Simplified Relation Model of Soil Saturation Permeability Coefficient and Air-Entry Value and Its Application

Tao, Gaoliang; Wu, Zhijia; Li, Wentao; Li, Yang; Dong, Heming

doi:10.3390/fractalfract5040180

Cited by 6 publications

(2 citation statements)

References 23 publications

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“…Generally, geomaterials can be regarded as an open non-linear self-organizing system. When there are no external conditions to interfere with its self-organizing characteristics, the evolution of internal spatial structure exhibits certain orderliness [32][33][34][35]. The fractal structure is closely related to its composition and natural conditions: the fractal dimension represents the spatial structure characteristics formed by the long-term evolution of geomaterials.…”

Section: Introductionmentioning

confidence: 99%

Fractal Analysis of Particle Distribution and Scale Effect in a Soil–Rock Mixture

Ding

Sheng

et al. 2022

Fractal Fract

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A soil–rock mixture (SRM) is a type of heterogeneous geomaterial, and the particle distribution of SRM can be described by fractal theory. At present, it is difficult to quantify the fractal dimension of a particle size distribution and understand the scale effect in SRMs. In this study, the fractal theory and discrete element method (DEM) were introduced to solve this problem. First, the particle gradation of SRM was dealt with by using fractal theory. The fractal structure of particle distribution was studied, and a method of calculation of the fractal dimension is presented in this paper. Second, based on the fractal dimension and relative threshold, the particle gradations of SRMs at different scales were predicted. Third, numerical direct shear tests of SRM at different scales were simulated by using the DEM. The scale effects of shear displacement, shear zone, and shear strength parameters were revealed. Last, taking the maximum particle size of 60 mm as the standard value, the piece-wise functional relationship between shear strength parameters and particle size was established. The results are as follows: for SRM in a representative engineering area, by plotting the relationship between particle cumulative mass percentage and particle size, we can judge whether the SRM has a fractal structure; in Southwest China, the frequency of the fractal dimension of the SRM is in the normal distribution, and the median fractal dimension is 2.62; the particle gradations of SRMs at different scales calculated by fractal dimension and relative threshold can expand the study scope of particle size analysis; when the particle size is less than 70 mm, the strength parameters show a parabolic trend with the particle size increases, and if not, a nearly linear trend is found. The proposed method can describe the fractal characteristics of SRM in a representative engineering area and provides a quantitative estimation of shear strength parameters of SRM at different scales.

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Section: Introductionmentioning

confidence: 99%

Fractal Analysis of Particle Distribution and Scale Effect in a Soil–Rock Mixture

Ding

Sheng

et al. 2022

Fractal Fract

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“…The determination of soil air-entry value is of important meaning to explore the permeability of unsaturated soil. Soils with different textures have different air-entry values; for example, the air-entry value of clay is larger than sand [63]. Rawls et al [64] provided a series of typical air-entry values for soils with different textures (Table 1).…”

Section: Fractal Model Of the Swccmentioning

confidence: 99%

Evaluation of Soil-Water Characteristic Curves for Different Textural Soils Using Fractal Analysis

Yang

et al. 2023

Water

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The soil-water characteristic curve (SWCC) is an essential tool to determine hydraulic and mechanical properties of unsaturated soils. As an inherent influencing factor, soil texture controls the characteristics of SWCCs. Fractal theory can quantitatively describe the physical characteristics of soil. This study used particle size distribution data and water content data contained in the UNSODA2.0 database to explore the fractal characteristics of 12 soil types with different textures under different matrix suctions. The SWCC fractal model was adopted to characterize the hydraulic properties of soil with various soil textures. The findings revealed that the mass fractal dimensions of particles from these 12 different soil types significantly differed and were closely related to the clay content. Fractal dimension increased with increasing clay content. The fractal dimension established a good relationship between soil structure and hydraulic properties. Fractal analysis can be used to determine the connection between physical properties and soil hydraulic parameters. The estimated results of the SWCC fractal model indicated that it had a good performance regarding the description of SWCCs for the 12 soil textures. The soil structure could be described through fractal dimensions, which can effectively indicate soil hydraulic characteristics. The estimated fractal dimension of this model could be obtained by particle size distribution. Furthermore, using the SWCC fractal model, we found that the SWCC of coarse textured soil changed sharply in the low suction stage and its residual water content was small, and the SWCC of fine textured soil changed gently with a large residual water content. The water retention capacity followed the order clay > silty clay > sandy clay > clay loam > silty clay loam > sandy clay loam > loam > silt loam > sandy loam > silt > loamy sand > sand.

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Response and prediction of unsaturated permeability of loess to microstructure

Wang

2023

Geomech. Geophys. Geo-energ. Geo-resour.

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The study of water infiltration helps to investigate the pollutants' migration, grasp the mechanism of the water cycle, and correctly evaluate water resources. This paper reveals the mechanism of compacted loess's one-dimensional vertical water infiltration characteristics using a low-cost water infiltration device. In addition, it investigates particle arrangement and pore size distribution characteristics using nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The test finding suggests that the loess's early-stage infiltration rate is significant, and the dry density is not related to the infiltration characteristics. With the advance of the wetting front, the infiltration rate decreases under air resistance. The unsaturated permeability decreases with dry density at lower matric suction while unaffected by the dry density at higher matric suction. Moreover, the volume and connectivity of pores mainly control the water infiltration characteristics. Finally, based on the test results, a method for rapidly predicting the unsaturated permeability of loess is proposed. The results of the study help predict contaminant transport and guide groundwater extraction and management.

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Simplified Relation Model of Soil Saturation Permeability Coefficient and Air-Entry Value and Its Application

Cited by 6 publications

References 23 publications

Fractal Analysis of Particle Distribution and Scale Effect in a Soil–Rock Mixture

Fractal Analysis of Particle Distribution and Scale Effect in a Soil–Rock Mixture

Evaluation of Soil-Water Characteristic Curves for Different Textural Soils Using Fractal Analysis

Response and prediction of unsaturated permeability of loess to microstructure

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