Influence of dry density on moisture migration parameter of unsaturated expansive soil

Based on considering the influences of dry density and water content, the calculation of two parameters, water volume change w(2)(m) and permeability coefficient k(w), about moisture migration of unsaturated expansive soil is studied. It is shown that the w(2)(m) and k(w) are not constants but functions of matric suction that is closely connected with water content. So the parameters change with the change of water content. In addition, they are influenced by dry density clearly and change with the change of it. Furthermore, it is shown that the relationship between k(w), m(2)(w) and matric suction is nonlinear by taking the soil density and water content into account. The results provide the fundamental data for further research on water sub-field change in unsaturated expansive soil ground.