soil Semi-Empirical Dielectric Model Based on the Dielectric Variation Characteristics of an Electrical Double-Layer Solution

Author

Jin, Xiao, Bai, Ruiqiang, Gao, Xiaoqing, Yang, Wen, Yu, Ye, and Li, Zhenchao

Abstract

The complex permittivity of bound water is an uncertain factor in the modeling of soil permittivity. Based on the electrical double-layer theory, this study divides soil bound water into strongly and weakly bound components. These strongly and weakly bound components are assumed to be cation solutions in the adsorption and diffusion layers, respectively. The characteristic functions of the permittivity of weakly bound water were proposed to describe the variation in the complex permittivity of weakly bound water with changes in moisture, and a soil semi-empirical dielectric model (SEM) was established based on these characteristic functions. Through further fitting, this SEM only requires the soil temperature, moisture, clay content, and microwave frequency to obtain the soil complex permittivity. Measured data from 20 soils and four SEMs were used for model validation. The results show that this SEM can accurately calculate the complex permittivity of sand, silt, clay, and soils with low organic matter and low salinity in the range of 0–0.5 volume moisture content at 1.4–18 GHz. The characteristic functions link the electrical properties of clay with the complex permittivity of bound water. The two constituent formulas of the characteristic functions (the cation concentration and electric field strength) are almost independent of soil texture. Soil texture affects the soil complex permittivity by changing the contents of strongly and weakly bound water. This phenomenon suggests that the dielectric algorithm of bound water is minimally affected by soil texture. The dielectric algorithms of bound water utilized in the existing SEMs are reasonable.

Published
2023
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