Effects of fiber parameters and confining pressure on mechanical properties of fiber reinforced aeolian sandy soil

The influences of fiber length (3-18 mm), fiber content (0.1%-0.3%) and confining pressure (30-300 kPa) on strength characteristics of polypropylene fiber reinforced aeolian sandy soil (FRASS) were investigated via unconsolidated-undrained triaxial compression tests. Fibers included in FRASS were randomly distributed. Test results show that failure strength and residual strength of FRASS are substantially enhanced with increasing fiber length, fiber content and confining pressure under given test schedule. The increase in fiber length or fiber content results in a significant increment in cohesion, but a negligible increment in internal friction angle. As fiber length increases, a transition from strain softening to strain hardening is observed for FRASS, while the ductility appears to be unchanged. As fiber content increases, FRASS with fiber length of 3 mm maintains strain softening state and its ductility almost has no change, on the contrary, FRASS with fiber length of 9 mm, as well as 18 mm, presents a transition behavior from strain softening to strain hardening and ductility deserves a remarkable increment. As confining pressure increases, the ductility and the degree of strain hardening of FRASS increase. Failure strength-confining pressure relationship of FRASS exhibits bilinear behavior with bilinearity break occurring at critical confining pressure. At confining pressures less than the critical, the reinforcing effect of fiber inclusion is more pronounced in increasing internal friction angle. At confining pressures higher than the critical, the reinforcing effect of fiber inclusion is more pronounced in the enhancement of cohesion.