Abstract: Palm trees are extensively cultivated in southern China, and the palm fibers extracted from the tree bark boast notable tensile strength and durability. Consequently, palm fibers have gradually found application in geotechnical engineering in recent years to reinforce clay. To investigate its mechanical properties, damage patterns, and underlying constitutive relationships under stress, fibers measuring 6 mm, 12 mm, and 18 mm in length were chosen and incorporated into clay at mass ratios of 0.2%, 0.4%, 0.6%, and 0.8%,respectively.Unconfined compressive strength tests on the palm fiber-reinforced clay revealed a significant increase in clay strength following the addition of palm fibers.Optimal reinforcement was achieved by mixing 12 mm palm fibers into the clay at a 0.8% ratio, resulting in a 27% increase in strength compared to regular clay. Furthermore, the reinforced clay demonstrated exceptional damage tolerance and residual strength, prolonging the damage process. This was attributed to the formation of a three-dimensional soil network within the clay, which restricted soil particle slippage and enhanced clay integrity, ultimately leading to improved ductility. Furthermore, the uniaxial compressive stress-strain model for concrete was introduced to analyze the unconfined compressive strength test data. The results revealed a high degree of consistency between model results and test data. These research outcomes offer valuable insights for the utilization of palm fiber-reinforced clay in geotechnical engineering.

Key words: fiber-reinforced soil, palm fiber, unconfined compressive strength, reinforcement mechanism, constitutive model