Study on rock expansion constitutive model based on humidity field theory

According to the limitation of the available expansion constitutive model, based on the humidity field theory and expansion test, the expansion rates of the free expansion and loaded expansion under the lateral restraint were analyzed and the derived constitutive model would have the theoretical base. Among them, the parameter variation would have the physical significance. The study result showed that in the expansion constitutive model, the strain and stress logarithms and the stress linear combination would be in negative correlation function relationship. When an axial stress was small, a logarithmic function fitting could be applied approximately. When an axial stress was high, a linear function fitting could be applied approximately. A water absorption rate of the expansive rock and the axial stress would be in a negative logarithmic function relation.In the fitted constitutive model, the related coefficient would be over 0.97 and could say that the constitutive model could have a good consistency to the related data fitting. The study results could provide the guidance to the 3D expansive theory.