Abstract: Ecological slope protection combines the benefits of slope safety and ecological restoration, presenting a promising and promotable method for slope protection. The ecological substrate, as the core structural layer of ecological slope protection technology, must exhibit both mechanical strength and vegetative support (mechanical-vegetative performance). The mechanical-vegetative performance of existing ecological substrates requires further improvement, highlighting the necessity for developing new ecological substrates. Nano-SiO₂ (NS) and basalt fiber (BF) demonstrate excellent performance in enhancing the mechanical properties of slope soil. However, research on their vegetative effects and erosion resistance are relatively limited. To address these issues, this study modified clay using two cement contents, four Nano-SiO₂ contents, and three fiber contents. Mechanical, vegetative, and erosion-resistant properties were investigated through unconfined compressive strength tests, direct shear tests, cracking tests, scanning electron microscopy analysis, as well as vegetative growth and erosion resistance tests. The results indicate that adding NS and BF together effectively enhances compressive and residual strength, with the greatest relative improvement at a combination ratio of 5% cement + 0.9% BF + 1.5% NS, achieving a 133.05% increase compared to ordinary cement soil. Additionally, NS and BF significantly improve the cohesion and shear strength of the cement soil. Calcium silicate hydrate (C-S-H) enhances the mechanical interlocking between hydration products and BF by encapsulating the fibers, thereby improving soil strength, crack resistance, and erosion resistance. The pozzolanic reaction and nucleation effect of NS further amplify this improvement. Furthermore, the ecological substrate cement soils with composite ratios of 3% cement + 0.3% BF + 1.5% NS and 5% cement + 0.9% BF + 1.5% NS both achieve germination rate over 80%, meeting planting requirements with good plant growth performance. In the erosion tests, erosion resistance is significantly enhanced, with erosion rates of only 10.24% and 3.60% under the synergistic effect of vegetation.

Key words: nano-SiO₂, basalt fiber, ecological substrates, mechanical properties, crack resistance, scanning electron microscope, ecological slope protection