In the southwestern mountainous areas of China, the terrain is steep and geological disasters occur frequently, especially landslides, which pose a great threat to human life and property. To reduce structural damage to rockfall barriers under the impact of landslide debris in the southwest region, this study uses a slope protection project in Shannan City, Tibet, as a case study. It proposes the use of a self-developed polyurethane-polypropylene fiber stabilized soil material as a buffer layer and explores its optimal formulation and mechanism of action. The experiment includes basic performance tests and scanning electron microscopy (SEM) analysis. The results show that when the polyurethane content is 6% and the fiber content is 0.2%, the stabilized soil achieves optimal basic performance. The unconfined compressive strength of the stabilized soil increases from 107.6 kPa to 931.5 kPa, a 765.7% increase; the cohesion increases from 23.4 kPa to 83.4 kPa, a 256.4% improvement; and the internal friction angle increases from 43.4° to 60.3°, a 39.3% increase. Polyurethane enhances the bonding force between gravel soil particles and the cohesion of the soil through coating, bonding, and filling actions; fibers enhance shear strength and ductility through friction and interlocking effects, collectively improving the mechanical properties of the stabilized soil.

Polyurethane; Polypropylene fiber; Buffer material; Curing mechanism