Abstract
Particle size grading impacts salt-frost heaving and dissolution collapse events of salinized soil on northwestern China’s arid and cold region highways. However, the influencing mechanisms remain unclear and the impact of varying particle size grading needs further investigation. Hence, this study focused on these effects and the number of freeze–thaw cycles on the characteristic changes in highway salinized soil in arid and cold regions. Three soil columns with different gradations were prepared to explore the gradation and the number of freeze–thaw cycle affects on salinized soil’s salt-frost heaving and dissolution collapse characteristics. The multi-functional physical simulation platform conducted multiple freeze–thaw cyclic tests in the laboratory. Test results confirmed significant and conclusive effects of gradation and the number of freeze–thaw cycles on salinized soil’s salt-frost heaving and dissolution collapse behaviors. Poorly graded salinized soil with high coarse particle content caused repeated freeze and thaw engineering hazards, significantly affecting salinized soil’s displacement and deformation behaviors during freezing. Contrarily, an increased range of fine particles more easily involved the characteristics of salinized soil during thawing. Therefore, the fourth freeze–thaw cycle was a crucial time node. After four freeze–thaw cycles, the displacement and deformation of original salinized soil and B-grade salinized soil samples (poorly graded with high fine particle content) tended to be stable. In contrast, the displacement and deformation of A-grade salinized soil samples (poorly graded with high coarse particle content) increased the growth rate. The present research results contribute to in-depth knowledge of the effects of gradation and freeze–thaw cycles on the characteristics of salinized soil in northwestern China, providing excellent referenced data support for the prevention and control of highway salinized soil failures and other engineering projects in arid and cold regions of northwest China.
Highlights
Saline soils are widely distributed in the world, and in China, saline soils are mainly distributed in the northwest of the country [1]
From a macroscopic perspective, the displacement and deformation of the salinized soil samples with A-grade at the freezing stage exceeded those at the thawing stage
Some test parameters, including the number of freeze–thaw cycles, environmental temperature, and particle grading, were selected for analysis of the variation rules of overall displacement and deformation, and salt-frost heaving amount and coefficient, dissolution collapse amount and coefficient of different salinized soil samples with varying gradations under other freeze-thaw cyclic condition were investigated in depth
Summary
Saline soils are widely distributed in the world, and in China, saline soils are mainly distributed in the northwest of the country [1]. These areas are often located in seasonally frozen or permafrost regions. Salt-frost heave is caused by temperature changes and usually occurs in autumn, late winter or early spring [2,3]. Salinized soil extensively occurs in the Dushanzi Region (in the northern section of the Dushanzi–Kuqa Highway in Xinjiang). The salinized soil properties change with repeated temperature changes over many years, affecting the regular operation of engineering buildings [5,6,7,8,9]. An in-depth exploration of salinized ground conditions on the Dushanzi–Kuqa Highway was strongly needed
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