Mechanical Properties of Fly Ash Reinforced Subgrade Soil in Seasonally Frozen Area

Abstract

Abstract: In order to investigate the influence of freeze-thaw cycle on the mechanical properties of subgrade soil reinforced with fly ash, unconfined compression test and triaxial shear test were carried out on saline soil with different freeze-thaw cycle times, moisture content and fly ash content. What's more, the changes of stress-strain curve, unconfined compressive strength, cohesion and internal friction angle of soil after freeze-thaw cycle were studied. Based on Design-Expert 8.0 software, the influence of freeze-thaw cycle times, fly ash content, moisture content and the interaction of various factors on the mechanical properties of saline soil was explored. The results show that the unconfined compressive strength, cohesion and internal friction angle of saline soil decrease after several freeze-thaw cycles, and the mechanical parameters of soil decrease rapidly after 1 to 7 freeze-thaw cycles. With the increase of fly ash content, the internal friction angle, cohesion, unconfined compressive strength and shear strength of saline soil increase at first and then decrease. Based on the theory of significance analysis, the interaction between freeze-thaw cycles and moisture content has a significant effect on the unconfined compressive strength and cohesion of saline soil. The interaction between fly ash content and freeze-thaw cycles only has obvious significance on unconfined compressive strength. In order to improve the strength and frost-thaw resistance of subgrade soil and speed up the comprehensive utilization of fly ash, it is recommended to add 15% fly ash to subgrade soil according to the mass ratio. The mechanical index of compacted saline soil after seven freeze-thaw cycles is taken as the reference value of engineering design.

Key words: subgrade soil, fly ash, fly ash reinforcing subgrade soil, seasonal freezing area, saline soil, freeze-thaw cycle, mechanical property

CLC Number:

TU43

CHENG Zhuo, CUI Gaohang, GAO Yuanhao, GANG Haohang, GAO Zening, YANG Zheng, ZHANG Xin. Mechanical Properties of Fly Ash Reinforced Subgrade Soil in Seasonally Frozen Area[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(11): 3854-3864.

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