AbstractThis research investigates the behavior of sand
reinforced with polypropylene fiber. To do this, 40 direct
shear tests and 40 triaxial tests were performed on the
coastal beaches of Babolsar, a city in the North of Iran. The
effect of parameters such as fiber content, length of fiber
and normal or confining pressure on the behavior of Babolsar
sand have been studied. In this study, four various fiber
contents (0, 0.25, 0.5 and 1 percent), three different lengths
of fiber (6, 12 and 18 mm) and four normal or confining
pressures (50, 100, 200 and 400 kPa) have been employed.
The test results show that fiber inclusion has a significant
effect on the behavior of sand. In both direct shear and triaxial
tests, the addition of fibers improved shear strength
parameters (C, '), increased peak shear strength and axial
strain at failure, and also limited the amount of post-peak
reduction in shear resistance. The comparison of the test
results revealed that due to better fiber orientation toward
the direction of principal tensile strain in triaxial test as
compared to direct shear tests, the fiber efficiency and its
effect on soil behavior is much more significant in triaxial
specimens.