Abstract
Fiber-reinforced soil is an excellent engineering material that has become a focus of research. Most studies focus on the conventional mechanical properties of reinforced soil, such as its tensile, compressive, and shear strength, and rarely study its creep-related mechanical properties. However, when such soil is used as backfill, the creep effect should not be ignored. This study explored the characteristics of creep mechanics in reinforced soil, the fiber-reinforcement mechanism, and the dynamics of microstructures before and after creep tests. Direct shear creep tests were carried out using a direct shear creep tester on soil reinforced with natural palm fibers of equal length (1.5 cm) in different amounts (0%, 0.2%, 0.6%, 1.0%). Microscale tests were carried out on the reinforced soil samples before and after the creep tests by polarized light and scanning electron microscopy. The results show that the fiber reinforcement can restrain the deformation and enhance the long-term strength of soil. However, a nonlinear relationship between the reinforcement effect and fiber content was found, with 0.6% being the optimal content. Palm fibers have rough surfaces, grooves, and independent pore chambers, which increase the effective contact area and interaction with the soil. With increases in fiber content, the fibers interweave to form a nestled network structure, which increases the strength and integrity of the soil. Fiber addition changes the microstructure of the soil pores; the proportion of large pores decreases and that of small pores increases. Under the effect of creep, the pore changes follow the principle of pore homogenization; large pores are destroyed and transformed into small pores, causing the porosity of reinforced soil to decrease faster and be less porous than unreinforced soil. This research can provide technical reference for the engineering application of palm fiber-reinforced soil.
Highlights
In recent years, fiber-reinforced soil technology has developed rapidly and has been widely used in engineering to improve soil masses
The creep mechanical properties of palm fiberreinforced soil were studied by direct shear creep tests. e interfacial mechanism of reinforced soil was explored by using polarized light microscopy and scanning electron microscopy (SEM)
Reinforcement no longer increases when fiber contents are beyond 0.6%
Summary
Fiber-reinforced soil technology has developed rapidly and has been widely used in engineering to improve soil masses. Test results show that fiber reinforcement can inhibit soil fracture development and enhance soil toughness, deformation resistance, and strength [1, 2]. A uniform distribution of fibers in soil that makes full contact with the soil particles can make the mechanical properties of fibrous soil close to isotropic and enhance its integrity [3, 4]. Palm fibers have medium strength, high elongation, wear and corrosion resistance, low cost, and good mechanical properties [9]. Fiber-reinforced soil is an excellent engineering material and the study of its mechanical properties has become a hot research topic in the geotechnical field. Ranjan et al [10] studied medium- and coarse-sand fiber-reinforced soil through indoor triaxial experiments. Ranjan et al [10] studied medium- and coarse-sand fiber-reinforced soil through indoor triaxial experiments. e results showed that
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