Biopolymer-fiber treated soil has great application potential in civil engineering with better mechanical properties and environmental sustainability. However, the durability and strength degradation rules of biopolymerfiber treated soil with different residual moisture content (RMC) values subjected to severe weathering cycles remain unclear. The effects of wetting-drying (W-D) and freezing-thawing (F-T) cycles on xanthan gum biopolymer-jute fiber treated soil (XJTS) with different RMC values are experimentally investigated. Particular emphasis is placed on mechanical strength characteristics, stress-strain behavior, failure patterns, and associated microstructural evolution encompassing pore structure modifications. The results show that when the RMC value of the XJTS material is higher, its mechanical strength is more affected by the F-T cycle. The effect of the W-D cycles on the pore size and distribution in the XJTS material was more significant than F-T cycles, and the percentage of microfissure (>100 mu m) increased from 6.76 % to 50.01 % after the 20th W-D cycle.
