Indoor measurements of the soil-water characteristic curve (SWCC) often require a long equilibrium time

yet the actual soil changes may not meet this requirement. When the time scale is small

the SWCC may not reach equilibrium. If the equation for unsaturated soil is still established using the soil-water characteristic curve under equilibrium conditions

errors may occur. Therefore

the dynamic effect of the soil-water characteristic curve under non-equilibrium conditions was studied. Based on existing theories

we derived the relationship between the parameters of the soil-water characteristic curve and the rate of saturation change

and subsequently established a dynamic capillary hysteresis model using the derived dynamic parameters. We developed a self-designed SWCC rapid measurement device and conducted soil-water characteristic curve measurements for coarse sand and fine sand under varying rates of saturation change. The experimental research revealed that: 1) the parameters of the soil-water characteristic curve exhibit significant dynamic effects; 2) the air entry value and residual saturation are not constant

but vary depending on the rate of saturation change; and 3) the model was validated using the experimental results

and the prediction outcomes of the dynamic model closely matched the experimental results

demonstrating the model's rationality. This study provides a more practical theoretical basis for solving problems related to deformation

strength

and seepage in unsaturated soils.