Shear strength of alluvial soils reinforced with PP fibers

摘要

Alluvial soils can be defined as sediments that have not completed their geological formation have high void ratios, low bearing capacity, and low shear strength. To eliminate the unfavorable properties, various improvement methods can be applied, such as injection, compaction, and mixing. Polypropylene fibers, a kind of geosynthetic, are used to improve the geotechnical properties of soil. In this study, the shear strength characteristics of natural and polypropylene-reinforced alluvial soils were investigated. Firstly, the index properties were examined, the materials were classified, and an idealized soil profile was constituted. Afterward, direct shear experiments were conducted with loose and dense prepared, natural, and 0.5% and 1% polypropylene fiber-reinforced alluvial soils. To investigate the effect of density on shear strength, loose and dense samples were prepared at their liquid limits. The direct shear, test results showed that the dense prepared natural and polypropylene-reinforced samples had higher internal friction angles than did the loose samples. The density had a greater effect on the friction angles of the natural samples than the reinforced ones. The polypropylene fibers were prolonged at the predefined shear surface and increased the internal friction angle and shear resistance. The test results indicated that polypropylene fiber had a larger effect on the internal friction angle of coarse-grained (SC and SM-SC) alluvial soils. When the effect of PP fiber content on the internal friction angle of coarse-grained samples was examined, it was observed that 0.5% PP fiber additive caused a more significant increase than 1% PP fiber additive.