The modification of dispersive soils remains a prominent and challenging issue in the field of geotechnical engineering. Using lime, fly ash, and CaCl2 as benchmark materials, this study explores the potential of enzymeinduced calcite precipitation (EICP) technology to modify three kinds of dispersive soils. The modification effects of the four materials were systematically evaluated through crumb and pinhole tests. By linking the modification performance to curing time and material dosage, the study proposes a novel formula to compare the modification efficiency of the materials. To enhance practical applicability in engineering contexts, the study also investigates the impact of these materials on the mechanical properties of dispersive soils through unconfined compressive strength (UCS) tests. Furthermore, the modification mechanisms of the materials were compared using exchangeable sodium percentage (ESP) analysis, scanning electron microscopy (SEM), Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). The results indicate that both EICP technology and lime exhibit superior modification effects, effectively enhancing the resistance to water erosion and the mechanical properties of dispersive soils. Compared to lime, EICP technology demonstrates higher modification efficiency and greater environmental sustainability. Notably, low-concentration EICP solutions can effectively modify all three kinds of dispersive soils tested in this study.

To investigate the freeze-thaw resistance of hydroxypropyl methylcellulose (HPMC)-modified loess, the study analyzed the effects of HPMC dosage and the number of freeze-thaw cycles on the shear strength of modified loess through triaxial shear tests. The results indicated that the peak stress of modified loess exhibited a tendency to increase and then decrease with the increase of the dosage. The optimal dosage of HPMC was 0.5 %. When the confining pressure were 100kPa and 200kPa, the stress-strain relationship curves of modified loess with optimal dosage after freeze-thaw cycles exhibited a weak hardening behavior; at confining pressures of 300kPa and 400kPa, the stress-strain curves exhibited weak softening behavior. As the number of freeze-thaw cycles increased, the peak stress and shear strength indices of the optimal dosage of modified loess exhibited fluctuations. with the lowest values observed after five freeze-thaw cycles. Based on the peak stress, an anti-freezethaw modification effect parameter was proposed, which exhibited a positive correlation with the number of freeze-thaw cycles. The anti-freeze-thaw modification effect parameters for modified loess with optimal dosage were all greater than 1, indicating that the addition of HPMC significantly enhances the freeze-thaw resistance of seasonally frozen soil. HPMC functions both within the soil and at the air-water interface, forming hydrogen bonds, three-dimensional network structures, and flocculated agglomerates, thereby enhancing the strength and freeze-thaw resistance of the soil.