SHEAR STRENGTH OF SAND REINFORCED WITH RANDOMLY DISTRIBUTED POLYPROPYLENE FIBERS

Abstract

A study was undertaken to investigate the shear strength of sands reinforced with randomly distributed monofilament polypropylene fibers by carrying out direct shear tests. The effect of the fiber reinforcement content on the shear strength was investigated. The results of the tests indicated that peak shear stress, post-peak shear stress and ductile behavior of sand were affected significantly by the fiber reinforcement. The horizontal displacements at failure were also found comparable for reinforced and unreinforced sands under the same vertical normal stress. Fiber reinforcement could reduce soil brittleness and providing smaller loss of post-peak strength. Thus there appeared to be an increase in residual shear strength angle of the sand by adding fiber reinforcements. The oven dried sand was mixed with the fibers at different percentages by dry weight of the sand. Two observation sets were taken to ignore the error which can be made during experimental work. The test results of these two sets showed that the shear strength of the sand increased with increasing the fiber content, also it was noticed that it showed significant effect at higher normal loads. The effect of aspect ratio of the fiber on shear strength of the sand was also checked and concluded that if we increase the aspect ratio or length of the fiber at lower normal loads then shear strength is not so affected and on the other hand at higher normal loads shear strength increases more. Failure shear stress is decreased at lower normal loads with increased aspect ratio but at higher normal loads, it is increased.