Deformation properties and erosion resistance of loess treated via enzyme-induced calcium carbonate precipitation (EICP) and wool fiber reinforcement (WFR)

Loess is characterized by special porous, weak cementation, and under compactness, thereby presenting unique collapsible behavior and easily triggering slope instability and foundation settlement. In this paper, the method of enzyme-induced calcium carbonate precipitation (EICP), in conjunction with wool fiber reinforcement (WFR), was utilized to improve the treatment process of loess. Based on collapsibility tests, the optimal fiber reinforcement condition was obtained by analyzing the effect of fiber length, fiber content, and consolidation pressure on the collapsible behavior of EICP-WFR treated loess. Based on the erosion model test, the reliability of EICP-WFR method was validated by analyzing how rainfall intensity, slope gradient, rainfall duration, and fiber content influence the erosion resistance of the loess slope. Test results revealed that with the increase of fiber length and fiber content, the collapsibility coefficients of EICP-WFR treated loess presented the trend of first rise and then drop, and the collapsible deformation of EICP-WFR treated loess was appreciably lower than that of untreated loess. As the consolidation pressure increases, the collapsibility coefficient of EICP-WFR treated loess increased first and then decreased. Under low and medium consolidation pressures, the addition of fiber helps reduce the collapsibility, whereas the collapsibility increased to some extent under high consolidation pressures. Compared with WFR treated loess slope, the surface erosion of EICP-WFR treated loess was markedly reduced by 12.0%-17.4%, and the erosion depth was reduced when rainfall intensity, slope gradient, and rainfall duration kept constant. As the intensity of rainfall and the gradient of slopes increase, the cumulative runoff and mass loss showed an upward trend, and the slope erosion caused by continuous rainfall was appreciably larger than that of interval rainfall, with EICP-WFR treatment reducing erosion by 10.1% under interval rainfall compared with continuous rainfall. As the fiber content increases, the cumulative runoff and mass loss decreased, with mass loss reduced by 14.8% when fiber content increased from 0.25% to 1.00%. The findings can offer guidelines for the practice of slope protection engineering.