Soil reinforcement using randomly distributed fibres to improve the shear strength has been identified as an effective and environment-friendly technique in engineering applications. Loess used in geotechnical constructions can suffer from cracking due to shear failure. To increase loess shear strength, triaxial compression tests were carried out to evaluate the effect of randomly distributed fibre reinforcement on the mechanical response of loess soil to load. In the present investigation, five groups of loess specimens were prepared with three fibre contents (i.e., 0.5%, 0.75%, and 1% by weight of dry loess) and two different fibre lengths (i.e., 9 mm and 18 mm). The experimental results indicate that the addition of fibre to soil significantly improves the failure stress and shear strength parameters of the loess compared with unreinforced loess specimens. As fibre content increases up to 0.75%, the cohesion of reinforced soil is greatly improved, whereas the amount of increase of the internal friction angle is much less significant. However, the cohesion decreases with the fibre content exceeding 0.75%, as the excessive fibre content may influence the formation of homogeneous mixture, resulting in interfacial mechanical interactions between the fibre surface and soil to be impaired. Loess specimens reinforced with longer fibre exhibited a greater cohesion than those reinforced with shorter fibre, while the internal friction angle is nearly insensitive to the fibre length. As the fibre length increases from 9 to 18 mm, the cohesion increases by 23.2%. In addition, the macro-morphology of fibre-reinforced specimens after triaxial shear tests suggests that an appropriate choice of fibre has the potential to increase soil cracking resistance capacity.
Triaxial compression test Fibre reinforcement Reinforced loess Shear strength
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The authors thank the editor and two anonymous reviewers for their constructive comments which improve the quality of the manuscript greatly.
Financial support of the Major Program of the National Natural Science Foundation of China (grant no. 41790440) and the China Postdoctoral Science Foundation (no. 2019T120871) are gratefully acknowledged. The support provided by China Scholarship Council (CSC) during a visit of the first author (Lian) to Texas A&M University is sincerely acknowledged.
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