Numerical simulation of electroosmosis in unsaturated compacted clay

The moisture content of a road subgrade in cold regions will increase after freeze-thaw cycles, resulting in subgrade strength and stiffness losses. Electroosmosis is widely used in treating saturated soft soils to decrease the moisture content. The induced moisture migration during electroosmosis in unsaturated soil is much more complex than that of saturated soil because of a series of nonlinear changes in soil properties. This study first uses an exponential function to characterize the relationship between electroosmotic permeability and saturation degree. Then, a one-dimensional model is developed to simulate the electroosmosis-induced moisture migration in unsaturated soil. Simulation results show that electroosmosis reduces the saturation degree of the unsaturated soil, indicating that it can be applied to subgrade dewatering. Key parameters such as soil pore size distribution coefficient, air entry value, and effective voltage significantly affect moisture migration. Electroosmotic properties of unsaturated soils are extremely important to the efficiency of electroosmosis.