Abstract：Coupled unsaturated flow in claystone has high effect on strength and stability of underground engineering. Based on experimental results of unsaturated flow in claystone，mechanical and unsaturated flow coupled constitutive model is applied to simulate the shrinkage and swelling phenomena in claystone tunnel during excavation，concrete support and ventilation processes. The whole flow process in claystone from state of saturated to desaturated state and then to resaturated state is obtained from the numerical results. The achievements are quite useful to explain the argillization and collapse mechanism in practice，and have great theoretical and practical significance.
