Dynamic Behavior of Geosynthetic-Reinforced Expansive Soil under Freeze-Thaw Cycles

Zhongnian Yang,Liang Zhang,Xianzhang Ling,Xuesen Liu,Guoyu Li,Fujun Niu,Wei Shi,Jia-Wen Zhou

doi:10.1155/2021/5526854

Abstract

Expansive soil has a significant impact on the stability of many key construction projects in cold regions. To study the physical and mechanical properties of expanded soil under the condition of freeze-thaw cycle, cryogenic cyclic triaxial tests were conducted on the dynamic and the displacement characteristics of geosynthetic-reinforced expansive soil subjected to the freeze-thaw cycles. Compared with the unreinforced expansive soil samples, the effects of freeze-thaw cycles on the soil dynamics were discussed. The dynamic shear modulus (Gd) and damping ratio (λ) of the expansive soil samples are improved by reinforcement. Reinforced soil can inhibit the axial compression of the sample and restrain the frost heave deformation of the sample during the freezing process. Meanwhile, it can delay the structural damage effect caused by frost heave and reduce the rate of change of the Gd and the λ with the freeze-thaw cycle. At the same time, reinforced soil can inhibit the axial expansion, reduce the rate of reduction of the Gd, stabilize it with a higher rate, and reduce the influence of the freeze-thaw cycles on the λ of the expansive soil sample. Finally, the change of mechanical properties of expansive soil under the condition of reinforcement is obtained. The main conclusions of this paper can be used to reinforce the roadbed and foundation engineering of frozen soil in a cold region and provide support for the fiber reinforcement method of expansive soil.

Highlights

Expansive soil, identified as unsuitable construction materials for engineering, is low-graded because of its inferior mechanical properties, such as low strength and high potential for swelling and shrinkage [1, 2]
Geogrid can constrain the frost heave deformation of samples during freezing and reduce the number of cracks and delay the structural damage effect caused by frost heave
(2) e reinforced expansive soil shows smaller strain changes than the unreinforced soil under different freeze-thaw cycles and reinforcement can restrain the axial deformation of expansive soil samples under freeze-thaw conditions. e axial compression or expansive displacement of the reinforced sample is lower than the unreinforced one, both in a confining pressure of 50 kPa and 10 kPa, after seven freeze-thaw cycles

Summary

Introduction

Expansive soil, identified as unsuitable construction materials for engineering, is low-graded because of its inferior mechanical properties, such as low strength and high potential for swelling and shrinkage [1, 2]. E dynamic characteristics of reinforced soil are affected by many parameters, such as the properties of rebar, freeze-thaw cycle, loading times, confining pressure, frequency, and the amplitude of shear strain. Shahnazari et al [22] studied the influence of geogrids on the dynamic characteristics of sand through the triaxial test, and the result shows that the shear modulus of reinforced sand decreases under low confining pressure (

Experimental Scheme

Results and Discussion

A B C R2

Conclusion