<p>The widespread presence of dispersive soils in northern Shaanxi, China, has caused significant erosion and numerous dam failures. This study uses a rheological approach to investigate the mechanisms behind these issues. The effect of water content, Na⁺, and Ca²⁺ on the structural stability and rheological properties of dispersive soils was examined through various tests, including steady-state shear, oscillatory amplitude shear, particle size analysis, and zeta potential measurements. Results indicate that higher clay content increases soil shear strength but reduces fluidity. With abundant clay particles and Na⁺ ions, the soil's fluidity at low water content is similar to that of Ca²⁺-modified soil. However, as water content exceeds 30%, shear resistance drops significantly, making the soil more prone to flow. At low shear rates/strains, sand and silt particles provide shear resistance, while clay particles dominate at high shear rates/strains. Na⁺ and Ca²⁺ affect the shear properties by altering the diffuse double layer's thickness and cohesive forces under high water content conditions. The modifying effect of Ca²⁺ is significant only for soils with a clay content of ≥ 10%. A prediction model combining dispersion values with steady-state shear properties was developed to predict the rheological properties of dispersive soils in their plastic stages. To improve structural stability, dam design and maintenance strategies should be optimized based on the clay content and ionic characteristics of local soils.</p>