On the characterization of the shrinkage behavior and soil-water retention curves of four soils using centrifugation and
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ORIGINAL PAPER
On the characterization of the shrinkage behavior and soil-water retention curves of four soils using centrifugation and their relation to the soil structure Lincui Li 1 & Xi-An Li 1,2 & Haonan Lei 1 & Bo Hong 1 & Li Wang 1 & Hong Zheng 1 Received: 27 June 2020 / Accepted: 16 November 2020 # Saudi Society for Geosciences 2020
Abstract In this study, a consistent centrifuge procedure was applied to four soils. The height shrinkage, bulk density increase, soil shrinkage curve (SSC), and soil-water retention curve (SWRC) of the soils were analyzed. Scanning electron microscopy (SEM) tests and image processing techniques were adopted to qualitatively and quantitatively investigate the microstructure of the soils with different bulk densities. The results showed that under a matric suction ranging from 0 to 2000 kPa, the bulk density increased from an initial value of 1.30 g/cm3 to 1.60, 1.72, 1.61, and 1.57 g/cm3 for the soils retrieved from Chanhe, Qingyang, Yan’an, and Lvliang, respectively, resulting in corrected SWRCs considering soil shrinkage that was higher than the uncorrected SWRCs, consistent with previously published work. However, this difference was effectively reduced by retesting the soil samples. A reduction in water volume resulted in the same reduction in the bulk soil volume in the normal shrinkage state, while a shrinkage rate higher than one was found with increasing soil drying. More hydraulically active and connected macropores were detected in the low-density soil. The maximum pore diameter, total pore area ratio (PAR), pore size, and number distribution considerably changed with increasing density. The captured microstructural information is beneficial for the interpretation of the shrinkage behavior and hydraulic properties of soil. Keywords Centrifuge . Soil shrinkage . Soil-water retention curve . Dehydration pore area ratio distribution
Introduction The constitutive relationships between soil suction and hydraulic conductivity and the volumetric water content are known as the soil-water retention curve (SWRC) and hydraulic conductivity function (HCF) (Burdine 1952; Brooks and Corey 1964; Mualem 1976; van Genuchten 1980), respectively. The SWRC has been applied to examine or assess the water availability (Pham and Fredlund 2008), water and solute transport (Gao and Shao 2015; Karup et al. 2017; Vero et al. 2014), soil-water Responsible Editor: Zeynal Abiddin Erguler * Xi-An Li [email protected] 1
College of Geology Engineering & Geomatics, Changan University, Xi’an 710054, Shaanxi, China
2
Open Research Laboratory of Geotechnical Engineering, Ministry of Land and Resources, Xi’an 710054, Shaanxi, China
holding capacity (Martinez et al. 2014; Tripathy et al. 2002), hydraulic engineering (Villar and Lloret 2004; Peron et al. 2009; Jiang et al. 2017), shear strength (Vanapalli et al. 1996; Barbour 1998), and physical quality (Dexter 2004). Studies have shown that the soil hydraulic parameters obtained from the SWRC can be adopted to simulate evaporation (Ciocca et al. 2014
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