Tensile Strength of Fiber-Reinforced Soil

The tensile strength of soil is an important mechanical parameter that controls the development of tension cracks. In this study, randomly distributed polypropylene fibers were employed to improve soil tensile behavior. Direct tensile tests were conducted on fiber-reinforced soil specimens with different fiber contents and compacted at different water contents and dry densities. Desiccation tests were also performed to evaluate the effectiveness of fiber reinforcement in improving soil tensile cracking resistance. The tensile test results showed that fiber inclusion significantly increased the soil peak strength, reduced the postpeak strength, and changed the brittle tensile failure behavior to a more ductile one. Soil tensile strength increased with the increase in fiber content. The tensile strength of both reinforced and unreinforced specimens decreased with increasing water content and increased with increasing dry density. Moreover, a higher soil dry density showed a more positive effect in mobilizing the reinforcement benefit of fibers. Based on the fiber/soil interfacial interaction mechanisms, the fiber reinforcement benefits on soil tensile behavior were analyzed. A linear relationship was obtained between the fiber reinforcement benefit and the fiber/soil interfacial shear strength. The desiccation test results showed that fiber inclusion significantly decreased soil cracking. The surface crack reduction ratio increased while the average crack width and length decreased with increasing fiber content, suggesting that fiber reinforcement was efficient in impeding soil tensile failure.